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Journal Articles

Evaluation and modelling report of Task 9A based on comparisons and analyses of predictive modelling results for the REPRO WPDE experiments; Task 9 of SKB Task Force GWFTS - Increasing the realism in solute transport modelling based on the field experiments REPRO and LTDE-SD

Soler, J. M.*; Neretnieks, I.*; Moreno, L.*; Liu, L.*; Meng, S.*; Svensson, U.*; Trinchero, P.*; Iraola, A.*; Ebrahimi, H.*; Molinero, J.*; et al.

SKB R-17-10, 153 Pages, 2019/01

The SKB Task Force is an international forum on modeling of groundwater flow and solute transport in fractured rock. The WPDE experiments are matrix diffusion experiments in gneiss performed at the ONKALO underground facility in Finland. Synthetic groundwater containing several conservative and sorbing tracers was injected along a borehole interval. The objective of Task 9A was the predictive modeling of the tracer breakthrough curves from the WPDE experiments. Several teams, using different modelling approaches, participated in this exercise. An important conclusion from this exercise is that the modeling results were very sensitive to the magnitude of dispersion in the borehole opening, which is related to the flow of water. Focusing on the tails of the breakthrough curves, which are more directly related to matrix diffusion and sorption, the results from the different teams were more comparable. The modeling results have also been finally compared to the measured breakthroughs.

Journal Articles

Effects of fine-scale surface alterations on tracer retention in a fractured crystalline rock from the Grimsel Test Site

Tachi, Yukio; Ito, Tsuyoshi*; Akagi, Yosuke*; Sato, Hisao*; Martin, A. J.*

Water Resources Research, 54(11), p.9287 - 9305, 2018/11

 Percentile:100(Environmental Sciences)

Effects of fine-scale surface alterations on radionuclide migration in fractured crystalline rocks were investigated by a comprehensive approach coupling a series of laboratory tests, microscopic observations and modelling, using a single fractured granodiorite sample from the Grimsel Test Site, Switzerland. Laboratory tests including through-diffusion, batch sorption and flow-through tests using five tracers indicated that tracer retention was consistently in the sequence of HDO, Se, Cs, Ni, Eu, and as well as showing the existence of a diffusion-resistance layer near the fracture surface, cation excess and anion exclusion effects for diffusion. Microscale heterogeneities in structural properties around the fracture were clarified quantitatively by coupling X-ray CT and EPMA. A three layer model including weathered vermiculite, foliated mica and undisturbed matrix layers, and their properties such as porosity, sorption and diffusion parameters, could provide a reasonable interpretation for breakthrough curves and concentration distributions near fracture surface of all tracers, measured in flow-through tests.

Journal Articles

Oxidation and reduction behaviors of a prototypic MgO-PuO$$_{2-x}$$ inert matrix fuel

Miwa, Shuhei; Osaka, Masahiko

Journal of Nuclear Materials, 487, p.1 - 4, 2017/04

 Times Cited Count:2 Percentile:42.02(Materials Science, Multidisciplinary)

Oxidation and reduction behaviors of prototypic MgO-based inert matrix fuels (IMFs) containing PuO$$_{2-x}$$ were experimentally investigated by means of thermogravimetry. The oxidation and reduction kinetics of the MgO-PuO$$_{2-x}$$ specimen were determined. The oxidation and reduction rates of the MgO-PuO$$_{2-x}$$ were found to be low compared with those of PuO$$_{2-x}$$. It is note that the changes in O/Pu ratios of MgO-PuO$$_{2-x}$$ from stoichiometry were smaller than those of PuO$$_{2-x}$$ at high oxygen partial pressure. From these results, it can be said that MgO matrix lower the oxygen supply and release of PuO$$_{2-x}$$, which is preferable as the minor actinides incineration devices, since the high oxygen potentials of minor actinide oxides can cause certain problems in terms of thermochemical aspects such as enlarged cladding inner-surface corrosion.

Journal Articles

Development of glass melting process for LLW at the research project commissioned by the Ministry of Economy, Trade and Industry

Fukui, Toshiki*; Maki, Takashi*; Miura, Nobuyuki; Tsukada, Takeshi*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 23(2), p.169 - 173, 2016/12

The basic research programs for the next generation vitrification technology, which are commissioned project from Ministry of Economy, Trade and Industry of Japan, have been implemented from 2014 until 2018 for developing the advanced vitrification technology of low level wastes and high level liquid wastes.

Journal Articles

Toward advancement of nuclear data research in the resonance region

Kunieda, Satoshi; Shibata, Keiichi; Fukahori, Tokio; Kawano, Toshihiko*; Paris, M.*; Hale, G.*

JAEA-Conf 2015-003, p.33 - 38, 2016/03

We present recent progress of nuclear data evaluation method in the resolved resonance range. Our multi-channel R-matrix code now includes photon-channel and computational capability of charged-particle elastic scattering. We also present the physical constraint from the theory in the analysis of experimental data. Example analysis results are shown for $$^8$$Be and $$^{17}$$O compound system. Finally, perspectives are discussed toward the advancement of nuclear data in the resonance region including those for medium-heavy nuclei.

Journal Articles

Comparative modeling of an in situ diffusion experiment in granite at the Grimsel Test Site

Soler, J. M.*; Landa, J.*; Havlova, V.*; Tachi, Yukio; Ebina, Takanori*; Sardini, P.*; Siitari-Kauppi, M.*; Eikenberg, J.*; Martin, A. J.*

Journal of Contaminant Hydrology, 179, p.89 - 101, 2015/08

 Times Cited Count:22 Percentile:9.05(Environmental Sciences)

Matrix diffusion is a key process for radionuclide retention in crystalline rocks. An in-situ diffusion experiment in granite matrix was performed at the Grimsel Test Site (Switzerland). Several tracers (HTO, Na$$^{+}$$, Cs$$^{+}$$) were circulated through a borehole and the decrease in tracer concentrations was monitored for 2.5 years. Then, the borehole section was overcored and the tracer profiles in the rock were analyzed. Transport distances in the rock were 20 cm for HTO, 10 cm for Na$$^{+}$$ and 1 cm for Cs$$^{+}$$. The dataset was analyzed with diffusion-sorption models by different teams using different codes, with the goal of obtaining effective diffusivities (De) and rock capacity factors. There was a rather good agreement between the values from different teams, implied that De and capacity factors in the borehole damaged zone are larger than those in the bulk rock. However, HTO seems to display large discrepancies between measured and modeled results.

Journal Articles

Exploring of peptides with affinity to HER2 from random peptide libraries using radioisotope; Random hexapeptide libraries with fixed amino acid sequence at 1 and 2 positions

Sasaki, Ichiro; Hanaoka, Hirofumi*; Yamada, Keiichi*; Watanabe, Shigeki; Sugo, Yumi; Ohshima, Yasuhiro; Suzuki, Hiroyuki; Ishioka, Noriko

Peptide Science 2014, p.257 - 260, 2015/03

Journal Articles

Internally Cu-stabilized RHQT Nb$$_{3}$$Al superconductors with Ta matrix

Takeuchi, Takao*; Tagawa, Kohei*; Noda, Tetsuji*; Banno, Nobuya*; Iijima, Yasuo*; Kikuchi, Akihiro*; Kitaguchi, Hitoshi*; Kosuge, Michio*; Tsuchiya, Kiyosumi*; Koizumi, Norikiyo; et al.

IEEE Transactions on Applied Superconductivity, 16(2), p.1257 - 1260, 2006/06

 Times Cited Count:6 Percentile:58.78(Engineering, Electrical & Electronic)

Next generation nuclear fusion magnets would require a high-current conductor in fields more than 16 T. A CIC conductor of the rapid RHQT processed Nb$$_{3}$$Al may be a promising candidate. Good deformability of intermediately-formed bcc supersaturated-solid solution indeed allowed fabricating such a CIC conductor, which would be subsequently transformation annealed. Ag has been internally included as a basic constituent of a round strand so far, because Ag is almost non-reactive with Nb matrix during the RHQ. However, both of Ag and Nb are not suitable nuclei from the viewpoint of radioactivity when irradiated with neutrons. Recently, we have succeeded in replacing the Nb matrix with Ta that has the advantage of shorter half-life of radioactivity. In the present study, an attempt has been made to replace the Ag internal stabilizer with Cu, in the aim of further reducing radioactivity, based on anticipation that Ta would be less reactive with Cu than Nb did.

Journal Articles

Method for detection of separatrix surface using differential double probe

Amemiya, Hiroshi*; Uehara, Kazuya

Japanese Journal of Applied Physics, Part 1, 45(1A), p.247 - 249, 2006/01

 Times Cited Count:4 Percentile:80.11(Physics, Applied)

A method for detecting the separatrix surface in the edge plasma in Tokamak is presented. Two sets of double probes whose front surfaces are shifted by a small distance are mounted and the difference of the currents is measured using a differential amplifier. When the separatrix surface reaches the probes, a current increment appears in the differential amplifier, giving a signal of the arrival of the separatrix. Procedures of obtaining plasma parameters including the ion temperature are described.

Journal Articles

Estimation of covariance matrices for nuclear data of $$^{237}Np$$, $$^{241}Am$$ and $$^{243}Am$$

Nakagawa, Tsuneo

Journal of Nuclear Science and Technology, 42(11), p.984 - 993, 2005/11

 Times Cited Count:8 Percentile:44.28(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Present status of PSA methodology development for MOX fuel fabrication facilities

Tamaki, Hitoshi; Hamaguchi, Yoshikane; Yoshida, Kazuo; Muramatsu, Ken

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 6 Pages, 2005/10

A PSA procedure for MOX fuel fabrication facilities is being developed at the JAERI. This procedure consists of four steps, which are hazard analysis, accident scenario analysis, frequency evaluation and consequence evaluation. The proposed procedure is characterized by the hazard analysis step. The Hazard analysis step consists of two sub-steps. In the first sub-step, a variety of functions of equipment composing the facility are analyzed to identify potential abnormal events exhaustively. In the second sub-step, these potential events are screened to select abnormal events by using a risk matrix based on the rough estimation of likelihood and maximum unmitigated release of radioactive material. One of the unique technical issues in this research is the estimation of likelihood of criticality event. A method is also proposed as a part of PSA procedure taking into consideration of failure of a computerized control system for MOX powder handling process. The applicability of the PSA procedure was demonstrated through the trial application of it to a model plant of MOX fuel fabrication facility.

JAEA Reports

Annual report on operation, utilization and technical development of Hot Laboratories; From April 1, 2004 to March 31, 2005

Department of Hot Laboratories

JAERI-Review 2005-047, 95 Pages, 2005/09

JAERI-Review-2005-047.pdf:6.27MB

This is an annual report in 2004 fiscal year that describes activities of the Reactor Fuel Examination Facility (RFEF), the Waste Safety Testing Facility (WASTEF), and the Research Hot Laboratory (RHL) in the Department of Hot laboratories. In RFEF, BWR fuel rods were withdrawn from a fuel assembly irradiated for 5 cycles in the Fukushima-2 Nuclear Power Station Unit-1 and PIEs including nondestructive examination of those rods were carried out. In WASTEF, Slow Strain Rate Tests for detecting the susceptibility to IASCC, the corrosion test of reprocessing plant materials, tests for evaluating barrier performance in terms of waste disposal were performed. A secondary system pipe from the Mihama Nuclear Power Station Unit-3 was accepted to inspect the ageing fracture of it. In RHL, 15 lead cells are dismantled under the decommissioning plan at JAERI Tokai. And an arrangement of the RHL facility was started to use the storage of unirradiated nuclear materials.

JAEA Reports

Fabrication of inert-matrix nitride fuel pins for the irradiation test at JMTR

Nakajima, Kunihisa; Iwai, Takashi; Kikuchi, Hironobu; Serizawa, Hiroyuki; Arai, Yasuo

JAERI-Research 2005-027, 42 Pages, 2005/09

JAERI-Research-2005-027.pdf:4.15MB

Nitride fuel pins containing inert matrix such as ZrN and TiN were fabricated for the irradiation test at JMTR, aiming at understanding irradiation behavior of nitride fuel for transmutation of minor actinides. Minor actinides are surrogated by plutonium in the present fuel pin. This report describes the preparation and characterization of fuel pellets, and fabrication of fuel pins. The irradiation for 11 cycles from May 2002 to November 2004 at JMTR was completed without any failure of fuel pins.

Journal Articles

Radionuclide release from mixed-oxide fuel under high temperature at elevated pressure and influence on source terms

Hidaka, Akihide; Kudo, Tamotsu; Ishikawa, Jun; Fuketa, Toyoshi

Journal of Nuclear Science and Technology, 42(5), p.451 - 461, 2005/05

 Times Cited Count:5 Percentile:59.33(Nuclear Science & Technology)

The radionuclide release from MOX under severe accident conditions was investigated in VEGA program to contribute to the technical bases for safety evaluation including PSA for LWR using MOX. The MOX specimens irradiated at ATR Fugen were heated up to 3123K in helium at 0.1 and 1.0MPa. The release of volatile FP was slightly enhanced below 2200K compared with that of UO$$_{2}$$. The volatile FP release at elevated pressure was decreased as in the case with UO$$_{2}$$. The total fractional release of Cs reached almost 100% while almost no release of low-volatile FP even after the fuel melting. The release rate of plutonium above 2800K increased rapidly although the amount was small. Since the existing models cannot predict this increase, an empirical model was prepared based on the data. There is no large difference in FP inventories between UO$$_{2}$$ and MOX, and the fractional releases from MOX can be mostly predicted by the model for UO$$_{2}$$. This suggests that the consequences of LWR using MOX are mostly equal to those using UO$$_{2}$$ from a view point of risks.

Journal Articles

Radionuclide release from mixed-oxide fuel under severe accident conditions

Hidaka, Akihide; Kudo, Tamotsu; Fuketa, Toyoshi

Transactions of the American Nuclear Society, 91, p.499 - 500, 2004/12

The radionuclides release from MOX under severe accident conditions was investigated in the VEGA program to prepare the technical bases for safety evaluation including PSA for LWR using MOX. The MOX specimen irradiated at ATR Fugen was heated up to 3123K in He at 0.1MPa. The Cs release started at about 1000K and was enhanced below 2200K compared with that of UO$$_{2}$$. The possible reason is due to the formation of cracks connected to the high burn-up Pu spots. The total fractional releases were evaluated by alpha-ray, gamma-ray and ICP-AES and compared with the ORNL-Booth model. Although the model was prepared based on the tests with UO$$_{2}$$, the predictions are in reasonable agreement with the measurements. The VEGA test showed that the total releases from MOX are almost the same as those from UO$$_{2}$$ under extremely severe accident conditions. This indicates that the consequences of LWR using MOX are mostly equal to those using UO$$_{2}$$. The effect of difference between MOX and UO$$_{2}$$ on the consequences will be systematically investigated using the JAERI's source term code, THALES-2.

Journal Articles

Application of the two-dimensional Newcomb problem to compute the stability matrix of external MHD modes in a tokamak

Aiba, Nobuyuki*; Tokuda, Shinji; Ishizawa, Tomoko*; Okamoto, Masao*

Plasma Physics and Controlled Fusion, 46(11), p.1699 - 1721, 2004/11

 Times Cited Count:2 Percentile:92.17(Physics, Fluids & Plasmas)

The theory of the Newcomb equation has been applied to low-n external modes in a tokamak and a method has been developed to compute the stability matrix that gives the change of plasma potential energy due to external modes in terms of the surface values of the perturbations. By using this method, the spectral properties of the ideal external modes has been elucidated, such as coupling between external modes and internal modes, and the difference of the stability properties between a normal shear tokamak and a reversed shear tokamak. These results will be also useful in the stability analysis of resistive wall modes.

Journal Articles

Emittance compensation in a return arc of an energy-recovery linac

Hajima, Ryoichi

Nuclear Instruments and Methods in Physics Research A, 528(1-2), p.335 - 339, 2004/08

 Times Cited Count:12 Percentile:32.7(Instruments & Instrumentation)

Dilution of electron beam emittance through a return arc is one of critical problems in the design of an energy-recovery linac for high-power FEL and a synchrotron light source. We present that the emittance dilution can be compensated by establishing the matching between the phase ellipse orientation and the CSR kick direction, and the effect of coherent synchrotron radiation on the beam emittance dilution can be estimated from simple calculation of transfer matrices.

Journal Articles

Research and development of visualization tools on ITBL system infrastructure

Suzuki, Yoshio; Matsumoto, Nobuko*; Sai, Kazunori*; Yamagishi, Nobuhiro*

Keisan Kogaku Koenkai Rombunshu, 9(2), p.613 - 616, 2004/05

no abstracts in English

Journal Articles

Shielding design of the 200kW Pb-Bi spallation target for the transmutation experimental facility

Sasa, Toshinobu; Oigawa, Hiroyuki; Tayama, Ryuichi*; Hayashi, Katsumi*

Journal of Nuclear Science and Technology, 41(Suppl.4), p.30 - 33, 2004/03

The construction of Transmutation Experimental Facility (TEF) is planned under the framework of Japan Proton Accelerator Research Complex (J-PARC) project. A liquid lead-bismuth (Pb-Bi) spallation target with beam power of 600MeV-200kW will be installed into the TEF. Analyses were performed to determine the effective thickness of biological shield for Pb-Bi target by using both MCNPX and ATRAS code system. Thickness of around 6m should be required to decrease the radiation level. The streaming analyses through the proton injection beam duct and the primary cooling circuit piping were also performed. The result of the beam duct streaming shows good agreement between the results of MCNPX and DUCT-III. The additional shield must be installed to suppress the activation of accelerator components. In the case of streaming through the primary cooling circuit piping, it is proved that the radiation level at the exit of the shield is allowable. The radiation level can be much more reduced by optimizing the bending position and length of the piping.

Journal Articles

Development of Decommissioning Engineering Support System(DEXUS) of the Fugen Nuclear Power Station

Iguchi, Yukihiro*; Kanehira, Yoshiki*; Tachibana, Mitsuo*; Johnsen, T.*

Journal of Nuclear Science and Technology, 41(3), p.367 - 375, 2004/03

The Fugen Nuclear Power Station (NPS) was shut down permanently in March 2003, and preparatory activities are underway to decommission the Fugen NPS. An engineering system to support the decommissioning is being developed to create a dismantling plan using state-of-the-art software such as 3-dimentional computer aided design (3D-CAD) and virtual reality (VR). In particular, an exposure dose evaluation system using VR has been developed and tested. The total system can be used to quantify radioactive waste, to visualize radioactive inventory, to simulate the dismantling plan, to evaluate workload in radiation environments and to optimize the decommissioning plan. The system will also be useful for educating and training workers and for gaining public acceptance.

164 (Records 1-20 displayed on this page)