Yamaguchi, Takashi*; Katata, Genki; Noguchi, Izumi*; Sakai, Shigekatsu*; Watanabe, Yoko*; Uematsu, Mitsuo*; Furutani, Hiroshi*
Atmospheric Research, 151, p.82 - 92, 2015/01
To evaluate water and nitrogen input via fog water deposition, fog chemistry and deposition around a crater lake (Mashu) in northern Japan were investigated in the growing seasons of trees in 2006-2012. The fog samples were collected using an active fog collector and droplet size distribution was measured by a droplet size spectrometer. Compared to previous iterature of exposure experiments of acid mist on plants, fog acidity in this study did not seem to injure plant leaves. The visibility (VIS)-liquid water content of fog (LWC) relationship differed between summer and autumn. Fog water deposition was calculated from LWC empirically derived from past VIS data and deposition velocity estimated using wind speed and vegetation parameters. The water and nitrogen inputs via fog water deposition accumulated for each growing season were estimated as 107-161 mm and 20-41 meq m, respectively.
Itakura, Ryuji; Hosaka, Koichi*; Yokoyama, Atsushi; Ikuta, Tomoya*; Kannari, Fumihiko*; Yamanouchi, Kaoru*
Progress in Ultrafast Intense Laser Science XI; Springer Series in Chemical Physics, Vol.109, p.23 - 42, 2015/00
We investigate the multichannel dissociative ionization of ethanol in intense laser fields by the photoelectron-photoion coincidence momentum imaging and identify separately the ionization and subsequent electronic excitation in ethanol. From the energy correlation between a photoelectron and a fragment ion, we reveal the amount of the internal energy gained by ethanol cations from the laser field varies depending on the respective ionization and electronic excitation pathways.
Katata, Genki; Kajino, Mizuo*; Matsuda, Kazuhide*; Takahashi, Akira*; Nakaya, Ko*
Atmospheric Environment, 97, p.501 - 510, 2014/11
To investigate the impact of hygroscopic growth on dry deposition onto forest canopies, numerical simulations of PM2.5 sulfate deposition using a multi-layer atmosphere-SOiL-VEGetation model (SOLVEG) ware performed. The scheme of particle dry deposition in SOLVEG was extended for application to a broad-leaved forest. An aerosol hygroscopic model based on the widely used -Khler theory was incorporated into the model to calculate water uptake by the aerosols. The model accurately reproduced essential turbulent exchange fluxes (momentum, heat, and water vapor) over the canopies and the soil temperature and moisture for a deciduous broad-leaved forest in central Japan. Temporal variations in the measured PM2.5 sulfate deposition velocity were generally reproduced by the model. By considering an increase in particle diameter due to hygroscopic growth, the prediction accuracy of the modeled deposition velocity under humid conditions was improved. Numerical experiments for varying aerosol size distributions and hygroscopic properties showed that the geometric mean diameter and hygroscopicity of particles have a large influence on hygroscopic growth levels. The results also suggested that the deposition velocity of wet particles increased due to hygroscopic growth when the relative humidity (RH) was approximately 50%, and that the velocity reached five times greater than that under dry conditions when RH exceeded 95%.
Otosaka, Shigeyoshi; Nakanishi, Takahiro; Suzuki, Takashi; Sato, Yuhi; Narita, Hisashi*
Environmental Science & Technology, 48(21), p.12595 - 12602, 2014/11
From August 2011 to July 2013, a sediment trap was deployed at 100 km east of the Fukushima Daiichi Nuclear Power Plant and sinking particles were collected. Sinking flux of Cs decreased over time with seasonal fluctuation. The Cs fluxes were mainly affected by two principal modes. One was a rapid sinking of radiocesium-bound particles (moderate mode). This mode was dominant especially in the early post-accident stage, and was presumed to establish the distribution of radiocesium in the offshore seabed. Another was the secondary transport of particles attributed to turbulence near the seabed and was observed in winter (turbulence mode). Although the latter process would not drastically change the distribution of sedimentary radiocesium, attention should be paid as this key process redistributing the accident-derived radiocesium may cumulatively affect the long-term distribution.
Yokoyama, Yuta*; Uozumi, Yuki; Asaoka, Hidehito
Journal of Crystal Growth, 405, p.35 - 38, 2014/11
Si-Ge structures forming new shapes on a Si(110)-162 reconstructed surface were investigated via scanning tunneling microscopy. Pyramidal-shaped Si-Ge nanoislands lying along the 1 1 1 directions were formed on the striped structure at Ge coverage between 3 and 6 monolayers. However, when a single monolayer of Ge was deposited on the Si(110)-162 surface, single-domain of 162 striped structure disappeared, and a new double-domain striped structure was formed over the surface along directions that differed from the 1 1 2 directions. This structure represents a new Si-Ge striped structure that forms by the mixing of Ge and Si due to high temperature annealing. These results indicate that the surface structure changes specifically with trace amounts of Ge.
Kurikami, Hiroshi; Kitamura, Akihiro; Yokuda, Satoru*; Onishi, Yasuo*
Journal of Environmental Radioactivity, 137, p.10 - 17, 2014/11
We performed a simulation of sediment and Cs behavior in the Ogaki Dam Reservoir during a heavy rainfall event occurred in 2013. One-dimensional river and reservoir simulation scheme TODAM was applied for calculating the time dependent migration of sediment and Cs in dissolved and sediment-sorbed forms in the reservoir. Continuous observational data achieved in upper rivers were used as the input boundary conditions for the simulation. The simulation results were compared with the continuous data achieved in the lower river and we confirmed the predicted values of sediment and Cs in sediment-sorbed form at the exit of reservoir satisfactorily reproduced the observational data. The simulation result of a heavy rainfall event shows that the reservoir plays an important role to delay and buffer the contamination movement in heavy rainfall events.
Nagai, Takayuki; Uehara, Akihiro*; Fujii, Toshiyuki*; Sato, Nobuaki*; Kofuji, Hirohide; Myochin, Munetaka; Yamana, Hajimu*
Journal of Nuclear Materials, 454(1-3), p.159 - 163, 2014/11
The redox equilibrium of UO/UO couple was measured in LiMoO-NaMoO eutectic melt at 550C by cyclic voltammetry and absorption spectrophotometry. The standard redox potential of UO/UO couple was approximately evaluated by cyclic voltammetry. Further, the absorption spectrum and equilibrium potential were measured, repeatedly adding UO source material into the melt containing UO. From the correlation between the equilibrium potential of the melt and the concentration ratio [UO]/[UO] spectrophotometrically evaluated, the standard redox potential of UO/UO couple was determined to be -0.8470.010 V vs. O/O.
Ogawa, Tatsuhiko; Sato, Tatsuhiko; Hashimoto, Shintaro; Niita, Koji*
Nuclear Instruments and Methods in Physics Research A, 763, p.575 - 590, 2014/11
A new theoretical approach is developed to reproduce the stochastic distributions of secondary particle energy and angle with conservation of momentum and energy in reactions ejecting more than one ejectiles using inclusive cross-section data. The summation of energy and momentum in each reaction is generally not conserved in Monte-Carlo particle transport simulation based on the inclusive cross-sections because the particle correlations are lost in the inclusive cross-section data. However, the energy and angular distributions are successfully reproduced by randomly generating numerous sets of reaction-final-state configurations which are compliant with the conservation laws, and sampling one set considering their likelihood. This developed approach was applied to simulation of (n,xn) reactions (x 2) of various targets and to other reactions such as (n,np) and (n,2n). The calculated secondary particle energy and angular distributions were compared with those of the original inclusive cross-section data to validate the algorithm. The calculated distributions reproduce the trend of original cross-section data considerably well, and the agreement between the calculated and the original data is particularly good for heavy targets. This approach is beneficial to improve the accuracy of event-by-event analysis in particle transport simulation, which is critical for soft-error analyses and detector performance prediction.
Sako, Hiroyuki; Sugimura, Hitoshi; Ahn, J. K.*; Han, Y.*; Hasegawa, Shoichi; Hwang, S. H.*; Ichikawa, Yudai; Imai, Kenichi; Kiuchi, Ryuta*; Ozawa, Kyoichiro; et al.
Nuclear Instruments and Methods in Physics Research A, 763, p.65 - 81, 2014/11
We developed a prototype TPC for an H-dibaryon search experiment at J-PARC. To investigate its performance, we conducted tests with Ar-CH (90:10) and Ar-CF (95:5), where the former is mainly used. The detection efficiency was measured to be 98% at the beam rate up to cps/cm, and 90% at the rate of cps/cm. Based on the measured horizontal resolution of 0.19-0.46 mm at the drift length of 5-20 cm, the position resolution of better than 0.3 mm is estimated in 1 T magnetic field. The ion backflow fraction was measured to be 5% and reduced up to 3% at the gain of . The horizontal position distortion due to ion backflow in the gate operation was suppressed within mm at the beam rates up to cps/cm. On the other hand, the distortion with the gate open was measured to be mm. The distortion in the final experiment is estimated to be mm.
Kamiya, Junichiro; Ogiwara, Norio; Hotchi, Hideaki; Hayashi, Naoki; Kinsho, Michikazu
Nuclear Instruments and Methods in Physics Research A, 763, p.329 - 339, 2014/11
One of the main sources of beam loss in high power accelerators is unwanted stray magnetic fields from magnets near the beam line, which can distort the beam orbit. The most effective way to shield such magnetic fields is to perfectly surround the beam region without any gaps with a soft magnetic high permeability material. This leads to the manufacture of vacuum chambers (beam pipes and bellows) with soft magnetic materials. Using this heat treatment, the ratio of the integrated magnetic flux density along the beam orbit between the inside and outside of the beam pipe and bellows became small enough to suppress beam orbit distortion. The outgassing rate of the materials with this heat treatment was reduced by one order magnitude compared to that without heat treatment. By installing the beam pipes and bellows of soft magnetic materials as part of the Japan Proton Accelerator Research Complex 3 GeV rapid cycling synchrotron beam line, the closed orbit distortion was reduced by more than 80%. In addition, a 95.5% beam survival ratio was achieved by this COD improvement.
Kitamura, Yasunori; Eguchi, Yuta
Nuclear Science and Engineering, 178(3), p.401 - 413, 2014/11
A series of integral reactor physics experiments conducted at the Very High Temperature Reactor Critical Assembly (VHTRC) was analyzed and assembled into a benchmark through an extensive peer-review process under the International Reactor Physics Experiment Evaluation Project (IRPhEP). This benchmark provides the experimental data with respect to criticalities of 7 core configurations and temperature effect on reactivity up to 200C with explicit experimental uncertainties newly evaluated. It further presents the benchmark models and corresponding values with proper simplification, so that it can be utilized by reactor designers for validating their analytical tools employed to design next-generation reactors and for establishing the safety basis for operation of those reactors.
Yokoyama, Kenji; Ishikawa, Makoto
Nuclear Science and Engineering, 178(3), p.350 - 362, 2014/11
In order to provide a reactor physics benchmark problem of burnup reactivity coefficients, experimental data of relationship between excess reactivity and accumulated thermal power acquired during experimental fast reactor JOYO MK-I duty power operation in the late 1970s have been evaluated and analyzed. All possible uncertainty factors were evaluated and quantified by utilizing knowledge obtained after the MK-I duty power operation and calculation results based on the latest reactor physics analysis methods. Meanwhile, the present evaluated data have been registered to the International Reactor Physics Benchmark Experiments Project (IRPhEP), with the expectation that this data will be widely used. In the present paper, the evaluation of nominal values and uncertainties is described with a focus on the measurement technique uncertainty which is a dominant uncertainty factor of the burnup reactivity coefficient.
Ishikawa, Makoto; Ikegami, Tetsuo*; Sanda, Toshio*
Nuclear Science and Engineering, 178(3), p.335 - 349, 2014/11
Under the IRPhEP framework, nine ZPPR critical experimental cores performed as the cooperative JUPITER program between the USA and Japan are established in the benchmarks to study large FBR core physics. These benchmarks cover a wide variety of core concepts including homogeneous and heterogeneous configurations, clean and engineering-mockup cores of 600-1,000 MW(electric)-class sizes, and various kinds of core parameters. Detailed experimental information has recently been dug out from the ANL original documents and scrutinized very carefully to establish the benchmark model and to evaluate the experimental uncertainty quantitatively. The benchmarks supply users with the heterogeneous cell model and three-dimensional core configuration with preserving the important physical features of the ZPPR cores. Further, the benchmark handbook includes the as-built information of the ZPPR cores as a complete set of electrical form, therefore, a user can develop his own benchmark model if necessary. The analysis of the benchmark with the latest method demonstrates the usefulness both for the improvement of analytical methods and for the validation of nuclear data.
Aoto, Kazumi; Dufour, P.*; Hongyi, Y.*; Glats, J. P.*; Kim, Y.-I.*; Ashurko, Y.*; Hill, R.*; Uto, Nariaki
Progress in Nuclear Energy, 77, p.247 - 265, 2014/11
Much of the basic technology for the Sodium-cooled fast Reactor (SFR) has been established through long term development experience with former fast reactor programs, and is being confirmed by the Phnix end-of-life tests, the restart of Monju, the lifetime extension of BN-600 and the startup of CEFR. Planned startup in 2014 for BN-800 and PFBR will further enhance the confirmation of the SFR basic technology. Nowadays, the SFR development has advanced to aiming at establishment of the Generation-IV system which is dedicated to sustainable energy generation and actinide management, and several advanced SFR concepts are under development. Generation-IV International Forum is an international collaboration framework where various R&D activities are progressing for the Generation-IV SFR development, and will play a beneficial role of promoting them thorough providing an opportunity to share the past experience and the latest data of design and R&D among countries developing SFR.
Progress of Theoretical and Experimental Physics (Internet), 2014(11), p.113D02_1 - 113D02_10, 2014/11
A new method of estimating fission barrier heights is presented. Potential energy surface is calculated with the spherical-basis method, which is based on construction of the KTUY mass formula. Under a restriction of symmetric fission, some higher (neighboring Fm) and lower (neighboring Ds) fission barrier regions are found, and the origin of these appearances is discussed in the framework of the spherical-basis method. Systematical properties of fission barrier heights are studied in the unknown neutron-deficient superheavy nuclear mass region, where the nuclear fission governs the limit of existence of nuclei.
Yamaguchi, Tetsuji; Takeda, Seiji; Nishimura, Yuki; Iida, Yoshihisa; Tanaka, Tadao
Radiochimica Acta, 102(11), p.999 - 1008, 2014/11
An attempt was made to select thermodynamic data with uncertainties and to evaluate the solubility of radioelements with uncertainties considering variation in groundwater chemistry. The thermodynamic data was selected by reviewing the JAEA-TDB released in 2012. Data for Nb, Pd and Pa were revised from the viewpoint of the consistency of the data selection process. Data for Se, U and Pa were revised from the viewpoint of the conservativeness. Up-to-date ternary calcium-metal(IV)-OH complexes were adopted for Zr, Th, U, Np and Pu. A Monte Carlo-based probabilistic calculation code, PA-SOL, was used for probabilistic analysis of the solubility.
Tojo, Hiroshi; Yamada, Ichihiro*; Yasuhara, Ryo*; Yatsuka, Eiichi; Funaba, Hisamichi*; Hatae, Takaki; Hayashi, Hiroshi*; Itami, Kiyoshi
Review of Scientific Instruments, 85(11), p.11D865_1 - 11D865_3, 2014/11
In incoherent Thomson scattering diagnostics, stray light of the incident laser, which is frequently generated at the vacuum windows, also causes wrong evaluations of the signal intensities. Because the laser goes through the vacuum windows many times in a double-pass (or multi-pass) scattering system, complicate temporal structures can be seen in the output signals. In this paper, Singular Value Decomposition (SVD) is applied to the output signals in a Thomson scattering diagnostic on Large Helical Device (LHD). The analyzed data were all measured signals for each one spectral channel over one plasma shot. Some noises were filtered and Te was evaluated within good accuracies especially in the second pass (forward scattering). We compared the errors in Te (0.8 - 1.3 keV) from the noise-filtered and from non-filtered data. Use of the filtered data enables suppressing the error in Te measured from the second pass by a factor of 0.5 at the most.
Shinohara, Koji; Ishii, Keiichi*; Ochiai, Kentaro; Baba, Mamoru*; Sukegawa, Atsuhiko; Sasao, Mamiko*; Kitajima, Sumio*
Review of Scientific Instruments, 85(11), p.11E823_1 - 11E823_4, 2014/11
A neutron flux array is one of the important plasma diagnostics to obtain the information on fast ion population. However, the limited flux owing to its collimator results in the small number of pulse counts and the large statistical error. The method to increase the pulse counts is required. Here, we propose a multi-stage neutron detection system, in which several sets of a scintillator and photo-multiplier tube (PMT) are placed in a line-of-sight. In order to evaluate the performance of the multi-stage detection system, we have carried out experiments on a two-stage detection system using a neutron beam at FNS (Fusion Neutronics Source) of JAEA (Japan Atomic Energy Agency). The results have shown the concept of the multi-stage detection system works as expected. In the best setup, the test two-stage system reached about 1.7 (1.8) times the efficiency of a single scintillator and PMT system for 2.54 (14) MeV neutrons.
Schwehr, K. A.*; Otosaka, Shigeyoshi; Merchel, S.*; Kaplan, D. I.*; Zhang, S.*; Xu, C.*; Li, H.-P.*; Ho, Y.-F.*; Yeager, C. M.*; Santschi, P. H.*; et al.
Science of the Total Environment, 497-498, p.671 - 678, 2014/11
A new, accurate and simple pH-dependent solvent extraction method combined with accelerator mass spectrometry (AMS) measurement for I/I isotopes and iodine speciation (iodide, iodate, and organo-I) quantification in liquids of any ionic strength has been developed. We then validated the AMS method for activity concentration measurements with a recently developed gas chromatography mass spectrometry method for I concentrations of 1 Bq/L or higher. This technique was applied to I-contaminated groundwater from the Savannah River Site, USA, and demonstrated changes of I and I concentrations and speciation along a pH, redox potential, and organic carbon gradient. The data suggest that I/I and species distribution is strongly pH dependent. The new method can now be applied to a wide range of chemically-diverse aquatic systems, including uncontaminated environments.
Adachi, Hiroto; Maekawa, Sadamichi
Solid State Communications, 198, p.22 - 25, 2014/11
Spin pumping refers to the spin current injection driven by magnetization dynamics from a ferromagnet into adjacent nonmagnetic conductors. Conventionally, ferromagnetic resonance is used to drive the magnetization dynamics and the spin pumping. Recently a new type of spin pumping driven by acoustic waves, i.e., the acoustic spin pumping, has been reported. We present a linear-response theory of the acoustic spin pumping.
Umeda, Koji; Asamori, Koichi; Makuuchi, Ayumu; Kobori, Kazuo
Tectonophysics, 634, p.116 - 126, 2014/11
The geophysical and geochemical observations are significant indications that the invasion of mantle fluids into the crust, driven by upwelling asthenosphere from the Okinawa trough, triggers the notable left-lateral shearing in the zone in the present-day subduction system. In addition, the existence of aqueous fluids in and below the seismogenic layer could change the strength of the zones, and alter the local stress regime, resulting in the occurrence of the 1997 earthquake doublet.
Xu, Y.*; Ma, Y.*; Sakurai, Junya*; Teraoka, Yuden; Yoshigoe, Akitaka; Demura, Masahiko*; Hirano, Toshiyuki*
Applied Surface Science, 315, p.475 - 480, 2014/10
The NiAl foils were heat treated in water vapor at 873 K for 1 h followed by H reduction at 873 K for 1 h. The effects of the water vapor treatment and the H reduction on the surface structure of the NiAl foils were investigated by means of scanning electron microscopy and synchrotron radiation X-ray photoemission spectroscopy. Both Ni and Al were oxidized during the water vapor treatment; fine NiO particles were formed on the surface, accompanied by the formation of Al(OH) and NiAlO/AlO. The NiO particles were reduced to metallic Ni and the Al(OH) was decomposed to AlO, whereas the NiAlO and AlO remained unchanged during the H reduction, forming a Ni-enriched porous structure on the surface layer of NiAlO/ AlO.
Furukawa, Tomohiro; Kondo, Hiroo; Kanemura, Takuji; Hirakawa, Yasushi; Yamaoka, Nobuo*; Hoashi, Eiji*; Suzuki, Sachiko*; Horiike, Hiroshi*
Fusion Engineering and Design, 89(7-8), p.1674 - 1678, 2014/10
One key issue in the development of the IFMIF is the corrosion/erosion of the lithium components. At Osaka University, lithium free-surface flow experiments to verify the design of the IFMIF target have been carried out, and the test assembly was operated in high-speed lithium flow for 1200 hours at 300 C. Since the test assembly is important to understand the corrosion/erosion behavior as the demonstration experimental data, the metallurgical analysis was been performed. Slight irregularities which were trace of high-speed lithium flow were observed at the tip of the nozzle. On the other hand, mottled unevenness with many micro-cracks of a few micrometer depths was observed at the inlet of the nozzle, whose velocity ratio was 0.1-0.4 as compared with the nozzle tip. It was estimated that the phenomena was caused by carburizing from liquid lithium, and it was newly proven that carbon control in lithium was also important for corrosion / erosion protection of the IFMIF components.
Hirose, Takanori; Nozawa, Takashi; Stoller, R. E.*; Hamaguchi, Dai; Sakasegawa, Hideo; Tanigawa, Hisashi; Tanigawa, Hiroyasu; Enoeda, Mikio; Kato, Yutai*; Snead, L. L.*
Fusion Engineering and Design, 89(7-8), p.1595 - 1599, 2014/10
The material properties, focusing on the properties used for design analysis were re-assessed and newly investigated for various heats including F82H-IEA. Moreover, irradiation effects on those properties were studied in this work. As for thermal properties, thermal conductivity that has significant impacts on the thermo-hydraulic properties of the blanket was investigated on several heats of F82H including F82H-IEA. According to the measurements, the thermal conductivity falls in the range 28.31.1 W/m/K at 293 K. Although this is comparable with that of the other ferritic/martensitic steels, it is 20% lower than the published value for F82H-IEA. The re-assessment on the published value revealed that the thermal diffusivity was over-estimated. As for irradiation effects on the physical properties, electric resistivity was measured after irradiation up to 6 dpa at 573 K and 673 K. The reduction of resistivity in F82H and its welds were 3% and 6%, respectively.
Iwai, Yasunori; Sato, Katsumi; Yamanishi, Toshihiko
Fusion Engineering and Design, 89(7-8), p.1534 - 1538, 2014/10
The ion exchange membrane such as Nafion is a key material for electrolysis cells of the Water Detritiation System. Long-term exposure of Nafion ion exchange membrane into 1.3810Bq/kg of tritiated water was conducted at room temperature for up to 2 years. The ionic conductivity of Nafion ion exchange membrane after immersed in tritiated water was changed. The change in color of membrane from colorless to yellowish was caused by active radical reactions. Infrared Fourier transform spectrum of the membrane immersed in tritiated water revealed a small peak for bending vibration of C-H situated at 1437 cm demonstrating the formation of hydrophobic functional group in the membrane. The high-resolution solid state F NMR spectrum of the membrane after immersed in tritiated water was similar to that of membrane irradiated with -rays. From the F NMR spectrum, any distinctive degradation in the membrane structure by interaction with tritium was not measured.
Edao, Yuki; Kawamura, Yoshinori; Yamanishi, Toshihiko; Fukada, Satoshi*
Fusion Engineering and Design, 89(9-10), p.2062 - 2065, 2014/10
Tritium transfer behavior through hydrophobic paints, epoxy resin and acrylic-silicon resin, was investigated experimentally. The authors measured the amount of tritium permeated through the paint membranes which exposed in HTO atmosphere of 2100 Bq/cm. The most of tritium permeated through the paints in the form of HTO at room temperature. Tritium permeation through the acrylic-silicon paint was explained a linear sorption/release model and that through the epoxy paint was suggested to be controlled by a one-dimensional diffusion model. While effective diffusivity was 1.0101.810 m/s at 21C26C for epoxy membrane, the diffusivity was found to be hundreds times larger than that for cement-paste coated with epoxy paint. Hence, tritium diffusivity through interface between cement-paste and the epoxy paint was considered to be most effective in the overall tritium transfer process. Tritium transfer behavior in the interface is important to explain the mechanism of tritium transfer behavior in concrete walls.
Maruyama, Takahito; Aburadani, Atsushi; Takeda, Nobukazu; Kakudate, Satoshi; Nakahira, Masataka; Tesini, A.*
Fusion Engineering and Design, 89(9-10), p.2404 - 2408, 2014/10
For maintenance of ITER, a system to remotely handle the shield blanket modules is necessary because of high -ray field. Blanket handling will be carried out by robotic devices such as power manipulators. The manipulator should have a non-contact sensing system to install and grasp a module, and the manipulator is required to be accurate within 5 mm in translational motion and 1 degree in rotational motion. The Robot Vision System (RV) was adopted as the non-contact sensing system. To satisfy the requirements, three widely used methods of RV were adopted: Stereo Vision, Visual Feedback and Visual Servoing. Stereo Vision is a RV method using two cameras. In Visual Feedback, the manipulator moves to the target position in many sequential steps. In Visual Servoing, the manipulator moves in order to fit the current picture with the target picture. Also, note that it is completely dark in the vacuum vessel and lighting is needed. Tests for grasping a module using those three methods were carried out and the measuring error of the RV system was studied. The results of these tests were that the accuracy of the manipulator's movements was within 1 mm and 0.3 degrees using RV. This satisfies the requirements; therefore, it is concluded that RV is suitable as the non-contact sensing system for the ITER BRHS.
Kanemura, Takuji; Kondo, Hiroo; Hoashi, Eiji*; Suzuki, Sachiko*; Yamaoka, Nobuo*; Horiike, Hiroshi*; Furukawa, Tomohiro; Hirakawa, Yasushi; Wakai, Eiichi
Fusion Engineering and Design, 89(7-8), p.1642 - 1647, 2014/10
In the Engineering Validation and Engineering Design Activities (EVEDA) of the International Fusion Materials Irradiation Facility (IFMIF), a device to measure thickness variation of a high-speed (15 m/s) liquid lithium (Li) jet must be developed. The required measurement precision is 0.1 mm. For this purpose, we newly focused on a laser-based distance meter. This paper describes the result of an applicability test of the new sensor conducted in the Osaka University Li Loop. In the experiment, thickness variation of a Li jet (10 mm in thickness) was measured at the sampling frequency of 500 kHz in the velocity range of 10 to 15 m/s at the Li temperature of 573 K under argon atmosphere of 0.12 MPa. To evaluate the applicability of the device, the measurement precision of the Li level was evaluated. As a result, the precision was approximately 9 m. Thus, we concluded that the laser-based distance meter is applicable to the measurement of the Li target thickness.
Tobita, Kenji; Federici, G.*; Okano, Kunihiko
Fusion Engineering and Design, 89(9-10), p.1870 - 1874, 2014/10
The goal of the DEMO reactor design under the Broader Approach (BA) is to develop possible pre-conceptual designs of DEMO by addressing key design issues and options in physics, technology and system engineering for DEMO. The joint work between EU and Japan for the DEMO design started with a benchmark of systems codes. Cross-checking between the EU systems code PROCESS and the JA systems code TPC showed a good agreement for relatively conservative plasma parameters. In parallel, critical design issues on DEMO have been studied. In order to resolve the problem on divertor heat removal, a reduction of divertor heat load due to plasma detachment and advanced divertor concepts such as super-X and snowflake configuration has been investigated. Regarding remote maintenance (RM), various RM concepts based on different sector segmentations and access ports has been studied to allow reasonable plant availability under severe in-vessel dose rate.
Hayashi, Takao; Sakurai, Shinji; Shibanuma, Kiyoshi; Sakasai, Akira
Fusion Engineering and Design, 89(9-10), p.2299 - 2303, 2014/10
Remote handling (RH) system is necessary for the maintenance and repair of in-vessel components of JT-60SA. Design study of RH system, focusing on the deployment of remote pipe cutting tool for JT-60SA divertor cassette is reported in this conference. Some cooling pipes on the outboard side in the divertor cassette should be cut and welded in the vacuum vessel. The outer diameter, thickness and material of the cooling pipe is 59.7 mm, 2.7 mm and SUS316L, respectively. Cutting tool head equips a disk cutter blade and rollers which are subjected to the reaction force. The cooling pipe is cut by rotating the cutting tool head with pushing out the disk cutter blade. Newly developed cutting tool indicates that the cooling pipe is cut by pushing out the disk cutter blade up to 30.5 mm in radius, i.e. 61 mm in diameter.
Nozawa, Takashi; Kim, S.*; Ozawa, Kazumi; Tanigawa, Hiroyasu
Fusion Engineering and Design, 89(7-8), p.1723 - 1727, 2014/10
A SiC/SiC composite is a promising candidate material for the advanced fusion DEMO blanket. For the design of the DEMO, the stability of high-temperature strength of SiC/SiC composites needs to be identified. Additionally, strength anisotropy needs to be clarified because of its unique fabric architecture. This study therefore aims to evaluate mechanical properties by various modes at elevated temperatures, eventually providing a stress envelope for the design. A P/W Tyranno-SA3 fiber reinforced CVI SiC matrix composite with multilayered SiC/PyC interface was evaluated in this study. Tensile and compressive tests were conducted by the SSTT specifically arranged for the high-temperature use. In-plane shear properties were contrarily estimated by the off-axial tensile method assuming that the mixed mode failure criterion is valid for composites. All tests were performed in vacuum. The preliminary test results indicate no degradation of both proportional limit stress (PLS) and the ultimate tensile strength at temperatures below 1000C. Similarly, no significant degradation of high-temperature compressive and in-plane shear properties were identified, finally providing the stress envelope at elevated temperatures for the design.
Ota, Masayuki; Takakura, Kosuke; Ochiai, Kentaro; Sato, Satoshi; Konno, Chikara
Fusion Engineering and Design, 89(9-10), p.2164 - 2168, 2014/10
Titanium is contained in lithium titanate, which is a tritium breeding material candidate. In the nuclear design, accurate nuclear data are needed. However, few benchmark experiments had been performed for titanium. Thus we performed a benchmark experiment with a titanium assembly and a DT neutron source at JAEA/FNS. The assembly was a titanium slab of 45 cm45 cm40 cm covered with 5 or 10 cm thick LiO blocks. Dosimetry reaction rates were measured by the foil activation method of niobium, aluminum, indium, gold and tungsten inside the assembly. And fission rates of U and U were measured by using micro fission chambers. This experiment was analyzed by using Monte Carlo neutron transport code MCNP5-1.40 with recent nuclear data libraries of ENDF/B-VII.0, ENDF/B-VII.1, FENDL-2.1, JEFF-3.1.2, JENDL-3.3, JENDL-4.0, and JENDL-4.0u. The calculation results were compared with the measured one in order to validate nuclear data libraries of titanium.
Ikeda, Yoshitaka; Okano, Fuminori; Hanada, Masaya; Sakasai, Akira; Kubo, Hirotaka; Akino, Noboru; Chiba, Shinichi; Ichige, Hisashi; Kaminaga, Atsushi; Kiyono, Kimihiro; et al.
Fusion Engineering and Design, 89(9-10), p.2018 - 2023, 2014/10
Disassembly of the JT-60U torus was started in 2009 after 18-years D operations, and was completed in October 2012. The JT-60U torus was featured by the complicated and welded structure against the strong electromagnetic force, and by the radioactivation due to D-D reactions. Since this work is the first experience of disassembling a large radioactive fusion device in Japan, careful disassembly activities have been made. About 13,000 components cut into pieces with measuring the dose rates were removed from the torus hall and stored safely in storage facilities by using a total wokers of 41,000 person-days during 3 years. The total weight of the disassembly components reached up to 5,400 tons. Most of the disassembly components will be treated as non-radioactive ones after the clearance verification under the Japanese regulation in future. The assembly of JT-60SA has started in January 2013 after this disassembly of JT-60U torus.
Sakamoto, Yoshiteru; Nakamura, Makoto; Tobita, Kenji; Uto, Hiroyasu; Someya, Yoji; Hoshino, Kazuo; Asakura, Nobuyuki; Tokunaga, Shinsuke
Fusion Engineering and Design, 89(9-10), p.2440 - 2445, 2014/10
Several concepts of DEMO have been proposed so far with plasma physics assumptions. At the same time, plasma performances foreseen in DEMO have been developed experimentally in tokamaks. However there are large gaps between the physics design parameters of the DEMO concepts and the simultaneous achieved parameters in tokamak experiments. Since one of the foreseeable integrated plasma performances is the ITER steady-state scenario, the projection of the scenario parameter to DEMO concept has been analyzed by using the systems code. The fusion power of 1GW can be obtained with the plasma major radius of 9 m. The same power can be obtained with 8 m if the distance between TF coil and plasma surface is reduced from 2 m to 1.5 m. Furthermore, it was found that the heat load on the divertor region is increased with increasing the normalized density and is decreased with increasing the normalized beta.
Someya, Yoji; Tobita, Kenji; Yanagihara, Satoshi*; Kondo, Masatoshi*; Uto, Hiroyasu; Asakura, Nobuyuki; Hoshino, Kazuo; Nakamura, Makoto; Sakamoto, Yoshiteru
Fusion Engineering and Design, 89(9-10), p.2033 - 2037, 2014/10
In the replacement period of a fusion power reactor, the assembly of blanket or divertor modules need to be removed from the reactor in order to minimize remote maintenance in the vacuum vessel and to attain a reasonable plant availability. In the hot cell, the modules will be removed from the backplate of the assembly. Here, note that the active cooling must be done by a way that does not cause contamination of the hot cell environment due to dispersion of tritium and tungsten dust. In this sense, the cooling scenario is adopted that the existing pipe of cooling water in the assembly is connected to a different cooling water system in the hot cell. In this scenario, the temperature of the assembly is maintained about 40-100C. On the other hand, the structural material (RAFM) of the blanket and divertor is not recycled due to its high contact dose rate. It should be crushed into small pieces to reduce volume of the waste and required storage space. Here, the decay heat must be removed by natural convection to keep the temperature below 65C for preventing water evaporation from the mortar. The RAFM is kept in the interim storage during 12 years until the required temperature conditions for mortar are ensured and then is disposed of.
Nakamura, Makoto; Tobita, Kenji; Gulden, W.*; Watanabe, Kazuhito*; Someya, Yoji; Tanigawa, Hisashi; Sakamoto, Yoshiteru; Araki, Takao*; Matsumiya, Hisato*; Ishii, Kyoko*; et al.
Fusion Engineering and Design, 89(9-10), p.2028 - 2032, 2014/10
After the Fukushima Dai-ichi nuclear accident, a social need for assuring safety of fusion energy has grown gradually in the Japanese (JA) fusion research community. DEMO safety research has been launched as a part of BA DEMO Design Activities (BA-DDA). This paper reports progress in the fusion DEMO safety research conducted under BA-DDA. Safety requirements and evaluation guidelines have been, first of all, established based on those established in the Japanese ITER site invitation activities. The amounts of radioactive source terms and energies that can mobilize such source terms have been assessed for a reference DEMO, in which the blanket technology is based on the Japanese fusion technology R&D programme. Reference event sequences expected in DEMO have been analyzed based on the master logic diagram and functional FMEA techniques. Accident initiators of particular importance in DEMO have been selected based on the event sequence analysis.
Aoyagi, Mitsuhiro; Ito, Satoshi*; Hashizume, Hidetoshi*
Fusion Engineering and Design, 89(7-8), p.1227 - 1231, 2014/10
A 3D MHD flow simulation was conducted to clarify the effects of the inlet flow condition on the result of the validation experiment carried out previously and on the design window of the first wall using a three-surface-multi-layered channel. MHD pressure drop was influenced by the inlet condition largely. The numerical model with turbulent velocity profile showed qualitatively good agreement with the experimental result. The first wall temperature distribution obtained by the 3D simulation corresponded well the one by the 2D simulation assuming fully developed flow. This meant complicated three-dimensional inlet flow condition generated in the L-shape elbow would not affects the existing design window.
Hayashi, Takumi; Isobe, Kanetsugu; Nakamura, Hirofumi; Kobayashi, Kazuhiro; Oya, Yasuhisa*; Okuno, Kenji*; Oyaizu, Makoto; Edao, Yuki; Yamanishi, Toshihiko
Fusion Engineering and Design, 89(7-8), p.1520 - 1523, 2014/10
Tritium confinement is the most important safety issue in the fusion reactor. Tritium behavior on the water metal boundary is very important to design tritium plant with breading blanket system using cooling water. A series of tritium permeation experiment into pressurized water or water vapor jacket with He or Ar have been performed through pure iron piping with/without 7 micro-meter gold plating, which contained about 1 kPa of pure tritium gas at 423 K, with monitoring the chemical forms of tritium. Also, deuterium permeation experiments from heavy water vessel through various metal piping, such as pure iron (Fe), nickel (Ni), stainless steel (SS304), and pure iron with 10 micro-meter gold plating, were performed at 573 K and at 15 MPa. Recently, using the above heavy water system, we have succeeded to detect simultaneous hydrogen isotopes transfer from and to the metal surface by introducing H gas to the metal piping after stabilized deuterium permeation was detected.
Kanai, Akihiko*; Park, C.*; Noborio, Kazuyuki*; Kasada, Ryuta*; Konishi, Satoshi*; Hirose, Takanori; Nozawa, Takashi; Tanigawa, Hiroyasu
Fusion Engineering and Design, 89(7-8), p.1653 - 1657, 2014/10
The present study reports the compatibility of a reduced-activation ferritic steel F82H and Ni exposed to liquid Pb-Li flow using a rotating disk apparatus at 873 K. Cross-sectional observations revealed that grain boundary attack of Pb caused a liquid metal embrittlement of Ni and formation of pitting holes and Cr-depleted zone in F82H.
Takahara, Shogo; Abe, Tatsuya*; Iijima, Masashi; Shimada, Kazumasa; Shiratori, Yoshitake
Health Physics, 107(4), p.326 - 335, 2014/10
Probabilistic dose assessment is one of the useful methods to describe the information on the dose distributions in the population. To use this assessment, statistically characterized data on the pathway-relevant contributors are necessary. The objectives of the paper are to determine the statistical values and the distribution forms of the contributors to external exposures, as well as to identify the causes of the variabilities of them. To achieve the objectives, we have measured and surveyed ambient dose rate and time spent outdoors in Fukushima Prefecture. The measurements and surveys were performed with the cooperation of indoor workers, outdoor workers and pensioners. These results allowed us to determine the statistically characters of the individual doses and its contributors. In addition, these contributors had the variabilities attributed to the spatial distributions of deposited radionuclides, as well as the temporal and interpopulational differences of behavioral patterns.
Kawamura, Hideyuki; Kobayashi, Takuya; Furuno, Akiko; Usui, Norihisa*; Kamachi, Masafumi*
Journal of Environmental Radioactivity, 136, p.64 - 75, 2014/10
Numerical simulations on oceanic radioactive cesium dispersions in the North Pacific were conducted with a focus on the long-term variation of the radioactive cesium concentration after the Fukushima disaster. It was suggested that the Cs concentration had already been reduced to the pre-Fukushima background value in the wide area within the North Pacific 2.5 years after the Fukushima disaster.
Misumi, Kazuhiro*; Tsumune, Daisuke*; Tsubono, Takaki*; Tateda, Yutaka*; Aoyama, Michio*; Kobayashi, Takuya; Hirose, Katsumi*
Journal of Environmental Radioactivity, 136, p.218 - 228, 2014/10
Major controls on spatiotemporal variations of Cs activity in seabed sediments derived from the Fukushima Dai-ichi Nuclear Power Plant accident during the first year after the accident were investigated by using numerical simulations. The model successfully reproduced major features of the observed spatiotemporal variations of Cs activity in sediments. The spatial pattern of Cs in sediments, which mainly reflected the history of Cs activity in the bottom water overlying the sediment and the sediment particle size distribution, became established during the first several months after the accident. Taking Cs activities in sediments in the coastal area and in the vicinity of the power plant into account, increased the simulated total inventory of Cs in sediments off the Fukushima coast to a value on the order of 10 Bq.
Tachi, Yukio; Ochs, M.*; Suyama, Tadahiro
Journal of Nuclear Science and Technology, 51(10), p.1177 - 1190, 2014/10
The integrated sorption and diffusion (ISD) model for bentonite was developed to predict the long-term migration of radionuclides (RNs). The basic premise in the ISD model was to consistently use the same simple model design and parameters for describing RNs sorption as well as the clay surface chemistry. A 1-site non-electrostatic surface complexation model in combinations with 1-site ion exchange model was selected to keep model characteristics relatively robust when applied to compacted systems. Fundamental model parameters were evaluated from titration data for purified montmorillonite. The resulting model was then parameterized on the basis of selected sorption datasets for Np(V), Am(III) and U(VI), which cover key geochemical conditions such as pH, ionic strength and carbonate. The sorption trends for these RNs can be quantitatively described by the model considering a full suite of surface species including carbonate species which are consistent with aqueous RNs speciation.
Tachi, Yukio; Yotsuji, Kenji; Suyama, Tadahiro; Ochs, M.*
Journal of Nuclear Science and Technology, 51(10), p.1191 - 1204, 2014/10
The integrated sorption and diffusion (ISD) model for compacted bentonites was developed based on the consistent combination of (1) the porewater chemistry model, (2) the thermodynamic sorption model (TSM), and (3) the diffusion model based on the electrical double layer (EDL) theory. This ISD model was successfully tested for various actinides with a complex chemistry (Np(V), Am(III), U(VI) under conditions where carbonate complexes are formed), by using published diffusion and sorption data (, , ) as a function of partial montmorillonite density. Quantitative agreements were observed as same as monovalent cations (Cs, Na), anions (Cl, I, TcO) previously reported. The ISD model could be therefore seen to be able to predict sorption and diffusion behavior of various complex radionuclides in compacted bentonites.
Abe, Satoshi; Satou, Akira; Takeda, Takeshi; Nakamura, Hideo
Journal of Nuclear Science and Technology, 51(10), p.1164 - 1176, 2014/10
Saito, Kimiaki; Petoussi-Henss, N.*
Journal of Nuclear Science and Technology, 51(10), p.1274 - 1287, 2014/10
Conversion coefficients of radionuclide deposition density to the ambient dose equivalent rate at 1 m height above ground were calculated for exponentially distributed sources in the ground. Firstly, Monte Carlo transport simulations assuming exponential distributions in the ground were performed to obtain ambient dose equivalent for mono-energetic ray sources having different relaxation depths; next, on the basis of the simulated data, conversion coefficients for radionuclides were composed considering recent nuclear decay data. The ambient dose equivalent rates were then compared to the effective dose rates for reference adults and a new-born baby. It was confirmed that the ambient dose equivalent sufficiently overestimates effective doses.
Chai, G.-L.*; Hou, Z.*; Shu, D.-J.*; Ikeda, Takashi; Terakura, Kiyoyuki*
Journal of the American Chemical Society, 136(39), p.13629 - 13640, 2014/10
Carbon alloy catalysts (CACs) are promising catalysts for oxygen reduction reaction (ORR) to substitute Pt. However, despite extensive studies on CACs the reaction sites and mechanisms for ORR are still in controversy. Herein, we present rather general consideration on possible ORR mechanisms for various structures in nitrogen doped CACs based on the first principles calculations. Our study indicates that only a particular structure of a nitrogen pair doped Stone-Wales defect provides a good active site. The ORR activity of this structure can be tuned by the curvature around the active site, which makes its limiting potential approaching the maximum limiting potential (0.80 V) in the volcano plot for the ORR activity of CACs. The calculated results can be compared with the recent experimental ones of the half wave potential for CAC systems that range from 0.60 V to 0.80 V in the reversible-hydrogen-electrode scale.
Kobayashi, Riki*; Kaneko, Koji; Saito, Kotaro*; Mignot, J.-M.*; Andr, G.*; Robert, J.*; Wakimoto, Shuichi; Matsuda, Masaaki*; Chi, S.*; Haga, Yoshinori; et al.
Journal of the Physical Society of Japan, 83(10), p.104707_1 - 104707_5, 2014/10
The effect of electron doping by the substitution of Rh for Ru on unconventional magnetic order in CeRuAl was investigated via neutron powder diffraction. In Ce(RuRh)Al with = 0.05, 0.12, 0.2, reorientation of the ordered moment from the - to the -axis takes place in all samples, while the ordering vector = (0 1 0) remains unchanged within this concentration range. The moment reorientation is accompanied by an enhancement in its size by a factor of 2.4, from =0.43 at = 0 to =1.06, 1.04, and 1.02 for = 0.05, 0.12 and 0.2, respectively. The continuous decrease in Nel temperature (), despite an abrupt increase in , underlines the strong anisotropy in the exchange interaction in CeRuAl, and the fact that this anisotropy is easily suppressed by electron doping.
Akiyama, Kazuki; Takahashi, Masanori; Tsukamoto, Masaki*; Miyauchi, Yoshihiro*; Wada, Hiroshi*
Nippon Genshiryoku Gakkai-Shi, 56(10), p.656 - 660, 2014/10
This report shows the yield of low-level radioactive wastes and high-level radioactive wastes at the nuclear power plant and reprocessing plant, and those detailed managements are reported.
Nippon Kikai Gakkai-Shi, 117(1151), p.688 - 689, 2014/10
Bierwage, A.; Todo, Yasushi*; Aiba, Nobuyuki; Shinohara, Koji
Nuclear Fusion, 54(10), p.104001_1 - 104001_14, 2014/10
Dynamics of fast ions and shear Alfvn waves are simulated using MEGA, a global nonlinear hybrid code. The scenario is based on JT-60U shot E039672, driven by strong negative-ion-based neutral beams (N-NB), just before the onset of a so-called Abrupt Large Event (ALE). It is found that modes with toroidal mode numbers = 2, 3, 4 can be destabilized, besides the = 1 mode studied previously. The properties of the modes with n 1 are sensitive to the value of the plasma beta and the form of the fast ion distribution, so simulation conditions are set up as realistically as possible. When the fast ion drive exceeds a certain threshold, the = 3 mode is enhanced through a convective amplification process while following fast ions that were displaced by the field fluctuations. The fast ion transport in several cases is analyzed and implications of the results for the explanation of ALEs are discussed.
Todo, Yasushi*; Van Zeeland, M. A.*; Bierwage, A.; Heidbrink, W. W.*
Nuclear Fusion, 54(10), p.104012_1 - 104012_13, 2014/10
The hybrid code MEGA, which simulates the interaction between fast ions and an MHD fluid, is extended with realistic beam deposition profile and collisions. It is used for multi-phase simulations, where classical simulations (fast ion source + collisions) and hybrid simulations (source + collisions + MHD) are run alternatingly. In a multi-phase simulation of DIII-D discharge 142111, it is found that the stored beam ion energy is saturated due to toroidal Alfvn eigenmodes (TAE) at a level lower than in the purely classical simulation. This is consistent with the experimental observation. After the stored fast ion energy is saturated, it is demonstrated by hybrid simulations that the fast ion spatial profile is significantly flattened due to the interaction with the multiple TAEs with amplitude / and / of order 10e-4. The temperature fluctuations caused by TAEs are of the order of 1% of the equilibrium temperature. This is also comparable with ECE measurements in the experiment.
Kajimoto, Tsuyoshi*; Shigyo, Nobuhiro*; Sanami, Toshiya*; Iwamoto, Yosuke; Hagiwara, Masayuki*; Lee, H. S.*; Soha, A.*; Ramberg, E.*; Coleman, R.*; Jensen, D.*; et al.
Nuclear Instruments and Methods in Physics Research B, 337, p.68 - 77, 2014/10
The energy spectra of neutrons were measured by a time-of-flight method for 120 GeV protons on thick graphite, aluminum, copper, and tungsten targets with an NE213 scintillator at the Fermilab Test Beam Facility. Neutron energy spectra were obtained between 25 and 3000 MeV at emission angles of 30, 45, 120, and 150. The spectra were parameterized as neutron emissions from three moving sources and then compared with theoretical spectra calculated by PHITS and FLUKA codes. The yields of the theoretical spectra were substantially underestimated compared with the yields of measured spectra. The integrated neutron yields from 25 to 3000 MeV calculated with PHITS code were 16-36% of the experimental yields and those calculated with FLUKA code were 26-57% of the experimental yields for all targets and emission angles.
Ishibashi, Masayuki; Ando, Tomomi*; Sasao, Eiji; Yuguchi, Takashi; Nishimoto, Shoji*; Yoshida, Hidekazu*
Oyo Chishitsu, 55(4), p.156 - 165, 2014/10
Understanding of long-term history of water-conducting features such as flow-path fractures is key issue to evaluate deep geological environment for geological disposal of high-level radioactive waste (HLW). Thus, we conducted study on the geological features and the long-term behavior of flow-path fractures based on the data obtained at -300m levels in the Mizunami Underground research laboratory (MIU), central Japan. Total 1670 fractures were mapped in underground gallery at the -300m levels. Flow-path fractures occupy about 11% of all fractures. The flow-path fractures are divided into grout filling fractures and low inflow-rate fractures. All of the grout filling fractures is filled with calcite as fracture filling minerals without conspicuous host rock alteration around fractures. The low inflow-rate fractures possessed similar geological character with the sealed fractures which are not acted as flow-path. The geological character of fracture filling and host tock alteration around fractures indicates the history of the formation at the time of intrusion and emplacement of host granite (Stage I), then filling at hydrothermal event (Stage II), and finally opening and elongation during exhumation stage (Stage III). In conclusion, the present flow-path fractures were formed by opening and/or elongation of pre-existed fractures, which were filled at the hydrothermal event, at the time of exhumation.
Kurosaki, Yuzuru; Akagi, Hiroshi; Yokoyama, Keiichi
Physical Review A, 90(4), p.043407_1 - 043407_9, 2014/10
We theoretically propose a new control scheme of temporal wave-packet separation for oriented molecules, based on nonresonant dynamic Stark effect (DSE) in the dipole limit. In the scheme linearly-polarized single-cycle THz pulses are employed as control fields. In this work the proposed scheme is applied to the temporal wave-packet separation of the binary mixture of alkali halide isotopologues, CsI and CsI. We assume that before applying the control pulse one of the isotopologues is oriented along the field polarization direction and the other along the opposite direction and then they are electronically excited from the ground-state PEC to the excited-state counterpart. Numerical wave-packet propagations reveal that a THz pulse yields a temporal wave-packet separation of about 2 ps between the two isotopologue photodissociations.
Mitamura, Hiroyuki*; Watanuki, Ryuta*; Kaneko, Koji; Onozaki, Norimichi*; Amo, Yuta*; Kittaka, Shunichiro*; Kobayashi, Riki*; Shimura, Yasuyuki*; Yamamoto, Isao*; Suzuki, Kazuya*; et al.
Physical Review Letters, 113(14), p.147202_1 - 147202_5, 2014/10
Magnetic field () variation of the electrical polarization (c) of the perfect triangular lattice antiferromagnet RbFe (MoO) is examined up to the saturation point of the magnetization for B. is observed only in phases for which chirality is predicted in the in-plane magnetic structures. No strong anomaly is observed in at the field at which the spin modulation along the c axis exhibits a discontinuity to the commensurate state. These results indicate that ferroelectricity in this compound originates predominantly from triangular-spin chirality. The obtained field-temperature phase diagrams of ferroelectricity well agree with those theoretically predicted for the spin chirality of a Heisenberg spin triangular lattice antiferromagnet.
Yuri, Yosuke; Yuyama, Takahiro; Ishizaka, Tomohisa; Ishibori, Ikuo; Okumura, Susumu
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.862 - 865, 2014/10
Sanada, Hiroyuki; Sato, Toshinori; Horiuchi, Yasuharu*; Mikake, Shinichiro; Okihara, Mitsunobu*; Yahagi, Ryoji*; Kobayashi, Shinji*
Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 7 Pages, 2014/10
The Japan Atomic Energy Agency (JAEA) is implementing the Mizunami Underground Research Laboratory (MIU) Project to establish the scientific and technological basis for the geological disposal of High-level Radioactive Waste (HLW) in crystalline rocks. Excavation cycle times were recorded during the Ventilation Shaft sinking and compared with the planned excavation cycle times for evaluation of the baseline design plan. This included review of the cycle times in the design process and comparison with the actual construction results. The recorded results indicate that actual cycle times were twice as long as the design plan. This paper describes discussions on differences in cycle times between the design and result.
Aoyagi, Kazuhei; Tsusaka, Kimikazu*; Nohara, Shintaro*; Kubota, Kenji*; Tokiwa, Tetsuya*; Kondo, Keiji*; Inagaki, Daisuke*
Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 8 Pages, 2014/10
In a construction of a deep underground facility such as repository for high-level radioactive waste (HLW) disposal, significant changes in hydrogeomechanical properties around a gallery are expected. This zone is called an Excavation Damaged Zone (EDZ). For the safety of HLW disposal, it is necessary to investigate extent and hydrogeomechanical characteristics of an EDZ. In this research, the authors conducted in situ surveys such as seismic refraction survey, geological observation around a gallery, borehole television survey, and hydraulic tests in the Horonobe Underground Research Laboratory. From the results of those surveys, the authors concluded that the extent of the area with high-density of fractures and high hydraulic conductivity was estimated to be about 0.2 to 1.2 m into the gallery wall. The authors also compiled the information of the extent of an EDZ and hydrogeomechanical properties inside and outside of an EDZ as a conceptual model. Since the conceptual models provide the basic idea for determining flow and solute transport in an EDZ, the result of this research provides a useful data for a safety assessment of the HLW disposal.
Sato, Toshinori; Mikake, Shinichiro; Kobayashi, Shinji*; Tsuji, Masakuni*
Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 10 Pages, 2014/10
Japan Atomic Energy Agency is operating Mizunami Underground Research Laboratory project focusing on crystalline rock. Grouting for reducing water inflow is an essential countermeasure technology utilized during construction of underground facilities. Pre-excavation grouting and post-excavation grouting using Ordinary Portland cement, super-fine Portland cement and liquid-type colloidal silica were performed to investigate their performance as countermeasures for reducing groundwater inflow at many locations in the shafts and galleries in the laboratory. The results show that pre-excavation grouting successfully attained the target hydraulic conductivity of 2 Lu for Ordinary Portland cement and 0.2 Lu for super-fine Portland cement using criteria of Lugeon value and changing W/C. Liquid-type colloidal silica was able to drastically lower the hydraulic conductivity of 0.29 Lu and seemed to be stable for water pressures of at least 5 MPa and to be important material used in deep underground.
Onoe, Hironori; Iwatsuki, Teruki; Saegusa, Hiromitsu; Onuki, Kenji; Takeuchi, Ryuji; Sanada, Hiroyuki; Ishibashi, Masayuki; Sato, Toshinori
Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 10 Pages, 2014/10
The selection of a geological disposal site for high-level radioactive waste (HLW) will be done taking into consideration performance of the geological environment. Geological environments would likely be influenced for several decades by changes due to the construction and operation of a large underground facility such as a HLW repository. Therefore, the post-closure recovery of the geological environment after backfilling of a facility is an important aspect for the safety assessment of geological disposal of HLW. With a focus on the hydraulic pressure and hydrochemical recovery processes around underground galleries in fractured crystalline rock, the groundwater recovery experiment will be conducted at the Mizunami Underground Research Laboratory to evaluate the natural groundwater and hydrochemical recovery of the rock mass. This paper provides an outline of the groundwater recovery experiment plan and progress of the supporting field investigations.
Tsuji, Masakuni*; Funehag, J.*; Kobayashi, Shinji*; Sato, Toshinori; Mikake, Shinichiro
Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 10 Pages, 2014/10
Silica sol is a material that seems to fulfill the non-hazardous requirement and capable of penetrating into narrow fractures. The rock grouting strategy with silica sol has been studied and applied for some recent projects in Sweden. The design methodology is based on the determination of the fracture transmissivity distribution and the theoretical penetration length. In 2008, grouting with silica sol was applied in the construction of a short tunnel at 450 m depth in the sp Hard Rock Laboratory, the TASS-tunnel. In 2010, a grouting experiment with silica sol was performed in a gallery at 300 m depth in the Mizunami Underground Research Laboratory (MIU experiment). It can be suggested that Swedish methodology can be applied to design and evaluate the grouting works in Japanese rock with higher intensity of fractures in general. Furthermore, an additional pumping time or the use of Japanese silica sol might improve the grouting quality in Sweden.
Hayano, Akira; Matsukawa, Shun*; Xu, Z.*; Itakura, Kenichi*
Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 9 Pages, 2014/10
In generally, the geological observation of a gallery wall is performed based on geologists' traditional techniques. However, to reduce the differences in data quality attributable to geologists' individual judgments and experiences, it is necessary to provide a method to acquire objective data that are unaffected by a geologist's subjectivity. It is also necessary to reduce the work volume associated with geological observations of gallery walls. Three-dimensional laser scanning (3DLS) is useful as a means for achieving this goal. In this study, acquisition of geometric data of fractures distributed on the gallery wall has been conducted using 3DLS data while clarifying the geological observation data necessary for modeling of a fractured rock mass. The acquired geometric data of fractures were compared with data acquired by a geologist. Consequently, the fractures were extracted by visible reading of images generated from 3DLS data, then geometric data was generated.
Asahina, Daisuke*; Aoyagi, Kazuhei; Tsusaka, Kimikazu*; Houseworth, J.*; Birkholzer, J.*
Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 9 Pages, 2014/10
We present ongoing collaborative work applying a rigid-body-spring network (RBSN), a special type of lattice model, to simulate laboratory experiments conducted in the Horonobe Underground Research Laboratory (URL) in Japan. The Horonobe URL Project, which began in 2001, has developed a URL at a depth of about 350 m in a sedimentary rock called the Koetoi and Wakkanai formation. The basic capabilities of RBSN modeling are demonstrated through two standard laboratory tests: (1) split-cylinder (Brazilian) test; and (2) uniaxial compression test. Bulk material properties (i.e., Young's modulus, the strength parameters such as tensile strength, cohesion, and internal friction angle) estimated by the experiments are directly used for the mechanical parameters of springs. Tensorial representations of stress are obtained within the lattice elements and compared with Mohr-Coulomb failure criteria for fracture simulation. Agreement between the numerical and laboratory test results is good with respect to stress development, tensile/compressive strength, and fracture pattern, under the assumption of homogeneous systems using the RBSN model. The connection of hydraulically active fractures is also addressed for both of the simulation studies.
Tsusaka, Kimikazu*; Inagaki, Daisuke*; Nago, Makito*; Ijiri, Yuji*
Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 9 Pages, 2014/10
This study describes the analysis performed on the West Access Shaft of the Horonobe Underground Research Laboratory, which was expected to intersect a fault at the depth of approximately 320 m. Field observation, and measurement data were used to determine analysis conditions including magnitude and orientation of in-situ stress, boundary conditions, and rock mass properties. The fault was modeled as having a dip angle of 40 degrees and apparent thickness of 5 m (equivalent to the height of the excavated rock wall). The shaft sinking procedure was simulated using three-dimensional excavation analysis. The excavation involved installing concrete lining at every 2 m span. The analysis considered two cases of maximum in situ principal stress orientation: (1) perpendicular to and (2) parallel to the fault plane orientation. The results of the analysis indicate that the maximum excavation-induced stress, developed in a single-span lining concrete, was in the direction perpendicular to the maximum in situ principal stress orientation, unaffected by the fault plane orientation. The influence of the fault plane orientation on the excavation-induced stress state was found to be significant above and below the fault rather than in the fault. Another observation was that the excavation-induced stress magnitude appeared to be greater when the maximum in situ principal stress orientation was parallel to the fault plane orientation.
Tsusaka, Kimikazu*; Inagaki, Daisuke*; Niunoya, Sumio*; Jo, Mayumi*
Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 9 Pages, 2014/10
The Japan Atomic Energy Agency (JAEA) has been promoting the Horonobe Underground Research Laboratory Project in Hokkaido since 2001 to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment in sedimentary rocks of Japan. In the project, investigations on mechanical property of in-situ rock mass were conducted in order to evaluate the methodology to build a mechanical dataset of the rock mass based on the results of laboratory tests using rock cores and borehole logs. In this paper, the methodology to be applied for the surface-based investigation around the URL was studied based on the results of in-situ investigation in the galleries at 250 m and 350 m depths.
Nakamura, Hiroki; Okumura, Masahiko; Machida, Masahiko
RSC Advances (Internet), 4(95), p.52757 - 52761, 2014/10
In order to evaluate the selectivity for specific cations in ion-exchange of zeolites, we calculate the ion-exchange isotherms in various zeolites using Monte Carlo simulation techniques. The calculation results agree well with experiments. Furthermore, we examine the Si/Al-ratio dependence on the cation selectivity and find that the Cs selectivity once increases with the Si/Al ratiobut saturates above a certain value. These results reveal that the selectivity for Cs is enhanced cooperatively by microporous structure and the Si/Al ratio of the zeolite framework. The present simulation scheme is promising in selecting useful materials for Cs decontamination in waste treatments.
Kimura, Atsushi; Nagasawa, Naotsugu; Taguchi, Mitsumasa
Radiation Physics and Chemistry, 103, p.216 - 221, 2014/10
Large quantities of polysaccharide-based biomass are ubiquitous on Earth, and they possess unique structures, distinctive properties, and offer the advantages of being non-toxic and biodegradable. Ionizing radiation is widely used as a convenient tool for the modification of the polysaccharides via decomposition, grafting, and cross-linking. Until now, radiation cross-linked materials have only been produced either from polysaccharide derivatives or using cross-linking reagents, as certain natural polysaccharides have poor solubility in water and organic solvents as well as low chemical reactivity. These limitations could possibly be circumvented by the use of room temperature ionic liquids (RTILs), which can cleave the hydrogen bonds of the polysaccharides to form solutions. In this study, we focus on the application of RTILs as "specific solvents for the dissolution of polysaccharides," and their use in establishing a "proper reaction field for radiation cross-linking." For the first time in this study, we have demonstrated the possibility of producing cellulose gels by -ray irradiation of cellulose in RTILs under humid conditions. The gel fraction could be controlled by adept regulation of following conditions: initial concentration of cellulose, irradiation temperature, water content, and the absorbed dose. The cellulose gel thus obtained had an electronic conductivity of 3.0 mS cm, showing great potential for applications in optoelectronic and medical devices.
Haema, K.*; Oyama, Tomoko; Kimura, Atsushi; Taguchi, Mitsumasa
Radiation Physics and Chemistry, 103, p.126 - 130, 2014/10
For biological and medical applications, radiation sterilization of gelatin was evaluated in terms of radiation stability. It was found that electron beam irradiation decomposed the gelatin and that the weight-averaged molar mass decreased by approximately 7-10% with sterilization doses in the range of 5-25 kGy. Also, we found that the hydrolysis rate in 37C water was affected by the irradiation. On the other hand, crosslinking was predominantly induced when the gelatin was irradiated in water solution and radiation-crosslinked (RX) gelatin hydrogel was fabricated. Using gel fraction and gel permeation chromatography analysis of the eluted sol, it was determined that the RX-gelatin hydrogel was stable for 7 days in water at 37C.
Sato, Tatsuhiko; Kataoka, Ryuho*; Yasuda, Hiroshi*; Yashiro, Seiji*; Kuwabara, Takao*; Shiota, Daiko*; Kubo, Yuki*
Radiation Protection Dosimetry, 161(1-4), p.274 - 278, 2014/10
We applied our simulation technique to the analysis of air shower induced by mono-energetic protons and alpha particles, which are the dominant component of SEP. The results of the simulations were summarized in a database containing particle fluxes for each condition as a function of the atmospheric depth. This database was then incorporated into our developing Warning System of AVIation Exposure to SEP called WASAVIES. In this system, the aircrew doses due to SEP exposure are estimated within 6 hours after the flare onset, using the established database multiplied with the SEP fluxes incident to the earth. The MHD Cube model is employed in the determination of the incident SEP fluxes. The procedures for the air shower simulation together with some initial results of the aircrew dose calculations for past ground-level enhancement (GLE) events will be presented at the meeting.
Takayama, Tomohiro*; Yaresko, A.*; Matsumoto, Akiyo*; Nuss, J.*; Ishii, Kenji; Yoshida, Masahiro*; Mizuki, Junichiro; Takagi, Hidenori*
Scientific Reports (Internet), 4, p.6818_1 - 6818_6, 2014/10
The complex iridium oxide NaIrO with a B-site ordered spinel structure was synthesized in single crystalline form, where the chiral hyper-kagome lattice of Irions, as observed in the spin-liquid candidate NaIrO, was identified. The average valence of Ir is 4.33+ and, therefore, NaIrO can be viewed as a doped analogue of the hyper-kagome spin liquid with Ir. The transport measurements, combined with the electronic structure calculations, indicate that the ground state of NaIrO is a low carrier density semi-metal. We argue that the semi-metallic state is produced by a competition of the molecular orbital splitting of orbitals on Ir triangles with strong spin-orbit coupling inherent to heavy Ir ions.
Awual, M. R.; Hasan, M. M.*
Sensors and Actuators B; Chemical, 202, p.395 - 403, 2014/10
The functionalized mesoporous silica based fine tuning meso adsorbent was developed for ultra trace lead (Pb(II)) detection and removal from wastewater. The design of the ligand into ordered pore based meso adsorbent transformed the Pb(II) detection and removal systems into smart and stable assemblies. The ability of the meso adsorbent to detect and remove Pb(II) from aqueous solutions has been studied and discussed with different optimized conditions of concentrations, the amount of meso adsorbent, concentration of coexisting electrolyte and pH. The design of such a tunable meso adsorbent offered a simple procedure in such toxic Pb(II) ions removal without using high tech, sophisticated instruments.
Tsuzuki, Tatsuya*; Mitamura, Naoki*; Amamoto, Ippei
Shakai, Kankyo Hokokusho 2014 (Internet), p.6 - 7, 2014/10
Ebihara, Kenichi; Kaburaki, Hideo; Itakura, Mitsuhiro
"Hagane No Kikaiteki Tokusei Ni Oyobosu Suiso No Koka To Sono Hyoka" Shimpojium Yokoshu (USB Flash Drive), 6 Pages, 2014/09
Since hydrogen(H) embrittlement is one factor causing degradation and/or fracture of steel, understanding its mechanism is required. The grain-boundary(GB) decohesion due to segregation of H is considered to cause the delayed fracture of high strength steels and the cold cracking in welding. In the model based on GB decohesion, information of strength of GBs estimated in the atomic scale is used for the estimation of strength or crack propagation in the macroscopic scale. However the modeling between the atomic and the macroscopic scales is not clear. In particular, the validity of the model using the elastic continuum around nano-cracks for stress concentration at the crack tip is not clear. Thus, we examined the difference of the stress distribution around the nano-crack which was estimated by molecular dynamics and by a continuum calculation. As a result, the discrepancy became remarkable at high strain. The stress concentration was not simulated by the elastic continuum model.
Yang, L.-W.*; Kitao, Akio*; Huang, B.-C.*; Go, Nobuhiro*
Biophysical Journal, 107(6), p.1415 - 1425, 2014/09
In this study, a general linear response theory (LRT) is formulated to describe time-dependent and -independent protein conformational changes upon CO binding with myoglobin. Using the theory, we are able to monitor protein relaxation in two stages. The slower relaxation is found to occur from 4.4 to 81.2 picoseconds and the time constants characterized for a couple of aromatic residues agree with those observed by UV Resonance Raman (UVRR) spectrometry and time resolved X-ray crystallography. The faster "early responses", triggered as early as 400 femtoseconds, can be best described by the theory when impulse forces are used. The newly formulated theory describes the mechanical propagation following ligand-binding as a function of time, space and types of the perturbation forces. The "disseminators", defined as the residues that propagate signals throughout the molecule the fastest among all the residues in protein when perturbed, are found evolutionarily conserved and the mutations of which have been shown to largely change the CO rebinding kinetics in myoglobin.
Noguchi, Hiroki; Terada, Atsuhiko; Onuki, Kaoru; Hino, Ryutaro
Chemical Engineering Research & Design, 92(9), p.1659 - 1663, 2014/09
The Japan Atomic Energy Agency has been conducting research and development on the thermo-chemical iodine-sulfur (IS) process, which is one of the most attractive water-splitting hydrogen production methods that uses nuclear thermal energy. The sulfuric acid decomposer is one of the key components of the IS process. The boiling heat transfer coefficients of sulfuric acid solutions are required to design the sulfuric acid decomposer. These coefficients were measured in aqueous solutions where the mole fraction of HO ranged from 0.17 to 0.37 (heat flux range from 16.9 kW/m to 5.6 kW/m) and compared with the empirical correlations formulated for binary mixtures. A combination of the Stephan-Krner correlation, using the empirical constant A = 2.00, and the Nishikawa-Fujita correlation was used to predict the experimental results with an accuracy of 10%.
Arifi, E.*; Ishimatsu, Koichi*; Iizasa, Shinya*; Namihira, Takao*; Sakamoto, Hiroyuki*; Tachi, Yukio; Kato, Hiroyasu*; Shigeishi, Mitsuhiro*
Construction and Building Materials, 67(Part.B), p.192 - 196, 2014/09
The Fukushima Dai-ichi Nuclear Plant accident has resulted in a large amount of radioactively contaminated concrete. The possible application of the pulsed power discharge to reduce the amount of contaminated concrete as radioactive waste was investigated. The contaminated concrete was decontaminated by separating contaminated matrix from uncontaminated coarse aggregate under pulsed power discharge process. In this study, a stable Cs isotope was used to simulate radioactively contaminated concrete. As a result, while the volume of reclaimed aggregate from contaminated concrete could be reproduced was up to 60%, nevertheless Cs detected in the reclaimed aggregate was only approximately 3%. Thus most of the Cs were dissolved in water during the discharge process. It is expected that the pulsed power could reduce the contaminated concrete waste by reusing aggregate. Further investigations are requested to test the applicability of this method under the realistic conditions close to the actual waste.
Sakamaki, Keiko; Kataoka, Masaharu; Maeda, Toshikatsu; Iida, Yoshihisa; Kamoshida, Michio; Yamaguchi, Tetsuji; Tanaka, Tadao
Corrosion Engineering, Science and Technology, 49(6), p.450 - 454, 2014/09
Corrosion experiments of a carbon steel plate embedded in bentonite mixture were conducted toverify our models assessing Eh evolution induced by corrosion of carbon steel overpack. Theexperimental results showed that the Eh decreased for the first 200 days and was subsequentlystabilised at around -450 mV; corrosion products were identified as magnetite and Fe waspresent mostly as divalent Fe within a 5 mm range from the carbon steel plate. Reactive transportmodelling was performed to assess the Eh evolution in the system using kinetic dissolution modelfor metallic iron and thermodynamic equilibrium models for other chemical reactions and closelyreproduced the experimental results. The models were verified only under the conditionsemployed in this study.
Nagai, Haruyasu; Yamazawa, Hiromi*
Gempatsu Jiko Osen; Fukushima Daiichi Gempatsu No Chikyu Kagakuteki Sokumen, p.175 - 187, 2014/09
Nishiyama, Tomokazu; Yagyu, Junichi; Nakamura, Shigetoshi; Masaki, Kei; Okano, Fuminori; Sakasai, Akira
Heisei-26-Nendo Hokkaido Daigaku Sogo Gijutsu Kenkyukai Hokokushu (DVD-ROM), 6 Pages, 2014/09
Hosha Kagaku, (30), p.19 - 20, 2014/09
最近開発した3次元核図表の紹介を日本放射化学会の学会誌「放射化学」のニュース(トピックス)にて行う。原子の質量値版, 半減期版の写真を紹介してその外観を示し、鉄56が原子の一核子当たりの質量が最小であることや、Tc, Pmに安定同位体がない事実などを例示する。さらに最近作製した紹介動画を二例紹介する。
Hoshina, Hiroyuki; Ueki, Yuji; Saiki, Seiichi; Seko, Noriaki
International Journal of Organic Chemistry, 4(3), p.195 - 200, 2014/09
2-Ethylhexyl hydrogen-2-ethylhexylphosphonate (EHEP) is commonly used as a metal extractant because it has a particular affinity for rare-earth metals like Scandium (Sc). To develop a highly-selective polymeric adsorbent of Sc(III), EHEP was introduced as a functional group onto a polyethylene fabric with radiation-induced graft polymerization (RIGP). The adsorption performances for Sc(III) were evaluated in aqueous solutions containing Sc(III) and Fe(III) by a column test. The adsorption capacities of Sc(III) and Fe(III) until the bed volume reached 5000 were 5.22 and 0.12 mg/g, respectively. The adsorbents showed 44 times higher Sc(III) adsorption capacity than that of Fe(III). These results indicated that the grafted adsorbent containing EHEP had an extremely high selectivity for Sc(III) adsorption.
Miyakawa, Kazuya; Nohara, Tsuyoshi; Tokiwa, Tetsuya; Yamazaki, Masanori*
International Journal of Rock Mechanics and Mining Sciences, 70, p.332 - 342, 2014/09
A large amount of groundwater drain induced by an excavation of an underground facility will influence parameters of site formations such as permeability. In this study, a spectral analysis was applied to long-term records of atmospheric response of pore pressure in order to obtain time history of rock permeability change at the Horonobe Underground Research Laboratory (URL) in Japan. This study revealed that the excavation of the URL has influenced aquifers around the URL, and has reduced the vertical hydraulic diffusivity in the aquifers. At the point of ca. 130 m distant away from the URL, the hydraulic diffusivity has decreased in approximately 70% after 5 years from start of excavation of the URL. At the point of ca. 860 m distant away from the URL, the vertical hydraulic diffusivity has decreased in approximately 26% even though pore pressure has not changed remarkably. These results indicate that groundwater consequently becomes difficult to flow, and then safe-side estimation with respect to geological disposal system was obtained. This study confirmed that long-term history of permeability change can be monitored by using long-period records of pore pressure and atmospheric pressure. During the development of a geological disposal system, which takes several tens of years, the vertical permeability can be monitored continuously from the start of the excavation through the post-closure of the repository.
Yoneda, Yasuhiro; Kohara, Shinji*; Kumada, Nobuhiro*; Wada, Satoshi*
Japanese Journal of Applied Physics, 53(9S), p.09PD01_1 - 09PD01_5, 2014/09
The atomic-scale structure of solid solution of BaTiO (BT) and KNbO (KN) has been studied using high-energy X-ray diffraction, X-ray absorption fine structure, and atomic pair-distribution function analysis techniques. We prepared BT-KN solid solution through KNbTiO, in which Ti and Nb atoms are arranged randomly. The average structure of BT-KN solid solution was cubic structure and the local strcuture is also reproduced by the cubic structure. It is rare that a solid solution synthesized from ferroelectric materials has a local strcuture of a paraelectric material. Since the original correlation of BT or KN was lost, ferroelectricity disappeared in the BT-KN solid solution.
Gonda, Mayuki; Ikeda, Kiyoshi; Nagaya, Shun
Joho No Kagaku to Gijutsu, 64(9), p.357 - 360, 2014/09
We introduce post-Great East Japan Earthquake situation of the Japan Atomic Energy Agency Library and our efforts to distribute information about the TEPCO Fukushima Daiichi Nuclear Power Station Accident. After that, we describe our activities about the archiving of information relating to the Fukushima Nuclear Accident and its feature.
Miyamura, Hiroko; Kawamura, Takuma; Suzuki, Yoshio; Idomura, Yasuhiro; Takemiya, Hiroshi
Joho Shori Gakkai Rombunshi, 55(9), p.2216 - 2224, 2014/09
In numerical simulations, variations of calculation results with respect to a variable axis are often observed. When the target model is given in 3D, the simulation results become 4D. Such a multi-dimensional dataset given in more than 4D space is analyzed by detailed explorations of regions of interest (ROIs) in multi-dimensional space. However, for high-dimensional and large-scale datasets, this approach requires enormous processing time and effort, and may have difficulty in capturing all the ROIs. Therefore, we propose a technique that is based on a concept of spatiotemporal image. In our technique, a space axis is created by octree, a variable axis is defined in the direction perpendicular to the space axis. Our technique is applied to the results of 3D seismic simulations of a nuclear plant, and regions with characteristic frequency responses of each region are analyzed. Through the analyses, it is demonstrated that our technique can effectively capture ROIs from 4D datasets.
Ito, Kei; Kunugi, Tomoaki*; Ohno, Shuji; Kamide, Hideki; Ohshima, Hiroyuki
Journal of Computational Physics, 273, p.38 - 53, 2014/09
In the volume-of-fluid algorithm, the calculations of the interface normal and curvature are crucially important for accurately simulating interfacial flows. In this paper, the authors develop a height function method that works appropriately on an unstructured grid. In the process, the definition of the height function is discussed, and the high-precision calculation method of the interface normal is developed to meet the necessary condition for a second-order method. The curvature calculation method is also discussed and the approximated quadric curve of an interface is employed to calculate the curvature. Following a basic verification, the developed height function method is shown to successfully provide superior calculation accuracy and highly reduced computational cost compared with conventional calculation methods in terms of the interface normal and curvature.
Yamaguchi, Masaaki; Kitamura, Akihiro; Oda, Yoshihiro; Onishi, Yasuo*
Journal of Environmental Radioactivity, 135, p.135 - 146, 2014/09
We applied a model, to predict long term cesium distribution on Fukushima area, based on the USLE and simple sediment discharge formulas. Sensitivity analysis was conducted here to narrow the range of the output results due to the uncertainties of parameters. The preliminary calculation indicated significant deposition of sand portion within river basins. On the other hand the most of the eroded silt and clay portions were transported downstream to the river mouths. Annual sediment outflow into the ocean from Abukuma River and its total from the other 13 river basins vary between calculation cases based on the variation of land use, landform or precipitation. On the other hand, contributions of those parameters are relatively small for Cs concentration within transported soil. This indicates the total amount of Cs outflow into the ocean could be controlled by amount of soil erosion and transport, and total amount of Cs remaining within the basin.
Iwamoto, Yukiharu*; Yamano, Hidemasa
Journal of Fluid Science and Technology (Internet), 9(3), p.JFST0055_1 - JFST0055_13, 2014/09
Wall pressure measurements were conducted for a 90 degree elbow of which the axis curvature coincided with its inner diameter (125 mm). Results showed that distributions of fluctuating normalized pressures obtained here and those made by Shiraishi et al. (2006) for the Reynolds number of 3,250,000 coincided within 0.02 of the dynamic pressure. The peak intensity having the Strouhal number of 0.5 was quantitatively in accordance with that of the data obtained in the experimental setup that Shiraishi et al. used (Yamano et al., 2011), suggesting that the law of dynamical similarity could be applied with regard to this oscillation. Cross correlations of pressure fluctuations showed that the pressure fluctuation having the Strouhal number of 0.5 propagated as a planar wave with the bulk velocity.
Awual, M. R.
Journal of Industrial and Engineering Chemistry, 20(5), p.3493 - 3501, 2014/09
A novel conjugate adsorbent was developed for simultaneous Au(III) detection and recovery from urban mining waste. This adsorbent has the large surface are to volume ratios and uniformly shaped pores in the nanostructures in its cage cavities. Therefore, the conjugate adsorbent permitted to fast and specific Au(III) ions capturing via a colorimetric naked eye visualization based on stable complexation mechanism. The detection limit and sorption capacity of the novel adsorbent at optimum conditions was 0.22 g/L and 183.42 mg/g, respectively. The design in such novel adsorbent offered a simple procedure for ultra trace Au(III) detection and recover without using highly sophisticated instruments.
Awual, M. R.; Shenashen, M. A.*; Jo, Akinori*; Shiwaku, Hideaki; Yaita, Tsuyoshi
Journal of Industrial and Engineering Chemistry, 20(5), p.2840 - 2847, 2014/09
We developed a potentially high performance adsorbent for sustainable treatment of soluble inorganic trace phosphate from water by zirconium(IV) loaded bifunctional fibers. In the presence of common chloride and sulfate, phosphate adsorption was not adversely affected but slightly enhanced due to coion and Donnan invasion mechanism. Trace phosphorus (0.0143 mM) was also removed in presence of relatively high amounts of competing anions at high feed flow rate. In competitive arsenate and phosphate adsorption, this novel adsorbent slightly preferred phosphate to arsenate. The adsorbent is reversible and keeps remaining functionality to further reuse in many cycles.
Uchida, Teppei; Sunaoshi, Takeo*; Konashi, Kenji*; Kato, Masato
Journal of Nuclear Materials, 452(1-3), p.281 - 284, 2014/09
Experiment and simulation studies on physical properties of actinide oxides have been carried out. Thermal expansion is important data to evaluate the various properties from molecular dynamics (MD) simulation. In this study, thermal expansion of PuO was evaluated by experiment and MD simulation. In the experimental study, thermal expansion of PuO pellet was determined by a dilatometer in the temperature range of 300-1923 K. In the MD simulation, Born-Mayer-Huggins interatomic potential with a partially ionic model and Morse potential were employed. Lattice constants of PuO were evaluated in the temperature range of 300-2800 K by MD simulation, and thermal expansion was evaluated. The experimental data was good agreement with the MD simulation result. Evaluation formula for thermal expansion of PuO in the temperature range of 300-2800 K was derived from both data.
Tobita, Toru; Nakagawa, Sho*; Takeuchi, Tomoaki; Suzuki, Masahide; Ishikawa, Norito; Chimi, Yasuhiro; Saito, Yuichi; Soneda, Naoki*; Nishida, Kenji*; Ishino, Shiori*; et al.
Journal of Nuclear Materials, 452(1-3), p.241 - 247, 2014/09
Three kinds of Fe-based model alloys, Fe-0.018 atomic percent (at.%) Cu, Fe-0.53at.%Cu, and Fe-1.06at.%Cu were irradiated with 2 MeV electrons up to the dose of 210 dpa at 250C. After the irradiation, the increase in Vickers hardness and the decrease in electrical resistivity were observed. The increase in hardness by electron irradiation is proportional to the product of the Cu contents and the square root of the electron dose. The decrease in electrical resistivity is proportional to the product of the square of Cu contents and the electron dose. Cu clustering in the materials with electron irradiation and thermal aging was observed by means of the three dimensional atom probes (3D-AP). The change in Vickers hardness and electrical resistivity is well correlated with the volume fraction of Cu clusters.
Chekushina, L.*; Dyussambayev, D.*; Shaimerdenov, A.*; Tsuchiya, Kunihiko; Takeuchi, Tomoaki; Kawamura, Hiroshi; Kulsartov, T.*
Journal of Nuclear Materials, 452(1-3), p.41 - 45, 2014/09
Uwaba, Tomoyuki; Ito, Masahiro*; Nemoto, Junichi*; Ichikawa, Shoichi; Katsuyama, Kozo
Journal of Nuclear Materials, 452(1-3), p.552 - 556, 2014/09
The BAMBOO code was verified by results for the out-of-pile bundle compression test with large diameter pin bundle deformation under the bundle-duct interaction (BDI) condition. The pin diameters of were 8.5 mm and 10.4 mm, which are targeted as preliminary fuel pin diameters for the upgraded core of the prototype FBR and for demonstration and commercial FBRs studied in the FaCT project. In the bundle compression test, bundle cross-sectional views were obtained from X-ray computer tomography (CT)images and local parameters of bundle deformation were measured by CT image analyses. In the verification, calculation results of bundle deformation obtained by the BAMBOO code analyses were compared with the experimental results from the CT image analyses. The comparison showed that the BAMBOO code reasonably predicts deformation of large diameter pin bundles under the BDI condition by assuming that pin bowing and cladding oval distortion are the major deformation mechanisms.
Tobita, Toru; Udagawa, Makoto; Chimi, Yasuhiro; Nishiyama, Yutaka; Onizawa, Kunio
Journal of Nuclear Materials, 452(1-3), p.61 - 68, 2014/09
To investigate the changes in the mechanical properties of cladding materials irradiated with high neutron fluence, two types of cladding materials were fabricated using the submerged-arc welding and electroslag welding methods. The tensile tests, Charpy impact tests and fracture toughness tests were conducted before and after neutron irradiation with a fluence of 10 n/cm at 290 C. With neutron irradiation, the yield strength and ultimate strength increased, and the total elongation decreased. The Charpy upper-shelf energy was reduced and the ductile-to-brittle transition temperature was increased with neutron irradiation. There was no obvious decrease in the elastic-plastic fracture toughness (J) of the cladding materials at high neutron fluence. The tearing modulus decreased with neutron irradiation, and considerable low J values were observed at high temperatures submerged-arc-welded cladding materials.
Kitatani, Fumito; Harada, Hideo; Takamine, Jun; Kureta, Masatoshi; Seya, Michio
Journal of Nuclear Science and Technology, 51(9), p.1107 - 1113, 2014/09
Neutron resonance densitometry (NRD) has been proposed to quantify nuclear materials in particle-like debris of melted spent nuclear fuel formed in severe nuclear reactor accidents. NRD proposed here is a hybrid of neutron resonance transmission analysis and neutron resonance capture analysis using a pulsed neutron generator and the neutron time-of-flight technique. In this study, the effects of impurities and sample thickness on the measurement statistical uncertainty were examined using a linear absorption model.
Kamiyama, Kenji; Konishi, Kensuke; Sato, Ikken; Toyooka, Junichi; Matsuba, Kenichi; Zuyev, V. A.*; Pakhnits, A. V.*; Vityuk, V. A.*; Vurim, A. D.*; Gaidaichuk, V. A.*; et al.
Journal of Nuclear Science and Technology, 51(9), p.1114 - 1124, 2014/09
Recently, a design option which leads molten fuel to upward discharge has been considered to minimize technical difficulties for practical application to JSFR. In the present study, a series of experiments which consisted of three out-of-pile tests and one in-pile test were conducted to investigate effectiveness of the upward discharge option on eliminating energetics potential. Experimental data which showed a sequence of upward fuel-discharge and effects of initial pressure conditions on upward-discharge were obtained through the out-of-pile and in-pile test. Preliminary extrapolation of the present results to the supposed condition in early phase of the CDA in the JSFR design, suggested that sufficient upward flow rate of molten-fuel was expected to prevent the core-melting from progressing beyond the fuel subassembly scale and that the upward discharge option would be effective in eliminating the energetic potential.
Yamato, Masaaki; Nagase, Fumihisa; Amaya, Masaki
Journal of Nuclear Science and Technology, 51(9), p.1125 - 1132, 2014/09
To evaluate fracture resistance of LWR fuel rods under LOCA and post-LOCA cooling conditions, four-point-bend tests were performed on non-irradiated Zircaloy cladding samples that were ruptured, oxidized in high-temperature steam, and quenched in flooding water. The bend test methodology was designed to apply a uniform bending moment to the entire rupture region and to generate tensile stress on the ruptured side. The fracture bending moment of the cladding decreased with oxidation temperature and hydrogen concentration as well as oxidation amount. Comparison with bending moments estimated from design basis seismic ground motion indicated that the cladding is unlikely to be fractured by seismic loads during post-LOCA cooling if high-temperature oxidation is kept below 15% ECR, the oxidation limit of the Japanese LOCA criteria.
Cheng, S.; Tagami, Hirotaka; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu; Takeda, Shohei*; Nishi, Shimpei*; Nishikido, Tatsuya*; Zhang, B.*; Matsumoto, Tatsuya*; et al.
Journal of Nuclear Science and Technology, 51(9), p.1096 - 1106, 2014/09
Studies on debris bed self-leveling behavior with non-spherical particles are crucial in the assessment of actual leveling behavior that could occur in core disruptive accident of sodium-cooled fast reactors. Although in our previous publications, a simple empirical model (based model), with its wide applicability confirmed over various experimental conditions, has been successfully advanced to predict the transient leveling behavior, up until now this model is restricted to calculations of debris bed of spherical particles. Focusing on this aspect, in this study a series of experiments using non-spherical particles was performed within a recently-developed comparatively larger-scale experimental facility. Based on the knowledge and data obtained, an extension scheme is suggested with the intention to extend the base model to cover the particle-shape influence. Through detailed analyses, it is found that by coupling this scheme, good agreement between experimental and predicted results can be achieved for both spherical and non-spherical particles given current range of experimental conditions.
Kai, Takeshi; Tokuhisa, Atsushi*; Moribayashi, Kengo; Fukuda, Yuji; Kono, Hidetoshi; Go, Nobuhiro*
Journal of the Physical Society of Japan, 83(9), p.094301_1 - 094301_5, 2014/09
Nagai, Yuki; Ota, Yukihiro; Machida, Masahiko
Journal of the Physical Society of Japan, 83(9), p.094722_1 - 094722_5, 2014/09
Nakano, Hiroki*; Sakai, Toru
Journal of the Physical Society of Japan, 83(10), p.104710_1 - 104710_7, 2014/09
The magnetization process of the =1/2 Heisenberg antiferromagnet on the kagome lattice is studied by the numerical diagonalization method. We successfully obtain a new result of the magnetization process of a 42-site cluster in the entire range. Our analysis clarifies that the critical behavior around one-third of the height of the saturation is different from the typical behavior of the well-known magnetization plateau in two-dimensional systems.
Kitamura, Akihiro; Imaizumi, Yoshitaka*; Yamaguchi, Masaaki; Yui, Mikazu; Suzuki, Noriyuki*; Hayashi, Seiji*
Kankyo Hoshano Josen Gakkai-Shi, 2(3), p.185 - 192, 2014/09
Annual discharge rates of radioactive cesium through selected rivers due to the Fukushima Dai-ichi Nuclear Power Plant accident were simulated by two different watershed models. One is the Soil and Cesium Transport, SACT, model which was developed by Japan Atomic Energy Agency and the other one is the Grid-Catchment Integrated Modeling System, G-CIEMS, which was developed by National Institute of Environmental Studies. We choose the Abukuma, the Ukedo, and the Niida rivers for the present study. Comparative results showed that while components and assumptions adopted in two models differ, both methods predicted the same order of magnitude estimates.
Machida, Akihiko; Saito, Hiroyuki; Sugimoto, Hidehiko*; Hattori, Takanori; Sano, Asami; Endo, Naruki*; Katayama, Yoshinori; Iizuka, Riko*; Sato, Toyoto*; Matsuo, Motoaki*; et al.
Nature Communications, 5, p.5063_1 - 5063_6, 2014/09
Iron hydride FeH, is thermodynamically stable only at high hydrogen pressure of several GPa. To investigate the hydrogenation process and hydrogen state in iron hydride, it is necessary to carry out the in-situ measurement under high pressure and high temperature. In this study, we performed the in-situ neutron diffraction measurement of Fe-D system using the high pressure neutron diffractometer PLANET in the MLF, J-PARC, and determined the deuterium occupying sites and occupancies in fcc-FeD. We found the minor occupation of tetrahedral sites under high pressure and high temperature. We considered the mechanism of the minor occupation based on the Quantum-mechanical calculation.
Kawamura, Takuma; Idomura, Yasuhiro; Miyamura, Hiroko; Takemiya, Hiroshi
Nihon Shimyureshon Gakkai Rombunshi, 6(2), p.15 - 26, 2014/09
In this paper, we propose a novel remote visualization system based on particle-based volume rendering (PBVR). The system consists of a Server, which generates particles (rendering primitives), and a Client, which process volume rendering, and particles are transferred from Server to Client. The size of particle data is determined by the resolution of rendering images, and is significantly smaller than the original volume data. The smallness of the particle data is useful also for achieving a high frame rate. In the system, Server is highly parallelized on multiple GPGPUs using a hybrid MPI-CUDA programing model. The particle generation is accelerated by two orders of magnitudes compared with CPU, and structured and unstructured volume data with a hundred million cells are processed within a second. The total performance of remote visualization is compared against a commodity visualization tool, and an order of magnitude faster processing speed is achieved.
Shinoda, Yoshihiko; Tsuchida, Shoji*; Kimura, Hiroshi*
Nippon Genshiryoku Gakkai Wabun Rombunshi, 13(3), p.94 - 112, 2014/09
Fukushima Daiichi Nuclear Power Plant accident (Fukushima accident) has brought about a great change in many people's perceptions about nuclear power plant safety. When discussing future energy options for Japan, it is important to have a full grasp of the attitude of a large number of people towards nuclear energy. The Atomic Energy Society of Japan has conducted annual questionnaire survey of 500 adults who live within 30 kilometers of Tokyo Station. The aim of this survey is to assess trends in public attitude towards nuclear energy. The authors that designed the questionnaire entries of this survey have been managing questionnaire data as members of the Data Management Working Group under the Social and Environmental Division of the Atomic Energy Society of Japan. We confirmed the change in public attitude towards nuclear energy through this periodical survey after the Fukushima accident. In particular, public concerns about the use of nuclear energy increased after the Fukushima accident, and many people have raised doubts over the use of nuclear energy in the future.
Mukai, Kazuo; Arai, Masanobu; Ito, Kazuhiro; Okawachi, Yasushi
Nippon Genshiryoku Gakkai-Shi, 56(9), p.554 - 560, 2014/09
Tanaka, Masaaki; Takaya, Shigeru; Fujisaki, Tatsuya*
Nippon Kikai Gakkai Kanto Shibu Ibaraki Koenkai 2014 Koen Rombunshu, p.203 - 204, 2014/09
As flow-induced vibration (FIV) in the hot-leg piping with the short elbow (curvature radius corresponds to diameter) is one of the targeted issues in this study, numerical estimation method for dynamic analysis of mechanical stress on piping has been developed. As the preliminary step in development of the fluid-structure mechanical interaction simulation method, time history response analysis of piping by using the time history data of fluid pressure obtained by the unsteady hydraulics simulation as its boundary condition was attempted. Through the numerical results, potential capability of the dynamic analysis of piping were confirmed and unsteady behavior of pipe due to the unsteady flow phenomena was analyzed.
Sihver, L.*; Kohama, Akihisa*; Iida, Kei*; Oyamatsu, Kazuhiro*; Hashimoto, Shintaro; Iwase, Hiroshi*; Niita, Koji*
Nuclear Instruments and Methods in Physics Research B, 334, p.34 - 39, 2014/09
Accurate calculations of the nucleon + nucleus and nucleus + nucleus total reaction cross sections are of great importance for designing accelerator facilities and estimating dose in particle therapy with particle and heavy ion transport calculations, because the probability of nuclear reactions in the calculations depends on the cross sections. The Kurotama model assumes a target nucleus to be Black Sphere (BS), and gives the total reaction cross sections systematically using its radius determined from proton-nucleus elastic scattering data. However, the BS model breaks down below around 100 MeV/u. In this study, we developed the "hybrid Kurotama" model by connecting the BS model to the semi-empirical model of Tripathi et al. at low energies. The model has been tested against available p + He, p + nucleus, and nucleus + nucleus data and an overall better agreement has been found than for earlier published models. This model is suitable to be used in particle transport calculations.
Owada, Kenji; Mizuki, Junichiro*; Matsushita, Mitsuyoshi*; Namikawa, Kazumichi*
Physical Review B, 90(10), p.104109_1 - 104109_12, 2014/09
The paraelectric (PE) to ferroelectric (FE) first-order phase transition of 0.91Pb(ZnNb)O-0.09PbTiO ( = 455 K on cooling) has been studied by the complementary use of X-ray diffuse scattering (XDS) and coherent X-ray scattering (CXS). XDS was mainly used to investigate the FE regions, while CXS was mainly used to investigate the PE regions above on cooling. The diffuse scattering intensity due to the appearance of FE regions shows a maximum at K. The diffuse scattering is dynamic in nature and the softening trend changes to a hardening trend at . This means that the FE instability is maximum at and therefore the FE regions are well stabilized below . The spatial autocorrelation function obtained by CXS, corresponding to the texture of PE regions, starts to rapidly change at about and is most unstable at . We conclude that a heterophase fluctuation occurs between and near the phase transition. The heterophase fluctuation can be expected to correlate to the low-frequency dielectric dispersion and contribute to the phase transition as a precursor phenomenon of the first-order phase transition.
Shobuda, Yoshihiro; Chin, Y. H.*; Takata, Koji*
Physical Review Special Topics; Accelerators and Beams, 17(9), p.091001_1 - 091001_41, 2014/09
A new theory is developed to evaluate longitudinal and transverse impedances of any size of ceramic break that is sandwiched between metal chambers. The theory has been numerically compared with the codes ABCI and CST studio. Excellent agreements are obtained with both codes, in particular with ABCI. The theory successfully reproduces resonance structures of the impedance due to trapped modes inside the ceramic break, which are enhanced by the difference of the dielectric constants between the ceramic and the surrounding space. Moreover, the theory can evaluate the impedance of the ceramic break with Titanium Nitride coating. We discuss several characteristics of the impedances, especially the difference between the impedances of the ceramic break covered with and without a conductive wall on its outer surface.
Shobuda, Yoshihiro; Chin, Y. H.*
Physical Review Special Topics; Accelerators and Beams, 17(9), p.092801_1 - 092801_8, 2014/09
The exponentially tapered beam position monitor (BPM) has been proposed by Linnecar to produce a flat and wide-band frequency response for beam position signals. However, it still has a large ringing fluctuation on the amplitude of the transfer function. This paper aims at improving the overall characteristics of the transfer function. With the help from the window function theory, we investigate the correlation between the shape of the electrode and the resulting transfer function. Finally, we propose a polynomial shape for the electrode that provides a much flatter response function. Three-dimensional results using the CST STUDIO are also presented to demonstrate the validity of the polynomial shape even in more realistic conditions.
Sanetullaev, A.*; Tsang, M. B.*; Lynch, W. G.*; Lee, J.*; Bazin, D.*; Chan, K. P.*; Coupland, D.*; Hanzl, V.*; Hanzlova, D.*; Kilburn, M.*; et al.
Physics Letters B, 736, p.137 - 141, 2014/09
Petoussi-Henss, N.*; Bolch, W. E.*; Eckerman, K. F.*; Endo, Akira; Hertel, N.*; Hunt, J.*; Menzel, H. G.*; Pelliccioni, M.*; Schlattl, H.*; Zankl, M.*
Physics in Medicine and Biology, 59(18), p.5209 - 5224, 2014/09
ICRP Publication 116 (ICRP116) on "Conversion Coefficients for Radiological Protection Quantities for External Radiation Exposures", provides fluence-to-dose conversion coefficients for organ absorbed doses and effective dose for external exposures. ICRP116 supersedes the ICRP74, expanding also the particle types and energy ranges considered. The coefficients were calculated using the ICRP/ICRU computational phantoms representing the Reference Adult Male and Reference Adult Female, together with Monte Carlo codes simulating the radiation transport in the body. Idealised whole-body irradiation from unidirectional and rotational parallel beams as well as isotropic irradiation was considered. Comparison of the effective doses with operational quantities revealed that the latter quantities continue to provide a good approximation of effective dose for photons, neutrons and electrons for the conventional energy ranges considered previously, but not at the higher energies of ICRP116.
Physics of Plasmas, 21(9), p.092508_1 - 092508_10, 2014/09
In fusion plasmas, the impact of the higher-order flows in the moment approach of the neoclassical transport theory on an estimate of the friction coefficients is examined multilaterally. Their effects have not been consistently taken into account thus far in the widely used neoclassical transport codes based on the moment equations when diffusivities are calculated in the collision-dominated Pfirsch-Schlter regime. Due to the matrix element expressions applicable to arbitrary mass and temperature ratios and the rigorous way of numerically calculating the higher-order flows and the resultant friction coefficients, it is clearly revealed that incorporating the higher-order flow effects precisely is of great importance especially for plasmas including multiple hydrogenic ions and other lighter species with similar masses.
Sakamoto, Kan*; Shibata, Hiroki; Une, Katsumi*; Ouchi, Atsushi*; Aomi, Masaki*; Kurata, Masaki
Proceedings of 2014 Water Reactor Fuel Performance Meeting/ Top Fuel / LWR Fuel Performance Meeting (WRFPM 2014) (USB Flash Drive), 7 Pages, 2014/09
The depth profiles of hydrogen were measured at outer surface of fuel claddings corroded in high temperature steams at 1073-1473 K to examine the barrierness of surface oxide layer against the hydrogen absorption/desorption. The results indicated that the oxide layer would be no longer the barrier against the hydrogen under some conditions although it remained as the barrier against the oxidation.
Ueno, Fumiyoshi; Komatsu, Atsushi; Igarashi, Takahiro; Yamamoto, Masahiro
Proceedings of European Corrosion Congress 2014 (EUROCORR 2014) (USB Flash Drive), 10 Pages, 2014/09
In this paper, the effect of phosphorous concentration in grain boundary (GB) on intergranular corrosion (IC) progress was studied to understand GB corrosion behavior of stainless steels in boiling nitric acid solution. Phosphorus (P) added extra high purity type 310 stainless alloy was corroded in boiling nitric acid solution, and P in GB was detected by three-dimensional atom probe. IC progress considering with P profile in GB was studied by numerical simulation using cellular automaton method. As the results, we concluded that P concentration change around 1.4at% in GB of the alloy caused IC rate change in boiling nitric acid solution. The developed numerical method could simulate GB corrosion change with P distribution in GB.
Kugo, Teruhiko; Sugino, Kazuteru; Uematsu, Mari Mariannu; Numata, Kazuyuki*
Proceedings of International Conference on the Physics of Reactors; The Role of Reactor Physics toward a Sustainable Future (PHYSOR 2014) (CD-ROM), 12 Pages, 2014/09
The present paper summarizes calculation results for an international benchmark proposed under the framework of the Working Party on scientific issues of Reactor Systems (WPRS) of the Nuclear Energy Agency of the OECD. It focuses on the large size oxide-fueled SFR. Library effect for core performance characteristics and reactivity feedback coefficients is analyzed using sensitivity analysis. The effect of ultra-fine energy group calculation in effective cross section generation is also analyzed. The discrepancy is about 0.4% for a neutron multiplication factor by changing JENDL-4.0 with JEFF-3.1. That is about -0.1% by changing JENDL-4.0 with ENDF/B-VII.1. The main contributions to the discrepancy between JENDL-4.0 and ENDF/B-VII.1 are Pu capture, U inelastic scattering and Pu fission. Those to the discrepancy between JENDL-4.0 and JEFF-3.1 are Na inelastic scattering, Fe inelastic scattering, Pu fission, Pu capture, Pu fission, U inelastic scattering, Pu fission and Pu nu-value. As for the sodium void reactivity, JEFF-3.1 and ENDF/B-VII.1 underestimate by about 8% compared with JENDL-4.0. The main contributions to the discrepancy between JENDL-4.0 and ENDF/B-VII.1 are Na elastic scattering, Na inelastic scattering and Pu fission. That to the discrepancy between JENDL-4.0 and JEFF-3.1 is Na inelastic scattering. The ultra-fine energy group calculation increases the sodium void reactivity by 2%.
Proceedings of International Conference on the Physics of Reactors; The Role of Reactor Physics toward a Sustainable Future (PHYSOR 2014) (CD-ROM), 11 Pages, 2014/09
A burnup sensitivity analysis solver based on generalized perturbation theory has been developed in a multi-purpose analysis framework MARBLE. The new solver has capability to calculate sensitivity coefficients based on the diffusion theory for transmuted nuclear fuel composition after burnup, i.e. atomic number density, with respect to nuclear data not only in 2-dimensional R-Z model but also in 3-dimensional Hexagonal-Z model. In the present paper, a new numerical verification method named component-wise direct calculation is proposed to check the results of each term. A numerical experiment of the new verification method was performed, and it shows that the new verification method is valid. In addition, a sample application result is shown in order to evaluate calculation model effects due to difference between 2- and 3-dimensional models.
Takano, Kazuya; Mori, Tetsuya; Kishimoto, Yasufumi; Hazama, Taira
Proceedings of International Conference on the Physics of Reactors; The Role of Reactor Physics toward a Sustainable Future (PHYSOR 2014) (CD-ROM), 13 Pages, 2014/09
This paper describes details of the IAEA/CRP benchmark calculation by JAEA on the control rod withdrawal test in the Phenix End-of-Life Experiments. The power distribution deviation by the control rod insertion/withdrawal, which is the major target of the benchmark, is well simulated by calculation. In addition to the CRP activities, neutron and photon transport effect is evaluated in the nuclear heating calculation of the benchmark analysis. It is confirmed that the neutron and photon transport effect contributes to the improvement of the absolute power calculation results in the breeder blanket region.
Pascal, V.*; Prulhire, G.*; Vanier, M.*; Fontaine, B.*; Devan, K.*; Chellapandi, P.*; Kriventsev, V.*; Monti, S.*; Mikityuk, K.*; Chenu, A.*; et al.
Proceedings of International Conference on the Physics of Reactors; The Role of Reactor Physics toward a Sustainable Future (PHYSOR 2014) (CD-ROM), 16 Pages, 2014/09
2009年に仏Phenix炉のEnd of Life試験において、定格出力時における制御棒の非対称引抜が径方向出力分布に与える影響を目的とする「制御棒引抜試験」が実施された。IAEAのTWG-FR(高速炉技術作業部会)において本試験に対するベンチマーク解析を実施するための共同研究プロジェクト(CRP)が立ち上げられ、CEA, ANL, IGCAR, IPPE, IRSN,原子力機構, KIT, PSIから専門家が参加し本CRPを進めている。ここでは、「制御棒引抜試験」の概要及び制御棒非対称引抜に伴う出力分布変化に対する測定結果について述べるとともに、本CRPにて得られた解析結果を基に、測定結果との差及び解析結果同士の差の要因について考察する。
Proceedings of International Conference on the Physics of Reactors; The Role of Reactor Physics toward a Sustainable Future (PHYSOR 2014) (CD-ROM), 13 Pages, 2014/09
Monte Carlo analysis has been performed to investigate the impact of the exact resonance elastic scattering model on the Doppler reactivity coefficient for the UO pin cell geometry with the parabolic temperature profile. As a result, the exact scattering model affects the coefficient similarly for both the flat and parabolic temperature profiles; it increases the contribution of uranium-238 (U) resonance capture in the energy region from 16 eV to 150 eV and does uniformly in the radial direction. Then the following conclusions hold for both the exact and asymptotic resonance scattering models. The Doppler reactivity coefficient is well reproduced with the definition of the effective fuel temperature (equivalent flat temperature) proposed by Grandi et al.
Uematsu, Mari Mariannu; Kugo, Teruhiko; Numata, Kazuyuki*
Proceedings of International Conference on the Physics of Reactors; The Role of Reactor Physics toward a Sustainable Future (PHYSOR 2014) (CD-ROM), 15 Pages, 2014/09
In the frame work of the working party on reactor and system (WPRS) of the OECD/NEA, the benchmark on SFR was conducted. Within the OECD/NEA/WPRS benchmark, study on medium size metallic fuel core was performed using a code system for fast reactor core calculation with deterministic method MARBLE and with a Monte Carlo method MVP. The latest nuclear library JENDL-4.0 is used for evaluation of eigenvalues (k) and reactivity (sodium void, Doppler and control rod worth) calculations. Depletion calculations are conducted using MARBLE/BURNUP with deterministic method for flux calculation and MVP-BURN with Monte Carlo method. The analysis results and discrepancies between different analysis methods are summarized in this paper. Sensibility studies of eigenvalue and sodium void reactivity of the medium size metallic fuel benchmark core are also conducted to determine the main reactions contributing to the difference between JENDL-4.0 and other libraries JEFF-3.1 and ENDF/B-VII.
Proteins: Structure, Function, and Bioinformatics, 82(9), p.1985 - 1999, 2014/09
Proteasome is involved in the degradation of proteins. Proteasome activators bind to the proteasome core particle (CP) and facilitate opening a gate of the CP, where Tyr8 and Asp9 in the N-termini tails of the CP form the ordered open gate. Four different molecular dynamics simulations were carried out: ordered- and Tyr8Gly/Asp9Gly disordered-gate models of the CP complexed with an ATP-independent PA26 and ordered- and disordered-gate models of the CP complexed with an ATP-dependent PAN-like activator. In the ordered-gate models, the substrate in the activator was more stable than that in the CP. In the disordered-gate models, the substrate in the activator was more destabilized than in the ordered-gate models. Thus, it was concluded that the dynamics of the N-termini tails entropically play a key role in the translocation of the substrate.
Kawachi, Tetsuya; Nishikino, Masaharu; Daido, Hiroyuki
Purazuma, Kaku Yugo Gakkai-Shi, 90(9), P. 579, 2014/09
2014年5月25日から30日に米国コロラド州フォートコリンズのコロラド州立大学において第14回X線レーザー国際会議(International Conference on X-Ray Lasers 2014: ICXRL 2014)が開催された。本国際会議は、1980年代から30年近くにわたって世界各地で隔年開催されてきた。今回の参加者は、米国を中心にヨーロッパ諸国, 日本, 韓国, 中国等より約90名であった。この国際会議では、レーザー励起プラズマを用いた軟X線レーザーだけでなく、超短パルスレーザーによる高次高調波や相対論的プラズマからの軟X線放射やX線自由電子レーザー等のコヒーレントX線源の開発とその利用技術を専門とする世界中の研究者が集まり、最新の成果報告と議論が行われた。これらの内容について報告する。
Kai, Takeshi; Yokoya, Akinari; Ukai, Masatoshi*; Fujii, Kentaro; Higuchi, Mariko; Watanabe, Ritsuko
Radiation Physics and Chemistry, 102, p.16 - 22, 2014/09
Ban, Yasutoshi; Hakamatsuka, Yasuyuki; Tsutsui, Nao; Urabe, Shunichi; Hagiya, Hiromichi; Matsumura, Tatsuro
Radiochimica Acta, 102(9), p.775 - 780, 2014/09
Optical absorption spectra of Np in 3 mol/dm nitric acid at elevated temperatures were measured using an optical glass cell with a water jacket having a light path of 1 cm, and molar extinction coefficients of Np(VI), , were obtained at various temperature. The values of was found to decrease with increasing the temperature, and could be described by the equation = -0.14+85.5, where is the temperature. Oxidation of Np(V) to Np(VI) in 3 mol/dm nitric acid at elevated temperatures was observed using the optical glass cell. Oxidation of Np(V) proceeded as pseudo-first order with respect to Np(V) concentration. The rate equation in the temperature range of 336-362 K was obtained as follows: -d[Np(V)]/dt = 2.210 exp[-6510/()][Np(V)], where and [Np(V)] indicate the gas constant and Np(V) concentration at time , respectively.
Shinka O Tsuzukeru Kozo Seibutsugaku; Aratana Tampakushitsu Kino No Kaimei To Soshutsu, p.93 - 109, 2014/09
Li, D. X.*; Yamamura, Tomoo*; Nimori, Shigeki*; Homma, Yoshiya*; Honda, Fuminori*; Haga, Yoshinori; Aoki, Dai*
Solid State Communications, 193, p.6 - 10, 2014/09
We present the large reversible magneto caloric effect of the ferromagnetic semiconductor EuS which shows a maximum magnetic entropy change of 37 J/K kg at 10.4 K, an adiabatic temperature change of 10.4 K and a relative cooling power of 782 J/kg at 18.5 K for a magnetic field change of 5 T. The present results indicate that EuS has excellent refrigeration performance at the temperatures near 20 K, and thus can be considered as the potential magnetic refrigerant material for liquefaction of hydrogen.
Yoneda, Yasuhiro; Aoyagi, Rintaro*; Fu, D.*; Takenaka, Tadashi*
Transactions of the Materials Research Society of Japan, 39(3), p.247 - 250, 2014/09
BiNaTiO and NaNbO are O perovskite ferroelectric materials and they are considered to be promising lead-free ferroelectric materials because of their relatively high piezoelectric properties in lead-free piezoelectric ceramics. The purpose of this work was to clarify the local structures of Li-substituted BiNaTiO and NaNbO to elucidate the mechanism of the stabilization of the ordered ferroelectric phase.
Yoshida, Kensuke*; Fujioka, Shinsuke*; Higashiguchi, Takeshi*; Ugomori, Teruyuki*; Tanaka, Nozomi*; Ohashi, Hayato*; Kawasaki, Masato*; Suzuki, Yuhei*; Suzuki, Chihiro*; Tomita, Kentaro*; et al.
Applied Physics Express, 7(8), p.086202_1 - 086202_4, 2014/08
We demonstrate high conversion efficiency for extreme ultraviolet (EUV) emission at 6.5-6.7 nm from multiple laser beam-produced one-dimensional spherical plasmas. Multiply charged-state ions produce strong resonance emission lines, which combine to yield intense unresolved transition arrays in Gd, Tb, and Mo. The maximum in-band EUV conversion efficiency was observed to be 0.8%, which is one of the highest values ever reported due to the reduction of plasma expansion loss.
ESI-News, 32(4), p.155 - 162, 2014/08
This report compiled the information on distribution and mode of occurrence of uranium deposit was compiled from the published data. Distribution of uranium deposit suggests that geological environments suitable for geological isolation are widely distributed in the Japanese Islands, despite their location in a geologically active area. The mode of occurrence of the uranium deposits indicates that formation of uranium-bearing mineral as well as sorption is expected in both sedimentary and crystalline rocks. The functioning of the natural barrier would be expected in various geological environments in the Japanese Islands, because mineralization and sorption are regarded as a barrier function to retard the migration of radionuclides in HLW, and because of the uranium deposits in the various rock types.
Kato, Aitaro*; Saiga, Atsushi; Takeda, Tetsuya*; Iwasaki, Takaya*; Matsuzawa, Toru*
Earth, Planets and Space (Internet), 66, p.86_1 - 86_8, 2014/08
To understand the mechanism of an intensive non-volcanic seismic swarm in the Kii Peninsula, Japan, we used a dense seismic linear array to measure fine-scale variations of seismic velocities and converted teleseismic waves. A low-velocity anomaly confined to just beneath the seismic swarm area is clearly imaged, which spatially correlates with an uplifted surface area, and a highly conductive and strong attenuative body. These results suggest that fluids such as partial melt or water are present beneath this non-volcanic seismic swarm area. It is notable that the island arc Moho below the seismic swarm area is at depths of ca. 32 km in the northern part of the seismic swarm area, and shallows to ca. 20 km towards the south, due to an upwardly raised structure of serpentinized mantle wedge. In addition, we show that hydrated oceanic crust of the subducting Philippine Sea slab is characterized by low-velocities with a high Poisson's ratio at depths shallower than 40 km. Water released from the subducting oceanic crust could cause serpentinization of the mantle wedge and infiltration into the forearc base of the overlying plate. The interaction between dehydration of the subducting oceanic crust and hydration of the mantle wedge and overlying plate exerts an important role in driving the non-volcanic seismic swarm activity in the Kii Peninsula.
Hikari Araiansu, 25(8), p.47 - 51, 2014/08
Mizuta, Eiichi*; Kuboyama, Satoshi*; Abe, Hiroshi; Iwata, Yoshiyuki*; Tamura, Takashi*
IEEE Transactions on Nuclear Science, 61(4), p.1924 - 1928, 2014/08
Radiation effects in silicon carbide power MOSFETs caused by heavy ion and proton irradiation were investigated. In the case of ions with high LET, permanent damage (increase in both drain and gate leakage current with increasing LET) was observed and the behavior is similar to the permanent damage observed for SiC Schottky Barrier diodes in our previous study. In the case of ions with low LET, including protons, Single Event Burnouts (SEBs) were observed suddenly although there was no increase in leakage current just before SEBs. The behavior has not been observed for Si devices and thus, the behavior is unique for SiC devices.
Isotope News, (724), p.82 - 85, 2014/08
Baba, Motoyoshi*; Nishikino, Masaharu; Hasegawa, Noboru; Tomita, Takuro*; Minami, Yasuo*; Takei, Ryota*; Yamagiwa, Mitsuru; Kawachi, Tetsuya; Suemoto, Toru
Japanese Journal of Applied Physics, 53(8), p.080302_1 - 080302_4, 2014/08
A grazing incidence reflection-type soft X-ay microscope, using a Fresnel zone plate and a soft X-ray laser with wavelength 13.9 nm and pulse width 7 ps, was developed. Submicron size groove structures made on a Pt film were clearly captured at a single shot exposure, with spatial resolution of about 360 nm. A wide field view of 100 m square was secured under the Kohler illumination. This microscope also had a large depth of focus of more than 100 m and was proven to have a sufficient performance for observing surface morphological changes.
Awual, M. R.; Yaita, Tsuyoshi; Taguchi, Tomitsugu; Shiwaku, Hideaki; Suzuki, Shinichi; Okamoto, Yoshihiro
Journal of Hazardous Materials, 278, p.227 - 235, 2014/08
Conjugate materials can provide chemical functionality, enabling an assembly of the ligand complexation ability to metal ions that are important for applications, such as separation and removal devices. In this study, we developed ligand immobilized conjugate adsorbent for selective cesium (Cs) removal from wastewater. The adsorbent was synthesized by direct immobilization of DB24C8 onto inorganic mesoporous silica. The obtained results revealed that adsorbent had higher selectivity towards Cs even in the presence of a high concentration of Na and K and this is probably due to the Cs- interaction of the benzene ring. The proposed adsorbent was successfully applied for radioactive Cs removal to be used as the potential candidate in Fukushima nuclear wastewater treatment. The adsorbed Cs was eluted with suitable eluent and simultaneously regenerated into the initial form for the next removal operation after rinsing with water.
Kato, Masato; Uchida, Teppei; Matsumoto, Taku; Sunaoshi, Takeo*; Nakamura, Hiroki; Machida, Masahiko
Journal of Nuclear Materials, 451(1-3), p.78 - 81, 2014/08
Linear thermal expansion of PuO was measured by dilatometry in an oxygen partial pressure-controlled atmosphere. The measured data of PuO slightly increased with deviation . The linear thermal expansion of PuO was determined as a function of temperature and O/M ratio, and the equation for the thermal expansion coefficient was derived. Heat capacity of PuO was evaluated using this equation. The effect of O/M ratio on heat capacity was small. In addition to the vibration and dilatational terms, it is important to analyze the Schottky term in evaluating heat capacity of PuO.
Ikeda, Takashi; Hou, Z.*; Chai, G.-L.*; Terakura, Kiyoyuki*
Journal of Physical Chemistry C, 118(31), p.17616 - 17625, 2014/08
N-doped carbon-based nanomaterials are attracting a great interest as promising Pt-free electrode catalysts for polymer electrolyte fuel cells (PEFCs). In this computational study, we demonstrate that N-doped graphene edges can exhibit enhanced catalytic activity toward oxygen reduction reactions by controlling their electron-donating and -withdrawing abilities, and basicity, resulting in higher selectivity of 4e reduction via inner and outer sphere electron transfer at edges in acidic conditions, respectively. Our simulations also show that 2e reduction occurs selectively in the presence of pyridinic N next to carbonyl O at zigzag edges. This study thus rationalizes the roles of doped N in graphenelike materials for oxygen reduction reactions.
Hou, Z.*; Shu, D.-J.*; Chai, G.-L.*; Ikeda, Takashi; Terakura, Kiyoyuki*
Journal of Physical Chemistry C, 118(34), p.19795 - 19805, 2014/08
In most of the N-doped graphene which attracts strong attention in the context of precious-metal free catalysts and nanoelectronics, the oxygen content is generally higher than or at least comparable to the nitrogen content. We perform density functional theory calculations to study the interplay of oxidized monovacancies and the nitrogen doping, motivated by the fact that MV is more frequently observed and more chemically active than divacancy and Stone-Wales defect. We determine the phase diagrams of un-doped and nitrogen-doped oxidized MVs as a function of temperature and partial pressure of O and H gases. The modification of the electronic structure of MV by oxidation and N doping is studied. Our results show that the ether group is a common component in stable configurations of oxidized MVs. Most of the stable configurations of oxidized MVs do not induce any carriers.
Shibata, Hiroki; Hayashi, Hirokazu; Akabori, Mitsuo; Arai, Yasuo; Kurata, Masaki
Journal of Physics and Chemistry of Solids, 75(8), p.972 - 976, 2014/08
Gibbs free energies of formation of six Ce-Cd intermetallic compounds, CeCd, CeCd, CeCd, CeCd, CeCd and CeCd, were evaluated systematically using electrochemical techniques in the temperature range from 673 to 923 K in the LiCl-KCl-CeCl-CdCl molten salt bath. The linear dependence of the Gibbs free energies of formation on temperature yields to the enthalpies and entropies of formation of these intermetallic compounds. By extrapolating the molar Gibbs free energy of Ce-Cd intermetallic compounds to the Cd distillation temperature, it was clear that the molar Gibbs free energy of Ce in Ce-Cd intermetallic compounds decreases gradually from CeCd to CeCd and attains to the minimum value at CeCd. This suggests on the Cd distillation from the U-Pu-Ce-Cd alloy that the dissolution of U or Pu into CeCd should be mostly taken into consideration.
Ando, Masanori; Hirose, Yuichi*; Karato, Takanori*; Watanabe, Sota*; Inoue, Osamu*; Kawasaki, Nobuchika; Enuma, Yasuhiro*
Journal of Pressure Vessel Technology, 136(4), p.041406_1 - 041406_10, 2014/08
To compare and assess the creep-fatigue life evaluation methods for stress concentration point, a series of creep-fatigue test was performed with notched specimens made of Mod.9Cr-1Mo steel. Mechanical creep-fatigue tests and thermal creep-fatigue test were performed. A series of Finite Element Analysis was also carried out to predict the number of cycles to failure by the several creep-fatigue life evaluation methods. Then these predictions were compared with the test results. Several types of evaluation methods such are stress redistribution locus (SRL) method, simple elastic follow-up method and the methods described in the JSME FRs code were applied. Through the comparisons, it was appeared that SRL method gave rational conservative prediction of the creep-fatigue life for all conditions tested in this study. The JSME FRs code gave an evaluation over 70 times conservative lives comparing with the test results.
Nakano, Hiroki*; Sakai, Toru; Hasegawa, Yasumasa*
Journal of the Physical Society of Japan, 83(8), p.084709_1 - 084709_7, 2014/08
Motivated by a recent finding of a spin-flop phenomenon in a system without anisotropy in spin space reported in the = 1/2 Heisenberg antiferromagnet on the square-kagome lattice, we study the = 1/2 Heisenberg antiferromagnets on two other lattice composed of vertex-sharing triangles using the numerical diagonalization method. One is a novel lattice including a shape with four teeth; the other is a distorted kagome lattice, which includes a shape with six teeth. We find in the magnetization processes of these systems that a magnetization jump accompanied by a spin-flop phenomenon occurs at the higher-field-side edge of the magnetization plateau at one-third the height of saturation.
Saito, Hiroyuki; Kato, Seiichi*; Katagiri, Masahiko*
Materials Transactions, 55(8), p.1114 - 1116, 2014/08
Anodized aluminum samples with different surface oxide layer thicknesses (approximately 0.3 and 3 m) were hydrogenated at 9 GPa and 600C for 24 h. A few large crystals of AlH, less than 50 m in particle size, were formed when the aluminum sample with the thicker oxide layer was hydrogenated, whereas the sample with the thinner oxide layer was uniformly hydrogenated to form AlH crystals less than 10 m in particle size. It is likely that the surface oxide layer inhibits not only the hydrogenation reaction of aluminum but also the spontaneous nucleation of AlH.
Cheng, S.; Tagami, Hirotaka; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu; Nakamura, Yuya*; Takeda, Shohei*; Nishi, Shimpei*; Zhang, B.*; Matsumoto, Tatsuya*; et al.
Mechanical Engineering Journal (Internet), 1(4), p.TEP0022_1 - TEP0022_16, 2014/08
To clarify the mechanisms underlying the debris-bed self-leveling behavior, several series of experiments were elaborately designed and conducted within a variety of conditions in recent years, under the collaboration between Japan Atomic Energy Agency (JAEA) and Kyushu University. The current contribution, including knowledge from both experimental analyses and empirical model development, is focused on a recently developed comparatively larger-scale experimental facility using gas-injection to simulate the coolant boiling. Based on the experimental observation and quantitative data obtained, influence of various experimental parameters, including gas flow rate ( 300 L/min), water depth (180 mm and 400 mm), bed volume (3 7 L), particle size (1 6 mm), particle density (beads of alumina, zirconia and stainless steel) along with particle shape (spherical and irregularly-shaped) on the leveling is checked and compared. As for the empirical model development, aside from a base model which is restricted to calculations of spherical particles, the status of potential considerations on how to cover more realistic conditions (esp. debris beds formed with non-spherical particles), is also presented and discussed.
Yamano, Hidemasa; Tobita, Yoshiharu
Mechanical Engineering Journal (Internet), 1(4), p.TEP0028_1 - TEP0028_17, 2014/08
This paper describes experimental analyses using SIMMER-III/IV, which are two/three-dimensional multi-component multi-phase Eulerian fluid-dynamics codes, for the purpose of the code validation. Two topics of key phenomena in core disruptive accidents were presented in this paper: duct-wall failure and fuel discharge/relocation behavior. These experimental analyses indicated the validity of the SIMMER-III/IV computer code for the duct wall failure and fuel discharge/relocation behavior.
Takeda, Takeshi; Nakamura, Hideo
Mechanical Engineering Journal (Internet), 1(4), p.TEP0015_1 - TEP0015_13, 2014/08
RELAP5 code analysis was performed on one of abnormal transient tests conducted with the ROSA/LSTF simulating a PWR station blackout transient with TMLB' scenario in 1995. The LSTF test revealed core uncovery by core boil-off took place a little after hot leg became empty of liquid. The code indicated remaining problems in the predictions of reverse flow U-tubes in SG during long-term single-phase liquid natural circulation. Sensitivity analyses were performed to clarify effectiveness of depressurization of and coolant injection into SG secondary-side as accident management measures. SG secondary-side depressurization was initiated by fully opening the safety valve in one of two SGs with incipience of core uncovery. Coolant injection was done into the secondary-side of the same SG at low pressures considering availability of fire engines. The SG depressurization with the coolant injection was found to well contribute to maintain core cooling by the actuation of accumulator system.
Iigaki, Kazuhiko; Ono, Masato; Shimazaki, Yosuke; Tochio, Daisuke; Shimizu, Atsushi; Inoi, Hiroyuki; Takada, Shoji; Sawa, Kazuhiro
Mechanical Engineering Journal (Internet), 1(4), p.TEP0021_1 - TEP0021_13, 2014/08
On March 11th, 2011, the Great East Japan Earthquake which is one of the largest earthquakes in japan occurred and the maximum acceleration in observed seismic wave in the HTTR exceeded the design value in a part of input seismic motions. Therefore, a visual inspection, a seismic analysis and a performance confirmation test of facilities were carried out in order to confirm the integrity of facility after the earthquake. The seismic analysis was carried out for the reactor core structures by using the response magnification factor method. As the results of the evaluation, the generated stress in the graphite blocks in the reactor core at the earthquake were well below the allowable values of safety criteria, and thus the structural integrity of the reactor core was confirmed. The integrity of reactor core was also supported by the visual inspections of facilities and the operation without reactor power in cold conditions of HTTR.
Akita, Koichi; Hayashi, Kengo*; Takeda, Kazuya*; Sano, Yuji*; Suzuki, Hiroshi; Moriai, Atsushi; Oya, Shinichi*
Mechanical Engineering Journal (Internet), 1(4), p.SMM0029_1 - SMM0029_8, 2014/08
Compressive residual stresses induced by peening techniques improve the strength properties of steels, such as fatigue and stress corrosion cracking. However, the compressive residual stress might be reduced owing to thermal and mechanical loading in-service. In this study, the behavior of surface and internal residual stresses of a laser-peened ferritic steel under quasi-static tensile loading was investigated by X-ray and neutron diffraction. The complementary use of these diffraction techniques provided decisive experimental evidence for elucidating the relaxation process. The critical applied stress of peened samples subjected to a tensile loading can be estimated from the von Misses yield criterion with the maximum tensile residual stress inside the sample.
Yoshida, Hiroyuki; Nagatake, Taku; Takase, Kazuyuki; Kaneko, Akiko*; Monji, Hideaki*; Abe, Yutaka*
Mechanical Engineering Journal (Internet), 1(4), p.TEP0025_1 - TEP0025_11, 2014/08
In this study, to develop the predictive technology of two-phase flow dynamics under earthquake acceleration, a detailed two-phase flow simulation code with an advanced interface tracking method TPFIT was expanded. In addition, the bubbly flow in a horizontal pipe excited by oscillation acceleration and under the fluctuation of the liquid flow was simulated by using the modified TPFIT. In the results, it was confirmed that the modified TPFIT can predict time dependent velocity distribution around the bubbles and shapes of bubbles qualitatively. The main cause of bubble deformation observed is large shear stress at the lower part of the bubble, and this large shear stress is induced by the velocity difference between the liquid phase and bubble. Moreover, we discussed about the difference between both effects of flow rate fluctuation and structure vibration on two-phase flow. In the results, bubble acceleration of the structure vibration case was larger than that of the flow rate fluctuation case. Finally, it was concluded that unsteady shear stress induced by vibration of the pipe wall was one of the main driving forces of bubble motion in structure vibration case.
Horiguchi, Naoki; Yoshida, Hiroyuki; Kaneko, Akiko*; Abe, Yutaka*
Mechanical Engineering Journal (Internet), 1(4), p.TEP0026_1 - TEP0026_11, 2014/08
As revealed by Fukushima Daiichi nuclear disaster, countermeasures against severe accident in nuclear power plants are an urgent need. In particular, from the viewpoint of protecting containment and suppressing the diffusion of radioactive materials, it is important to develop a device which allows filtered venting of contaminated high pressure gas. In the filtered venting system that used in European reactors, so called Multi Venturi Scrubbers System is used to realize filtered venting without any power supply. This system is able to define to be composed of Venturi Scrubbers (VS) and a bubble column. In the VS, scrubbing of the contaminated gas is promoted by both gas releases through a submerged VS and gas-liquid contact with splay flow formed by liquid suctioned through a hole provided in the throat part of the VS. This type of VS is called self-priming ones. However, the mechanism of the self-priming VS are understood insufficiently in the previous studies. In this study, to understand operation characteristics of the VS for filtered venting, we discussed the mechanisms of self-priming phenomena and hydraulic behavior in the VS. In this paper, we conduct visualized observation of the hydraulic behavior in the VS and measure the liquid flow rate in the VS for understanding self-priming. As results, it is shown that the possibility that the VS decontamination performance falls low level with no self-priming.
Yokoyama, Keiichi; Matsuoka, Leo*
Nippon Genshiryoku Gakkai-Shi, 56(8), p.525 - 528, 2014/08
With respect to the isotope separation of cesium, one of the long-lived fission products, the background, principle, feasibility, and research activity in Kansai Photon Science Institute are described.
Ishiyama, Shintaro; Baba, Yuji; Fujii, Ryo*; Nakamura, Masaru*; Imahori, Yoshio*
Nippon Kinzoku Gakkai-Shi, 78(8), p.317 - 321, 2014/08
Low temperature synthesis of lithium-nitride compound was conducted on the lithium target for BNCT by N/HO mixing gas squirt in the ultra high vacuum chamber, and the following results were derived; (1) Lithium-nitride compound was synthesized on the lithium target under 101.3 Pa N gas squirt at room temperature and in the ultra high vacuum chamber under the pressure of 110 Pa. (2) Remarkable contamination by O and C was observed on the lithium-nitride compound synthesized under the squirt pressure of 13.3-80 Pa/1.33-4.7 Pa N/HO mixing gas. (3) No contamination and synthesis of Li-N compound was observed under the squirt pressure of 0.013-0.027 Pa/0-0.005 Pa N/HO mixing gas. (4) Contamination by O and C was enhanced with excessive addition of HO at the pressure of over 1.33 Pa.
Ishiyama, Shintaro; Baba, Yuji; Fujii, Ryo*; Nakamura, Masaru*; Imahori, Yoshio*
Nippon Kinzoku Gakkai-Shi, 78(8), p.322 - 325, 2014/08
To remove high level of contaminants by O and C from LiN surface for boron neutron capture therapy target, high temperature thermal desorption was conducted up to 1123 K in ultra high vacuum and the following results were derived; (1) During thermal desorption up to 1023 K, typical three peaks of vacuum pressure disturbance due to vaporization of contaminants were observed in vacuum pressure-temperature curve. (2) Over-layered contaminants with high melting temperature below 1023 K on LiN surface is completely removed by high temperature thermal desorption up to 1123 K in ultra high vacuum. (3) From these desorption results, it is suggested that these contaminants corresponding to these vaporization peaks are HO and Li compounds with high melting temperature below 1023 K, of which LiOH and LiCO were synthesized by decomposition process of LiN with residual HO and CO in low temperature.
Ando, Masanori; Hasebe, Shinichi; Kobayashi, Sumio; Kasahara, Naoto*; Toyoshi, Akira*; Omae, Takahiro*; Enuma, Yasuhiro*
Nuclear Engineering and Design, 275, p.408 - 421, 2014/08
To clarify the failure mode of a semispherical tubesheet structure originally designed for SG in the JSFR, a cyclic thermal loading test was performed using a tubesheet model test structure. The tubesheet model made of Mod.9Cr-1Mo steel was subjected to 1,873 cycles of severe thermal transient loads using a large-scale sodium loop, in which sodium heated to 600C and 250C was flowed repeatedly with periods for each transient of 2 and 1 h, respectively. After the test, the test model was inspected by PT. Then, observation using a SEM and hardness testing were performed. A thermal-hydraulic analysis was also performed to validate the measured temperature history during the thermal transient. Through these examinations and evaluation with thermal-hydraulic analysis, the manner of failure in the tubesheet under cyclic thermal loading is discussed.
Ando, Masanori; Hasebe, Shinichi; Kobayashi, Sumio; Kasahara, Naoto*; Toyoshi, Akira*; Omae, Takahiro*; Enuma, Yasuhiro*
Nuclear Engineering and Design, 275, p.422 - 432, 2014/08
In this study, the strength of a tubesheet test model simulating a semispherical tubesheet structure subjected to cyclic thermal transients was evaluated using the finite element analysis (FEA). A test model made of Mod.9Cr-1Mo steel was subjected to 1,873 cycles of severe thermal transient loading using a large-scale sodium loop, in which elevated-temperature sodium at 600C and 250C was flowed repeatedly and kept at the final temperature for 2 and 1 h, respectively. Heat transfer analysis and stress analysis were performed using the sodium temperature data measured during the test. Then, the elastic and inelastic stress analysis results were used to investigate the failure mechanism by creep-fatigue damage and evaluate the failure strength. The evaluation based on the results of inelastic analysis estimated the number of cycles to failure within a factor of 3.
Sato, Hiroyuki; Yan, X.; Tachibana, Yukio; Kunitomi, Kazuhiko
Nuclear Engineering and Design, 275, p.190 - 196, 2014/08
Three major improvements have since been made to further increase efficiency for the GTHTR300. First, the cycle parameters are upgraded by utilizing the newly-acquired design data including those from component tests. Next, the core design is optimized to raise the reactor outlet coolant temperature from the baseline of 850C to the level of 950C demonstrated on the long-term test reactor operation. Finally, an advanced type of turbine blade material that has only recently entered in commercial service in aircraft engine is found to be useable for this design to realize a turbine inlet temperature of 950C without requiring blade cooling. These design improvements result in a nearly 5% gain in overall plant efficiency and enable the GTHTR300 to break the 50% efficiency barrier of nuclear plant while using only the existing technologies.
Cheng, S.; Matsuba, Kenichi; Isozaki, Mikio; Kamiyama, Kenji; Suzuki, Toru; Tobita, Yoshiharu
Nuclear Engineering and Design, 275, p.133 - 141, 2014/08
Analyses of severe accidents for SFRs have indicated that the accident might proceed into a transition phase where a large whole-core-scale pool containing sufficient fuel to exceed prompt criticality by fuel compaction might be formed. Local fuel-coolant interaction (FCI) in the pool is regarded as one of the probable initiators that could lead to such compactive fluid motions. To clarify the mechanisms underlying this interaction, in this study a series of experiments was conducted by delivering a given quantity of water into a simulated molten fuel pool. Based on the experimental data obtained from a variety of conditions, interaction characteristics including the pressure-buildup as well as resultant mechanical energy release and its conversion efficiency, is checked and compared. It is found that under our experimental conditions the water volume, melt temperature and water release position have remarkable impact on the interaction, while the role of water subcooling seems to be less prominent. The analyses also suggest that the pressurization and resultant mechanical energy release during local FCIs should be intrinsically limited, due to an observed suppressing role caused by the increasing of coolant volume entrapped within the pool as well as the transition of boiling mode. Evidence and data from this work will be utilized for verifications of advanced fast reactor safety analysis codes.
Shiraishi, Junya; Aiba, Nobuyuki; Miyato, Naoaki; Yagi, Masatoshi
Nuclear Fusion, 54(8), p.083008_1 - 083008_8, 2014/08
Toroidal rotation effects are self-consistently taken into account not only in the linear magnetohydrodynamic (MHD) stability analysis but also in the equilibrium calculation. The MHD equilibrium computation is affected by centrifugal force due to the toroidal rotation. To study the toroidal rotation effects on resistive wall modes (RWMs), a new code has been developed. The RWMaC modules, which solve the electromagnetic dynamics in vacuum and the resistive wall, have been implemented in the MINERVA code, which solves the Frieman-Rotenberg equation that describes the linear ideal MHD dynamics in a rotating plasma. It is shown that modification of MHD equilibrium by the centrifugal force significantly reduces growth rates of RWMs. Moreover, it can open a stable window which does not exist under the assumption that the rotation affects only the linear dynamics.
Kim, H.-S.*; Jeon, Y. M.*; Na, Y.-S.*; Ghim, Y.-C.*; Ahn, J.-W.*; Yoon, S. W.*; Bak, J. G.*; Bae, Y. S.*; Kim, J. S.*; Joung, M.*; et al.
Nuclear Fusion, 54(8), p.083012_1 - 083012_11, 2014/08
We evaluate the characteristics of global energy confinement in KSTAR () quantitatively by comparing it with multi-machine scalings, by deriving multiple regression equations for the L- and the H-mode plasmas, and evaluating confinement enhancement of the H-mode phase compared with the L-mode phase in each discharge. From the KSTAR database, of L-mode plasmas exhibits s to s and of H-mode plasmas s to s. The multiple regression equations derived by statistical analysis present the similar dependency on PL and slightly higher dependency on IP compared with the multi-machine scalings, however the dependency on elongation in both L- and H-mode plasmas draw the negative power dependency of and for H-mode and for L- mode database, respectively on the contrary to the positive dependency in all multi-machine empirical scalings. Although the reason is not clear yet, two possibilities are addressed. One is that the wall condition of KSTAR was not clean enough. The other is that striking points on the divertor plate were uncontrolled. For these reasons, as increases, the impurities from the wall can penetrate into plasmas easily. As a consequence, the confinement is degraded on the contrary to the expectation of multi-machine scalings.
Miyamoto, Seiji*; Isayama, Akihiko; Bandyopadhyay, I.*; Jardin, S. C.*; Khayrutdinov, R. R.*; Lukash, V.*; Kusama, Yoshinori; Sugihara, Masayoshi*
Nuclear Fusion, 54(8), p.083002_1 - 083002_19, 2014/08
Two well-established simulation codes, DINA and TSC, are compared with each other using benchmark scenarios in order to validate the ITER 2D disruption modelling by those codes. Although the simulation models employed in those two codes ought to be equivalent in the resistive time scale, it has long been unanswered whether the one of the two codes is really able to reproduce the other result correctly, since a large number of code-wise differences render the comparison task exceedingly complicated. In this paper, it is demonstrated that after simulations are set up accounting for the model differences, in general, a good agreement is attained on a notable level, corroborating the correctness of the code results. When the halo current generation and its poloidal path in the first wall are included, however, the situation is more complicated. Because of the surface averaged treatment of the magnetic field (current density) diffusion equation, DINA can only approximately handle the poloidal electric currents in the first wall that cross field lines. Validation is carried out for DINA simulations of halo current generation by comparing with TSC simulations, where the treatment of halo current dynamics is more justifiable. The particularity of each code is depicted and the consequence in ITER disruption prediction is discussed.
Ito, Takashi; Toyoda, Akihisa*; Higemoto, Wataru; Tajima, Minori*; Matsuda, Yasuyuki*; Shimomura, Koichiro*
Nuclear Instruments and Methods in Physics Research A, 754, p.1 - 9, 2014/08
A new muon beam profile monitor (MBPM) was developed to diagnose pulsed muon beams in J-PARC MUSE, mainly composed of a scintillation screen, a gated image intensifier (II), and a cooled CCD camera. The MBPM was designed to be compact so that it could be inserted into the bore of the SR spectrometer in the D1 area and used concurrently. The spatial resolution of the MBPM was evaluated to be in the range from one to two line-pair/mm, depending on II gain. Such high-resolution muon beam profiles were obtained online for a positive muon beam with a kinetic energy of 4 MeV. The contribution from decay positrons was significantly reduced owing to II gating. The linearity of the MBPM was evaluated on the bases of the number of decay positrons monitored by the SR spectrometer. A linear response within five percent deviations was confirmed over more than two orders of magnitude. In addition, 3D imaging capability, use in vacuum, and immunity against moderate magnetic fields were demonstrated.
Yokoyama, Akihito; Kada, Wataru*; Sato, Takahiro; Koka, Masashi; Yamamoto, Shunya; Kamiya, Tomihiro; Yokota, Wataru
Nuclear Instruments and Methods in Physics Research B, 332, p.334 - 336, 2014/08
A system is developed for the real-time position detection of single-ions which hits a target with spatial accuracy about 1 m. The system combines highly luminescent, sensitive, scintillators with a high sensitivity luminescence detection system. The real-time detection system contains a AlO:Eu scintillator, Eu implanting into -AlO. A single-crystal scintillator has been selected since position resolution of emission for powdery scintillator is limited by a grain size, several micrometers for ZnS for example. When the material is irradiated with an electron or ion beam, the Eu is activated and strong luminescence occurs. The detection system includes an image intensifier tube and an electron multiplier CCD camera. The results show that our system can be sufficiently sensitive to detect the hit of a single-ion in real time through simple improvement in emission intensity of the scintillator.
Nakajima, Kaoru*; Morita, Yosuke*; Kitayama, Takumi*; Suzuki, Motofumi*; Narumi, Kazumasa; Saito, Yuichi; Tsujimoto, Masahiko*; Isoda, Shoji*; Fujii, Yoshikazu*; Kimura, Kenji*
Nuclear Instruments and Methods in Physics Research B, 332, p.117 - 121, 2014/08
Our previous observation that an impact of sub-MeV C ion makes an ion track in a thin amorphous silicon nitride (a-SiN) film suggests emission of thousands of atoms from the cylindrical region. Sputtering yields of a-SiN films by C ions were evaluated in order to confirm this observation. A-SiN films deposited on Si(001) were irradiated with 540-keV C ions at fluences from 2.510 to 110 ions/cm. The compositional depth profiles of the irradiated samples were measured with high-resolution Rutherford backscattering spectroscopy, and the sputtering yields were estimated at 3900 500 N atoms/ion and 1500 1000 Si atoms/ion. The sputtering yield of N was two orders of magnitude larger than the elastic sputtering yield by the SRIM code or than the measured electronic sputtering yield of a-SiN by 50-MeV Cu ions previously reported. Such a large sputtering yield cannot be explained either by the elastic sputtering or by the electronic sputtering. However, an estimation of the synergistic effect based on the inelastic thermal spike model roughly explains the observed large sputtering yield, indicating that the synergistic effect of the nuclear and electronic stopping powers plays an important role.
Sakai, Takuro; Yasuda, Ryo; Iikura, Hiroshi; Nojima, Takehiro; Koka, Masashi; Sato, Takahiro; Ishii, Yasuyuki; Oshima, Akihiro*
Nuclear Instruments and Methods in Physics Research B, 332, p.238 - 241, 2014/08
We have successfully fabricated novel microscopic imaging devices made from UV/EB curable resin using an external scanning proton microbeams. The devices are micro-structured fluorescent plates that consist of an array of micro-pillars that align periodically. The base material used in the pillars is UV/EB curable resin and each pillar contains phosphor grains. The pattern exposures were performed using a proton beam writing technique. The height of the pillars depends on the range of the proton beam. Optical microscopy and scanning electron microscopy have been used to characterize the samples. The results show that the fabricated fluorescent plates are expected to be high-spatial-resolution imaging devices.
Hashimoto, Shintaro; Iwamoto, Yosuke; Sato, Tatsuhiko; Niita, Koji*; Boudard, A.*; Cugnon, J.*; David, J.-C.*; Leray, S.*; Mancusi, D.*
Nuclear Instruments and Methods in Physics Research B, 333, p.27 - 41, 2014/08
Recently, accelerator-based neutron sources have been considered for scientific research and medical applications, where deuteron-induced reactions of Li, Be, or C targets at low (50 MeV) incident energies are essential to produce high-intensity neutron beams. Description of the reactions in simulations of particle transport are required to estimate dose distributions. In this study, we developed a new method that combines the Intra-Nuclear Cascade of Lige (INCL) and Distorted Wave Born Approximation (DWBA), and incorporated it into the Particle and Heavy Ion Transport code System (PHITS). A proton-stripping process and transitions between discrete states of nuclei are considered in the method by INCL and DWBA, respectively. We applied the method to reproduce neutron spectra in the reactions on thin and thick targets. Results obtained by PHITS with the method successfully agreed with experimental data, which were not reproduced by the old model.
Oka, Kohei*; Tsuda, Yasutaka*; Makino, Takamasa*; Okada, Michio*; Hashinokuchi, Michihiro*; Yoshigoe, Akitaka; Teraoka, Yuden; Kasai, Hideaki*
Physical Chemistry Chemical Physics, 16(36), p.19702 - 19711, 2014/08
Oxidation of CuAu(111) by a hyperthermal O molecular beam was investigated by synchrotron X-ray photoemission spectroscopy. From the incident-energy dependence of O-uptake curve, dissociative adsorption of O is less effective on CuAu(111) than on Cu(111). The dissociative adsorption is accompanied by the Cu segregation on CuAu(111) as well on CuAu(100) and CuAu(110). Obvious growth of CuO cannot be observed at incident energy of 2.3 eV and it suggests that Au-rich layers prevent the diffusion of O atoms into bulk. Density functional theory calculations indicate that O adsorption shows same behavior on CuAu(111) and on Cu(111). The barrier of diffusion into subsurface in segregated CuAu(111) is higher than that of Cu(111). It indicates that segregated Au-rich layer works as a protective layer.
Nakagawa, Hiroshi; Yonetani, Yoshiteru; Nakajima, Kenji; Kawamura, Seiko; Kikuchi, Tatsuya; Inamura, Yasuhiro; Kataoka, Mikio; Kono, Hidetoshi
Physical Review E, 90(2), p.022723_1 - 022723_11, 2014/08
Molecular dynamics (MD) simulations and Quasi-Elastic Neutron Scattering (QENS) experiments were conducted on hydrated two DNA dodecamers with distinct deformability; 5'CGCGAATTCGCG3' and 5'CGCGTTAACGCG3'. The former is known to be rigid and the latter to be flexible. The mean-square displacements (MSDs) of DNA dodecamers exhibit so-called dynamical transition around 200-240 K for both sequences. To investigate the DNA sequence dependent dynamics, the dynamics of DNA and hydration water above the transition temperature were examined using both MD simulations and QENS experiments. The fluctuation amplitude of the AATT central tetramer is smaller, and its relaxation time is longer, than that observed in TTAA, suggesting that the AT step is kinetically more stable than TA. The sequence-dependent local base pair step dynamics correlate with the kinetics of breaking the hydrogen bond between DNA and hydration water. The sequence dependent DNA base pair step fluctuations appear above the dynamical transition temperature. Together with these results, we conclude that DNA deformability is related to the local dynamics of base pair step, themselves coupled to hydration water in the minor groove.
Jiao, L.; Liu, W.; Nagatake, Taku; Takase, Kazuyuki; Yoshida, Hiroyuki; Nagase, Fumihisa
Proceedings of 15th International Heat Transfer Conference (IHTC 2014) (USB Flash Drive), 11 Pages, 2014/08
In Fukushima Daiichi nuclear disaster, seawater was injected into the nuclear core, which may change the heat transfer characteristics in the reactor pressure vessels (RPV) due to the different physical properties of seawater and pure water. To remove molten fuel from the Fukushima Daiichi Nuclear Power Plants, it is necessary to know the current status of the reactors. Therefore, in this paper, we measured the basic thermal-hydraulic data in an annular tube with a co-axial heater, which includes the heat transfer rate and the pressure drop, using the sodium chloride aqueous solutions and the synthetic seawater as working fluids. The experiments were performed under atmosphere pressure, with the salinity, the fluid mass flux, the inlet temperature and the heat flux used as the parameters. The experimental results and analyses are reported in this paper and the basic influence of the salinity on the heat transfer and the hydraulic characters are proposed.
Koizumi, Yasuo; Takahashi, Kazuki*
Proceedings of 15th International Heat Transfer Conference (IHTC 2014) (USB Flash Drive), 13 Pages, 2014/08
Pool nucleate boiling heat transfer experiments were performed for water at 0.101 MPa to examine the elementary process of the nucleate boiling. Heat transfer surface was made from a copper printed circuit board. Direct current was supplied to heat it up. The Bakelite plate of the backside of a copper layer was taken off at the center portion of the heat transfer surface to expose the back side of the copper layer. The instantaneous variation of the backside temperature of the heat transfer surface was measured with an infrared radiation camera. Bubble behavior was recorded with a high speed video camera. In the isolated bubble region, surface temperature was uniform during waiting time. When boiling bubble generation started, a large dip in the surface temperature distribution was formed under the bubble. After the bubble left from the heat transfer surface, the surface temperature distribution returned to former uniform distribution. Surface temperature was not affected by the bubble generation beyond 1.8 mm from the center of the bubble. In the intermediate and high heat flux region, the variation of surface temperature and heat flux did not become large even though the heat flux increased. The heat flux variation was close to that at the isolated boiling region.
Kato, Masato; Hirooka, Shun; Ikusawa, Yoshihisa; Takeuchi, Kentaro; Akashi, Masatoshi; Maeda, Koji; Watanabe, Masashi; Komeno, Akira; Morimoto, Kyoichi
Proceedings of 19th Pacific Basin Nuclear Conference (PBNC 2014) (USB Flash Drive), 12 Pages, 2014/08
Uranium and plutonium mixed oxide (MOX) fuel has been developed for Japan sodium-cooled fast reactors. Science based fuel technologies have been developed to analyse behaviours of MOX pellets in the sintering process and irradiation conditions. The technologies can provide appropriate sintering conditions, irradiation behaviour analysis results and so on using mechanistic models which are derived based on theoretical equations to represent various properties.
Yokota, Hideharu; Tanaka, Shingo
Proceedings of 19th Pacific Basin Nuclear Conference (PBNC 2014) (USB Flash Drive), 10 Pages, 2014/08
For understanding mass transport mechanism in the rock as natural barrier, dipole tracer migration experiments were implemented for a fracture in mudstone of Wakkanai Formation at the G.L.-250m gallery of the Horonobe URL, northern Hokkaido, Japan. Results of its preliminary analysis by the analytical solution retrieved from one-dimensional advection-dispersion equation indicate that a fracture surface in mudstone has both reversible and irreversible sorption characteristics for Cs and Sr but only irreversible that for Co and Eu.
Sakamoto, Mizuki*; Ono, Noriyasu*; Asakura, Nobuyuki; Hoshino, Kazuo
Purazuma, Kaku Yugo Gakkai-Shi, 90(8), p.473 - 479, 2014/08
国際熱核融合実験炉ITERの建設が進む中、近年、原型炉(DEMO)に関する課題が活発に議論され、国内では文部科学省の原子力科学技術委員会核融合研究作業部会の下に「核融合原型炉開発のための技術基盤構築の中核的役割を担うチーム(合同コアチーム)」が作られ、IAEAではDEMO Programme Workshopが開催されている。このような背景の中で、直線型プラズマ生成装置の果たす役割とDEMOにおけるダイバータ設計の課題を議論する。直線型プラズマ生成装置の研究状況についての説明、トカマクDEMOでのダイバータの役割と熱粒子制御における課題の説明、現状のDEMO概念とダイバータ検討の概要、DEMO設計で重要な役割を果たすダイバータシミュレーションとモデリングの開発課題について解説する。
Rhm, W.*; Mares, V.*; Pioch, C.*; Agosteo, S.*; Endo, Akira; Ferrarini, M.*; Rakhno, I.*; Rollet, S.*; Satoh, Daiki; Vincke, H.*
Radiation Measurements, 67, p.24 - 34, 2014/08
In order to investigate the impact of the difference of the transport code on the response calculation of Bonner Sphere, EURADOS (European Radiation Dosimetry Group) initiated an exercise where six groups having experience in neutron transport calculations with the MC codes (MCNP, MCNPX, FLUKA, PHITS, MARS, or GEANT4) calculated the responses of a bare He proportional counter, a He proportional counter embedded in the middle of a 9 inch polyethylene sphere, and a He proportional counter centred in a 9 inch polyethylene sphere containing a lead shell, at neutron energies of 1, 10, 100, and 1,000 MeV.
Yamashita, Shinichi*; Hiroki, Akihiro; Taguchi, Mitsumasa
Radiation Physics and Chemistry, 101, p.53 - 58, 2014/08
It was aimed to develop a novel polymer gel dosimeter to overcome weakness of earlier ones. A cellulose derivative, hydroxypropyl cellulose (HPC), was chosen as a polymer composing gel matrices and processed with a radiation-crosslinking technique in advance to manufacture of a gel dosimeter. Two methacrylate-type monomers, 2-hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) dimethacrylate (9G), were selected as vinyl-type monomers polymerizing with irradiations. Visual change with irradiation of Co -rays was observed, and haze and UV-vis absorption analyses were conducted to quantify visual changes of irradiated dosimeters. Radiation-induced white turbidity was easily observable directly by our eyes even with Co -irradiation of 1 or 2 Gy. Sensitivity, which was evaluated by haze, toward -ray dose was dependent on the composition of the vinyl-type monomers. UV-vis spectroscopy indicated that there are at least two different mechanisms leading to white turbidity. It was shown that dose rate effect can be less significant by optimizing composition of the vinyl-type monomers.
Rai, D.*; Felmy, A. R.*; Moore, D. A.*; Kitamura, Akira; Yoshikawa, Hideki; Doi, Reisuke; Yoshida, Yasushi*
Radiochimica Acta, 102(8), p.711 - 721, 2014/08
The solubility of Ba(SeO, SO) precipitates was determined as a function of the BaSeO mole fractions, ranging from 0.0015 to 0.3830, and time with an equilibration period extending to as long as 302 days. Equilibrium/steady state conditions in this system are reached in 65 days. Pitzer's ion interaction model was used to calculate solid and aqueous phase activity coefficients. Thermodynamic analyses showed that the data do not satisfy Gibbs-Duhem equation, thereby demonstrating that a single-solid solution phase does not control both the selenate and sulfate concentrations. Our extensive data with [Ba], [SeO], and [SO] can be explained with the formation of an ideal BaSeO solid solution phase that controls the selenium concentrations and a slightly disordered/less-crystalline BaSO(s) that controls the sulfate concentrations. In these experiments the BaSO component of the solid solution phase never reaches thermodynamic equilibrium with the aqueous phase. Thermodynamic interpretations of the data show that both the ideal BaSeO solid solution phase and less-crystalline BaSO(s) phase are in equilibrium with each other in the entire range of BaSeO mole fractions investigated in this study.
Radioisotopes, 63(8), p.399 - 403, 2014/08
From the view point of applying to laboratory exercise of radioactivity measurement by a Liquid Scintillation Counter (LSC), Vietnamese vodkas have specific features as measurement samples, for example, they are colorless, have high concentration of ethanol, and only very few organic materials are included. Investigation was made to make sure that the Vietnamese vodkas are appropriate or not as a measurement sample for the LSC exercise. Direct measurements of C without any chemical pre-treatment were made on both radioactive concentrations and specific activities of three kinds of Vietnamese vodka and also pure ethanol reagent. The LSC measurements reveal that estimated C concentration is proportional to ethanol concentration in samples and that specific activity of C shows good agreement among the Vietnamese vodkas and pure ethanol, as well as the reference value of 0.25 Bq/g of Carbon. Thus the conclusion is derived that the Vietnamese vodkas can be applied with high accuracy to the LSC exercise as measurement samples.
Nishikino, Masaharu; Kawachi, Tetsuya; Daido, Hiroyuki
Reza Kenkyu, 42(8), p.678 - 679, 2014/08
第14回X線レーザー国際会議(International Conference on X-Ray Lasers 2014: ICXRL2014)が米国コロラド州の ロッキー山脈の麓、フォートコリンズのコロラド州立大学において5月25日30日に開催された。本国際会議は、1980年代から30年近くにわたって隔年で、世界各地で開催されてきた伝統のある会議であり、今回の参加者は、開催国の米国を中心にヨーロッパ諸国(フランス, ドイツ, イギリス, イタリア, ロシア, チェコ等), 日本, 韓国, 中国等より約90名であった。この国際会議では、レーザー励起プラズマを用いた軟X線レーザーだけでな く、超短パルスレーザーによる高次高調波や相対論的プラズマからの軟X線放射やX線自由電子レーザー等のコヒーレントX線源の開発とその利用技術を専門とする世界中の研究者が集まり、最新の成果報告と議論が行われた。
Onizawa, Takashi; Nagae, Yuji; Kikuchi, Kenji*
Tetsu To Hagane, 100(8), p.999 - 1005, 2014/08
The applicability of high chromium (Cr) steel as the main structural material in fast breeder reactors (FBR) has been explored to enhance the safety, the credibility and the economic competitiveness of FBR power plants. Tungsten (W) is believed to improve the high temperature strength of high Cr steels by solid-solution strengthening mechanism, although the long-term effectiveness and stability of such a strengthening mechanism has not fully been understood yet. High Cr steels controlling W content are produced and tensile tests, creep tests, aging tests and charpy impact tests were conducted to investigate the long-term material properties. It was observed that the short-term creep strength could be improved by W. However, there is almost no influence of W on the long-term creep strength. And it was observed that the impact properties after aging could be improved by decreasing of W. It was found that the optimal W content for excellent high Cr steel of FBR grade are 0.1 wt.%, under FBR operating conditions.
Saito, Hiroyuki; Takagi, Shigeyuki*; Matsuo, Motoaki*; Iijima, Yuki*; Endo, Naruki*; Aoki, Katsutoshi*; Orimo, Shinichi*
APL Materials (Internet), 2(7), p.076103_1 - 076103_7, 2014/07
LiFeH, which has the highest gravimetric hydrogen density of iron-containing complex hydrides reported so far, is synthesized by hydrogenation of a powder mixture of iron and LiH above 6.1 GPa at 900 C. synchrotron radiation X-ray diffraction measurements reveal that while kinetics require high temperature and thus high pressure for the synthesis, LiFeH is expected to be thermodynamically stable slightly below room temperature at ambient pressure; further synthetic studies to suppress the kinetic effects may enable us to synthesize LiFeH at moderate pressures. LiFeH can be recovered at ambient conditions where LiFeH is metastable.
Nakayama, Hiromasa; Takemi, Tetsuya*; Nagai, Haruyasu
Advances in Science & Research (Internet), 11, p.75 - 81, 2014/07
We have developed a local-scale high-resolution atmospheric dispersion model using Large-Eddy Simulation and tried to introduce it into SPEEDI-MP. In this study, our objectives are to first create a numerical model for LES on atmospheric dispersion in spatially-developing stable and unstable boundary layer flows which and compare to the existing wind tunnel experimental data. Based on the comparison, we discuss the basic performance of the LES model.
Haraga, Tomoko; Saito, Shingo*; Sato, Yoshiyuki; Asai, Shiho; Hanzawa, Yukiko; Hoshino, Hitoshi*; Shibukawa, Masami*; Ishimori, Kenichiro; Takahashi, Kuniaki
Analytical Sciences, 30(7), p.773 - 776, 2014/07
A simple and rapid method with low radiation exposure risk was developed for the determination of neodymium in spent nuclear fuel by CE with LIF detection using a fluorescent ligand having a macrocyclic hexadentate polyaminocarboxylate structure. The concentration of Nd(III) in a spent nuclear fuel sample was determined with no interference from various matrix elements, including lanthanides and uranium (at a 200-fold excess), with 92 3% recovery. This is due to method's high resolution based on establishing a ternary complex equilibrium during migration in which the hydroxyl ion plays an auxiliary role.
Ozu, Akira; Esaka, Fumitaka; Yasuda, Kenichiro
Bunseki Kagaku, 63(7), p.609 - 617, 2014/07
Decay ratios of the laser-induced fluorescence emitted from five types of asbestos and six types of building materials in the broad wavelength region from 350 to 700 nm were investigated by using an ultraviolet laser pulse of 266 nm. Dependence of the decay ratios on the wavelength were compared, and evaluated in an attempt to numerically discriminate asbestos from the other building materials. It was observed that the decay ratios of each material were not constant over the wavelength region and varied in the wavelength over time. The fluorescence of asbestos and the building materials except for rock fiber at above 500 nm decayed faster than that at below 500 nm. The wavelength region from 405 to 420 nm was found optimum to identify types of asbestos and to discriminate asbestos from the building materials by comparing the decay ratio at the delay time of 10 ns after the incidence of laser pulse.
Sakaguchi, Yoshifumi*; Asaoka, Hidehito; Uozumi, Yuki; Kawakita, Yukinobu; Ito, Takayoshi*; Kubota, Masato; Yamazaki, Dai; Soyama, Kazuhiko; Ailavajhala, M.*; Latif, R.*; et al.
Canadian Journal of Physics, 92(7/8), p.654 - 658, 2014/07
We report our recent results of neutron reflectivity measurements for Ag/a-Ge S (x=0.2, 0.4) films under light illumination. The neutron reflectivity measurements have been performed on a polarized neutron reflectometer (BL17, SHARAKU) at Japan Proton Accelerator Research Complex (J-PARC), Japan. By using the time-of flight instrument with intensive pulsed neutrons produced by 300kW proton beams, time evolution of the neutron reflectivity under a light illumination has been revealed, with at least 2-min time resolution. From the detailed analysis, it was found for Ag 50nm/Ge S 150nm films under a light illumination from the Ag layer side that there are two types of diffusion processes: a fast change observed in the first 10 min after illumination using a xenon lamp, which is then followed by a slow change observed after a 1 hour of additional light exposure. The result indicates that there is a comparatively stable (metastable) state in the Ag-doped Ge S layer in terms of Ag composition, and the next silver diffusion process occurs by affecting the Ag-doped Ge S layer / interface. This coincides with the Ge S results of Wagner et al. obtained for Ag/As-S films. These results are also in accord with the results reported by some of us by modeling of the Ag transport in Ge-Se glass showing the presence of slow and fast moving Ag ions. Our result demonstrated that the idea of a two-step reaction process can be applied to Ge-chalcogenide system. We also discuss illumination-side dependence and Ge-composition dependence of reaction process.
Saruta, Koichi; Kobayashi, Takao*
EUR-26577-EN, p.490 - 496, 2014/07
Fiber Bragg gratings (FBGs) are one of the promising sensor elements for structural health monitoring due to multi-point sensing capability of strain with a high sensitivity and spatial resolution. While current FBG strain sensors based on wavelength domain have been established and found a variety of applications, the number of FBGs in a single sensing arm is in practice limited up to several tens. This number of FBGs is insufficient to develop effective structural health monitoring systems by taking full advantage of multiplex capability of FBG sensors. We report a design and experimental demonstration of FBG strain sensor based on optical-time domain reflectometry (FBG-OTDR). In the presented method strain is measured as a change in the optical power reflected from FBGs, and each FBG signal is separated in time domain. Thus the number of FBGs is not limited by the spectrum range of the light source and the grating bandwidth. The experimental results show that 50 sensing points in a single sensing arm can be measured with an rms error of less than 1 microstrain.
Enerugi Rebyu, 34(7), p.46 - 49, 2014/07
The 2014 Nuclear Security Summit was held in The Hague on March 24-25, 2014, and included participation from 53 countries and four international organizations. The Summit resulted in the Hague Communiqueacute; that was adopted by all 53 countries present at the Summit. In addition, a number of joint statements were made by other groupings of countries participating in the Summit. This paper describes the results of the Hague summit and future issues as well as the importance of strengthening nuclear security.
Iwai, Yasunori; Sato, Katsumi; Yamanishi, Toshihiko
Fusion Science and Technology, 66(1), p.214 - 220, 2014/07
We have developed a honeycomb Pd catalyst applicable for the oxidation of the tritiated hydrocarbons. In this study, honeycomb Pd catalysts of three different densities, 2, 5 and 10 g/L, were prepared to investigate the effect of density on reaction rate. Tritiated methane was selected as a typical hydrocarbon. Overall reaction rate constant for tritiated methane oxidation on honeycomb Pd catalyst were determined with a flow-through system as a function of space velocity from 1000 to 6300 h, methane concentration in carrier from 0.004 to 100 ppm, temperature of catalyst from 322 to 673 K. The density of palladium deposited on the base material had little effect on reaction rate for tritiated methane oxidation. The overall reaction rate constant was proportional to the space velocity. The overall reaction rate constant was independent on the methane concentration when it was less than 10 ppm.
Matsubara, Akihiro; Kokubu, Yoko; Nishizawa, Akimitsu*; Miyake, Masayasu*; Ishimaru, Tsuneari; Umeda, Koji
Geochronology; Methods and Case Studies, p.3 - 30, 2014/07
Our ongoing efforts have been dedicated to development of a multi-nuclide AMS system for measurement of the rare radionuclides Be, C, Al, and Cl. In this article, the current status of the AMS system at the TONO-AMS-JAEA and our activities leading to development of a multi-nuclide AMS are presented.
Fujishima, Tadatsune; Mizukoshi, Yasutaka; Sakamoto, Naoki; Omori, Tsuyoshi
Hozengaku, 13(2), p.115 - 125, 2014/07
In order to develop fuels and materials for fast reactors, five hot laboratories as a facility using nuclear materials for post irradiation examination (PIE) are now in operation at the Oarai Research and Development Centre of Japan Atomic Energy Agency. More than 30 years have passed since the first hot run of these facilities was started, and it has been indispensable to maintain the principal equipment for continuous safe operation. For application to preventive maintenance and the safe operation, a new safety review method that could be applied for these facilities was developed by modification of periodic safety review tools using for Japanese commercialized power reactors. Effective repair or replacement of equipment before malfunction have been performed and the priority for preventive maintenance could be appropriately determined for stable management of hot facility operations by the developed method.
Hozengaku, 13(2), p.41 - 42, 2014/07
The road map to establish a fast reactor (FR) maintenance technology in the technical aspect became clear in the examination of the FR maintenance in the Japan Society of Maintenology (JSM). It is vital to acquire operation and maintenance experience of the plant to implement this road map, and to establish a fast reactor maintenance technology. On the other hand, even if components to be maintained are defined and the maintenance methods are established, improvement of the maintenance ability in the organizations and individuals, proper and reliable implementation of the maintenance are indispensable. To improve the ability for maintenance, the action of the organized education, training and technical transmission is necessary including a light water reactor. The examination of the FR maintenance technology is a good opportunity for the application of the maintenance principles established by the JSM to the FR.
Iwamoto, Yosuke; Yashima, Hiroshi*; Satoh, Daiki; Hagiwara, Masayuki*; Iwase, Hiroshi*; Nakamura, Takashi*; Shima, Tatsushi*; Tamii, Atsushi*; Hatanaka, Kichiji*
IAEA-TECDOC-1743, Annex (CD-ROM), p.177 - 188, 2014/07
A quasi-monoenergetic neutron field using Li(p,n) reaction for the higher energy range of 100 to 400 MeV has been developed at the RCNP cyclotron facility of Osaka University. The neutron energy spectra at angles from 0 to 30 have been investigated for the proton beams with the energies of 140, 250, 350 and 392 MeV. The highest neutron fluence reaches 1.0 10 n/sr/C, and the contribution of peak intensity to the total intensity varied between 0.4 and 0.5. Using the quasi-monoenergetic neutron beam, measurement of neutron induced activation cross sections, elastic scattering cross sections for neutron and a shielding benchmark experiment have been performed, successfully. Thus quasi-monoenergetic neutron field at RCNP are suitable for measurement of nuclear data, shielding experiments and the calibration of monitors in the energy region from 100 to 400 MeV.
Journal of Chemical Physics, 141(4), p.044501_1 - 044501_8, 2014/07
From both the polarized and depolarized Raman scattering spectra of supercritical water a peak located at around 1600 cm, attributed normally to bending mode of water molecules, was experimentally observed to vanish, whereas the corresponding peak remains clearly visible in the measured infrared (IR) absorption spectrum. In this computational study a theoretical formulation for analyzing the IR and Raman spectra is developed via first principles molecular dynamics combined with the modern polarization theory. We demonstrate that the experimentally observed peculiar behavior of the IR and Raman spectra for water are well reproduced in our computational scheme. We discuss the origins of a feature observed at 1600 cm in Raman spectra of ambient water.
Journal of Geophysical Research; Atmospheres, 119(13), p.8137 - 8159, 2014/07
Recent progress in modeling fogwater (and low cloud water) deposition over terrestrial ecosystems during fogwater droplet interception by vegetative surfaces is reviewed. Several types of models and parameterizations for fogwater deposition are discussed with comparing assumptions, input parameter requirements, and modeled processes. The relationships among deposition velocity of fogwater () in model results, wind speed, and plant species structures associated with literature values were gathered for model evaluation. Quantitative comparisons between model results and observations in forest environments revealed differences as large as two orders of magnitude, which were likely caused by uncertainties in measurement techniques over heterogeneous landscapes. Results from the literature review showed that values ranged from 2.1-8.0 cm s for short vegetation, whereas = 7.7-92 cm s and 0-20 cm s for forests measured by through fall-based methods and the eddy covariance method, respectively. This review also discusses the current understanding of the impacts of fogwater deposition on atmosphere-land interactions and over complex terrain based on results from numerical studies. Lastly, future research priorities in innovative modeling and observational approaches for model evaluation are outlined.
Awual, M. R.; Ismael, M.*; Khaleque, M. A.*; Yaita, Tsuyoshi
Journal of Industrial and Engineering Chemistry, 20(4), p.2332 - 2340, 2014/07
The functionalized mesoporous silica based meso adsorbent was developed for ultra trace Cu(II) detection and removal from wastewater. The meso adsorbent was fabricated by direct immobilization of ligand onto mesoporous silica monoliths. The calculated HOMO LUMO small energy gap suggested that the electrons excitation according to the electron/energy transfer mechanism was evident in the intense of color complexation during selective detection and removal. The adsorbent was successfully applied in the determination and removal of Cu(II) ions in environmental samples.
Harada, Masahide; Teshigawara, Makoto; Maekawa, Fujio; Oi, Motoki; Kasugai, Yoshimi; Takada, Hiroshi
Journal of Nuclear Materials, 450(1-3), p.104 - 109, 2014/07
Japan Spallation Neutron Source (JSNS) in Japan Proton Accelerator Research Complex (J-PARC) has three super-critical hydrogen moderators. The moderator piping has a multilayer structure; a cryogenic layer, a vacuum layer, a helium layer and a cooling water layer. Through the fabrication of the current (1st) moderators, we learned that thermal shrinkage between room temperature (R.T.) and cryogenic temperature at the cryogenic layer made the fabrication process very difficult. Therefore, for the spare (2nd) moderators, we proposed to use a low thermal shrinkage material, Invar, as a piping material. However, there were items to be solved for realizing the Invar duct inview of the fabrication. In this presentation, we report results of (1) Bending test, (2) Welding test and (3) Dissimilar joint test on the Invar duct. (1) In the bending test, the Invar ducts of 22 mm in diameter and 1.5 mm in thickness were tried to be bent into an elbow with 40 mm in radius. By pre-cooling the duct in the liquid nitrogen followed by the bending with slow speed (1 minute), the duct could be bent without any cracks. (2) Through some welding testes by TIG-welding, the proper groove geometry was determined. (3) For the dissimilar joint test, tensile specimens including a bonding region having size of 4 or 6 mm in diameter at the smallest part and 60 mm in length were cut from three rods made by Invar-A6061 and Invar-SS316L, respectively. Those rods were bonded by the friction welding. All specimens were examined at two temperatures, R.T. and 77 K (liquid nitrogen temperature), resulting that 0.2% proof stresses corresponding to the bonding strengths were larger than those of base materials for both the Invar-A6061 and the Invar-SS316L cases. The present result indicates that the Invar duct is available for the 2nd moderators.
Naoe, Takashi; Teshigawara, Makoto; Wakui, Takashi; Kinoshita, Hidetaka; Kogawa, Hiroyuki; Haga, Katsuhiro; Futakawa, Masatoshi
Journal of Nuclear Materials, 450(1-3), p.123 - 129, 2014/07
A JSNS mercury target vessel composed of type 316L stainless steel suffers radiation damage in the proton and neutron environment. In addition to this damage, the inner wall of the target vessel in contact with mercury is damaged as a result of the cavitation. The target vessel was replaced with a new target in November 2011, because the pneumatic bellows were damaged during the earthquake. Before replacing the target, disk specimens were cut from the beam window of the target vessel in order to investigate the cavitation damage inside the target vessel and to evaluate the change in the mechanical properties due to radiation damage. As a result, it was confirmed that flow-induced erosion damage was not observed on the flow guide. The cavitation damage was concentrated at the center and around both sides approximately 15 mm from the center of the beam window. Based on the detailed measurements, it was concluded that the eroded damage depth of the beam window was 250 m.
Tezuka, Masashi; Nakamura, Yasuyuki; Iwai, Hiroki; Sano, Kazuya; Fukui, Yasutaka
Journal of Nuclear Science and Technology, 51(7-8), p.1054 - 1058, 2014/07
The cutting technologies for removing the fuel debris and the internal core structure in 1F are needed in consideration of the situation in the core and so on. On the other hand, JAEA has been carrying out the decommissioning of the nuclear facilities ending the R&D, has several technologies and knowledge to dismantle the nuclear facilities. In particular, the cutting technologies of the plasma arc, the laser, and the abrasive water jet (AWJ) and the plasma jet have been developed. Therefore, based on the above, JAEA has carried out the cutting test for investigating the applicability of those cutting technologies to propose the method for removing the fuel debris and the internal core structure to the national project. In this paper, it is outlined on the test results of the plasma arc and the AWJ cutting technologies, and the future plan of the test of those technologies and the plasma jet cutting technology.