JAEA Abstracts

-Research results below have been sorted by order of journals name.

-Sorry, some research results below have no English abstract.

March 2011

39000333
Calculation of effective delayed neutron fraction with Monte Carlo perturbation techniques
Nagaya, Yasunobu; Mori, Takamasa
Annals of Nuclear Energy 38(2-3), p.254-260(2011) ; (JAEA-J 08564)

Alternative methods are proposed to estimate the effective delayed neutron fraction β_eff in Monte Carlo calculations: the eigenvalue methods jointly used with the differential operator sampling and correlated sampling techniques. In particular, the eigenvalue method with the differential operator sampling technique has a distinct feature that it gives a theoretically exact β_eff value. To verify the proposed methods, Monte Carlo calculations are performed for several systems with simple geometry. It is found that the results obtained with the proposed methods agree with the reference deterministic results within sufficiently small statistical uncertainties. The perturbed source effect must be taken into account to estimate an exact β_eff value.

39000334
Observation of longitudinal spin-Seebeck effect in magnetic insulators
Uchida, Kenichi*; Adachi, Hiroto; Ota, Takeru*; Nakayama, Hiroyasu*; Maekawa, Sadamichi; Saito, Eiji
Applied Physics Letters 97(17), p.172505_1-172505_3(2010) ; (JAEA-J 08565)

We propose a longitudinal spin-Seebeck effect, in which a magnon-induced spin current is injected parallel to a temperature gradient from a ferromagnet into an attached paramagnetic metal. The longitudinal spin-Seebeck effect is measured in a simple and versatile system composed of a ferrimagnetic insulator Y₃Fe₅O₁₂ slab and a Pt film by means of the inverse spin-Hall effect. The experimental results highlight the intriguing character of the longitudinal spin-Seebeck effect due to its own geometric configuration.

39000335
Gigantic enhancement of spin Seebeck effect by phonon drag
Adachi, Hiroto; Uchida, Kenichi*; Saito, Eiji; Oe, Junichiro; Takahashi, Saburo; Maekawa, Sadamichi
Applied Physics Letters 97(25), p.252506_1-252506_3(2010) ; (JAEA-J 08566)

We investigate both theoretically and experimentally a gigantic enhancement of the spin Seebeck effect in a prototypical magnet LaY₂Fe₅O₁₂ at low temperatures. Our theoretical analysis sheds light on the important role of phonons: the spin Seebeck effect is enormously enhanced by nonequilibrium phonons that drag low-lying spin excitations. We further argue that this scenario gives a clue to understand the observation of the spin Seebeck effect that is unaccompanied by a global spin current, and predict that the substrate condition affects the observed signal.

39000336
Synchrotron radiation photoelectron spectroscopy and near-edge X-ray absorption fine structure study on oxidative etching of diamond-like carbon films by hyperthermal atomic oxygen
Tagawa, Masahito*; Yokota, Kumiko*; Kitamura, Akira*; Matsumoto, Koji*; Yoshigoe, Akitaka; Teraoka, Yuden; Kanda, Kazuhiro*; Niibe, Masahito*
Applied Surface Science 256(24), p.7678-7683(2010) ; (JAEA-J 08567)

Surface structural changes of a hydrogenated diamond-like carbon (DLC) film exposed to a hyperthermal atomic oxygen beam were investigated by Rutherford backscattering spectroscopy (RBS), synchrotron radiation photoelectron spectroscopy (SR-PES), and near-edge X-ray absorption fine structure (NEXAFS). It was confirmed that the DLC surface was oxidized and etched by high-energy collisions of atomic oxygen. RBS and real-time mass-loss data showed a linear relationship between etching and atomic oxygen fluence. SR-PES data suggested that the oxide layer was restricted to the topmost surface of the DLC film. NEXAFS data were interpreted to mean that the sp² structure at the DLC surface was selectively etched by collisions with hyperthermal atomic oxygen, and an sp³-rich region remained at the topmost DLC surface. The formation of an sp³-rich layer at the DLC surface led to surface roughening and a reduced erosion yield relative to the pristine DLC surface.

39000337
Spectroscopic characterization of β-FeSi₂ single crystals and homoepitaxial β-FeSi₂ films by XPS and XAS
Esaka, Fumitaka; Yamamoto, Hiroyuki; Udono, Haruhiko*; Matsubayashi, Nobuyuki*; Yamaguchi, Kenji; Shamoto, Shinichi; Magara, Masaaki; Kimura, Takaumi
Applied Surface Science 257(7), p.2950-2954(2011) ; (JAEA-J 08568)

Chemical state analysis by a combination of X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) using synchrotron radiation is performed for β-FeSi₂ single crystals and homoepitaxial β-FeSi₂ films. The Si 2p XPS and Fe L-edge XAS spectra imply that the annealing at 1173 K to remove native oxide layers on the crystal induces the formation of FeSi in the surface. The formation of FeSi is also confirmed by Si K-edge XAS analysis. For the homoepitaxial β-FeSi₂ films grown on the crystals, the Si K-edge XAS spectra indicate that structurally homogeneous β-FeSi₂ films can be grown on the β-FeSi₂ single crystals when the substrate temperatures of 973 and 1073 K are applied for molecular beam epitaxy (MBE). Consequently, it is indicated that the combination of XPS and XAS using synchrotron radiation is a useful tool to clarify chemical states nondestructively.

39000338
Oxidation of TiNi surface with hyperthermal oxygen molecular beams
Okada, Michio*; Sowa, Makoto*; Kasai, Toshio*; Teraoka, Yuden
Applied Surface Science 257(9), p.4257-5263(2011) ; (JAEA-J 08569)

We report results of our detailed studies on the initial oxidation process of TiNi with a 2 eV hyperthermal oxygen molecular beam (HOMB) and thermal O₂ in the backfilling. The oxidation processes are monitored by X-ray photoemission spectroscopy (XPS) measurements in conjunction with synchrotron radiation (SR). In the early stages of oxidation, the precursor mediated dissociative adsorption is the dominant reaction mechanism. In the oxide formation process at higher O coverage, HOMB has the advantage in the dissociation process of O₂ molecules and can make growth of TiO₂ layers with the underlying TiO_x-rich and/or Ni-rich layers. We succeeded in fabricating a thick Ni-free TiO₂ layer, possibly blue colored rutile TiO₂, combining HOMB and surface annealing.

39000339
Quantum control study of ultrafast isotope-selective vibrational excitations of the cesium iodide (CsI) molecule
Kurosaki, Yuzuru; Yokoyama, Keiichi; Yokoyama, Atsushi
Computational and Theoretical Chemistry 963(2-3), p.245-255(2011) ; (JAEA-J 08570)

We study, using quantum optimal control theory (OCT), isotope-selective vibrational excitations on the ground-state potential energy curve for the mixture of two pure ensembles for ¹³³CsI and ¹³⁵CsI. Initial states are set to the condition that both ¹³³CsI and ¹³⁵CsI are in the vibrational ground level, i.e., (v₁₃₃, v₁₃₅) = (0, 0), and target states are set to three: (v₁₃₃, v₁₃₅) = (0, 2), (0, 3), and (0, 4), where molecular orientations are fixed parallel to the field polarization vector. Three total times (i.e., pulse durations), T = 460,000 au, 920,000 au, and 1,840,000 au, are set in the calculations and nine cases for the combination of target state and total time are investigated. It is suggested from the computational results that even when T is short, high-yield transitions into energetically-separated target states are possible through excitations skipping over more than one vibrational level at a time with intense fields including high overtones.

39000340
Density functional investigation of Fe_n clusters (n ≤ 6) with Cr substitutions; UB3LYP/LanL2DZ calculation
Nakazawa, Tetsuya; Igarashi, Takahiro; Tsuru, Tomohito; Kaji, Yoshiyuki
Computational Materials Science 50(3), p.982-990(2011) ; (JAEA-J 08571)

Geometric parameters, binding energies, natural populations, natural electron configurations and magnetic moments are obtained for the clusters of Fe_n, Cr_n and Fe_n-xCr_x (n = 2-6, x = 1-6) optimized under the constraint of well-defined point group symmetries at the UB3LYP/LanL2DZ level. The substitutional effects of Cr in Fen are found in the properties. The binding energies of Fen are generally decreased by successive substitutions of Cr for Fe atoms in the clusters. In the mixed Fe-Cr clusters most of Cr-Cr bond lengths are larger than the Fe-Fe and Fe-Cr bond lengths. Among the Fe-Fe, Fe-Cr and Cr-Cr bond lengths in the mixed clusters, the trend is found to become larger in that order. The larger distances between atoms in the mixed clusters are mostly caused by the strong repulsion due to magnetic frustration between atoms. The changes are associated with those of electronic structure by the Cr substitutions, especially with the extent of contribution of 4s and 3d electrons to bond.

39000341
Abundances of rare earth elements in crude oils and their partitions in water
Nakada, Ryoichi*; Takahashi, Yoshio*; Zheng, G.*; Yamamoto, Yuhei; Shimizu, Hiroshi*
Geochemical Journal 44(5), p.411-418(2010) ; (JAEA-J 08572)

Patterns of the entire range of REE in crude oils and coexisting water, collected from mud volcanoes in Xinjiang Province of China, are reported here for the first time. Crude oils show light REE enriched patterns with flat or depleted patterns in heavy REE, when normalized to chondrite. The REE concentrations in crude oils are larger than those in coexisting water by a factor of more than one hundred. Considering the hydrophobicity of oil and the high ionic characteristics of REE, it is strongly suggested that REE form complexes with ligands present in the crude oils. Based on the ¹³C NMR spectroscopy, it is found that small amounts of phenol and carboxyl groups are contained in the crude oil samples, which could possibly provide complexing sites for REE. REE patterns of crude oils are similar to those of coexisting mud samples collected from the same mud volcanoes, which suggests that the REE in crude oils are derived from rocks and sediments where crude oils were generated.

39000342
EXAFS study on the cause of enrichment of heavy REEs on bacterial cell surfaces
Takahashi, Yoshio*; Yamamoto, Mika*; Yamamoto, Yuhei; Tanaka, Kazuya
Geochimica et Cosmochimica Acta 74(19), p.5443-5462(2010) ; (JAEA-J 08573)

Among various natural samples, rare earth element (REE) pattern of bacteria exhibits anomalous enrichment at heavy REE (HREE) part, which can be a signature of bacteria-related materials. In this study, REE binding site on the cell surface of a Gram-positive bacterium (Bacillus subtilis) responsible for the HREE enrichment has been identified by extended X-ray absorption fine structure (EXAFS) coupled with the variation of REE distribution pattern. EXAFS showed that (1) HREE is bound to multiple phosphate site at lower REE-bacteria ratio (=[REE]/[bac]), but the fraction coordinated to carboxylate increased as the increase in the ratio and (2) the binding sites of light and middle REE change from phosphate with lesser coordination number to carboxylate site as the [REE]/[bac] ratio increases. On the other hand, the enrichment of HREE in the REE distribution patterns of bacteria was less marked as the increase in the [REE]/[bac] ratio. This result is consistent with the EXAFS results, since REE pattern of multiple phosphate site exhibits monotonous increase for HREE, while phosphate with lesser coordination number and carboxylate site have maxima around Sm. Based on these results, it was clear that phosphate site is more stable than carboxylate site as the binding site for REE. The average bond lengths between REE and oxygen were compared among various REE sorbed on bacteria, showing that the bond length was much shorter for HREE than those extrapolated from the trend between La and Dy due to the selective binding of HREE to the multiple phosphate site. Based on the results, it is thought that materials having such phosphate site can induce anomalous HREE enrichment in natural systems. Compared with other possible host phases of REE such as metal oxides and humic substances, the multiple phosphate site is unique to bacteria and bacteria-related materials such as biofilm and microbial mats, which leads to the potential of REE pattern as a biomarker in natural samples.

39000343
Superconducting property and strain effect study of the Nb₃Sn strands developed for ITER
Nunoya, Yoshihiko; Hemmi, Tsutomu; Nabara, Yoshihiro; Matsui, Kunihiro; Isono, Takaaki; Takahashi, Yoshikazu; Koizumi, Norikiyo; Okuno, Kiyoshi
IEEE Transactions on Applied Superconductivity 20(3), p.1443-1446(2010) ; (JAEA-J 08574)

Japan Atomic Energy Agency has developed Nb₃Sn strand for the ITER magnet, strand whose critical current density is about 1.4 times as large as that for ITER CS Model Coil. Magnetic field, temperature, and strain dependence on the critical current (Ic) of the strand are measured by the apparatus developed by the authors. Especially strain property is investigated in detail, and it is shown by strain tensor analysis that upper critical field dependence on strain can be naturally formulated by the high order polynomial terms of strain taking into account residual strain due to thermal contraction difference inside of the strand and applied strain externally. Correlation formula among field, temperature, strain and Ic for the strand is discussed and presented. Performance of superconducting cables composed of the developed strand is evaluated using the formula.

39000344
Charge enhancement effects in 6H-SiC MOSFETs induced by heavy ion strike
Onoda, Shinobu; Makino, Takahiro; Iwamoto, Naoya*; Vizkelethy, G.*; Kojima, Kazutoshi*; Nozaki, Shinji*; Oshima, Takeshi
IEEE Transactions on Nuclear Science 57(6), p.3373-3379(2010) ; (JAEA-J 08575)

39000345
Estimation of three-dimensional stress distribution and elastic moduli in rock mass of the Tono area
Nara, Yoshitaka*; Cho, S. H.*; Yoshizaki, Takaya*; Kaneko, Katsuhiko*; Sato, Toshinori*; Nakama, Shigeo; Matsui, Hiroya
International Journal of the Japanese Committee for Rock Mechanics (Internet) 7(1), p.1-9(2011) ; (JAEA-J 08576)

This study presents a back analysis based on three-dimensional finite element analysis in order to estimate the regional stress fields and the elastic moduli of a rock mass simultaneously from in situ measurements. In order to improve the accuracy of the estimation of three-dimensional stress field, heterogeneities in a rock mass consisting of geological layers with different elastic properties was considered. Back analysis was applied to determine the regional stresses for a broad field study that includes Tono Mine, the Shobasama Site and the Mizunami Underground Research Laboratory (MIU) Construction Site.

39000346
Immediate product after exposing Si(111)-7×7 surface to O₂ at 300 K
Yoshigoe, Akitaka; Teraoka, Yuden
Japanese Journal of Applied Physics 49(11), p.115704_1-115704_6(2010) ; (JAEA-J 08577)

Using real-time O 1s X-ray photoelectron spectroscopy together with Si 2p X-ray photoelectron spectroscopy, the oxygen bonding configurations of oxides shortly after exposing the Si(111)-7×7 surface to O₂ at 300 K are revealed. It is found that the ins structure firstly forms where one oxygen atom sits in the backbond of the silicon adatom. It is confirmed that the chemisorbed molecular oxygen, the so-called paul oxygen, is the adsorbate on top of the ins structure. It is also clarified that the ad-ins structure and the ins-tri structure, where ad means an oxygen atom adsorbed onto top of the silicon adatom and tri means the interstitial oxygen atom, appear after a short time. The results implying the presence of mobile O₂ on the surface were obtained.

39000347
Nanoscale surface modifications and formation of conical structures at aluminum surface induced by single shot exposure of soft X-ray laser pulse
Ishino, Masahiko; Faenov, A. Y.*; Tanaka, Momoko; Hasegawa, Noboru; Nishikino, Masaharu; Tamotsu, Satoshi*; Pikuz, T. A.*; Inogamov, N. A.*; Zhakhovskii, V. V.*; Skobelev, I. Yu.*; Fortov, V. E.*; Khohlov, V. A.*; Shepelev, V.*; Oba, Toshiyuki; Kaihori, Takeshi; Ochi, Yoshihiro; Imazono, Takashi; Kawachi, Tetsuya
Journal of Applied Physics 109(1), p.013504_1-013504_6(2011) ; (JAEA-J 08578)

39000348
Radiation-induced crosslinking of Nafion^® N117CS membranes
Iwai, Yasunori; Hiroki, Akihiro; Tamada, Masao
Journal of Membrane Science 369(1-2), p.397-403(2011) ; (JAEA-J 08579)

The successful formation of radiation-induced crosslinking in Nafion^® N117CS membranes was clearly demonstrated by tensile testing, a methanol uptake measurement, thermo-mechanical analysis (TMA) and fluorine-19 MAS NMR (¹⁹F NMR). The possibility of radiation-induced crosslinking of Nafion^® never had been considered with regard to the thermal stability of Nafion^® membranes, since the scission of PFAE pendant-chains in Nafion^® membranes in their protonated form begins at 523 K. To improve the thermal stability of Nafion^® membranes, Nafion^® membranes were soaked in sodium chloride prior to irradiation. The sodium-exchange Nafion^® membranes were irradiated with γ rays in an argon atmosphere at temperatures ranging from room temperature to 618 K. The irradiated membranes were re-exchanged to the protonated form. Fluorine-19 MAS NMR results for the alcohol-swollen membranes indicate peaks which originated due to radiation-induced crosslinking. An increase in percent elongation at break, a decrease in methanol uptake, and a decrease in the softening temperature at a differential TMA peak for membranes irradiated at 598 K compared to received membranes also add support for our new finding.

39000349
Hardening of Al-Cu-Mg alloy by energetic ion irradiation
Mitsuda, Tomoaki*; Kobayashi, Ippei*; Kosugi, Shinya*; Fujita, Naoki*; Saito, Yuichi; Hori, Fuminobu*; Semboshi, Satoshi*; Kaneno, Yasuyuki*; Nishida, Kenji*; Soneda, Naoki*; Iwase, Akihiro*
Journal of Nuclear Materials 408(2), p.201-204(2011) ; (JAEA-J 08582)

We irradiated Al-Cu-Mg alloy with 10 MeV iodine ions at room temperature and measured the surface microhardness. We analyzed the microstructure using a three-dimensional atom probe. Irradiation for 3.5 h led to an increase in hardness comparable to that obtained after 4 days of aging at 423 K. Precipitates of about 2.9 nm in diameter were distributed homogeneously over the irradiated region. The nanometer-sized precipitates produced by the irradiation caused a remarkable increase in hardness.

39000350
JENDL-4.0; A New library for nuclear science and engineering
Shibata, Keiichi; Iwamoto, Osamu; Nakagawa, Tsuneo*; Iwamoto, Nobuyuki; Ichihara, Akira; Kunieda, Satoshi; Chiba, Satoshi; Furutaka, Kazuyoshi; Otsuka, Naohiko*; Osawa, Takaaki*; Murata, Toru*; Matsunobu, Hiroyuki*; Zukeran, Atsushi*; Kamada, So*; Katakura, Junichi
Journal of Nuclear Science and Technology 48(1), p.1-30(2011) ; (JAEA-J 08583)

The fourth version of Japanese Evaluated Nuclear Data Library has been produced. In the new library, much emphasis is placed on the improvements of fission product and minor actinoid data. Two nuclear model codes were developed to evaluate the cross sections of fission products and minor actinoids. Coupled-channel optical model parameters, which can be applied to wide mass and energy regions, were obtained for nuclear model calculations. Thermal cross sections of actinoids were determined by considering recent experimental data or by the systematics of neighboring nuclei. A simultaneous evaluation was performed for the fission cross sections of important uranium and plutonium isotopes above 10 keV. The data on FP were re-evaluated, and new evaluations were performed for 30 nuclides. The data on light elements and structural materials were partly re-evaluated. The new library was released as JENDL-4.0 in May 2010.

39000351
Failure mechanism of silicide and aluminide fuels during power transient
Yanagisawa, Kazuaki
Journal of Nuclear Science and Technology 48(1), p.113-119(2011) ; (JAEA-J 08584)

An influence of fuel core density (2.2, 3.0 and 4.0 g/cc) on a fuel failure was studied comparing the silicide fuel (4.8 g/cc) as the reference. (1) The DNB value of the test specimens (below 4.8 g/cc) was 175 ± 24 °C, having no difference to the reference (180 ± 14 °C). (2) The reference fuel failed at the large temperature drop (above 94 °C) and the short time to quench (below 0.13 s). The test specimens did not fail until 106 cal per gram fuel plate due to the enhanced plasticity of the aluminum matrix. The lower the fuel density, the more the plasticity enhanced. (3) Irrespective to fuel density, the bow was increased with the increasing PCST. Experimental fact revealed that maximum bow at JRR-3 operating (below 228 °C) is 15% (0.4 mm), where the almost data are within 4% (0.1 mm). (4) For axial permanent strain evaluated by the plate thickness, the test specimens were expanded but the references were shrunk.

39000352
Diverse monitoring approaches reveal ¹⁴C dispersion pattern and its impact on the environment around the Tokai reprocessing plant
Koarashi, Jun; Fujita, Hiroki; Watanabe, Hitoshi; Sumiya, Shuichi
Journal of Nuclear Science and Technology 48(1), p.120-129(2011) ; (JAEA-J 08585)

Carbon-14 (¹⁴C) is of great interest in dose assessment due to the nuclear industry. We collected terrestrial environmental samples at various locations at different time intervals around the Tokai reprocessing plant (TRP), and measured their ¹⁴C concentrations. The results consistently gave the picture of ¹⁴C dispersion pattern that the prevailing wind conveyed ¹⁴C plume, and as a result caused elevated ¹⁴C concentrations in the area 2-3 km southwest of the main stack. The ¹⁴C increases were however quite temporary. The ¹⁴C concentrations in vegetations generally followed those in atmospheric CO₂, but seemed different in the integrated period of reflecting the atmospheric ¹⁴C level between vegetations. We found the highest ¹⁴C concentration of 374 Bq/kg-C^-1. The annual effective dose due to ¹⁴C was estimated to be only 0.07% of the annual effective dose limit. Thus, we conclude that the ¹⁴C releases from the TRP have a very slight impact both on the environment and on the public.

39000353
JENDL-4.0 benchmarking for fission reactor applications
Chiba, Go; Okumura, Keisuke; Sugino, Kazuteru; Nagaya, Yasunobu; Yokoyama, Kenji; Kugo, Teruhiko; Ishikawa, Makoto; Okajima, Shigeaki
Journal of Nuclear Science and Technology 48(2), p.172-187(2011) ; (JAEA-J 08586)

Benchmark testing for the newly developed Japanese evaluated nuclear data library JENDL-4.0 is carried out by using a huge amount of integral data. Benchmark calculations are performed with a continuous energy Monte Carlo code and with the deterministic procedure which has been developed for fast reactor analyses in Japan. Through the present benchmark testing using a wide range of benchmark data, significant improvement in the performance of JENDL-4.0 for fission reactor applications is clearly demonstrated in comparison with the former library JENDL-3.3. Much more accurate and reliable prediction for neutronic parameters for both thermal and fast reactors may become possible by using the library JENDL-4.0.

39000354
Numerical experiment for strontium-90 and cesium-137 in the Japan Sea
Kawamura, Hideyuki; Ito, Toshimichi; Kobayashi, Takuya; Otosaka, Shigeyoshi; Hirose, Naoki*; Togawa, Orihiko
Journal of Oceanography 66(5), p.649-662(2010) ; (JAEA-J 08588)

A numerical experiment is performed to reproduce a distribution of concentrations of ⁹⁰Sr and ¹³⁷Cs and estimate their total amounts in the Japan Sea. The concentrations of ⁹⁰Sr and ¹³⁷Cs in the surface layer is in the range of 1.0-1.5 Bq/m³ and 2.0-2.5 Bq/m³. The concentrations in the intermediate and deep layer are higher than those observed in the northwestern Pacific Ocean, indicating active winter convection in the Japan Sea. The total amounts of ⁹⁰Sr and ¹³⁷Cs in the seawater is evaluated to be 1.34 PBq (1 PBq = 10¹⁵ Bq) and 2.02 PBq, which demonstrates an estimation by observational data in the Japan Sea expeditions between 1997 and 2002 by Japan Atomic Energy Agency. The total amounts of ⁹⁰Sr and ¹³⁷Cs vary corresponding to deposition at the sea surface with the maximums of 4.86 PBq for ⁹⁰Sr and 7.33 PBq for ¹³⁷Cs in the mid-1960s.

39000355
Atomic structure and energetic stability of complex chiral silicon nanowires
Avramov, P.; Minami, Soma*; Irle, S.*; Chernozatonskii, L. A.*; Morokuma, Keiji*
Journal of Physical Chemistry C 114(35), p.14692-14696(2010) ; (JAEA-J 08589)

Atomic and electronic structure and energetic stability of newly proposed pentagonal and hexagonal chiral complex silicon nanowires (NWs) composed of five or six <1 1 0> oriented crystalline fragments were studied using the ab initio DFT method. The chirality of the wires was caused by consecutive shifts of each fragment by 1/5 or 1/6 of the wire unit cell parameter and rotations of 4° and 3.3° for achiral pentagonal or hexagonal wires, respectively. Chirality causes the HOMO-LUMO gap to reduce by 0.1 eV. Chiral silicon nanowires are found to be metastable structures with a 4.5 (kcal/mol)/Si atom potential barrier for reversible chiral ↔ achiral transformation.

39000356
Controlling branching in streamer discharge by laser background ionization
Takahashi, Eiichi*; Kato, Susumu*; Sasaki, Akira; Kishimoto, Yasuaki*; Furutani, Hirohide*
Journal of Physics D; Applied Physics 44(7), p.075204_1-075204_6(2011) ; (JAEA-J 08590)

Positive streamer branching in atmospheric argon gas was controlled by a KrF laser irradiation. This laser irradiation changes the amount of background ionization before the streamer discharge. Initial electron density formed by the KrF laser was evaluated by measuring ionization current. Characteristic "feather like" branching structure was observed and was suppressed only for the irradiated region. The threshold of ionization density which can influence to the branching was evaluated to be 5×10⁵/cm³. This suppression behavior was explained by the relation between a size of avalanche head and mean initial electron distance. These experimental results support the origin of the feather like structure comes from the branching model of Loeb-Meek that is probabilistic merging of individual avalanches.

39000357
Development of spin-polarized positron source using high energy proton beam
Maekawa, Masaki; Fukaya, Yuki; Yabuuchi, Atsushi; Kawasuso, Atsuo
Journal of Physics; Conference Series 262, p.012035_1-012035_4(2011) ; (JAEA-J 08591)

Using spin-polarized positrons, the excess spins in magnetic substances can be detected. For efficient measurements with spin-polarized positrons, a strong enough source emitting highly polarized positrons is needed. For this purpose, we focus on a ⁶⁸Ge radioisotope. This radioisotope decays to ⁶⁸Ga with a half-life of 280 days. The endpoint positron energy is 1.9 MeV and hence the theoretical longitudinal spin polarization is approximately 94%. This radioisotope can be produced though the nuclear reaction of ⁶⁹Ga (p,2n) ⁶⁸Ga. In this study, we report the production of ⁶⁸Ge by proton irradiation. We examined a metal form ⁶⁹Ga stable isotope and a GaN substrate as target materials. When the metal ⁶⁹Ga targets were used, the production rates of ⁶⁸Ge were 0.16 and 0.14 MBq/μA/h for 20 and 25 MeV, respectively. Using the GaN target, it was 0.24 MBq/μA/h. Thus, ⁶⁸Ge radioisotopes were generated in both targets. The spin polarizations of positrons emitted from ⁶⁸Ge and ²²Na were estimated to be approximately 90% and 30%, respectively.

39000358
Experimental analyses by SIMMER-III on debris-bed coolability and metallic fuel freezing behavior
Yamano, Hidemasa; Tobita, Yoshiharu
Journal of Power and Energy Systems (Internet) 5(1), p.2-18(2011) ; (JAEA-J 08592)

This paper describes experimental analyses using the SIMMER-III computer code. Two topics of key phenomena in core disruptive accidents were presented in this paper: debris-bed coolability and metallic fuel freezing behavior. Related experimental database were reviewed to choose suitable experiments. To analyze the debris-bed coolability, the ACRR-D10 in-pile experiments were selected. SIMMER-III well simulated the heat transfer mechanisms including conduction, boiling and channeling observed in the experiment. Metallic fuel may freeze onto the stainless steel (cladding or wrapper tube) together with eutectic formation during core disruption in a metallic-fueled reactor. The CAFÉ-UT2 experiment carried out using pure UO₂ melt to investigate such phenomena was selected for the experimental analysis. In spite of no eutectic formation model in the SIMMER-III code, the calculated fuel penetration behavior was in good agreement with the experimental data.

39000359
Development of system based code, 1; Reliability target derivation of structures and components
Kurisaka, Kenichi; Nakai, Ryodai; Asayama, Tai; Takaya, Shigeru
Journal of Power and Energy Systems (Internet) 5(1), p.19-32(2011) ; (JAEA-J 08593)

The present paper describes a new method for determining the target value of structural reliability in the framework of the System Based Code by considering the safety point of view. In the new method, the reliability target is derived from the proposal to a quantitative safety goal that was published by the nuclear safety commission of Japan and the quantitative safety design requirements on the core damage frequency and the containment failure frequency that were determined in the Fast Reactor Cycle Technology Development Project by Japan Atomic Energy Agency, by utilizing analysis models of a probabilistic safety assessment (PSA). The present method was applied to determination of the reliability target of the structures and components which constitute the reactor cooling system in the Japanese sodium-cooled fast reactor. As a result, we confirmed that the present method combined with the PSA analysis model for internal initiating events is applicable to determination of the reliability target associated with a random failure of the structures and components, and that the method related to seismic initiating events can derive the target value of the occurrence frequency at which any of the important structures and components fails due to an earthquake.

39000360
Effectiveness of carbon-ion beams for apoptosis induction in rat primary immature hippocampal neurons
Kaminuma, Takuya*; Suzuki, Yoshiyuki*; Shirai, Katsuyuki*; Mizui, Toshiyuki*; Noda, Shinei*; Yoshida, Yukari*; Funayama, Tomoo; Takahashi, Takeo*; Kobayashi, Yasuhiko; Shirao, Tomoaki*; Nakano, Takashi*
Journal of Radiation Research 51(6), p.627-631(2010) ; (JAEA-J 08594)

The direct biological effects of radiation, particularly accelerated heavy particle ions, on neurons are not fully known. Hence, the direct effect of carbon-ion beams on immature neurons was investigated by comparing to the effect of X-rays in vitro using primary hippocampal neurons. Primary neurons were prepared from hippocampi of fetal rats at embryonic day 18 from timed pregnant Wistar rats and cultured with Banker's methods. At 7 Days In Vitro (DIV), the cells were irradiated with 140 kV X-ray and 18.3 MeV/amu carbon-ion beams (LET = 108 keV/μm). The cells were fixed with 4% paraformaldehyde at 12 hours after irradiation. Then, the cells were treated with terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and DAPI staining for measuring the percentage of apoptosis (apoptotic index: AI). AI in sham-irradiated hippocampal neurons was 18%. The value of AI (AIs) of the cells irradiated with X-rays at 10 or 30 Gy were 15% or 23%, respectively. AI in cells irradiated with carbon-ion beams at 1 Gy, 3 Gy, 5 Gy and 10 Gy were 22%, 23%, 24% and 33%, respectively. AI was significantly increased by carbon-ion beams at 10 Gy (p < 0.001). The apoptosis of hippocampal neurons increased in a dose-dependent manner following both X-ray and carbon-ion beams irradiation. Carbon-ion beams were about 10-fold more effective than X-rays for apoptosis induction in immature hippocampal neurons.

39000361
Pulse radiolysis study on free radical scavenger edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), 2; A Comparative study on edaravone derivatives
Hata, Kuniki; Lin, M.; Katsumura, Yosuke*; Muroya, Yusa*; Fu, H.*; Yamashita, Shinichi; Nakagawa, Hidehiko*
Journal of Radiation Research 52(1), p.15-23(2011) ; (JAEA-J 08595)

A comparative study using the pulse radiolysis technique was carried out to investigate transient absorption spectra and rate constants for the reactions of OH radical and N₃ radical with edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) and its four analogue compounds, 1,3-dimethyl-2-pyrazolin- 5-one, 3-methyl-1-(pyridin-2-yl)-2-pyrazolin-5-one, 1-phenyl-3-trifluoromethyl-2-pyrazolin-5-one and 1-(4-chlorophenyl)-3-ethyl-2-pyrazolin-5-one. The results showed that, unlike reaction mechanisms previously proposed, the phenyl group of edaravone played an important role in the reaction with OH radical and OH adducts to the phenyl group were formed. Quantum chemical calculations also strongly supported this attribution and suggested that the most favorable site for attacks by OH radical is the ortho position of the phenyl group. Moreover, the rate constants for the reactions of edaravone and its analogues towards OH radical and N₃ radical were about 8.0×10⁹, and 4.0×10⁹ dm³ mol^-1s^-1, respectively. Edaravone displayed higher reactivity compared to the others, in contrast a previous report in which 3-methyl-1-(pyridin-2-yl)-2-pyrazolin-5-one showed the highest reactivity towards OH radical.

39000362
Gaussian-like ion beam shaping by double scattering
Yuri, Yosuke
Journal of the Physical Society of Japan 79(12), p.125002_1-125002_2(2010) ; (JAEA-J 08596)

In order to perform different irradiation modes with a high accuracy such as spot beam irradiation and uniform scanning irradiation, a beam with a Gaussian-like transverse intensity distribution, which here represents a smooth distribution without a fine structure, is necessary for charged-particle applications. However, the transverse intensity distribution of an ion beam extracted from an accelerator is usually complicated and asymmetric. Scattering an ion beam by a material such as a thin foil is a simple way to transform the beam distribution into a Gaussian-like one. However, this method is not perfect since the degree of the transformation depends on the beam optics (as well as on the density and thickness of the scatterer). We thus propose a possible simple way to compensate the imperfection in the distribution transformation caused by a single scatterer, namely, the use of two scatterers installed at separate locations in the beam line. By multiply-scattering the beam twice at different locations, it is expected that the whole of the transverse phase-space distribution is smoothed better, and it is possible to obtain a Gaussian-like beam regardless of the beam optics and observation locations. In order to verify the above expectation, numerical simulations were carried out.

39000363
Magnetic field and pressure phase diagrams of uranium heavy-fermion compound U₂Zn₁₇
Tateiwa, Naoyuki; Ikeda, Shugo*; Haga, Yoshinori; Matsuda, Tatsuma; Yamamoto, Etsuji; Sugiyama, Kiyohiro*; Hagiwara, Masayuki*; Kindo, Koichi*; Onuki, Yoshichika*
Journal of the Physical Society of Japan 80(1), p.014706_1-014706_8(2011) ; (JAEA-J 08597)

We have performed the magnetization measurements in high magnetic fields up to 53 T on single crystals of an uranium heavy fermion compound U₂Zn₁₇. In the antiferromagnetic state below the Néel temperature T_N = 9.7 K, a metamagnetic transition is found at H_c ≃ 32 T for the field along the [1120] direction (a-axis). The magnetic phase diagram for the field along the [1120] direction is given. We have also carried out high pressure resistivity measurement on U₂Zn₁₇ using a diamond anvil cell up to 8.7 GPa. The Néel temperature T_N is almost pressure-independent up to 4.7 GPa and starts to increase at the higher pressure region. The pressure dependences of the coefficient of T² term in the electrical resistivity A, an antiferromagnetic gap Δ and a characteristic temperature T_ρmax are discussed.

39000364
Glass-glass transition in a Potts model
Yokota, Terufumi
Journal of the Physical Society of Japan 80(1), p.014708_1-014708_6(2011) ; (JAEA-J 08598)

A Potts model with two kinds of local states is introduced and studied within the mean field theory using the replica method. The model includes frustration effects against the long-range ferromagnetic order. A transition line between two mixed glassy phases appears. The appearance of the two glassy phases is related to the existence of the two kinds of local states.

39000365
Design and fabrication of novel photonic crystal waveguide consisting of Si-ion implanted SiO₂ layers
Umenyi, A. V.*; Hommi, Masashi*; Kawashiri, Shinya*; Shinagawa, Teruyoshi*; Miura, Kenta*; Hanaizumi, Osamu*; Yamamoto, Shunya; Inoue, Aichi; Yoshikawa, Masahito
Key Engineering Materials 459, p.168-172(2011) ; (JAEA-J 08599)

A new type of two-dimensional photonic crystal (2-D PhC) waveguide was designed using finite difference time domain method to operate at a wavelength of 1.55 μm applicable to optical fiber-communication systems. We estimated that a triangular-lattice 2-D PhC structure formed by air holes with a diameter of 465 nm and a period of 664 nm suit our purpose. To form a core of the waveguide, Si ions were implanted into a SiO₂ layer by using a 400-kV ion implanter. The implantation energy was 80 keV and the implantation amount was 1×10¹⁷ ions/cm². The electron beam resist was spin-coated on a substrate and the designed pattern was written lithographically in the resist using Electron Beam. Atomic force microscope measurements revealed that the diameter and the period of air holes of the waveguide were 466 and 666 nm. These values were nearly equal to the designed ones. We thus succeeded in fabricating 2-D PhC waveguides in a Si-ion-implanted SiO₂ layer.

39000366
A Study of atomic interaction between suspended nanoparticles and sodium atoms in liquid sodium
Saito, Junichi; Ara, Kuniaki
Nuclear Engineering and Design 240(10), p.2664-2673(2010) ; (JAEA-J 08601)

39000367
Experimental validation of effectiveness of rod-type burnable poisons on reactivity control in HTTR
Goto, Minoru; Shiozawa, Shusaku; Fujimoto, Nozomu; Nakagawa, Shigeaki; Nakao, Yasuyuki*
Nuclear Engineering and Design 240(10), p.2994-2998(2010) ; (JAEA-J 08602)

In block type high temperature gas-cooled reactors (HTGRs), insertion depth of control rods (CRs) into a core should be retained as shallow as possible to keep fuel temperature below limit through a burnup period. Using burnable poisons (BPs) to control reactivity is considered as a method to resolve this problem as in case of light water reactors (LWRs). BPs design method for LWRs has been validated by experimental data, however, that for HTGRs have not been yet, because there was not burnup characteristics data of HTGRs required for the validation. The High Temperature engineering Test Reactor (HTTR) is a block type HTGRs and it uses BPs to control reactivity. The HTTR has been operated up to middle burnup, and thereby the experimental data was expected to show effect of the BPs on the reactivity control. Hence, in order to validate the BPs design method, we investigated whether the BPs have functioned as designed. As a result, the CRs insertion depth has been retained shallow within allowable range, and then the BPs design method was validated.

39000368
Experimental investigation on self-leveling behavior in debris beds
Zhang, B.*; Harada, Tetsushi*; Hirahara, Daisuke*; Matsumoto, Tatsuya*; Morita, Koji*; Fukuda, Kenji*; Yamano, Hidemasa; Suzuki, Toru; Tobita, Yoshiharu
Nuclear Engineering and Design 241(1), p.366-377(2011) ; (JAEA-J 08603)

In the present study, we elected to use depressurization boiling to simulate an axially increasing void distribution in the debris bed. Bottom-heating boiling was also chosen to confirm characteristics of the self-leveling process do not depend on the boiling mode. Particle size, shape, bed volume and density along with boiling intensity and total volume were taken as experimental parameters to obtain the general characteristics of the self-leveling process. Experiments with simulant materials were conducted and analyzed. The good concordance of the transient processes obtained from the different boiling methods sufficiently demonstrates the results obtained exhibit these general self-leveling characteristics. Comparisons of deduced time variations of the inclination angle provide qualitative tendencies based on the experimental parameters considered influential to self-leveling behavior. The rationale behind the definition introduced for equivalent power density is also presented.

39000369
Quasi-monoenergetic neutron energy spectra for 246 and 389 MeV ⁷Li(p,n) reactions at angles from 0° to 30°
Iwamoto, Yosuke; Hagiwara, Masayuki*; Satoh, Daiki; Iwase, Hiroshi*; Yashima, Hiroshi*; Itoga, Toshio*; Sato, Tatsuhiko; Nakane, Yoshihiro; Nakashima, Hiroshi; Sakamoto, Yukio; Matsumoto, Tetsuro*; Masuda, Akihiko*; Nishiyama, Jun*; Tamii, Atsushi*; Hatanaka, Kichiji*; Theis, C.*; Feldbaumer, E.*; Jaegerhofer, L.*; Pioch, C.*; Mares, V.*
Nuclear Instruments and Methods in Physics Research A 629(1), p.43-49(2011) ; (JAEA-J 08604)

The authors measured the neutron energy spectra of a quasi-monoenergetic ⁷Li(p,n) neutron source with 246 and 389 MeV protons set at seven angles (0°, 2.5°, 5°, 10°, 15°, 20° and 30°), using a time-of-flight (TOF) method employing organic scintillators NE213 at the Research Center for Nuclear Physics (RCNP) of Osaka University. The energy spectra of the source neutrons were precisely deduced down to 2 MeV at 0° and 10 MeV at other angles. The cross sections of the peak neutron production reaction at 0° were on the 35-40 mb line of other experimental data, and the peak neutron angular distribution agreed well with the Taddeucci formula. Neutron energy spectra below 100 MeV at all angles were comparable, but the shapes of the continuum above 150 MeV changed considerably with the angle.

39000370
A Crossed photon-atom beam method for absolute measurement of total photoionization cross sections on isolated metal atoms; Measurements on Ba and Eu atoms
Obara, Satoshi*; Kobayashi, Ryoei*; Yagi, Shuichi*; Toyama, Yuko*; Kutluk, G.*; Osawa, Tetsutaro*; Ogura, Koichi; Shibata, Takemasa; Azuma, Yoshiro*; Nagata, Tetsuo*
Nuclear Instruments and Methods in Physics Research B 269(3), p.263-271(2011) ; (JAEA-J 08605)

A crossed photon-atom beam apparatus has been constructed for absolute measurement of total photoionization cross sections of isolated and neutral metallic atoms. Using this apparatus, measurements on Ba and Eu atoms have been made at their 4d giant resonance regions 110-140 eV and 140-180 eV, respectively. The target atom density was determined using the deposition rate on a quartz crystal sensor and the average velocity of the atoms obtained by a time-of-flight method combined with a pulsed electron gun. The number of photons was determined with use of a double ion chamber. The comparison of the measured cross-section values with previous experimental and theoretical results is reasonable, indicating that the crossed photon-atom beam method is fairly promising technique.

39000371
Attenuation of ambient dose equivalent from neutrons by thick concrete, cast iron and composite shields for high energy proton, ³He, ⁴⁸Ca and ²³⁸U ions on Cu targets for shielding design
Iwamoto, Yosuke; Ronningen, R. M.*
Nuclear Instruments and Methods in Physics Research B 269(3), p.353-363(2011) ; (JAEA-J 08606)

Data on neutron dose attenuation by thick concrete, cast iron, and cast iron plus concrete composite shields for heavy ions and protons having high energies (200 - 1000 MeV/u) are necessary for shielding designs of high-powered heavy ion accelerator facilities. Neutron production source terms, shield material attenuation lengths, and neutron dose rate reduction effectiveness of the bulk shielding in the angular range from 0° to 125° were determined by the Particle and Heavy Ion Transport Code (PHITS) for beams of 300 and 550 MeV/u ⁴⁸Ca ions, 200 and 400 MeV/u ²³⁸U ions, 800 MeV/u ³He and 1 GeV protons. Calculated results of interaction lengths of concrete and cast iron were also compared with similar work performed by Agosteo et al., and to experimental and other calculated data on interaction lengths. The agreement can be regarded as acceptable.

39000372
Precipitation behaviors of fission products by phosphate conversion in LiCl-KCl medium
Amamoto, Ippei; Kofuji, Hirohide; Myochin, Munetaka; Takasaki, Yasushi*; Yano, Tetsuji*; Terai, Takayuki*
Nuclear Technology 171(3), p.316-324(2010) ; (JAEA-J 08607)

The separation technique by phosphate conversion of FP from NaCl-KCl or NaCl-2CsCl as the medium of the spent electrolyte of pyroprocessing is being developed at RIAR in Russia. To ascertain the technical feasibility of applying this RIAR's method for recycling of spent electrolyte which composed of FP such as AL, ALE, and REE and 3LiCl-2KCl as the medium, preliminary study was undertaken at JAEA. This study occupies an auxiliary role which is forwarded as a part of FaCT Project of Japan. As a first approach, the thermodynamic analysis to understand the behaviours of FP in the electrolyte was carried out after literature research and acquisition of required thermodynamic properties. Preliminary experiment was then undertaken to observe the conversion behaviours of chlorides to phosphate. In this paper, these results are shown and are evaluated to discern the feasibility of the phosphate conversion method.

39000373
Fuel assembly design for plutonium conservation in a light water reactor with hard neutron spectrum
Uchikawa, Sadao; Okubo, Tsutomu; Nakano, Yoshihiro
Nuclear Technology 172(2), p.132-142(2010) ; (JAEA-J 08608)

The FLWR is a BWR-type reactor with hard neutron spectrum based on the well-experienced LWR technologies. The present paper has proposed a new concept of the fuel assembly design for the first stage of FLWR to conserve plutonium effectively with a fissile-plutonium conversion ratio of around 1.0, keeping negative void reactivity characteristics. The enriched UO₂ fuel rods are arranged in the peripheral region of the assembly, surrounding the MOX fuel rods in the central region. Performance evaluation shows that the FLWR/MIX concept is effective for controlling the void reactivity characteristics in the tight-lattice fuel rod configuration and promising under the framework of the UO₂ and MOX fuel technologies and related infrastructures which have been established for the current LWR-MOX utilization.

39000374
Evaluation of the white neutron beam spectrum for single-event-effects testing at the RCNP cyclotron facility
Iwamoto, Yosuke; Fukuda, Mitsuhiro*; Sakamoto, Yukio; Tamii, Atsushi*; Hatanaka, Kichiji*; Takahisa, Keiji*; Nagayama, Keiichi*; Asai, Hiroaki*; Sugimoto, Kenji*; Nashiyama, Isamu*
Nuclear Technology 173(2), p.210-217(2011) ; (JAEA-J 08609)

The 30° white neutron beam at RCNP facility has been characterized as a prove suitable for testing of single event effects (SEEs) in semiconductors in the neutron energy range from 1 to 300 MeV using the 392-MeV proton incident reaction on a 6.5-cm-thick tungsten target. The neutron spectrum in measurements were demonstrated to provide a neutron spectrum similar to the terrestrial one at sea level, but with an enhancement in the intensity of a factor of 1.5×10⁸. The average neutron intensity and spectrum from 10 to 300 MeV at RCNP were almost same as those at WNR. The calculated RCNP neutron flux using PHITS generally agreed with the measured RCNP data within a factor of two. As the neutron density per pulse for RCNP is 500 times lower than that for WNR, the pileup probability of single-event transient currents and false multiple-bit upsets is reduced. Such conditions at RCNP are suitable for accelerated SEE testing to get meaningful results in realistic time frame.

39000375
Anisotropic spin freezing in lightly-doped La_2-xSr_xCuO₄
Matsuda, Masaaki; Fujita, Masaki*; Takeda, Masayasu; Kakurai, Kazuhisa; Yamada, Kazuyoshi*
Physica C 470(Suppl.1), p.S82-S83(2010) ; (JAEA-J 08611)

We performed polarized neutron scattering experiments in lightly-doped La_1.982Sr_0.018CuO₄, which shows both Néel ordering and spin-glass state at low temperatures. Three-dimensional neutron polarization analysis was performed on diffuse magnetic peaks in the spin-glass phase. From the analysis, we concluded that the ratio of the spin components along the a, b and c axes is 0.8, 1.0 and 0.15, respectively, indicating that the low energy spin fluctuations (|E|<1.7 meV) have the XY anisotropy.

39000376
Morphology control of single-crystalline Si₃N₄ nanomaterials
Taguchi, Tomitsugu; Yamamoto, Hiroyuki; Shamoto, Shinichi
Physica E 43(1), p.539-452(2010) ; (JAEA-J 08612)

Three kinds of single-crystalline Si₃N₄ nanomaterials, Si₃N₄ nanowires, nanobelts and nanosheets, were synthesized by the heat treatment of Si powder in N₂ gas. The Si₃N₄ nanowires and nanobelts are produced when the synthesis temperature and flow rate of N₂ gas are lower than 1300 °C and 0.5 l/min, respectively. The number ratio of Si₃N₄ nanowires to Si₃N₄ nanobelts decreases with increase in the synthesis temperature and flow rate of N₂ gas. When synthesis temperature and flow rate of N₂ gas are higher than 1400 °C and 0.75 l/min, respectively, a lot of Si₃N₄ nanosheets of at least 2 μm in width and ranging from 1.5 to 4 nm in thickness are produced. Thus the morphology of Si₃N₄ nanomaterials can be controlled by changing not only synthesis temperature but also flow rate of N₂ gas.

39000377
EPR and ab initio calculation study on the EI4 center in 4H- and 6H-SiC
Carlsson, P.*; Son, N. T.*; Gali, A.*; Isoya, Junichi*; Morishita, Norio; Oshima, Takeshi; Magnusson, B.*; Janzén, E.*
Physical Review B 82(23), p.235203_1-235203_11(2010) ; (JAEA-J 08613)

Electron Paramagnetic Resonance (EPR) studies of the EI4 center in 4H- and 6H-Silicon Carbide (SiC) were carried out. The EI4 center was drastically enhanced in electron-irradiated high-purity semi-insulating materials by annealing at 700-750 °C. An additional large-splitting ²⁹Si hf structure and ¹³C hf lines of the EI4 defect were observed. Comparing the data obtained from the hf interactions and the annealing behavior, and also from ab initio supercell calculations of different carbon-vacancy-related complexes, we propose a complex between a carbon vacancy-carbon antisite and a carbon vacancy at the third-neighbor site of the antisite in the neutral charge state, (V_C-C_SiV_C)⁰, as a new defect model for the EI4 center.

39000378
Reanalysis of the (J = 5) state at 592 keV in ¹⁸⁰Ta and its role in the ν-process nucleosynthesis of ¹⁸⁰Ta in supernovae
Hayakawa, Takehito; Mohr, P.*; Kajino, Toshitaka*; Chiba, Satoshi; Mathews, G.*
Physical Review C 82(5), p.058801_1-058801_4(2010) ; (JAEA-J 08614)

We analyze the production and freeze-out of the isomer ¹⁸⁰Ta in the ν-process. We consider the influence of a possible low-lying intermediate (J = 5) state at 592 keV using a transition width estimated from the measured half-life. This more realistic width is much smaller than the previous estimate. We find that the 592 keV state leads only to a small reduction of the residual isomer ratio from the previous result. The isomer ratio changes from 0.39 to 0.38, whereas previously it was estimated that this transition could reduce the ratio to R = 0.18. This finding strengthens the evidence that ¹³⁸La and ¹⁸⁰Ta are coproduced by neutrino nucleosynthesis with an electron neutrino temperature of kT ≈ 4 MeV.

39000379
Novel extrapolation method in the Monte Carlo shell model
Shimizu, Noritaka*; Utsuno, Yutaka; Mizusaki, Takahiro*; Otsuka, Takaharu*; Abe, Takashi*; Homma, Michio*
Physical Review C 82(6), p.061305_1-061305_4(2010) ; (JAEA-J 08615)

39000380
Signatures of hadron-quark mixed phase in gravitational waves
Sotani, Hajime*; Yasutake, Nobutoshi*; Maruyama, Toshiki; Tatsumi, Toshitaka*
Physical Review D 83(2), p.024014_1-024014_8(2011) ; (JAEA-J 08616)

We calculate stellar oscillations including the hadron-quark mixed phase considering the finite size effects. We find that it is possible to distinguish whether the mixed phase exists or not in stars, even if one will observe the gravitational waves of the fundamental mode. Additionally, the normalized eigenfrequencies of pressure modes depend strongly on the stellar mass and on the adopted equation of state. Especially, in spite of the fact that the radius of the neutron star with 1.4 times the solar mass, which is standard mass, is almost independent from the equation of state with quark matter, the frequencies of pressure modes depend on the adopted equation of state. Thus, via observing the many kinds of gravitational waves, it will be possible to make a restriction on the equation of state.

39000381
Role of AtPolζ, AtRev1 and AtPolη in UV light-induced mutagenesis in Arabidopsis^1[W]
Nakagawa, Mayu*; Takahashi, Shinya*; Tanaka, Atsushi; Narumi, Issei; Sakamoto, Ayako
Plant Physiology 155(1), p.414-420(2011) ; (JAEA-J 08617)

39000382
Advanced tokamak research in JT-60U and JT-60SA
Isayama, Akihiko; JT-60 Team
Plasma and Fusion Research (Internet) 5, p.S1003_1-S1003_7(2010) ; (JAEA-J 08618)

39000383
Development of advanced tokamak operation scenarios in JT-60U and JT-60SA
Suzuki, Takahiro; JT-60 Team
Plasma and Fusion Research (Internet) 5, p.S2008_1-S2008_6(2010) ; (JAEA-J 08619)

Integrated high performance was achieved in wall-stabilized reversed shear plasma, where high H_H98(y,2)=1.7, β_N=2.7, f_GW=0.87, f_BS=0.9, f_NI=0.95 were simultaneously realized at ITER/DEMO-relevant q₉₅=5.3. The achieved β_N was above no-wall β_N limit (1.9) and close to the ideal-wall β_N limit (2.9) for this discharge. The β_N was limited by appearance of resistive wall mode (RWM) when toroidal rotation velocity at q=3 surface became smaller than critical velocity. In another discharge, fully relaxed current profile was realized at high f_BS=0.5 under fully non-inductive current drive (CD) condition at q₉₅=5.8, using lower-hybrid CD and neutral beam (NB) CD with bootstrap current. Integration of operation scenario for steady-state high performance is a mission in JT-60SA, where DEMO-equivalent β_N=4.3 is aimed, utilizing highly shaped configuration, closely-placed conducting wall, low ripple rate, and RWM control coils. Steady-state q profile will be maintained by off-axis CD by negative-ion based NB with bootstrap current for 60-100 s. Operation scenario to build up I_p with small consumption of magnetic flux is a key issue in realization of compact DEMO, SlimCS. Fully non-inductive buildup of I_p and recharging of Ohmic coil current were demonstrated in JT-60U. Development of whole operation scenario from buildup of I_p to steady sustainment of high performance plasma is a great challenge in JT-60SA.

39000384
Transport simulation of helical plasmas using the TASK/TX code
Miki, Masayuki*; Fukuyama, Atsushi*; Honda, Mitsuru
Plasma and Fusion Research (Internet) 5, p.S2040_1-S2040_4(2010) ; (JAEA-J 08620)

It is widely accepted that the radial electric field strongly affects plasma confinement through the transport process. We have analysed the time evolution of the radial electric field and the radial transport in plasmas in a helical magnetic configuration by extending the TASK/TX code, which is a one-dimensional dynamic transport code originally developed for axisymmetric plasmas. To apply TASK/TX to helical plasmas, we have included two additional effects; helical neoclassical viscosity force and diffusion due to magnetic braiding. Plasma transport simulation is carried out mainly using the LHD parameters. We obtained negative radial electric field (ion root) with ion heating and positive radial electric field (electron root) with electron heating. Effects of magnetic braiding are also studied.

39000385
Three-dimensional analysis of beamlet deflection in a MeV accelerator for ITER NBI
Kashiwagi, Mieko; Taniguchi, Masaki; Umeda, Naotaka; Mizuno, Takatoshi; Tobari, Hiroyuki; Dairaku, Masayuki; Watanabe, Kazuhiro; Inoue, Takashi
Plasma and Fusion Research (Internet) 5, p.S2097_1-S2097_4(2010) ; (JAEA-J 08621)

An accelerator which generates deuterium negative ion beams of 1 MeV, 40 A for 3600 s is required for the ITER neutral beam injector (NBI). To realize such a high power accelerator, numerical studies have been carried out in parallel to acceleration tests in JAEA. After long pulse acceleration tests up to 30 s, it was found that parts of grid were melt around the grid apertures. In order to investigate how the grids melted, a three dimensional beam analysis was carried out in combination with 2D beam analysis code and gas flow code. The analysis clarified that the beamlet was deflected due to their own space charge repulsion and magnetic field at extraction grid, which led to direct interceptions of the beamlets at the grids. The power loads at the grid by these deflected beamlets were found to be more than 20 kW/cm². For next long pulse tests, a new extraction grid with aperture offset and field shaping plate has been designed so as to compensate the beamlet deflections.

39000386
Equation of state of structured matter at finite temperature
Maruyama, Toshiki; Yasutake, Nobutoshi*; Tatsumi, Toshitaka*
Progress of Theoretical Physics Supplement (186), p.69-74(2010) ; (JAEA-J 08622)

We investigate the properties of nuclear matter at the first-order phase transitions (FOPT) such as liquid-gas phase transition and hadron-quark phase transition. As a general feature of the FOPT of matter consisting of many species of charged particles, there appears a mixed phases with geometrical structures called "pasta" due to the balance of the coulomb repulsion and the surface tension between two phases. The equation of state (EOS) of mixed phase is different from the one obtained by a bulk application of the Gibbs conditions or by the Maxwell construction due to the effects of the non-uniform structure. We show that the charge screening and strong surface tension make the EOS close to that of the Maxwell construction. The thermal effects are elucidated as well as the above finite-size effects.

39000387
Production of a fluorescence probe in ion-beam radiolysis of aqueous coumarin-3-carboxylic acid solution, 1; Beam quality and concentration dependences
Maeyama, Takuya*; Yamashita, Shinichi; Baldacchino, G.*; Taguchi, Mitsumasa; Kimura, Atsushi; Murakami, Takeshi*; Katsumura, Yosuke
Radiation Physics and Chemistry 80(4), p.535-539(2011) ; (JAEA-J 08623)

Aqueous coumarin-3-carboxylic Acid (3CCA) solutions were irradiated with eight different ion beams covering LET range from 0.5 to above 2000 eV/nm. G-values of 7OH-3CCA, one of hydroxylated products in radiolysis of the solutions, have been determined by fluorescence-HPLC technique in 3CCA concentration range from 0.1 to 26 mM. The formation yield of 7OH-3CCA increased with increasing concentration of 3CCA while it decreased with increasing LET value of ion beam. Compared with our previous reports on G(^●OH) at a scavenging capacity of 10⁷ s with absorption spectroscopy, it was found that G(7OH-3CCA) is about (4.7±0.6)% of G(^●OH), which is consistent for all of the ion beams used in the present study. However, 7OH-3CCA yields in high CCA concentration region, especially by using extremely high LET ions, were much higher than expected values based on the above conversion factor and G(^●OH) value predicted in theoretical work.

39000388
Semi-empirical formula for γ-ray streaming through bend duct with arbitrary flexion angles
Matsuda, Norihiro; Sasamoto, Nobuo
Radiation Protection Dosimetry 140(3), p.211-217(2010) ; (JAEA-J 08624)

Semi-empirical formulas for the duct streaming of γ-rays are useful as ever for application to practical shielding designs. Based on the algorithm of the DIN's formula, a new semi-empirical formula has been developed. Major improvements are the re-definition of the duct leg region, introduction of the γ-ray energy dependent total dose albedo and formulation for the bend duct with arbitrary flexion angles. Validity of the formula was verified through benchmark analyses of γ-ray streaming through three-legged duct with rectangular bend and the one with the flexion angle of 137°.

39000389
Distribution of Cs and Am in the solution-bentonite colloids-granite ternary system; Effect of addition order and sorption reversibility
Iijima, Kazuki; Tomura, Tsutomu*; Tobita, Minoru*; Suzuki, Yasuyuki*
Radiochimica Acta 98(9-11), p.729-736(2010) ; (JAEA-J 08625)

Distribution behavior of Cs and Am in the synthetic groundwater-bentonite colloids-granite ternary system was investigated. Radionuclide sorbed onto the bentonite colloids is desorbed by addition of granite, indicating that the sorption of Cs and Am onto the bentonite colloids are reversible. The sorption model based on cation exchange and surface complexation reaction considering high edge site density for bentonite colloids is applicable to explain the sorption behavior of Am and Cs in the ternary system.

39000390
Microwave-induced supercurrent in a ferromagnetic Josephson junction
Hikino, Shinichi*; Mori, Michiyasu; Takahashi, Saburo*; Maekawa, Sadamichi
Superconductor Science and Technology 24(2), p.024008_1-024008_5(2011) ; (JAEA-J 08626)

We study the supercurrent resulting from coupling of the Josephson-phase and the spin-wave excited by microwave radiation in a ferromagnetic Josephson junction, in which two superconductors are separated by a ferromagnet. To explore how the spin wave excitation affects the current-voltage curve, the resistively shunted junction model, which is an equation of motion for the Josephson-phase, is extended by considering the gauge invariance including magnetization. When the magnetization is driven by the microwave adjusted to the ferromagnetic resonance frequency, the dc supercurrent is induced in the junction, and the current-voltage curve shows step structures as a function of applied voltage. The position of each step in voltage is proportional to the microwave frequency multiplied by even number. This means that the even number of magnons is necessary for the singlet Cooper pair to go through the ferromagnetic layer. The magnitudes of step-height can be controlled by tuning the shape of interface. Our results present a new route to observe the spin-wave excitation by the Josephson effect.

39000391
Identification of asbestos by laser-induced fluorescence microscopy (in Japanese)
Ozu, Akira; Esaka, Fumitaka; Yasuda, Kenichiro
Bunseki Kagaku 60(1), p.75-80(2011) ; (JAEA-J 08627)

Microscopic studies on laser-induced fluorescence emitted from asbestos (chrysotile) and a building material (glass-wool: a substitute material for asbestos) fibrous particle excited by a ultra-violet (266 nm) laser, have been conducted by visualizing those particles with the fluorescence. The fluorescence characteristics observed under the microscope agreed approximately with those observed in the determination using bulk samples. The decay ratio of the fluorescence intensity at 540 nm and other wavelength was in good agreement with that with bulk sample. The total amount of the intensity of glass-wool per unit area at > 350 nm was 23 times larger than that of chrysotile, corresponding to that with bulk sample. A practical microscopic method used to discriminate asbestos by combining the decay ratio and total amount of the intensity are proposed.

39000392
Dissolution techniques with microwave heating devices for radiochemical analysis of ash and cement-solidified product samples (in Japanese)
Haraga, Tomoko; Ishimori, Kenichiro; Kato, Kenichi; Kameo, Yutaka; Takahashi, Kuniaki
Bunseki Kagaku 60(1), p.87-90(2011) ; (JAEA-J 08628)

In order to dissolve radioactive ash (fly ash and bottom ash) and cement-solidified product of radioactive liquid wastes, a dissolution method using microwave heating devices was developed. In present method, most metal elements in samples were extracted with HCl and HNO₃ to sample solution and a precipitate with silica as the main ingredient was decomposed with HF and HNO₃. As a result, fluoride residue was sufficiently reduced and more than 99% of radionuclides were recovered to sample solution. The ash and cement-solidified product samples were successfully dissolved in a shorter time as compared with a conventional method by external heating.

39000393
Commentaries for third secondary national examination on fiscal 2010 for the professional engineer of nuclear and radiation; Commentaries including key point for compulsory examination (in Japanese)
Sasaki, Satoru; Suto, Toshiyuki; Yamamoto, Kazuyoshi
Genshiryoku eye 56(12), p.66-73(2010) ; (JAEA-J 08629)

39000394
Commentaries for third secondary national examination on fiscal 2010 for the professional engineer of nuclear and radiation; Commentaries (Part 1) including key point for elective examinations (in Japanese)
Sasaki, Satoru; Suto, Toshiyuki; Harada, Akio; Kurihara, Ryoichi; Yamamoto, Kazuyoshi; Tsuchida, Noboru; Shimizu, Isamu; Nomura, Toshibumi
Genshiryoku eye 57(1), p.66-75(2011) ; (JAEA-J 08630)

39000395
Development of world-class mono-energetic neutron irradiation fields with high quality; Establishment of important technical platform for neutron use (in Japanese)
Tanimura, Yoshihiko
Genshiryoku eye 57(2), p.37-40(2011) ; (JAEA-J 08631)

Ten mono-energetic neutron irradiation fields have been developed at the Facility of Radiation Standards in Nuclear Science Research Institute. In these fields, mono-energetic neutrons can be stably generated over a wide energy range with five digits from 8 keV to 19 MeV using an accelerator and they are used for the performance test of the neutron detectors.

39000396
Commentaries for third secondary national examination on fiscal 2010 for the professional engineer of nuclear and radiation; Commentaries (Part 2) including key point for elective examinations (in Japanese)
Sasaki, Satoru; Suzuki, Soju; Nakano, Junichi; Takamatsu, Misao; Matoba, Ichiyo*; Nakano, Makoto*; Oketani, Koichiro*; Natsume, Tomohiro*
Genshiryoku eye 57(2), p.66-75(2011) ; (JAEA-J 08632)

39000397
Photocathode dc electron gun for next-generation light-sources (in Japanese)
Nagai, Ryoji; Hajima, Ryoichi; Nishimori, Nobuyuki
Hikari Araiansu 22(1), p.38-43(2011) ; (JAEA-J 08634)

An energy-recovery linac (ERL) is a new class of electron accelerator to generate a small-emittance and high average current electron beam at high-repetition rate. Now, ERL is considered as a promising device for next-generation light sources which have ultra-short pulse and high-coherency. An electron gun to produce a small-emittance electron beam with high-average current is the most important component for an ERL to exploit its full potential because the emittance and current of the ERL beam are determined by performance of its electron gun. A dc electron gun is able to generate a high-current electron beam of ultrasmall initial emittance, when it is equipped with a semiconductor photocathode having a negative electron affinity (NEA) surface. To suppress emittance growth by space charge effect, the gun voltage must be 500 kV or higher. In this paper, we present details of the electron gun design and results of a high-voltage testing.

39000398
Status and plan of ageing management technical evaluation on nuclear power stations (in Japanese)
Suzuki, Masahide; Nishiyama, Toshiaki*
Hozengaku 9(4), p.2-8(2011) ; (JAEA-J 08637)

39000399
PET imaging of pheochromocytomas by using ⁷⁶Br-MBBG (in Japanese)
Watanabe, Shigeki; Ishioka, Noriko
Isotope News (680), p.2-6(2010) ; (JAEA-J 08638)

39000400
Pyroreprocessing development for next generation energy; Reducing high-level radioactive waste volume (in Japanese)
Amamoto, Ippei
Journal of MMIJ 1(127), p.1-7(2011) ; (JAEA-J 08639)

The pyroprocess as a non-aqueous reprocessing, is oriented as a complementary concept for the Fact Project. The pyroprocess possesses some inherent problems that have yet to be solved. The purification and recycling of the spent electrolyte as a regenerated medium by removing its fission products (FP) must be further investigated to reduce the volume of high-level radioactive waste (HLW). Some FP elements dissolved in the medium are apt to remain in the spent electrolyte after recovering actinoid elements. To remove such FP, the zeolite sorption is applied as it is considered the most suitable method, but its concept should be modified in order to reduce the generating waste volume. As one of the solutions, the electrolyte recycle process by phosphates is being developed. In this paper, the author has discussed the pyroprocess development, highlighting the spent electrolyte treatment from the viewpoint of economical and environmental load reduction.

39000401
Stress measurement technique using neutron diffraction and its applications (in Japanese)
Suzuki, Hiroshi
Journal of the Vacuum Society of Japan 53(12), p.713-719(2010) ; (JAEA-J 08640)

Neutron diffraction is the only method by which residual stresses inside materials at centimeter-order depth can be measured nondestructively. Residual lattice strains in (hkl) can be evaluated from the shift of the diffraction peak from its original position under the stress-free condition. Residual stresses can be calculated by applying Hooke's law to lattice strains measured in three orthogonal directions. In addition, the neutron diffraction method can evaluate macroscopic deformation of engineering materials by measuring microstructural factors such as microstrains. Therefore, the neutron diffraction technique is very helpful in the design and development of engineering components, as well as in studies on materials engineering. This paper shows principle of neutron stress measurement and engineering neutron diffractometers as well as some applications.

39000402
Simulation of radial flow generated by rotating a set of screens and disks (in Japanese)
Ogiwara, Norio
Journal of the Vacuum Society of Japan 53(12), p.773-776(2010) ; (JAEA-J 08641)

Generation of radial gas flow by not only rotation of a set of screens radiating from the axis in all directions but also rotation of a combination of radial screens and disks perpendicular to the axis was investigated by Monte Carlo simulation. The followings are revealed: (1) Radial flow is effectively enhanced by rotation of the set of screens with the velocity ratio rω/<v> of greater than 2; where <v> is the mean velocity of the gas molecules, and rω is an additional circumferential velocity due to rotation. Moreover, the compression ratio becomes greater than 10⁶ with the velocity ratio greater than 3. (2) The special combination of parallel disks and radial screens has both a large pumping efficiency greater than 0.5 and a large compression ratio greater than 10⁵ with the velocity ratio of 3.

39000403
Probabilistic safety assessment of flammable gas leakage in the HTTR-IS hydrogen production plant (in Japanese)
Kudo, Junichi*; Sakaba, Nariaki; Takahashi, Makoto*; Wakabayashi, Toshio*
Nippon Genshiryoku Gakkai Wabun Rombunshi 9(4), p.360-367(2010) ; (JAEA-J 08643)

The HTTR-IS system is one of the plants producing hydrogen with nuclear power. Such a system has high safety requirements. One of the safety studies to be conducted is the probabilistic safety assessment (PSA) study for concerned hydrogen explosion, which was not studied previously. Therefore, this study is conducted for the preliminary PSA of flammable gas leakage in the HTTR-IS system. First, a master logic diagram (MLD) was developed to identify initiating events. After identifying initiating events, event tree analysis (ETA) and fault tree analysis (FTA) were performed to quantify the average frequency of an accident. The initial result of the PSA shows that the nominal frequency of explosion is 2.5×10^-4 1/y. This frequency is higher than the criterion defined in this paper and unacceptable. Installments of additional components are investigated in order to reduce frequency. As a result, the average frequency of explosion is decreased to 7.9×10^-7 1/y.

39000404
Challenge to gain a new insight into water under high temperatures and pressures; Toward full understanding of water (in Japanese)
Ikeda, Takashi; Katayama, Yoshinori
Nippon Genshiryoku Gakkai-Shi 53(1), p.42-44(2011) ; (JAEA-J 08644)

Liquid water exhibiting various properties according to its surroundings is still a major research target in wide fields of physics, chemistry, and biology. In this review, we first describe the behavior of water under pressures and temperatures revealed recently by combining first principles molecular dynamics simulations and in situ X-ray diffraction experiments. We then give an outlook for future subjects.

39000405
Separation of cesium from nitric acid media with mixed oxides of tantalum, titanium and silicon
Yamagishi, Isao; Morita, Yasuji
Nippon Ion Kokan Gakkai-Shi 21(3), p.175-180(2010) ; (JAEA-J 08645)

Binary hydrous oxides of Si, Ti, Zr, Nb and Ta were synthesized under the hydrothermal condition to separate Cs from nuclear waste. Their selectivity toward Cs and chemical stability were examined in nitric acid media. Tantalates containing Si or Ti as well as titanosilicate showed high distribution coefficients above 100 ml/g in 3 M nitric acid. Perovskite phase (NaTaO₃) in the tantalate disappeared with increasing Si or Ti content, and pyrochlore phase formed. Exchange capacity for Cs in 3 M nitric acid increased with content of Si or Ti in the tantalates up to specific molar ratios of Si/Ta = 0.5 or Ti/Ta = 0.26. The Cs capacity of these tantalates unaltered even after contact with nitric acid at 90 °C but that of titanosilicate decreased to 1/20 of its initial capacity due to destruction of the structure. The tantalate of Si showed rapid adsorption kinetics and higher capacity for Cs than that of Ti.

39000406
R&D of atomic energy grid infrastructure AEGIS (in Japanese)
Suzuki, Yoshio; Tatekawa, Takayuki; Kim, G.; Kino, Chiaki; Miyamura, Hiroko; Teshima, Naoya; Hayashi, Sachiko*; Aoyagi, Tetsuo; Takemiya, Hiroshi; Nakajima, Norihiro
Nippon Keisan Kogakkai Rombunshu (Internet) 15(2), p.1051-1054(2010) ; (JAEA-J 08646)

We have developed the Atomic Energy Grid InfraStructure (AEGIS) for establishing computational infrastructure for nuclear field. In this R&D we have inherited the knowledge and skills in ITBL Infrastructure developed in the national project ITBL (Information Technology Based Laboratory), which aims at establishment of virtual research environment where supercomputers and data bases are connected by network. Here we have focused on two issues: improvements of safety and usability. For the safety, we have made the authentication mechanism double with both the personal certification and the machine certification. For the usability, we have developed the grid-enabled client API to use grid functions on a user terminal. By those R&Ds, we have successfully contributed to various nuclear researches, such as "full scale 3D vibration simulator for an entire nuclear power plant", "simulation for predicting quake-proof capability of nuclear power plants", and so on.

39000407
Effect of liquid metal composition and test material on cavitation erosion (in Japanese)
Yada, Hiroki; Kurachi, Hiroaki*; Tsukimori, Kazuyuki; Hattori, Shuji*
Nippon Kikai Gakkai Rombunshu, A 77(773), p.146-153(2011) ; (JAEA-J 08647)

Cavitation erosion tests using a vibratory apparatus were carried out to study the effect of liquid metal composition and test material of different stainless steels. The relative temperature was defined as the percentage between freezing and boiling points. At relative temperature at 14°C, the erosion rate is 10-12 times in various lead - bismuth alloys, and 2-5 times in sodium, as compared with that in deionized water. When SUS304 was exposed to cavitation in PbBi, the surface was work hardened 20% harder compared with original surface. In deionized water, SUS304 was work hardened by 5%. Therefore, we can conclude that larger collapse pressure can be estimated to act on the specimen surface in lead - bismuth, as compared with that in water. The erosion rate of stainless steels depends on hardness and Hirayama's Ni equivalent. Erosion resistance is the highest for SUS304 and decreases in order of a 9Cr-1Mo steel and SUS403.

39000408
Large Japan-EU joint experiment; JT-60SA project, has been launched (in Japanese)
Mori, Masahiro
Pariti 26(1), p.16-18(2011) ; (JAEA-J 08648)

39000409
Current status and prospect on R&D of nuclear hydrogen production technology (in Japanese)
Inagaki, Yoshiyuki
Petorotekku 34(1), p.49-53(2011) ; (JAEA-J 08649)

39000410
Radiation chemistry of liquid water with heavy ions; Steady-state and pulse radiolysis studies
Yamashita, Shinichi; Taguchi, Mitsumasa; Baldacchino, G.*; Katsumura, Yosuke
Charged Particle and Photon Interactions with Matter; Recent Advances, Applications, and Interfaces , p.325-354(2010) ; (JAEA-J 08654)

Irradiation effects induced by heavy ions are much different from those by low-LET radiations. Such distinctiveness has been applied to cancer therapy, surface processing, analytical techniques, and so on. However, detailed mechanism through which such distinctiveness appears has not been clarified yet. In this chapter, what have experimentally been found recently, especially within these five years, in water radiolysis with positively-charged atomic heavy ions are shown. Steady-state radiolysis studies and pulse radiolysis studies are separately summarized because these two approaches inherently involve own advantages and limitations. Gathering reported products yields and kinetics, track structures and intra-track dynamics are discussed. One of the most characteristic features of recent studies is that track-segment or -differential yields were intensively measured compared to earlier studies.

39000411
Computational human phantoms and their applications to radiation dosimetry
Saito, Kimiaki
Charged Particle and Photon Interactions with Matter; Recent Advances, Applications, and Interfaces , p.623-646(2010) ; (JAEA-J 08655)

Computational human phantoms with Monte Carlo simulations have been widely utilized for dosimetry in radiation protection and other fields. This text introduces typical computational human phantoms with diverse examples on their applications. Some examples of dosimetric quantities for radiation protection purposes obtained using simulations with the phantoms are shown and discussed after brief explanation of a dosimetry system employed in radiation protection. Further, some important applications of the phantom techniques to fields other than usual perspective radiation protections are discussed. Through these examples, usefulness and potential of the phantoms will be demonstrated.

39000412
Charged particle and photon interactions with matter; Recent advances, applications, and interfaces
Hatano, Yoshihiko; Katsumura, Yosuke; Mozumder, A.*
Charged Particle and Photon Interactions with Matter; Recent Advances, Applications, and Interfaces , 1045p.(2010) ; (JAEA-J 08656)

The edition of this book has been motivated by strongly positive comments on the former edition of the book with a similar title "Charged Particle and Photon Interactions with Matter. Chemical, Physicochemical, and Biological Consequences with Applications.", eds. A.Mozumder and Y.Hatano, Marcel Dekker, New York (2004), which was motivated by a long term (1985-1995) IAEA-project to survey the basic research of the entitled subjects accomplished in the past 100 years after the big findings of ionizing radiation by Curie and Roentgen. The editors received soon after the publication of the former version the strongly positive comments on it from international academic communities asking them to edit further the latter version to survey further the recent advances with future perspectives, applications, and interfaces. Upon these requests, therefore, this book with 36 chapters has been edited.

39000413
Release of mantle helium and its tectonic implications
Umeda, Koji; Ninomiya, Atsushi; Asamori, Koichi
Helium; Characteristics, Compounds, and Applications , 28p.(2010) ; (JAEA-J 08657)

Helium is the lightest noble gas and both stable isotopes, ³He and ⁴He, are produced in the crust in a ratio of ∼ 0.02 R_A, with R_A being the atmospheric ³He/⁴He ratio of 1.4×10^-6. Higher values are an indication of helium from the mantle where ³He captured during planetary accretion has been stored. It has been suspected for some time that degassing of the planet does not occur homogeneously over the Earth's surface, but is rather concentrated along plate boundaries, where the dynamics of the lithosphere are more intense and mantle helium from the Earth's interior can be more easily transported to the surface. We indicate that the spatial distribution of ³He/⁴He ratios in gas samples from crustal fluids are considered to provide potentially useful information for determining not only latent magmatic activity but also potential pathways for mantle volatiles, such as in tectonically active zones.

39000414
A Self-calibration method for the edge Thomson scattering diagnostic in ITER
Yatsuka, Eiichi; Hatae, Takaki; Kusama, Yoshinori
Journal of Plasma and Fusion Research SERIES, Vol.9 , p.12-17(2010) ; (JAEA-J 08658)

Calibration of spectral transmissivity of the collection and transmission optics is one of the most crucial issues in Thomson scattering diagnostic system. In ITER, since the vacuum vessel will be radioactivated, it will not be easy to calibrate the spectral transmissivity nearby the vacuum vessel. By injecting additional calibration laser and fitting both of two Thomson scattering lights, one can obtain electron temperature T_e and relative transmissivity of each spectral channel of polychromator from Thomson scattering signal itself. As a calibration laser, Ruby laser is a promissing candidate because wavelength of it is desirable not to differ from both of main laser and lower limit of observation so much. Even when spectral transmissivity is unknown, T_e will be obtained with less than 10 % of accuracy, which is a requirement of edge T_e measurement in ITER.

39000415
Removal of fission products in the spent electrolyte using iron phosphate glass as a sorbent
Amamoto, Ippei; Mitamura, Naoki*; Tsuzuki, Tatsuya*; Takasaki, Yasushi*; Shibayama, Atsushi*; Yano, Tetsuji*; Nakada, Masami; Okamoto, Yoshihiro
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM) , 6p.(2010) ; (JAEA-J 08661)

The main objective of this development is to recycle the purified eutectic medium of the pyroreprocessing, delaying its disposal for as long as possible. We have introduced the simple filtration method to remove the rare earth element (REE) particles which were formed due to the conversion of REE chlorides to phosphates. Here, the iron phosphate glass is used as a filtration medium for the removal of FP particles. However, some soluble FP such as compounds of alkali-metals, alkaline-earth metals, etc. still remain in the eutectic medium. This time around, on an experimental basis, the iron phosphate glass has been used as a sorbent instead, to remove the soluble FP. We have obtained some positive results and have intention to incorporate it into the spent electrolyte recycle process as a part of the FP separation and immobilization system.

39000416
Regulatory research for geological disposal of high-level radioactive waste in Japan
Nakayama, Shinichi; Watanabe, Yoshio*; Kato, Masami*
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM) , 7p.(2010) ; (JAEA-J 08662)

The Nuclear and Industrial Safety Agency of the Ministry of Economy, Trade and Industry (NISA) has renewed its regulatory role and its need for regulatory support research on radioactive waste management, with recent circumstances of radioactive waste management in Japan being taken into consideration. In response, a technical supporting organization, the Japan Nuclear Energy Safety Organization (JNES), in 2009 released the five-year research plan "Regulatory Support Research Plan on Radioactive Waste Management 2010-2014", in cooperation with the research institutes of the Japan Atomic Energy Agency (JAEA) and the National Institute of Advanced Industrial Science and Technology (AIST). In October 2007, all three parties signed an agreement of cooperative study on geological disposal, which facilitated joint studies and exchanges of staff, data, and results. One of the ongoing joint studies has focused on regional-scale hydrogeological modeling using JAEA's Horonobe Underground Research Laboratory.

39000417
Determination of environmental uranium concentration by utilizing γ-ray emission from the progeny radionuclides
Tanaka, Tadao; Shimada, Taro; Ito, Takeshi*; Sukegawa, Takenori
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM) , 7p.(2010) ; (JAEA-J 08663)

γ-ray from the progeny radionuclides of U-238, such as Th-234, Pa-234m and Ra-226, has been utilized for the evaluation of uranium concentration. In the present study, we proposed an evaluation method for U-238 concentration of background level in environment and for probate of vast land areas, in which the γ-ray radiations from Th-234, Pa-234m, Ra-226 is measured with the portable Ge detector. The U-238 concentration estimated by the in-situ metrology with portable Ge detector was in the order of 0.01 Bq/g in radioactive concentration, and was in comparable level with the concentrations decided by the ICP-MS established as high sensitive uranium analytical method. The method may be available for the U-238 concentration determination in vast land areas for the site release after decommissioning nuclear fuel handling facilities.

39000418
The Long-term stability of geological environments in the various rock types in Japan from the perspective of uranium mineralization
Sasao, Eiji
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM) , 8p.(2010) ; (JAEA-J 08664)

Long-term stability of the geological environment is one of the important keys for geological disposal of high-level radioactive waste in the Japanese Islands due to their location in a tectonically active island-arc. Uranium occurrences in Japan have been subjected to many geological processes inherent to the island-arc setting. Mode of occurrence of the uranium mineralization can be instructive as these could provide useful information on the long-term stability of the geological environment. Uranium mineralization is mainly in Tertiary sedimentary rocks and granitic rocks and less commonly in Cretaceous and Paleo/Mesozoic sedimentary sequences or metamorphic rocks. A variety of rocks host the Japanese uranium mineralization suggesting that geological environments suitable for geological isolation are widely distributed in the Japanese Islands, despite their location in a geologically active area. This effort will support building confidence in deep geological disposal.

39000419
Development of new ultrafiltration techniques maintaining in-situ hydrochemical conditions for colloidal study
Aosai, Daisuke; Yamamoto, Yuhei; Mizuno, Takashi
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM) , 8p.(2010) ; (JAEA-J 08665)

Size distribution of elements in groundwater is one of the most important information for understanding behavior of elements in deep underground environment. Size distribution is controlled mainly by groundwater physico-chemical parameters. Because the alteration of their physico-chemical states in groundwater cause changes of size distribution, systematic methodologies of ultrafiltration maintaining in-situ pressurized and anaerobic conditions is required. In this study, instrument for ultrafiltration maintaining in-situ pressurized/anaerobic conditions was developed and size distribution analysis was also conducted. The instrument developed in this study for consisted of passivated SUS materials is designed as to keep inner groundwater sample under a pressurized/anaerobic condition. Ultrafiltration was conducted at a borehole drilled from sub-stage at a depth of 200 m at the Mizunami Underground Research Laboratory site. The results obtained here indicate that ultrafiltration method is available for collection of filtered groundwater and passivation is an essential treatment before ultrafiltration.

39000420
Technical know-how for modeling of geological environment, 1; Overview and groundwater flow modeling
Saegusa, Hiromitsu; Takeuchi, Shinji; Maekawa, Keisuke; Osawa, Hideaki; Semba, Takeshi
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM) , 8p.(2010) ; (JAEA-J 08666)

Evaluation of the impact of uncertainties in the geological environment model is important to identify and prioritize key issues for further investigations. Therefore, a plan for site characterization should be made based on the result of the modeling. In this study, externalization of technical know-how and decision-making processes regarding groundwater flow modeling to be used for the planning of surface-based site characterization has been attempted based on experiences on Underground Research Laboratory project at Mizunami and Horonobe. The groundwater flow modeling is to be used for setting the area for the geological environment modeling, which is equal to an area including the groundwater flow system within the area from recharge area to discharge area, and for characterization of groundwater flow conditions. This report is summarized the detail work and its procedure regarding groundwater flow modeling based on the literature data and decision-making processes of the modeling.

39000421
Evaluation of the long-term evolution of the groundwater system in the Mizunami area, Japan
Mizuno, Takashi; Milodowski, A.*; Iwatsuki, Teruki
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM) , 9p.(2010) ; (JAEA-J 08667)

Palaeohydrogeologial study focused on fracture filling calcite distributed in Toki granite suggests that precipitation history of euhedral calcite can be divided into 4 periods (from I to IV in precipitation order). During precipitation period of Generation III calcite, seawater was penetrated into study area extensively. Current local distribution of Na-Cl type groundwater would be formed after the crystallization period of Generation III calcite. This suggests that source of Na-Cl type groundwater may be seawater penetrated between 18 Ma and 15 Ma. Before 1 Ma, major driving force of groundwater would be change of water table related to marine transgression/regression because landform of Tono area was almost flat. After 1Ma, groundwater flow has been controlled by topography due to uplift. The result of this study shows that detail analysis of multilayered calcite can provide a valuable information to evaluate long-term palaeohydrogeological changes of groundwater system.

39000422
In situ stress measurements in siliceous mudstones at Horonobe Underground Research Laboratory, Japan
Sanada, Hiroyuki; Nakamura, Takahiro; Sugita, Yutaka
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM) , 9p.(2010) ; (JAEA-J 08668)

As part of the research and development program on the HLW geological disposal, JAEA has been implementing the Horonobe Underground Research Laboratory (URL) project investigating sedimentary rock formations distributed in Horonobe area, Hokkaido, Japan. The authors have been implementing the research and development program at Horonobe to clarify the in situ stress conditions in siliceous mudstones at the URL. The objective of this work is to establish a strategy for an in situ stress measurement program for geological disposal and to develop an understanding of the in situ stress conditions in the deep underground formed by the sedimentary rocks. The application of several stress measurement methods to the Horonobe siliceous mudstones carried out during the surface-based investigations and the investigations during construction of the underground facilities, as well as information on the initial stress state around the Horonobe URL are described in this paper.

39000423
Advanced orient cycle; Progress on fission product separation and utilization
Yamagishi, Isao; Ozawa, Masaki; Mimura, Hitoshi*; Kanamura, Shohei*; Mizuguchi, Koji*
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM) , 10p.(2010) ; (JAEA-J 08669)

The present paper describes the progress on Fission Product (FP) separation in the Adv.-ORIENT (Advanced Optimization by Recycling Instructive Elements) cycle. The AMP-SG adsorbent (silica gel loaded with ammonium molybdophosphate) and CE-ALG microcapsule (alginate gel polymer enclosed with crown ether) were developed for separation of heat-generating elements, Cs and Sr, respectively. The AMP-SG adsorbed more than 99% of Cs from a simulated High-level Liquid Waste (HLLW). The CE-ALG adsorbed 0.0249 mmol/g of Sr. An electrodeposition is advantageous for both recovery and utilization of PGMs (Ru, Rh, Pd) and Tc. Pd was easily deposited on a Pt electrode. Reduction of Ru and Tc was accelerated in the presence of Pd or Rh. In the simulated HLLW, the redox reaction of Fe(III)/Fe(II) disturbed deposition of elements except for Pd. The deposit on Pt electrode from the simulated HLLW showed higher catalytic reactivity on electrolytic hydrogen production than that from solution containing only PGM.

39000424
An Analytical model on the sealing performance of space for the design of buffer material and backfill material
Sato, Haruo
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM) , 10p.(2010) ; (JAEA-J 08670)

The self-sealing function of the clearances between buffer material and overpack and tunnel wall or disposal pit wall and between backfill material and tunnel wall is expected for bentonite which will be used as buffer material and part of the backfill material. The sealing properties of Na-bentonite have been studied for distilled water and saline water conditions, for example, it is reported that Na-bentonite seals clearance even under saline water conditions in a range of effective bentonite densities, higher than 1.3 kg/dm³, for a bentonite dry density of 1.8 kg/dm³ and a clearance ratio of 10 % in experiments for Kunigel-V1. Although such information is useful for judging whether clearance is sealed, the filling properties of bentonite strongly depend on groundwater condition, silica sand content, montmorillonite content in the bentonite and the bentonite dry density, even though at the same effective bentonite density. In the present study, the author constructed an analytical model on the clearance filling performance for the design of buffer material and backfill material, based on the swelling properties of Na-montmorillonite which is the clay mineral constitute of Na-bentonite.

39000425
Evaluation of behavior of rare earth elements based on determination of chemical state in groundwater in granite
Yamamoto, Yuhei; Aosai, Daisuke; Mizuno, Takashi
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM) , 10p.(2010) ; (JAEA-J 08671)

Chemical state of rare earth elements (REEs) in deep groundwater was determined by combination of ultrafiltration techniques maintaining in-situ pressure and anaerobic conditions, speciation considering contribution of natural organic matters, and finger-printing method using REE pattern of stability constants for probable complexes of REEs in groundwater. Groundwater samples were collected from a borehole at a depth of 200 m in the Mizunami Underground Research Laboratory (MIU), Gifu, Japan. Spectroscopic analysis for colloidal matters on a membrane filter was also conducted to estimate chemical properties of colloidal ligands. Our results suggest that REEs-humic complexes were the dominant chemical states of REEs in groundwater. Presence of humic substance in groundwater was also confirmed by spectroscopic analysis. It is expected that behavior of REEs mainly depends on humic substances.

39000426
Development of comprehensive techniques for coastal site characterisation, 1; Strategic overview
Ota, Kunio; Amano, Kenji; Niizato, Tadafumi; Alexander, W. R.*; Yamanaka, Yoshiaki*
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM) , 10p.(2010) ; (JAEA-J 08672)

The assurance of the long-term stability of the geological environment is sine qua non for deep geological disposal. In Japan, since uplift/subsidence and climatic and sea-level changes would result in a significant change to hydraulic and hydrochemical conditions at coastal sites, it is of importance to establish comprehensive techniques for characterising the overall evolution of coastal sites over geological time. To this end, palaeohydrogeological study is ongoing in the coastal area around Horonobe in northern Hokkaido. A "Geosynthesis Data Flow Diagram" defining a methodology for characterising the palaeohydrogeological evolution of the site has been formulated and, based on the geosynthesis methodology, a basic strategy has been established for stepwise investigations from initial survey of existing information to the final borehole programme at any coastal site. This technique has now been tested and optimised with the progress of the investigations.

39000427
Study of weld residual stress field in the girth seam H6a of core shroud of boiling water reactor
Li, Y.; Kaji, Yoshiyuki; Igarashi, Takahiro
Proceedings of 18th International Conference on Nuclear Engineering (ICONE-18) (CD-ROM) , 6p.(2010) ; (JAEA-J 08673)

The heat affected zone (HAZ) of the girth seams of the core shroud is sensitive to the stress corrosion cracking due to neutron irradiation, corrosion and residual stress. We are focusing on the weld residual stress field around the girth seam H6a. The stress analysis adopted different approaches in ABAQUS to simulate the multiple-bead welding process. The Fully Coupled Temperature-Displacement Analysis (FCTDA) gave the much accurate results as compared with the experimental results. The axial stress fields in the crossing section of the wall of the core shroud were also clarified.

39000428
Influence of energy of helium ions on degradation of diglycolamide in N-dodecane
Sugo, Yumi; Taguchi, Mitsumasa; Sasaki, Yuji; Morita, Yasuji
Proceedings of 3rd Asia-Pacific Symposium on Radiation Chemistry (APSRC 2010) and DAE-BRNS 10th Biennial Trombay Symposium on Radiation & Photochemistry (TSRP 2010) (CD-ROM) , p.34-35(2010) ; (JAEA-J 08681)

A tridentate extractant, N,N,N',N'-tetraalkyldiglycolamide has high extractability for actinides such as americium and curium from nitric acid into n-dodecane. α-Radiolysis study of the organic extractants using an actinide radionuclide has some experimental difficulties. For example, a long-term exposure to actinides is required, and the extractants are contaminated with the radionuclide. These issues were solved by irradiation with helium ions provided by an accelerator. It was also found that the radiation chemical yield for the degradation of diglycolamide in n-dodecane by helium ions corresponding to the α-particles was less than that by γ-rays. In order to prove an effect of linear energy transfer (LET) on the radiolysis of diglycolamide in n-dodecane, the influence of energy of helium ions was further investigated. The radiation chemical yield gradually increased with the incident energy of helium ions. This result indicates that the degradation efficiency decreases with increasing LET value. Because the transient species are densely produced in the track by high LET radiations, and then decreased by recombination in the track at very early time.

39000429
A Maintenance method for the exhaust valves on the alpha-tight hot cell under a ventilating condition
Mizukoshi, Yasutaka; Kushida, Naoya
Proceedings of 47th Annual Meeting of the Working Group "Hot Laboratories and Remote Handling" (HOTLAB 2010) (CD-ROM) , 4p.(2010) ; (JAEA-J 08682)

On alpha tight hot cell under ventilating that has containment capability of nuclear materials, a safe and efficient maintenance method of exhaust valves which controlled negative pressure in hot cell was established at Fuels Monitoring Facility. The hot cell which required the exhaust valve maintenance needed to stop the ventilating during maintenance work because the valves could not be removed from operating exhaust system. And it was made known from prior work evaluation that this method involved long-term work, much costs and radiation waste, and large work risk. Therefore, a new method of valve maintenance under ventilating was needed due to the reductions of work period, costs and work risk.

39000430
Evaluation of required activity of SO₃ decomposition catalyst for iodine-sulfur process
Imai, Yoshiyuki; Kubo, Shinji; Goto, Minoru; Shimakawa, Satoshi; Tachibana, Yukio; Onuki, Kaoru
Proceedings of 5th International Topical Meeting on High Temperature Reactor Technology (HTR 2010) (CD-ROM) , 4p.(2010) ; (JAEA-J 08683)

Required performance of SO₃ decomposition catalyst for Iodine-Sulfur process was investigated. Heat transfer area needed for shell and tube type SO₃ decomposer exchanging heat from VHTR was calculated by applying Yagi-Kunii and Zukauskas's equation for filled layer-SiC tube and SiC tube-He gas flow heat transfer respectively and the minimum space velocity for catalyst was 1000 h^-1. To transform minimum space velocity to more universal kinetic rate constant, we introduced forward/reverse SO₃ decomposition equation. To achieve equilibrium SO₃ decomposition ratio above 0.5 MPa, rate constant k₁ should be more than 1.5 s^-1 for SO₃ decomposition catalyst.

39000431
Long-term high-temperature operation in the HTTR, 2; Core physics
Goto, Minoru; Fujimoto, Nozomu; Shimakawa, Satoshi; Tachibana, Yukio; Nishihara, Tetsuo; Iyoku, Tatsuo
Proceedings of 5th International Topical Meeting on High Temperature Reactor Technology (HTR 2010) (CD-ROM) , 8p.(2010) ; (JAEA-J 08684)

In the High Temperature Engineering Test Reactor (HTTR), which is a Japanese block-type HTGR, reactivity is controlled by control rods (CRs) and burnable poisons (BPs). The CRs insertion depth into the core should be retained shallow during burnup period, because the large insertion depth leads to significant disturbance of the power distribution, and consequently fuel temperature rises above the limit. Thus, the controllable reactivity with the CRs during operation is small, and then reactivity control through the burnup period largely depends on the BPs. It has not been confirmed an effectiveness of BPs on reactivity control on block-type HTGRs. The HTTR succeeded in long-term high temperature operation, and its burnup reached about 370EFPD. Thereby it became possible to confirm the effectiveness of BPs on reactivity control on the HTTR using its burnup data. We focused on a burnup change in the CRs insertion depth into the core to confirm whether the BPs functioned as designed. Additionally, we compared the change in the CRs insertion depths between analysis results and the experimental data to confirm validity of a whole core burnup calculation with the SRAC/COREBN. As a result, the experimental data showed that although the CRs insertion depth into the core was increased with burnup, it was retained the allowable depth. Meanwhile, the analysis result of the CRs insertion depth was in good agreement with the experimental data.

39000432
Experimental techniques for nuclear data; State of the art and future prospects
Harada, Hideo
Proceedings of 5th Workshop on Neutron Measurements, Evaluations and Applications (NEMEA-5) , p.43-48(2011) ; (JAEA-J 08685)

Recent advancements in experimental techniques mainly used for the determination of the neutron capture cross sections are reviewed, related to advanced reactor systems, accelerator driven systems, and advanced fuel cycles. Here, experimental techniques include intense neutron sources, advanced detectors, and methodologies. The technique using laser Compton scattering γ-rays is included as one of the new methodologies. These experimental techniques have been utilized for obtaining new nuclear data and also reducing uncertainties of nuclear data. The recent new results and the achieved uncertainties using these techniques are discussed using some examples. We conclude with some speculations on the future prospects achieved by the improved experimental techniques.

39000433
Estimation of digital single event transient pulse-widths in logic cells from high-energy heavy-ion-induced transient current in a single MOSFET
Makino, Takahiro; Onoda, Shinobu; Hirao, Toshio; Oshima, Takeshi; Kobayashi, Daisuke*; Ikeda, Hirokazu*; Hirose, Kazuyuki*
Proceedings of 9th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-9) , p.169-172(2010) ; (JAEA-J 08686)

Digital Single Event Transient (DSET) pulse-widths in an inverter cell fabricated with the 0.2 mm FD-SOI process were estimated from high-energy heavy-ion-induced transient current in a single n-type MOSFET fabricated with the 0.2 mm FD-SOI process. We verified that the estimation method is applicable to the DSET pulse-widths estimation in the case of high-energy heavy-ion irradiation.

39000434
Applicability of finite element method to collapse analysis of steel connection under compression
Zhou, Z.; Nishida, Akemi; Kuwamura, Hitoshi*
Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and the 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive) , 5p.(2010) ; (JAEA-J 08689)

It is often necessary to study the collapse behavior of steel connections. In this study, the limit load of the steel pyramid-to-tube socket connection subjected to uniform compression was investigated by means of FEM and experiment. The steel connection was modeled using 4-node shell element. Three kinds of analysis were done:linear buckling analysis, nonlinear buckling analysis and Riks method analysis. For linear buckling analysis uniform pressure was loaded directly. For nonlinear buckling analysis uniform pressure was loaded gradually and nonlinear material properties and large displacement were considered. For Riks method analysis uniform pressure was loaded by using the modified Riks method, and nonlinear material properties and large displacement were considered. The results of FEM analysis were compared with the experimental results. It can be concluded that arc length analysis is most suitable for collapse analysis of steel connection under compression.

39000435
Elastic-plastic connection model describing dynamic interactions of component connections
Nishida, Akemi; Araya, Fumimasa; Kushida, Noriyuki; Kondo, Makoto; Sakai, Michiya*; Shiogama, Yuzo*
Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and the 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive) , 6p.(2010) ; (JAEA-J 08690)

The objective of this research is to contribute to the seismic design evaluation of nuclear facilities through the construction of a numerical evaluation system which is able to evaluate both global and local behaviors of facilities under severe seismic events. As one of the technology components to realize this objective, we are developing a physical model describing the dynamic interaction characteristics of component connections, called as the elastic-plastic connection model. We focused on the joints of the support structures of the component and the building in nuclear plants which generally designed as fixed/pinned boundaries, and tried to consider their dynamic interaction effects. In this paper, we show the proposal of the elastic-plastic connection model and the application of the model to a numerical simulation using a real plant data. The precision of the model was optimized by adjusting its parameters using the data obtained in the experiment.

39000436
Measurements of thermal-neutron capture cross-sections for radioactive nuclides
Nakamura, Shoji
Proceedings of the Scientific Workshop on Nuclear Data Measurements, Theory and Applications , p.87-92(2010) ; (JAEA-J 08691)

In the transmutation study of FPs and MAs, the accurate data of neutron capture cross-sections are necessary to evaluate reaction rates. However, there are discrepancies among the reported data for the thermal-neutron capture cross-sections for those nuclides. The discrepancies reach to 10∼20%. Therefore, our concern was focused to re-measure the cross-sections of those FPs and MAs. In this workshop, JAEA's activities for the neutron capture cross-section measurements of FPs and MAs will be presented.

39000437
Present status of the JAEA-AMS-TONO (in Japanese)
Kokubu, Yoko; Ishimaru, Tsuneari; Nishizawa, Akimitsu*; Suzuki, Mototaka*; Owaki, Yoshio*; Nishio, Tomohiro*; Kitazawa, Toshiyuki*
Dai-12-Kai AMS Shimpojiumu Hokokushu , p.5-8(2011) ; (JAEA-J 08692)

39000438
Seawater circulation in the Japan Sea based on iodine-129 (in Japanese)
Suzuki, Takashi; Minakawa, Masayuki*; Kabuto, Shoji; Togawa, Orihiko
Dai-12-Kai AMS Shimpojiumu Hokokushu , p.69-72(2010) ; (JAEA-J 08693)

39000439
Study on the behavior of concrete lining and rock mass during shaft excavation in the Horonobe URL Project, 1 (in Japanese)
Inagaki, Daisuke; Tsusaka, Kimikazu; Ijiri, Yuji*; Koike, Masashi*; Hatsuyama, Yoshihiro*
Dai-40-Kai Ganban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM) , 6p.(2011) ; (JAEA-J 08694)

39000440
A Study on the behaviour of concrete lining and rock mass during shaft excavation at the Horonobe URL project, 2 (in Japanese)
Tsusaka, Kimikazu; Inagaki, Daisuke; Koike, Masashi*; Ijiri, Yuji*; Hatsuyama, Yoshihiro*
Dai-40-Kai Ganban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM) , p.7-12(2011) ; (JAEA-J 08695)

39000441
Evaluation of applicability of a new quantitative rock mass classfication method at the Mizunami Underground Research Laboratory (in Japanese)
Asai, Hideaki; Kuji, Masayoshi*; Horiuchi, Yasuharu; Matsui, Hiroya
Dai-40-Kai Ganban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM) , p.13-18(2011) ; (JAEA-J 08696)

Considering the design, construction and safe operation of large underground facilities such as for the geological disposal of high-level radioactive waste, an important requirement is to utilize a rock mass classification method that can estimate site specific rock mechanical properties based on surface-based investigations and geological observations during excavation. For this study, a new quantitative rock mass classification method based on the Japanese Geotechnical Society standard was proposed and applied to the sedimentary formations and the granite at the Mizunami Underground Research Laboratory. The results were compared with the rock mass classification system developed by the Central Research Institute of Electric Power Industry and commonly used in Japan. Then the applicability of the new rock mass classification could be evaluated.

39000442
Test execution of liquid-type grout at depth of 300m of Mizunami Underground Research Laboratory (in Japanese)
Nobuto, Jun*; Tsuji, Masakuni*; Kusano, Takashi*; Mikake, Shinichiro; Kamiya, Akira; Ishii, Yoji
Dai-40-Kai Ganban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM) , p.179-184(2011) ; (JAEA-J 08697)

At Mizunami Underground Research Laboratory, the water inflow should be minimized, considering water treatment expense. Although cement grout has been applied to reduce water inflow up to 460 m depth, water inflow through small fractures which cement grout cannot penetrate can not be neglected at deeper underground. Liquid-type grout which has high durability as well as good penetrability was therefore tested at the depth of 300 m. Test results indicated that liquid-type grout could sufficiently reduce hydraulic conductivity of rock mass with less than 1Lu, and could keep improvement effect even after applied water pressure of more than 9 MPa was applied.

39000443
Pre-excavation grouting with micro-fine cement below four hundreds meter depth (in Japanese)
Ishii, Yoji; Mikake, Shinichiro; Kamiya, Akira; Watanabe, Kazuhiko; Nobuto, Jun*; Kusano, Takashi*
Dai-40-Kai Ganban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM) , p.185-190(2011) ; (JAEA-J 08698)

The "Mizunami Underground Research Laboratory" has been carrying out scientific research in granite to establish the technological basis for high-level radioactive waste disposal. To get reliable information on the rock mass geology and hydrogeology and on the bedrock conditions, a pilot borehole investigation was carried out before sinking the Ventilation Shaft. A region with high hydraulic head and low hydraulic conductivity was intersected by the pilot borehole at around GL-400m during these investigations. To reduce water inflow during excavation, pre-excavation grouting with micro-fine cement was done in this region before sinking the ventilation shaft. Despite the high hydraulic head and the low hydraulic conductivity, effective reduction of water-inflow was achieved.

39000444
Applicability of countermeasures during excavation and construction of the Mizunami Underground Research Laboratory (in Japanese)
Mikake, Shinichiro; Yamamoto, Masaru; Ikeda, Koki
Dai-40-Kai Ganban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM) , p.191-196(2011) ; (JAEA-J 08699)

JAEA's task is to provide the scientific and technical basis for safe geological disposal of high-level radioactive waste. This involves researches on development and improvement of techniques for characterization of the deep geological environment and a wide range of engineering for deep underground application at an underground research laboratory in crystalline rock, referred to as "Mizunami Underground Research Laboratory (MIU)". MIU is currently being constructed. As of October 2010, the Main and Ventilation Shafts had reached GL-460m (below ground level). This report describes the summary of construction, and pre-excavation grouting, supplementary excavation method.

39000445
Application of seismic tomography survey for monitoring EDZ development (in Japanese)
Sugita, Yutaka; Nakamura, Takahiro; Sanada, Hiroyuki
Dai-40-Kai Ganban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM) , p.230-235(2011) ; (JAEA-J 08700)

Excavation disturbed zones (EDZ) will usually develop around excavations when underground facilities are constructed. Consequently, the mechanical, hydraulic and geochemical properties of the rock mass will change as an EDZ develops. Estimation of the extent, variation in properties and their evolution in the EDZ area is important for assessing critical migration pathways of radionuclides in the disposal of high level radioactive waste. The authors examined the applicability of seismic tomography and borehole expansion tests for monitoring the changes in mechanical properties of an EDZ using a Mine-by experiment (horizontal drift, diatomaceous mudstone) in the Horonobe Underground Research Laboratory project. Simple seismic tomography surveys may be used for monitoring the EDZ.

39000446
Study on mechanisms of strain variation at great depth (in Japanese)
Horiuchi, Yasuharu; Hirano, Toru*; Ikeda, Koki; Matsui, Hiroya
Dai-40-Kai Ganban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM) , p.242-247(2011) ; (JAEA-J 08701)

Japan Atomic Energy Agency (JAEA) installed the intelligent type strain meters, at G.L-500m depth in pilot boreholes drilled from the 200m level in the ventilation and main shafts of the Mizunami Underground Research Laboratory (MIU). Strain variations due to several events including the excavation itself were monitored and analyzed. Monitoring results indicate that the intelligent type strain meter is able to measure very small fluctuations and detect rock deformation from blasting with 300m vertical separation from the measurement section. The strain meter can detect conditions in the rock mass such as differences in deformability.

39000447
Discrete and continuum approaches for the analysis of coupled thermal-mechanical processes in the near field of a HLW repository (in Japanese)
Shimizu, Hiroyuki; Koyama, Tomofumi*; Chijimatsu, Masakazu*; Fujita, Tomoo; Nakama, Shigeo
Dai-40-Kai Ganban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM) , p.248-253(2011) ; (JAEA-J 08702)

This paper reports on the results of the numerical simulations for the analysis of coupled thermal-mechanical processes in the near field of a HLW repository using Finite Element Method (FEM) and Distinct Element Method (DEM). The FEM approach provides quantitative information of the change of stress and strain during excavation and heating process. On the other hand, the DEM approach shows the crack propagation process at the borehole surface, and this result agrees qualitatively well with the experimental observation. By comparing these results obtained from both approaches, quantitative and qualitative insights into various aspects of the processes occurred in the near field can be obtained.

39000448
Variation of hydraulic properties on sedimentary rock due to shear deformation (in Japanese)
Goke, Mitsuo*; Ishii, Takashi*; Sanoki, Satoru*; Matsui, Hiroya; Sugita, Yutaka
Dai-40-Kai Ganban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM) , p.282-287(2011) ; (JAEA-J 08703)

In order to investigate the variation of hydraulic properties on soft rock due to shear deformation, permeability tests were performed on hard shale of the Wakkanai formation by axial flow and radial flow techniques under triaxial compression. The experimental results showed that the axial direction permeability increased to approximately 10 times lager than the initial one in residual strength zone. On the other hand, the radial direction permeability increased remarkably in strain softening zone. The results suggested that a permeability increase could be restrained, if the strain softening is not to be attained in the rock mass surrounding caverns by invention of construction methods.

39000449
Development of physical model describing the dynamic interaction characteristics of component connections for the analysis of an entire nuclear facility (in Japanese)
Nishida, Akemi
Dai-4-Kai Genshiryoku Shisutemu Kenkyu Kaihatsu Jigyo Heisei-21-Nendo Seika Hokokukai Shiryoshu (CD-ROM) , p.25-26(2010) ; (JAEA-J 08704)

The objective of this project is to contribute to the seismic design evaluation of nuclear facilities through the construction of a numerical evaluation system which is able to evaluate both global and local behaviors of facilities under severe seismic events especially. As one of the technology components to realize this objective, we are developing and incorporating into the system a physical model describing the dynamic interaction characteristics of component connections. In this paper, we summarized about the development of the connection interaction model and the application of the model to a real plant simulation. As the results, it was verified that the responses of plant components decreased in consideration of the partial damage of the connection. It was shown that the introduction of the dynamic interaction characteristics of component connections in detail was important in the seismic design evaluation of nuclear facilities under severe seismic events.

39000450
Optimization of the exchange period on high efficiency particulate air filter in Tokai Reprocessing Plant (in Japanese)
Fukuchi, Taira; Sanyoshi, Hirotaka; Yatogi, Hideo; Fukuari, Yoshihiro; Inami, Shinichi
Dai-7-Kai Saishori, Risaikuru Bukai Semina Tekisuto , p.170-171(2011) ; (JAEA-J 08705)

39000451
Prevention of false alarms from automatic fire alarm system in the Tokai reprocessing plant (in Japanese)
Ishii, Takahiro; Shimizu, Kazuyuki; Sakai, Katsumi; Inami, Shinichi
Dai-7-Kai Saishori, Risaikuru Bukai Semina Tekisuto , p.172-173(2011) ; (JAEA-J 08706)

The automatic fire alarm system installed in the Tokai reprocessing plant consists of more than 5,000 detectors in about 40 facilities for the moment. In this system, 57 non-fire cases have occurred for about 10 years from January 2001 to December 2010. and about half of these cases was due to the condensation of water vapor generated on the sensor. Therefore, the prevention of condensation is necessary to reduce such false alarms, and the measure for prevention of condensation has been taken by installing a mount for the detector basement. This mount facilitates that the detector does not contact directly to the surface of ceiling where is likely to change an environment due to changeable temperature and humidity. As a result, false alarms caused by condensation have not been found on the detectors with the mounts. This paper reports the details of the improved fire alarm system, and cause/measures for false alarms.

39000452
Simulation for SiC power electronic device developments (in Japanese)
Onuma, Toshiharu*; Miyashita, Atsumi; Yoshikawa, Masahito; Tsuchida, Hidekazu*; Iwasawa, Misako*
Heisei-21-Nendo Sentan Kenkyu Shisetsu Kyoyo Sokushin Jigyo "Chikyu Shimyureta Sangyo Senryaku Riyo Puroguramu" Riyo Seika Hokokusho , p.21-27(2010) ; (JAEA-J 08707)

Silicon carbide, being a wide-band-gap semiconductor, is an attractive material in the development of electronic devices operated under extreme conditions such as high power, high temperature, and high radiation. SiC is particularly attractive for use in MOS technology because among the compound semiconductors only silicon carbide has the thermal oxide SiO₂, which is a good insulator. However, it is known that SiO₂/SiC interfaces have a higher density of interface traps than SiO₂/Si interfaces and that the channel mobility of MOS devices is much lower than theoretically expected values. In order to improve these characteristics, it is important to understand the thermal oxidation process at the SiO₂/SiC interface. We performed large-scale first-principles molecular dynamics simulations of the SiO₂/SiC interface oxidation process. We also performed large-scale first-principles molecular dynamics simulations to generate amorphous SiO₂/SiC interface.

39000453
Roadmap for hydrogen production by High Temperature Gas-cooled Reactor (HTGR) (in Japanese)
Kunitomi, Kazuhiko; Onuki, Kaoru
Jisso Kano Na Enerugi Gijutsu De Kizuku Mirai; Honebuto No Enerugi Rodo Mappu, 2 , p.265-270(2010) ; (JAEA-J 08708)

Present technological level and future development items of the hydrogen production by High Temperature Gas-cooled Reactor (HTGR) were described. In addition, the reduction of CO₂ emission by the deployment of HTGR hydrogen production systems was investigated. Based on these evaluations, the roadmap for the hydrogen production by HTGR was determined. The reduction of CO₂ emission by the deployment of a 600 MWth HTGR system is evaluated at 113 ton/year in case that hydrogen produced by this system is used for fuel cell vehicles and industries. The HTGR hydrogen production system will make a big contribution to prevent global warming.

39000454
The Latest technology of impact analysis for structures (in Japanese)
Nishida, Akemi
Kenchiku Kozo Rikigaku-niokeru Saikin No Hatten To Tenbo, 2 , p.1-10(2010) ; (JAEA-J 08709)

The structural damages caused by impact loads have been assessed since the 1995 Hyogo-ken Nanbu Earthquake. In this report, an outline of the basic concepts and the main numerical analytical methods used to solve the impact problem is presented along with related studies in this field. In addition, the round robin analysis performed by the Japan Society of Civil Engineers is introduced. This analysis consists of a pre-analysis and a post-analysis for the identical predetermined experiment. Some different kinds of analysis are carried out by different organizations and the results are compared. Finally, the plan for guidelines of- architectural designs under impact loads is presented.

39000455
The Present status of computational software for impact analysis (in Japanese)
Nishida, Akemi
Kenchikubutsu No Taishogeki Sekkei Ni Kansuru Wakushoppu 2010 Shiryoshu , p.87-96(2010) ; (JAEA-J 08710)

Several organizations are energetically carrying out studies to develop numerical analytical methods to understand the effect of physical impact on structures. With the notable developments in computer technology, computational engineering, and destruction dynamics, the time response analysis of complicated impact phenomena can be easily carried out recently. However, some problems remain unresolved, e.g., the velocity effect of materials, primary response of RC structures (local response or stress wave response), secondary response (elastic-plastic response), large deformation, and contact problems. This paper reports on the present status of the numerical analysis of impact phenomena based on previous studies. This report will be helpful in formulating the guidelines for the inspection of impact resistance properties.

39000456
Destruction modes and impact resistance properties of a steel frame member (in Japanese)
Sakino, Yoshihiro*; Nishida, Akemi
Kenchikubutsu No Taishogeki Sekkei Ni Kansuru Wakushoppu 2010 Shiryoshu , p.143-152(2010) ; (JAEA-J 08711)

An important aspect in designing nuclear facilities is their safety, which is ensured by reducing the probability of radiation leakage, including that due to physical impact. We determined the factors necessary for testing the impact resistance of steel frame members of the facilities. Little research has been conducted on the impact resistance properties of steel frame members. After the Hyogo-ken Nanbu Earthquake, the relationship between strain rate and impact resistance properties has been studied. First, we classified destruction modes with regard to the limit state of the steel frame member against the impact force and provided an example of considering the impact velocity as an index of the required performance. Next, we reported about the studies of the strain rate dependence of materials and high-speed loading experiments on the steel member. Finally, we showed the formulated equations for finding the crack/penetration in the steel structure due to the impact force.

39000457
Hydrogen production technology with high-temperature gas-cooled reactor (in Japanese)
Inagaki, Yoshiyuki
Suiso Seizo, Kyuzo, Chozo Zairyo To Anzenka , p.92-98(2010) ; (JAEA-J 08712)

39000458
Electron absorbed fractions and S values in a mouse voxel phantom
Mohammadi, A.; Kinase, Sakae
KEK Proceedings 2010-9 , p.65-74(2010) ; (JAEA-J 08714)

For preclinical assessments of several radiopharmaceuticals, electron absorbed fractions (AFs) and S values were evaluated in a mouse voxel phantom. The sources were considered to be mono-energetic in the electron energy range 10 keV to 4 MeV. The radiation transport was simulated using the Monte Carlo method. Consequently, it was confirmed that the electron AFs were dependent on the masses of the source/target organs. The electron AFs for organ self-absorption (source = target) decreased with increasing electron energy which proved that it is certainly not always appropriate in small organs to assume a 100% localized electron energy absorption. The electron AFs for organ cross-fire depended on electron energy emitted by the source and the geometries of source and target. In addition, S values in the major organs of the mouse phantom were tabulated for ¹³¹I, ¹⁵³Sm, ¹⁸⁸Re, ⁹⁰Y and ¹¹¹In using the results of the photon and electron AFs. Comparison of S values in abdominal organs for only β-spectrum of the nuclides demonstrated that β-only S values increased with increasing mean energy of β-spectrum of the nuclide. The results of this study will be useful in determining the dose to the organs for mice similar in size to Digimouse.

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JAEA > JAEA Library > JOPSS > Papers Published in Journals [Back Issues] > March 2011