JAEA Abstracts

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

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

December 2008

36001557
Effects of neutron-irradiation-induced intergranular phosphorus segregation and hardening on embrittlement in reactor pressure vessel steels
Nishiyama, Yutaka; Onizawa, Kunio; Suzuki, Masahide; Anderegg, J. W.*; Nagai, Yasuyoshi*; Toyama, Takeshi*; Hasegawa, Masayuki*; Kameda, Jun*
Acta Materialia 56(16), p.4510-4521(2008) ; (JAEA-J 04829)

The effects of intergranular P segregation and hardening on the ductile-to-brittle transition temperature (DBTT) in several neutron-irradiated reactor pressure vessel steels with different bulk contents of P and Cu have been investigated using a scanning Auger microbe, a local electrode atom probe and positron annihilation spectroscopy. Increasing the neutron fluence at 563 K promotes intergranular P segregation. The content of P more significantly affects irradiation hardening than that of Cu due to distinct formation of P-rich precipitates arising from the stabilization of vacancies. Analyzing the correlations between the P segregation, hardening, fraction of intergranular fracture and DBTT, it is found neutron irradiation mitigates an embrittling effect of segregated P, and therefore the hardening more strongly affects the DBTT shift than the P segregation.

36001558
SR-PES and STM observation of metastable chemisorption state of oxygen on Si(110)-16 ×2 surface
Yamamoto, Yoshihisa*; Togashi, Hideaki*; Kato, Atsushi*; Takahashi, Yuya*; Konno, Atsushi*; Teraoka, Yuden; Yoshigoe, Akitaka; Asaoka, Hidehito; Suemitsu, Maki*
Applied Surface Science 254(19), p.6232-6234(2008) ; (JAEA-J 04831)

The room temperature adsorbed state of oxygen molecules on Si(110)-16 ×2 surface and the structural change after a mild annealing has been investigated by synchrotron radiation photoemission spectroscopy. As a result, despite the very small dosage of oxygen, Si²⁺ and Si³⁺ components already appear in addition to Si¹⁺. This is likely to be caused by a selective adsorption of O₂ molecules into the vicinity of already oxidized sites. After annealing, we found that binding energy of Si²⁺ and Si³⁺ increase and approach to their corresponding peak positions of a thermally-grown oxide, and this increase indicates relaxation of the Si-O bond length and Si-O-Si bond angle of metastable oxygen atoms.

36001559
Empirical abundance scaling laws and implications for the γ process in core-collapse supernovae
Hayakawa, Takehito; Iwamoto, Nobuyuki; Kajino, Toshitaka*; Shizuma, Toshiyuki; Umeda, Hideyuki*; Nomoto, Kenichi*
Astrophysical Journal 685(2), p.1089-1102(2008) ; (JAEA-J 04832)

36001560
Intracellular changes of metal elements by fucoidan extracted from brown seaweed; Cladosiphon okamuranus
Nagamine, Takeaki*; Takada, Hisashi*; Kusakabe, Takahiko*; Nakazato, Kyomi*; Sakai, Takuro; Oikawa, Masakazu*; Kamiya, Tomihiro; Arakawa, Kazuo; Iha, Masahiko*
Biological Trace Element Research 124(1), p.60-69(2008) ; (JAEA-J 04833)

This study was undertaken to elucidate the intracellular changes of metal elements after the administration of fucoidan extracted from Cladosiphon okamuranus. TRL1215 cells (normal rat liver cell line) were treated with 0, 0.1, or 1.0 mg/mL fucoidan. The cellular distribution of elements was analyzed using in-air micro-PIXE induced X-ray emission. In fucoidan-treated cells, the focal accumulation of Br (BrdU) was correlated spatially with phosphorous-rich region, suggesting that Br was localized within the nucleus. Al distribution provided a spatial association with Br map. These data suggest that fucoidan binding Al us postulated to be transferred into the nucleus.

36001561
Subcellular changes of essential metal shown by in-air micro-PIXE in oral cadmium-exposed mice
Nakazato, Kyomi*; Nagamine, Takeaki*; Suzuki, Keiji*; Kusakabe, Takahiko*; Moon, H. D.*; Oikawa, Masakazu*; Sakai, Takuro; Arakawa, Kazuo
Biometals 21(1), p.83-91(2008) ; (JAEA-J 04834)

To clarify the relation of essential metals to cadmium (Cd) toxicity, we evaluated metallothionein expression and analyzed the subcellular distribution of essential metals using in-air micro-PIXE. Four mice were dosed orally with 100 mg/L of Cd in drinking water for 1.5 or 2 years. Compared to the control, the Cd-exposed mice markedly accumulated zinc in the liver and renal cortex. Elemental maps showed that a large amount of Cd was spatially combined with zinc in the 1.5y-Cd mouse. The data suggest that zinc may contribute to protect against oral-administrated Cd toxicity.

36001562
Hydration affects both harmonic and anharmonic nature of protein dynamics
Nakagawa, Hiroshi; Jochi, Yasumasa*; Kitao, Akio*; Kataoka, Mikio
Biophysical Journal 95(6), p.2916-2923(2008) ; (JAEA-J 04835)

To understand the effect of hydration on protein dynamics, inelastic neutron scattering experiments were carried out on Staphylococcal nuclease samples at differing hydration levels: dehydrated, partially hydrated and hydrated. At cryogenic temperatures, hydration affected the collective motions with energies lower than 5 meV, while the high energy localized motions were independent of hydration. The prominent change was a shift of boson peak toward higher energy by hydration, suggesting hardening of harmonic potential at local minima on the energy landscape. The 240 K transition was observed only for the hydrated protein. Significant quasi-elastic scattering at 300 K was observed only for the hydrated sample, indicating that the origin of the transition is the motion activated by hydration water. The neutron scattering profile of the partially hydrated sample was quite similar to that of the hydrated sample at 100 and 200 K, while it was close to the dehydrated sample at 300 K, indicating that partial hydration is sufficient to affect the harmonic nature of protein dynamics, and that there is a threshold hydration level to activate the anharmonic motions. Thus, hydration water controls both the harmonic and anharmonic protein dynamics, by differing means.

36001563
Electron-beam-induced color imaging of acid-chromic polymer films
Maekawa, Yasunari; Yuasa, Kanako*; Enomoto, Kazuyuki; Matsushita, Harumi*; Kato, Jun*; Yamashita, Takashi*; Ito, Kazuo*; Yoshida, Masaru
Chemistry of Materials 20(16), p.5320-5324(2008) ; (JAEA-J 04837)

Polymer films with acid-responsive chromic dyes and acid generators have been designed for an electron beam (EB)-induced color imaging system. Arylsulfonic acid esters and triphenylsulfonium salts were used as an EB-sensitive acid generator; the acid (H⁺) allows a chromic reaction with rhodamine B base (RB) and 4,4'-bis(dimethylamino)benzhydrol (BH) to be triggered. Upon EB irradiation, poly(methyl methacrylate) (PMMA) films consisting of RB or BH and acid generators exhibited a characteristic absorption band with λmax at 560 and at 612 nm, respectively, and an isosbestic point. These spectral changes clearly indicate that colorless chromic dyes in PMMA are transformed selectively to the colored form. The color imaging of these films was performed by electron beam direct writing (EBDW) with a 50 nm diameter beam to form 100 - 1000 nm line and space patterns and was evaluated by optical and confocal laser microscopy. EBDW on the acid chromic polymer films, especially for BH, yielded clear color imaging of 100 - 200 nm line and space patterns with a dose of only 10 μC/cm². The confocal laser microscopy gave thinner lines than the laser wavelength (632.8 nm), probably because of the large change in refractive index of the patterned film induced by EB irradiation even with a low energy dose.

36001564
Spontaneous fission of neutron-deficient fermium isotopes and the new nucleus ²⁴¹Fm
Khuyagbaatar, J.*; Hofmann, S.*; Heßberger, F. P.*; Ackermann, D.*; Burkhard, H. G.*; Heinz, S.*; Kindler, B.*; Kojouharov, I.*; Lommel, B.*; Mann, R.*; Maurer, J.*; Nishio, Katsuhisa; Novikov, Y.*
European Physical Journal A 37(2), p.177-183(2008) ; (JAEA-J 04838)

Spontaneous fission of neutron-deficient fermium isotopes with neutron number N<144 was investigated. The nuclei were produced in fusion-evaporation reactions of ⁴⁰Ar beams with ^204,206-208Pb targets. The new isotope ²⁴¹Fm was identified, and the half-life 0.73 ms was determined. The half-life was significantly longer than the neighboring even-even isotopes ^242,244Fm, and the hindrance factor were calculated by the to be 1.1 ×10⁴ for ²⁴¹Fm and 5.2 ×10⁴ for ²⁴³Fm, being associated with the lower tunneing probability for nuclei having nuclear spins. The result suggests also the possible production and detection of ^239,237Fm becalsue of the stabilization against spontaneous fission.

36001565
Heavy-ion microbeams; Development and applications in biological studies
Funayama, Tomoo; Hamada, Nobuyuki*; Sakashita, Tetsuya; Kobayashi, Yasuhiko
IEEE Transactions on Plasma Science 36(4), p.1432-1440(2008) ; (JAEA-J 04844)

High-LET heavy charged particle radiation has been used in radiotherapy and radiation breeding because of its greater biological effectiveness compared with low-LET radiation. The health risk assessment for astronauts due to space radiation during interplanetary manned missions is also an important issue concerning the biological effects of heavy-ion radiation. Localized irradiation of specific regions within organisms using heavy-ion microbeam systems provides an attractive means of investigating the mechanism of heavy ion radiation action. Additionally, heavy-ion microbeams can be used as a radio-microsurgical tool for analyzing a broad range of biological phenomena. This paper reviews briefly the current status concerning the development of heavy-ion microbeams for use on living organisms with particular emphasis on its applications in biological studies in eukaryotes including plants, silkworm, nematode, and cultured plant and mammalian cells.

36001566
Transient behaviour of low enriched uranium silicide plate-type fuel for research reactors during reactivity initiated accident
Yanagisawa, Kazuaki
International Journal of Nuclear Energy Science and Technology 4(2), p.97-110(2008) ; (JAEA-J 04845)

The pulse irradiation tests were conducted on silicide mini-plate fuels, prepared for a peaceful application of nuclear energy. The major findings are: (1) Neither failure nor degradation of dimensional stability of the fuel occurred in the temperature below 400 °C. Beyond that level a dimensional stability was gradually degraded with an increase of temperature. (2)The fuels were intact at energy depositions <82 cal/g but were damaged at energy depositions of >94 cal/g, where the failure mode is wither through-plate cracking or fuel melt. A failure threshold must be existed between the two values.

36001567
Local structure of BiFeO₃-BaTiO₃ mixture
Yoneda, Yasuhiro; Yoshii, Kenji; Kohara, Shinji*; Kitagawa, Shuji*; Mori, Shigeo*
Japanese Journal of Applied Physics 47(9), p.7590-7594(2008) ; (JAEA-J 04846)

Local structure analysis of (1-x)BiFeO₃-xBaTiO₃ mixture was carried out by synchrotron radiation X-ray pair-distribution function (PDF) method. The PDF peak is resolved as a doublet due to the presence of two distinct bond length, Bi-O and Ba-O. Cubic perovskite lattice of (1-x)BiFeO₃-xBaTiO₃ solid solution distorts locally to accomodate the distinct Bi-O and Ba-O bond lengths.

36001568
Magnetic and dielectric properties of HoFe₂O₄ and R_1-xR'_xFe₂O₄ (R, R': rare earths)
Yoshii, Kenji; Yoneda, Yasuhiro; Maeda, Daisuke*; Yokota, Yusuke*; Michiuchi, Takamasa*; Komatsu, Takuma*; Ikeda, Naoshi*; Matsuo, Yoji*; Mori, Shigeo*
Japanese Journal of Applied Physics 47(9), p.7599-7602(2008) ; (JAEA-J 04847)

We have investigated the physical properties of HoFe₂O₄ and R_1-xR'_xFe₂O₄ (R, R': rare earths). Dielectric measurements showed their dielectric constants of 1000 at around room temperature, which is characteristic of the RFe₂O₄ series (R: rare earths). However, the magnetic transition temperatures and the coherency in dielectric response were found to be different from those of RFe₂O₄ reported so far. Interestingly, these materials suggested higher ferroelectric temperatures than those reported so far, suggesting a possibility of application of these materials.

36001569
Numerical analysis of the production profile of H⁰ atoms and subsequent H^- ions in large negative ion sources
Takado, Naoyuki*; Tobari, Hiroyuki; Inoue, Takashi; Hanatani, Junji*; Hatayama, Akiyoshi*; Hanada, Masaya; Kashiwagi, Mieko; Sakamoto, Keishi
Journal of Applied Physics 103(5), p.053302_1-053302_12(2008) ; (JAEA-J 04848)

The production and transport processes of H⁰ atoms are numerically simulated using a three-dimensional Monte Carlo transport code. The code was applied to the large JAEA 10 ampere negative ion source under the Cs-seeded condition to obtain a spatial distribution of surface-produced H^- ions. In the H₀ atom transport process, the energy relaxation of the H₀ atoms, which affects the surface H^- ion production rate, is taken into account. The result indicates that the surface H^- ion production is enhanced near the high-electron-temperature region where H₀ atom production is localized.

36001570
Interlaboratory comparison of positron annihilation lifetime measurements for synthetic fused silica and polycarbonate
Ito, Kenji*; Oka, Toshitaka*; Kobayashi, Yoshinori*; Shirai, Yasuharu*; Wada, Kenichiro*; Matsumoto, Masataka*; Fujinami, Masanori*; Hirade, Tetsuya; Honda, Yoshihide*; Hosomi, Hiroyuki*; Nagai, Yasuyoshi*; Inoue, Koji*; Saito, Haruo*; Sakaki, Koji*; Sato, Kiminori*; Shimazu, Akira*; Uedono, Akira*
Journal of Applied Physics 104(2), p.026102_1-026102_3(2008) ; (JAEA-J 04849)

Interlaboratory comparison of positron annihilation lifetime measurements using synthetic fused silica and polycarbonate was conducted with the participation of 12 laboratories. By regulating procedures for the measurement and data analysis the uncertainties of the positron lifetimes obtained at different laboratories were significantly reduced in comparison with those reported in the past.

36001571
Mechanisms of unexpected reduction in hole concentration in Al-doped 4H-SiC by 200 keV electron irradiation
Matsuura, Hideharu*; Minohara, Nobumasa*; Oshima, Takeshi
Journal of Applied Physics 104(4), p.043702_1-043702_6(2008) ; (JAEA-J 04850)

The hole concentration in Al-doped p-type 4H-SiC irradiated with electrons at 200 keV was investigated. By the irradiation at 200 keV electrons, only substitutional Carbon atoms (C) in SiC can be displaced. The reduction in hole concentration due to the electron irradiation was found to be mainly due to a decrease in Al acceptor concentration and not due to an increase in defect concentration. Based on the analysis of temperature dependence of hole concentration, two types of acceptor levels were detected and the density and energy level of each acceptor were determined.

36001572
Carcinogen adsorbent prepared from DNA complex by γ-ray irradiation
Furusawa, Kazuya*; Kita, Erika*; Saeki, Toshihiko*; Nagasawa, Naotsugu; Nishi, Norio*; Dobashi, Toshiaki*
Journal of Biomaterials Science; Polymer Edition 19(9), p.1159-1170(2008) ; (JAEA-J 04851)

To insolubilize DNA for preparing a novel carcinogen adsorbent, effects of γ-ray irradiation on aqueous solutions of mixtures of DNA with cross-linking biopolymers (CBP): gelatin, bovine serum albumin, carboxymethyl cellulose and hydroxyethyl-cellulose, O-[2-hydroxy-3-(trimethyl ammonio)-propyl], chloride have been studied. DNA-CBP hybrid gels were successfully prepared from aqueous mixtures of DNA with CBP in a limited range of irradiation dose. Gel fraction (Gf) and swelling ratio (S) of the hybrid gels were measured. The Gf and S of hybrid gels increased and decreased, respectively, with increasing irradiated dose. Adsorption of one of carcinogen, acridine orange, was also examined for the gels. From the experimental results, the optimum condition for preparing insolubilized homogeneous DNA gels was determined.

36001573
Anti-FGF23 neutralizing antibodies show the physiological role and structural features of FGF23
Yamazaki, Yuji*; Tamada, Taro; Kasai, Noriyuki*; Urakawa, Itaru*; Aono, Yukiko*; Hasegewa, Hisashi*; Fujita, Toshiro*; Kuroki, Ryota; Yamashita, Takeyoshi*; Fukumoto, Seiji*; Shimada, Takashi*
Journal of Bone and Mineral Research 23(9), p.1509-1518(2008) ; (JAEA-J 04852)

Fibroblast growth factor (FGF)23 is proposed to play a physiological role in the regulation of phosphate and vitamin D metabolism; deranged circulatory levels of FGF23 cause several diseases with abnormal mineral metabolism. We developed two antibodies (FN1 and FC1) that recognize the N- and C-terminal regions of FGF23, respectively. Both FN1 and FC1 inhibited FGF23 activity in a cell-based Klotho-dependent reporter assay. The present study using neutralizing antibodies confirms that FGF23 is a physiological regulator of phosphate and vitamin D metabolism. Then, we addressed the mechanism of action for these neutralizing antibodies. Structural analysis of the FGF23/FN1-Fab complex revealed that FN1 masked putative FGF receptor-binding sites in the N-terminal domain of FGF23, while biochemical analyses showed that FC1 interfered with the association between FGF23 and Klotho by binding to the C-terminal domain of FGF23. Taken together, our results suggest that the N- and C-terminal domains of FGF23 are responsible for association with cognate FGF receptors and Klotho, respectively, and that these interactions are indispensable for FGF23 activity.

36001574
Ab inito study on the ground and low-lying excited states of cesium iodide (CsI)
Kurosaki, Yuzuru; Matsuoka, Leo; Yokoyama, Keiichi; Yokoyama, Atsushi
Journal of Chemical Physics 128(2), p.024301_1-024301_7(2008) ; (JAEA-J 04853)

Potential energy curves (PECs) for the ground and low-lying excited states of the cesium iodide (CsI) molecule have been calculated using the MRSDCI method. PECs for 7 Λ-S states were first calculated and then those for 13 Ω states including spin-orbit coupling were obtained. Spectroscopic constants for the calculated ground X 0⁺-state PEC were found to agree well with experiment. Transition dipole moments (TDMs) between X 0⁺ and the other Ω states were also obtained and TDM between X 0⁺ and A 0⁺ was predicted to be the largest and that between X 0⁺ and B 0⁺ was the second largest around the equilibrium internuclear distance. Finally, vibrational levels of the X 0⁺ PEC for the two isotopic analogs, ¹³³CsI and ¹³⁵CsI, were numerically obtained and it was found that the v = 136 state of ¹³³CsI or ¹³⁵CsI is most isolated from any adjacent vibrational level.

36001575
Effects of ion irradiation on the hardness properties of graphites and C/C composites by indentation tests
Oku, Tatsuo*; Kurumada, Akira*; Imamura, Yoshio*; Ishihara, Masahiro
Journal of Nuclear Materials 381(1-2), p.92-97(2008) ; (JAEA-J 04855)

Four grades of graphites and two grades of C/C composites were irradiated by argon ions with 175 MeV. The load-depth curves were obtained from the micro indentation tests before and after ion irradiation, and the apparent hardness and the hardness property parameters B and D (close rerating to the strength and Young's modulus, respectively) were investigated. As a result, it is found that the apparent hardness and the parameters B and D increase due to argon ion irradiation, and that these micro hardness properties of the carbon materials are able to be expressed as a function of dpa values, including neutron irradiation data.

36001576
Effect of sodium nitrate on the diffusion of Cl^- and I^- in compacted bentonite
Ishidera, Takamitsu; Miyamoto, Shinya*; Sato, Haruo
Journal of Nuclear Science and Technology 45(7), p.610-616(2008) ; (JAEA-J 04858)

For safety assessment of TRU waste disposal, the effective diffusion coefficients (D_e) for CO₃^2-, Cl^- and I^- ions in compacted bentonite (Kunigel V1) were determined as a function of NaNO₃ concentrations from 0.01 to 5 mol/dm³. The D_e values increased from 10^-12 to 10^-11 m²/s with increasing NaNO₃ concentration. The rock capacity factor α, indicative of the effective porosity, were also increased with increasing NaNO₃ concentration. The maximum α values of 0.21 for Cl^- ion and of 0.25 for I^- ion at 5 mol/dm³ NaNO₃ concentration were lower than the net porosity of compacted bentonite (0.40). Therefore, the increases in the D_e values were interpreted by the decrease of anion exclusion effect. The D_e values for Cl^- and I^- ions normalized by the diffusivities for diffusants in the bulk water were found to increase in proportion to the α values on the log-log diagram. The maximum α value for CO₃^2- ion was higher than the net porosity. The high concentration of CO₃^2- ion was also found in the concentration profile in compacted bentonite. This retention of CO₃^2- ion was possibly accounted for by isotopic exchange of ¹⁴C with inactive carbon of calcite in Kunigel V1.

36001577
Corrosion products from carbon steel formed in compacted bentonite under reducing conditions
Ishidera, Takamitsu; Xia, X.*; Idemitsu, Kazuya*; Kikuchi, Yoshio*
Journal of Nuclear Science and Technology 45(8), p.763-772(2008) ; (JAEA-J 04859)

For safety assessment of high-level radioactive waste disposal, it is important to identify the forms of corrosion products migrating from overpack material into compacted bentonite. In this study, the carbon steel, which was previously corroded electrochemically under aerobic condition, was in contact with compacted Kunigel V1 and Kunipia F under reducing condition for 3-4 years at room temperature. The corrosion products migrating from carbon steel into compacted bentonites were investigated by the selective dissolution analysis, which can estimate the crystallinity of Fe-bearing compounds. The valence of iron in corrosion products was investigated spectrophotometrically. Furthermore, the alteration of smectite contained in compacted bentonite to Fe-smectite was analyzed by X-ray diffractometry (XRD). The results of selective dissolution and valence analysis suggested that the corrosion products in compacted bentonite were amorphous, non-crystalline or poorly ordered Fe(OH)₂ and Fe(OH)₃. In the XRD profiles, no diffraction peak suggesting the existence of Fe-smectite in the compacted bentonite was found. Therefore, the corrosion products in compacted bentonite were considered to have no effect on the alteration of smectite contained in Kunigel V1 and Kunipia F to Fe-smectite.

36001578
Mitigation technologies for damage induced by pressure waves in high-power mercury spallation neutron sources, 2; Bubbling effect to reduce pressure wave
Futakawa, Masatoshi; Kogawa, Hiroyuki; Hasegawa, Shoichi; Naoe, Takashi; Ida, Masato; Haga, Katsuhiro; Wakui, Takashi; Tanaka, Nobuatsu*; Matsumoto, Yoichiro*; Ikeda, Yujiro
Journal of Nuclear Science and Technology 45(10), p.1041-1048(2008) ; (JAEA-J 04860)

The life time of mercury target will be reduced by the cavitation damage induced by pressure waves. Micro-bubble injection into mercury is one of prospective technologies to mitigate the pressure waves. We have carried out damage tests using mercury loop with an impact generator to evaluate the bubbling effect on the pressure response and cavitation damage. The impulsive pressure was hardly changed but the damage was reduced remarkably by the micro-bubble injection. Numerical simulation was performed to investigate the bubbling effects. It was understandable that micro bubbles suppressed cavitation inception.

36001579
Experimental study on gas entrainment at free surface in reactor vessel of a compact sodium-cooled fast reactor
Kimura, Nobuyuki; Ezure, Toshiki; Tobita, Akira; Kamide, Hideki
Journal of Nuclear Science and Technology 45(10), p.1053-1062(2008) ; (JAEA-J 04861)

An innovative sodium cooled fast reactor has been investigated in a frame work of the fast reactor cycle technology development project. A compact reactor vessel (R/V) is designed to reduce the construction cost. One of the thermal hydraulic issues in this design is gas entrainment at a free surface in the R/V. A water experiment was performed using a partial model with 1/1.8th scale. The objective is to investigate occurrence conditions and the mechanism of the gas entrainment. It was found that there were two kinds of the gas entrainment phenomena and the occurrence conditions were far from the reactor condition. One type of the gas entrainments occurred at the wake region of the cold leg pipe due to larger horizontal velocity. Other one broke out at the region between the hot leg pipe and the R/V wall when the coolant level was low and the downward velocity was large.

36001580
Corrosion phenomenon of stainless steel in boiling nitric acid solution using large-scale mock-up of reduced pressurized evaporator
Ueno, Fumiyoshi; Kato, Chiaki; Motooka, Takafumi; Ichikawa, Shiro*; Yamamoto, Masahiro
Journal of Nuclear Science and Technology 45(10), p.1091-1097(2008) ; (JAEA-J 04862)

For purpose of life prediction of components in spent nuclear fuel reprocessing plants, corrosion test was performed about 36,000 hours using a large scale mock-up test apparatus of a reduced pressurized thermosiphon evaporator, and a corrosion mechanism of heat transfer tube made of an ultra-low carbon type 304 stainless steel in boiling nitric acid solution was studied. As the results, the tendencies of increases of amount of corrosion and corrosion rate were saturated when intergranular penetration and grain dropping occurred in turn. This result means that a linear estimation can be applied to the life prediction for corrosion. No difference in morphologies of intergranular corrosion existed among three portions could find even though amounts of corrosion were different. The amount of corrosion was dominated by tube surface temperature and heat flux. And the largest amount of corrosion could be seen at boiling starting portion and the top where indicated highest values of tube surface temperatures.

36001581
Evaluation of self-absorbed doses for the kidneys of a voxel mouse
Kinase, Sakae; Takahashi, Masa; Saito, Kimiaki
Journal of Nuclear Science and Technology, Supplement 5 (June 2008) , p.268-270(2008) ; (JAEA-J 04863)

Self-AFs for photons and electrons in the kidneys of a voxel mouse were evaluated using Monte Carlo simulation. The self-AFs for the kidneys of the voxel mouse were compared with those for the voxel humans. In addition, self-S values for ⁹⁰Y and ¹⁸F of potential interest in the kidney dosimetry were assessed using the self-AFs. It was found that photon self-AFs for the voxel mouse are significantly smaller than those for the voxel humans and that the electron self-AFs for the voxel mouse are consistent with those for the voxel humans in the energy range 10 -100 keV, followed by a sharp fall. The self-S values for the voxel mouse were found to be much larger than those for the voxel humans. Consequently, it may be concluded that a translation of the dose-response relationships in mice into those in humans requires the reliable dosimetry based on each sophisticated model.

36001582
Deep sea circulation of particulate organic carbon in the Japan Sea
Otosaka, Shigeyoshi; Tanaka, Takayuki; Togawa, Orihiko; Amano, Hikaru; Karasev, E. V.*; Minakawa, Masayuki*; Noriki, Shinichiro*
Journal of Oceanography 64(6), p.911-923(2008) ; (JAEA-J 04864)

Transport processes of particulate organic carbon (POC) were inferred from sediment trap experiments in the three regions of the Japan Sea (western and eastern Japan Basin and Yamato Basin) and radiocarbon measurement. Annual mean ¹⁴C/¹²C isotopic ratio decreased with depth and the vertical changes in the isotopic signature were considered to indicate mixing of two fractions; labile POC produced in the surface and refractory POC. From seasonal variations of POC flux of the two fractions, transport processes of POC in the Japan Sea were summarized as follows: (1) In the Japan Basin, both labile and refractory POC were supplied in spring and a reservoir of refractory POC was formed, and (2) in the Yamato Basin, larger amount of refractory POC were carried the interior and accumulated rapidly.

36001583
Carbon alloy catalysts; Active sites for oxygen reduction reaction
Ikeda, Takashi; Boero, M.*; Huang, S.-F.*; Terakura, Kiyoyuki*; Oshima, Masaharu*; Ozaki, Junichi*
Journal of Physical Chemistry C 112(38), p.14706-14709(2008) ; (JAEA-J 04865)

Nitrogen-doped carbon-based catalysts are attracting a renovated interest as potential Pt-free electrode catalysts for polymer electrolyte fuel cell. In this computational study, we inspect possible oxygen adsorption and reduction processes on various models for the exposed edges of these catalysts. The dynamics of an O₂ molecule solvated in water, mimicking the cathode environment, shows that O₂ adsorption depends on the morphology and atomic structure of the system. We show that carbon alloys with N dopants at specific sites can exhibit a metal-free catalytic activity.

36001584
Progress and issues in understanding the physics of ELM dynamics, ELM mitigation, and ELM control
Oyama, Naoyuki
Journal of Physics; Conference Series 123, p.012002_1-012002_17(2008) ; (JAEA-J 04866)

This paper reports progress and issues in physics understanding of dynamics, mitigation and control of ELMs, which have been recognized as one of the important issues in ITER. As for the ELM dynamics, studies of ELM precursor, filamentary structures during the collapse phase, dependence of ELM energy loss on the toroidal rotation and edge stability are progressed. In the small/no ELM regimes, expansion of the operational space toward low collisionality region has been achieved in type V ELM. In grassy ELM regime and QH-mode regime, ELM frequency dependence and EHO characteristics in term of edge rotation have been observed, respectively. As for the ELM control, the applicability of pellet pacing and external ELM control coils to ITER is discussed. Since the effect of toroidal rotation is now recognized as a fundamental parameter, the reliable prediction of edge rotation in ITER becomes more important.

36001585
Effect of toroidal field ripple and toroidal rotation on H-mode performance and ELM characteristics in JET/JT-60U similarity experiments
Oyama, Naoyuki; Saibene, G.*; Kamada, Yutaka; Kamiya, Kensaku; Loarte, A.*; Lönnroth, J.*; Parail, V.*; Sakamoto, Yoshiteru; Salmi, A.*; Sartori, R.*; Shinohara, Koji; Takenaga, Hidenobu; Urano, Hajime; de Vries, P.*; Yoshida, Maiko; JT-60 Team; JET-EFDA Contributors
Journal of Physics; Conference Series 123, p.012015_1-012015_13(2008) ; (JAEA-J 04867)

The effect of the toroidal field ripple and the edge toroidal rotation on H-mode and pedestal performance as well as ELM characteristics are investigated both in JET and JT-60U. In JT-60U, the amplitude of TF ripple was reduced from 1.2 % to 0.5 % after the installation of ferritic steel tiles. In JET, the ripple amplitude can actively be varied. In both devices, edge rotation in the same direction to the plasma current was reduced with increasing the ripple amplitude. Even at the same amplitude of 0.5 %, the achievable edge rotation in JT-60U was still lower than that in JET. A series of power and density scans performed at several ripple amplitude indicated that plasmas with smaller ripple amplitude and/or larger co-rotation are favorable to achieve higher pedestal pressure and plasma confinement in both devices. As for ELM characteristics, larger co-rotation seems to increase the ELM energy loss together with the reduction of the ELM frequency.

36001586
Calculation of dose contributions of electron and charged heavy particles inside phantoms irradiated by monoenergetic neutron
Sato, Daiki; Takahashi, Fumiaki; Endo, Akira; Omachi, Yasushi*; Miyahara, Nobuyuki*
Journal of Radiation Research 49(5), p.503-508(2008) ; (JAEA-J 04868)

The radiation-transport code PHITS with an event generator mode has been applied to analyze energy depositions of electron and charged heavy particles in two spherical phantoms and a voxel-based mouse phantom upon neutron irradiation. The calculations using the spherical phantoms quantitatively clarified the type and energy of charged particles which are released through interactions of neutrons with the phantom elements and contribute to the radiation dose. The relative contribution of electrons increased with increase in the size of the phantom and with decrease in the energy of the incident neutrons. Calculation with the voxel-based mouse phantom given 2.0-MeV neutron irradiation revealed that the doses to different locations inside the body are uniform, and that the energy is mainly deposited by recoil protons. The present study has demonstrated that analysis using PHITS can yield dose distributions that are accurate enough for RBE evaluation.

36001587
Production of ⁶⁷Cu via the ⁶⁸Zn(p,2p) ⁶⁷Cu reaction and recovery of ⁶⁸Zn target
Katabuchi, Tatsuya*; Watanabe, Satoshi; Ishioka, Noriko; Iida, Yasuhiko*; Hanaoka, Hirofumi*; Endo, Keigo*; Matsuhashi, Shimpei
Journal of Radioanalytical and Nuclear Chemistry 277(2), p.467-470(2008) ; (JAEA-J 04869)

The radionuclide ⁶⁷Cu was produced via the ⁶⁸Zn(p,2p) ⁶⁷Cu reaction by irradiating enriched ⁶⁸Zn targets with 70-MeV proton beam. ⁶⁷Cu was chemically separated from target zinc material by an ion-exchange chromatography method using Chelex-100 chelating ion-exchange resin. Procedure for recovery of the enriched ⁶⁸Zn was developed. The target recovery yield in this method was evaluated to be more than 97%.

36001588
Superconducting properties of CePt₃Si and CeIrSi₃ without inversion symmetry in the crystal structure
Onuki, Yoshichika; Miyauchi, Yuichiro*; Tsujino, Masahiko*; Ida, Yuki*; Settai, Rikio*; Takeuchi, Tetsuya*; Tateiwa, Naoyuki; Matsuda, Tatsuma; Haga, Yoshinori; Harima, Hisatomo*
Journal of the Physical Society of Japan 77(Suppl.A), p.37-42(2008) ; (JAEA-J 04870)

Superconducting upper critical field of CePt₃Si and CeIrSi₃ without inversion symmetry was studied in detail. In CePt₃Si coexisting with antiferromagnetism, rather isotropic critical field was observed. On the other hand, huge anisotropy was detected in CeIrSi₃. These results are discussed in connection with the formation of the heavy fermion state.

36001589
Heavy fermion superconductivity with the strong Pauli paramagnetic effect on NpPd₅Al₂
Aoki, Dai*; Haga, Yoshinori; Matsuda, Tatsuma; Tateiwa, Naoyuki; Ikeda, Shugo*; Homma, Yoshiya*; Sakai, Hironori; Shiokawa, Yoshinobu*; Yamamoto, Etsuji; Nakamura, Akio; Settai, Rikio*; Onuki, Yoshichika
Journal of the Physical Society of Japan 77(Suppl.A), p.159-164(2008) ; (JAEA-J 04871)

Superconducting properties are investigated on the new neptunium-based superconductor NpPd₅Al₂. The large electronic specific heat, anisotropy of magnetic as well as superconducting properties and strong paramagnetic effect implies spin-singlet pairing with anisotropic superconducting gap.

36001590
Antiferro-quadrupole state of orbital-degenerate Kondo lattice model with f² configuration
Onishi, Hiroaki; Hotta, Takashi*
Journal of the Physical Society of Japan 77(Suppl.A), p.199-201(2008) ; (JAEA-J 04872)

To clarify a key role of f orbitals in the emergence of antiferro-quadrupole structure of PrPb₃, we investigate the ground-state property of an orbital-degenerate Kondo lattice model by numerical diagonalization techniques. By analyzing an orbital correlation function, it is found that an antiferro-orbital state is favored by the so-called double-exchange mechanism which is characteristic of multi-orbital systems. We will report detailed results of correlation functions and discuss its possible relevance to antiferro-quadrupole structure in PrPb₃.

36001591
³¹P-NMR study of the neptunium-based filled-skutterudite NpFe₄P₁₂
Tokunaga, Yo; Aoki, Dai*; Homma, Yoshiya*; Sakai, Hironori; Chudo, Hiroyuki; Kambe, Shinsaku; Matsuda, Tatsuma; Ikeda, Shugo; Yamamoto, Etsuji; Nakamura, Akio; Haga, Yoshinori; Shiokawa, Yoshinobu*; Onuki, Yoshichika; Yasuoka, Hiroshi
Journal of the Physical Society of Japan 77(Suppl.A), p.211-213(2008) ; (JAEA-J 04873)

³¹P-NMR measurements have been performed on a single crystal of NpFe₄P₁₂ which is the first crystallized transuranium filled-skutterudite compound. The field-orientation dependence of the hyperfine interaction has been measured using the single crystal, and the results compared with those obtained previously in isostructural compounds UFe₄P₁₂ and PrFe₄P₁₂. We have also measured the field and temperature dependence of the nuclear spin-lattice relaxation rate in several fields between 1.8 and 8 T at temperatures between 4.2 and 300 K. The results are discussed on the basis of a localized picture for the 5f electrons.

36001592
Visualization of anharmonic thermal vibration in filled skutterudite compounds
Kaneko, Koji; Metoki, Naoto; Kimura, Hiroyuki*; Noda, Yukio*; Matsuda, Tatsuma; Kogi, Masafumi*
Journal of the Physical Society of Japan 77(Suppl.A), p.245-247(2008) ; (JAEA-J 04874)

In filled skutterudite compounds, the importance of rattling is suggested in connection with the formation of heavy quasiparticles and superconductivity. A combination of the single crystal neutron diffraction and the maximum entropy method (MEM) offers an ability to unveil the thermal motion of Pr in PrOs₄Sb₁₂ without any specific model. The result reveals the widely spread Pr nuclear density distribution at room temperature, which has a trapezoidal shape in the real space with the width of roughly 0.6 Å in the full width at half maximum. In contrast, the Pr distribution at 8 K has a sharp, isotropic gaussian shape, and the highest density locates at the center of the cage. These features indicate the strong anharmonicity of the Pr potential in the Sb cage.

36001593
Pressure effect on ferromagnet UTeS
Ikeda, Shugo*; Sakai, Hironori; Matsuda, Tatsuma; Tateiwa, Naoyuki; Aoki, Dai*; Homma, Yoshiya*; Nakamura, Akio; Yamamoto, Etsuji; Shiokawa, Yoshinobu*; Hedo, Masato*; Uwatoko, Yoshiya*; Haga, Yoshinori; Onuki, Yoshichika
Journal of the Physical Society of Japan 77(Suppl.A), p.359-361(2008) ; (JAEA-J 04875)

The ferromagnet UTeS was studied by measurement the resistivity under high pressure. The Curie temperature T_C rapidly increases from 87 K to 166 Kat 8 GPa. The result suggests that there is a correlation between the electrical conductivity and magnetic transition temperature, implying the strong hybridization.

36001594
Super clean sample of URu₂Si₂
Matsuda, Tatsuma; Aoki, Dai*; Ikeda, Shugo; Yamamoto, Etsuji; Haga, Yoshinori; Okuni, Hitoshi*; Settai, Rikio*; Onuki, Yoshichika
Journal of the Physical Society of Japan 77(Suppl.A), p.362-364(2008) ; (JAEA-J 04876)

In the process of the single crystal growth of actinide compounds, the amount of raw actinide material should be reduced as much as possible. Considering this point, the flux method is one of the most effective methods. In order to develop the new actinide compounds include the filled skutterudite, we have been searching the suitable condition for growing the single crystal. In these trial processes, we have succeeded to grow some of the other single crystals of rare-earth and actinides compounds. For example, the single crystal of UCu₂Si₂, UCu₂Ge₂, ThCu₂Ge₂, CeCu₂Si₂, and YbCu₂Si₂ were grown by the Sn-flux method. In the case of UCu₂Si₂ and YbCu₂Si₂, the de Haas-van Alphen signals are detected by using these crystals. Recently, we also succeeded in growing the highest quality single crystal of URu₂Si₂ by the Czochralski-pulling method in a tetra-arc furnace and detecting the de Haas-van Alphen signal.

36001595
Magnetic and superconducting properties of CeTX₃ (T:transition metal and X:Si and Ge) with non-centrosymmetric crystal structure
Kawai, Tomoya*; Muranaka, Hiroshi*; Measson, M.-A.*; Shimoda, Tetsuya*; Doi, Yusuke*; Matsuda, Tatsuma; Haga, Yoshinori; Knebel, G.*; Lapertot, G.*; Aoki, Dai*; Flouquet, J.*; Takeuchi, Tetsuya*; Settai, Rikio*; Onuki, Yoshichika
Journal of the Physical Society of Japan 77(6), p.064716_1-064716_9(2008) ; (JAEA-J 04877)

Physical properties of cerium compounds CeTX₃ were studied on single crystals. Electrical resistivity, magnetization as well as their pressure dependence revealed that the antiferromagnetism of CeCoGe₃ is destroyed under hydrostatic pressure above 5.4 GPa and the superconductivity appears above this pressure.

36001596
Split Fermi surface properties of LaTGe₃ (T:transition metal) and PrCoGe₃ with the non-centrosymmetric crystal structure
Kawai, Tomoya*; Muranaka, Hiroshi*; Endo, Toyoaki*; Nguyen, D.; Doi, Yusuke*; Ikeda, Shugo*; Matsuda, Tatsuma; Haga, Yoshinori; Harima, Hisatomo*; Settai, Rikio*; Onuki, Yoshichika
Journal of the Physical Society of Japan 77(6), p.064717_1-064717_15(2008) ; (JAEA-J 04878)

Fermi surfaces of the non-centrosymmetric LaTGe₃ and PrCoGe₃ have been studied in detail using the de Haas-van Alphen effect. Splitting of the conduction bands due to the spin-orbit interaction was clearly observed. These results are important in understanding the exotic superconductivity realized in non-centrosymmetric structure.

36001597
Lattice dynamics of LaFeAsO_1-xF_x and PrFeAsO_1-y via inelastic X-ray scattering and first-principles calculation
Fukuda, Tatsuo; Baron, A. Q. R.*; Shamoto, Shinichi; Ishikado, Motoyuki; Nakamura, Hiroki; Machida, Masahiko; Uchiyama, Hiroshi*; Tsutsui, Satoshi*; Iyo, Akira*; Kito, Hijiri*; Mizuki, Junichiro; Arai, Masatoshi; Eisaki, Hiroshi*; Hosono, Hideo*
Journal of the Physical Society of Japan 77(10), p.103715_1-103715_4(2008) ; (JAEA-J 04879)

The lattice dynamics of LaFeAsO_1-xF_x (x=0, 0.1) and PrFeAsO_1-y (y∼0.1) are investigated using inelastic X-ray scattering. Measurements of powder samples provide an approximation to the phonon DOS, while dispersion is measured from a single crystal of PrFeAsO_1-y. A model that agrees reasonably well with all of the data at room temperature is built from results of ab-initio calculations by reducing the strength of the Fe-As bond by 30%.

36001598
Positronium formation in room temperature ionic liquids
Hirade, Tetsuya
Materials Science Forum 607, p.232-234(2009) ; (JAEA-J 04880)

Positron lifetime measurements and age-momentum correlation measurements were performed for several ionic liquids to investigate free electrons through positronium (Ps, a bond state of an electron and a positron) formation. An injected positron forms spurs (cations and excess electrons) and thermalizes at the terminal spur where the positron has a chance to form Ps with one of excess electrons. When positrons and/or electrons are localized somewhere, their mobility becomes much smaller and Ps cannot be formed usually. It means that Ps formation can give information of reactions of mobile electrons and positrons. If the dry electrons can diffuse for long time, Ps formation is quite possible even at the later positron age such as 10∼100 ps. The slow Ps formation was observed in the room temperature ionic liquids.

36001599
Interlaboratory comparison of positron annihilation lifetime measurements
Ito, Kenji*; Oka, Toshitaka*; Kobayashi, Yoshinori*; Shirai, Yasuharu*; Wada, Kenichiro*; Matsumoto, Masataka*; Fujinami, Masanori*; Hirade, Tetsuya; Honda, Yoshihide*; Hosomi, Hiroyuki*; Nagai, Yasuyoshi*; Inoue, Koji*; Saito, Haruo*; Sakaki, Koji*; Sato, Kiminori*; Shimazu, Akira*; Uedono, Akira*
Materials Science Forum 607, p.248-250(2009) ; (JAEA-J 04881)

So far no standard procedure for the positron annihilation lifetime (PAL) technique has been established. A lack of the standards has led to difficulty in ensuring the equivalency and reliability of data from different laboratories. As a first, we conducted an interlaboratory comparison of PAL measurements for metal, polymer and silica glass with agreed procedures for data recording and analysis. The PAL data recorded at different laboratories were analyzed with a single lifetime component for the metal sample and with three components for the others, respectively. Based on the results of the reported positron and ortho-positronium lifetimes, the possible sources of the uncertainties in the PAL measurements are discussed. To reduce the effect of scattered γ rays, a lead shield was placed between the detectors. The uncertainty was significantly decreased, signifying that placing lead shields between the detectors effectively reduced the false signals due to the scattered γ rays.

36001600
Angle-correlated spectrum measurement for two neutrons emitted from (n,2n) reaction with the coincidence detection technique using a pencil-beam DT neutron source
Murata, Isao*; Takagi, Satoshi*; Kondo, Keitaro; Shiken, Kimiaki*; Miyamaru, Hiroyuki*; Mitsuda, Motoyuki; Maekawa, Fujio; Ochiai, Kentaro; Nishitani, Takeo
Nuclear Instruments and Methods in Physics Research A 595(2), p.439-446(2008) ; (JAEA-J 04883)

A technique was developed to measure the angle-correlated neutron energy spectrum with the coincidence detection technique using a pencil-beam DT neutron source at the Fusion Neutronics Source (FNS) of the Japan Atomic Energy Agency (JAEA). Triple differential cross-sections of the ⁵⁵Mn(n,2n) reaction were measured first, from which the total ⁵⁵Mn(n,2n) reaction cross-section was deduced and compared with JENDL-3.3. The agreement was sufficient to prove the validity of the technique. With the present measuring technique, a complete measurement of a medium-heavy or heavy element such as manganese would become possible through several measurements, because the angle dependence of the emitted neutrons from it is normally weak. The technique will be a useful tool for measuring the angle-correlated neutron spectrum of light elements such as beryllium for investigation of their complicated nuclear reaction mechanism.

36001601
Feasibility of lead-bismuth-cooled accelerator-driven system for minor-actinide transmutation
Tsujimoto, Kazufumi; Oigawa, Hiroyuki; Kikuchi, Kenji; Kurata, Yuji; Mizumoto, Motoharu; Sasa, Toshinobu; Saito, Shigeru; Nishihara, Kenji; Umeno, Makoto*; Takei, Hayanori
Nuclear Technology 161(3), p.315-328(2008) ; (JAEA-J 04884)

Feasibility was discussed for lead-bismuth cooled accelerator-driven system (ADS) to transmute minor actinides partitioned from high-level radioactive waste. Since lead-bismuth will cause considerable corrosion and erosion effects at high temperature, the fuel clad temperature must be kept as low as possible. Moreover, the most critical issue of ADS design is engineering viability of the high-power spallation target and the beam window. Thermal-hydraulic and structural analysis was carried out for both the fuel assembly and the beam window. In addition to the analysis in steady state, transient behaviors were also studied during typical transient and unprotected accidents. The results showed that engineering viability is reasonably achievable in nominal operation. For beam trip which will be the most frequent transient, the number of events to cause the failure of the beam window is estimated as more than 10⁵. For safety aspects of ADS during unprotected accidents, estimated results showed that ULOF would cause the most significant problem, if beam operation was kept. Therefore, high reliability of the beam shutdown is required for the ADS safety.

36001602
Characteristics and sinterability of MOX powder prepared by the microwave heating denitration method
Asakura, Koichi; Kato, Yoshiyuki; Furuya, Hirotaka
Nuclear Technology 162(3), p.265-275(2008) ; (JAEA-J 04885)

UO₂, PuO₂ and MOX (mixed oxide of U and Pu) powders were prepared by the MH (microwave heating de-nitration), ADU (Ammonia diuranate) and OX (oxalate) methods. The BET specific surface area, avarage particle size by air permiation method, bulk density, tap density, angle of repose, angle of spatula and cohesiveness of these powders were measured. The degree of surface roughness was evaluated from the ratio of BET surface area to the one calculated from average particle size and then flowability was evaluated on the basis of Carr's theory. These results were compared for the different powders and preperation methods as a parameter of calcination temperature. The degree of surface roughness in MH-MOX powder was larger than in ADU-UO₂ powder and smaller in OX-PuO₂ powder. These results could be understood using the concpt of Höttig and Tamman temperatures commonly cited in ceramics materials. As already reported for the general papers, the flowabilities of MH-MOX and ADU-UO₂ powders also decreased with increase of compressibility, and their absolute values were below 50 points. According to Carr's theory, the brderline between free-flowing and non-free-flowing powders is from 60 to 69 points. It is, therefore, necessary for the mixed powder of MH-MOX powder, ADU-UO₂ powder and dry recycled MOX scrap powder to be granulated to provide a free flowing feed to the pelletizing press in the MOX pellet fabrication process.

36001603
Development of analytical procedures of two-phase flow in tight-lattice fuel bundles for Innovative Water Reactor for Flexible Fuel Cycle
Yoshida, Hiroyuki; Onuki, Akira; Misawa, Takeharu; Takase, Kazuyuki; Akimoto, Hajime
Nuclear Technology 164(1), p.45-54(2008) ; (JAEA-J 04886)

An R&D project to investigate thermal-hydraulic performance in the tight-lattice rod bundles of the Innovative Water Reactor for Flexible Fuel Cycle (FLWR) has been in progress at Japan Atomic Energy Agency (JAEA) in collaboration with power companies, reactor vendors, and universities since 2002. The FLWR can realize favorable characteristics such as effective utilization of uranium resources, multiple recycling of plutonium, high burn-up and long operation cycle, based on matured LWR technologies. MOX fuel assemblies with tight lattice arrangement are used because they increase the conversion ratio by reducing the moderation of neutrons. Increasing the in-core void fraction also contributes to the reduction of neutron moderation. Information about the effects of the gap width and grid spacer configuration on the flow characteristics in the FLWR core is still insufficient. Thus, we are developing procedures for qualitative analysis of thermal-hydraulic performance of the FLWR core using an advanced numerical simulation technology. In this study, an advanced two-fluid model is developed to economize on the computing resources. In the model, interface structures larger than computational cells (such as liquid film) are simulated by the interface tracking method, and small bubbles and droplets are estimated by the two-fluid model. In this paper, we describe the outline of this model and the numerical simulations we performed to validate the model performance qualitatively.

36001604
Observation of 5f electrons in the itinerant limit; Three-dimensional electronic structure of UB₂
Okochi, Takuo; Fujimori, Shinichi; Yamagami, Hiroshi*; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*
Physical Review B 78(16), p.165110_1-165110_5(2008) ; (JAEA-J 04888)

We have derived the three dimensional band structure and Fermi surfaces of itinerant uranium compound UB₂ by soft X-ray angle resolved photoelectron spectroscopy. We have observed clear energy dispersions and Fermi surfaces with large contribution from U 5f states. The obtained results have been compared with the result of band-structure calculation within the local density functional approximation as well as the results of dHvA study. The qualitative agreement has been obtained in the size and topology of the Fermi surfaces with the band structure calculation and the dHvA measurement. Meanwhile, their band structure near the Fermi level is slightly different from the calculation. This might be due to a dynamic renormalization beyond the LDA band calculations even in the very itinerant 5f compound.

36001605
Nature of magnetic coupling between Mn ions in as-grown Ga_1-xMn_xAs studied by X-ray magnetic circular dichroism
Takeda, Yukiharu; Kobayashi, Masaki*; Okane, Tetsuo; Okochi, Takuo; Okamoto, Jun*; Saito, Yuji; Kobayashi, Keisuke*; Yamagami, Hiroshi; Fujimori, Atsushi; Tanaka, Arata*; Okabayashi, Jun*; Oshima, Masaharu*; Oya, Shinobu*; Hai, P. N.*; Tanaka, Masaaki*
Physical Review Letters 100(24), p.247202_1-247202_4(2008) ; (JAEA-J 04889)

36001606
Transition between internal transport barriers with different temperature-profile curvatures in JT-60U tokamak plasmas
Ida, Katsumi; Sakamoto, Yoshiteru; Takenaga, Hidenobu; Oyama, Naoyuki; Ito, Kimitaka*; Yoshinuma, Mikiro*; Inagaki, Shigeru*; Kobuchi, Takashi*; Isayama, Akihiko; Suzuki, Takahiro; Fujita, Takaaki; Matsunaga, Go; Koide, Yoshihiko; Yoshida, Maiko; Ide, Shunsuke; Kamada, Yutaka; JT-60 Team
Physical Review Letters 101(5), p.055003_1-055003_4(2008) ; (JAEA-J 04890)

A spontaneous transition phenomena between two meta-stable states of plasmas with internal transport barrier (ITB), that are characterized by different radial profiles of second derivative of ion temperature inside the ITB region where the ion temperature gradient is large, is observed in the steady-state phase of magnetic shear in the negative magnetic shear plasma in JT-60U tokamak. The curvature asymmetry factor evaluated from the radial profile of second derivative of ion temperature profiles changes from 0.08 (symmetric curvature ITB) to -0.43 (asymmetric curvature ITB) during transition phase.

36001607
Superconducting Pb island nanostructures studied by scanning tunneling microscopy and spectroscopy
Nishio, Takahiro*; An, Toshu*; Nomura, Atsushi*; Miyachi, Kosuke*; Eguchi, Toyoaki*; Sakata, Hideaki*; Lin, S.*; Hayashi, Nobuhiko; Nakai, Noriyuki; Machida, Masahiko; Hasegawa, Yukio*
Physical Review Letters 101(16), p.167001_1-167001_4(2008) ; (JAEA-J 04891)

Superconductivity of nanosized Pb-island structures whose radius is 0.8 to 2.5 times their coherence length was studied under magnetic fields using low-temperature scanning tunneling microscopy and spectroscopy. Spatial profiles of superconductivity were obtained by conductance measurements at zero-bias voltage. Critical magnetic fields for vortex penetration and expulsion and for superconductivity breaking were measured for each island. The critical fields depending on the lateral size of the islands and existence of the minimum lateral size for vortex formation were observed.

36001608
The Conjugate variable method in Hamilton-Lie perturbation theory; Applications to plasma physics
Tokuda, Shinji
Plasma and Fusion Research (Internet) 3, p.057_1-057_10(2008) ; (JAEA-J 04892)

The conjugate variable method, which is an essential ingredient in the path-integral formalism of classical statistical dynamics, is used in order to apply the Hamilton-Lie perturbation theory to a system of ordinary differential equations that does not have the Hamilton dynamic structure. The method endows the system with the Hamilton dynamic structure by doubling the independent variables; hence the canonical Hamilton-Lie perturbation theory becomes applicable to the system. The method is applied to two classical problems in plasma physics, a non-linear oscillator that can explode and the guiding center motion of a charged particle in a magnetic field, to demonstrate the effectiveness and to study the property of the conjugate variable method.

36001609
X-ray absorption spectrum for guanosine-5'-monophosphate in water solution in the vicinity of the nitrogen K-edge observed in free liquid jet in vacuum
Ukai, Masatoshi*; Yokoya, Akinari; Fujii, Kentaro; Saito, Yuji
Radiation Physics and Chemistry 77(10-12), p.1265-1269(2008) ; (JAEA-J 04895)

In order to substantiate the hydrated structure of DNA from the view point of the electronic properties, we develop a new spectroscopic technique for the photoelectrons ejected from solutions dissolving biological molecules using a soft X-ray synchrotron radiation (SPring-8, BL23SU) in combination with liquid jet technique in vacuum. In this paper, we present the first evidence of the spectrum of total photoelectron yields for a nucleotide, guanosine-5'-monophosphate, in solution in the energy region of so-called water window around nitrogen K-edge. A liquid nucleotide/water sample is maintained in the form of continuous thin water jet (diameter ∼ 20 μm) in vacuum and is intersected by a highly focused soft X-ray beam. The obtained spectrum in solution shows common features with the spectrum in solid film. Nitrogen atoms only exist in the base site, so that the spectral similarities can be explained by the hydrophobic property of the base site.

36001610
The Small-molecule Bcl-2 inhibitor HA14-1 sensitizes cervical cancer cells, but not normal fibroblasts, to heavy-ion radiation
Hamada, Nobuyuki*; Kataoka, Keiko*; Sora, Sakura*; Hara, Takamitsu*; Omura, Motoko*; Funayama, Tomoo; Sakashita, Tetsuya; Nakano, Takashi*; Kobayashi, Yasuhiko
Radiotherapy and Oncology 89(2), p.227-230(2008) ; (JAEA-J 04896)

This is the first study to demonstrate that the small-molecule Bcl-2 inhibitor HA14-1 renders human cervical cancer cells and their Bcl-2 over expressing radioresistant counterparts, but not normal fibroblasts, more susceptible to heavy ions. Thus, Bcl-2 may be an attractive target for improving the efficacy of heavy-ion therapy.

36001611
Energetic heavy ions overcome tumor radioresistance caused by overexpression of Bcl-2
Hamada, Nobuyuki*; Hara, Takamitsu*; Omura, Motoko*; Funayama, Tomoo; Sakashita, Tetsuya; Sora, Sakura; Yokota, Yuichiro; Nakano, Takashi*; Kobayashi, Yasuhiko
Radiotherapy and Oncology 89(2), p.231-236(2008) ; (JAEA-J 04897)

Overexpression of Bcl-2 is frequent in human cancers and has been associated with the radioresistance. Here we investigated the potential impact of heavy ions on Bcl-2 overexpressing tumors. Bcl-2 cells (Bcl-2 overexpressing HeLa cells) and Neo cells (neomycin resistant gene-expressing HeLa cells) exposed to γ-rays or heavy ions were assessed for the clonogenic survival, apoptosis and cell cycle distribution. Whereas Bcl-2 cells were more resistant to γ-rays and helium ions (16.2 keV/μm) than Neo cells, heavy ions (76.3-1610 keV/μm) gave the comparable survival regardless of Bcl-2 overexpression. Carbon ions (108 keV/μm) decreased the difference in the apoptotic incidence between Bcl-2 and Neo cells, and prolonged G₂/M arrest that occurred more extensively in Bcl-2 cells than in Neo cells. High-LET heavy ions overcome tumor radioresistance caused by Bcl-2 overexpression, which may be explained at least in part by the enhanced apoptotic response and prolonged G₂/M arrest. Thus, heavy-ion therapy may be a promising modality for Bcl-2 overexpressing radioresistant tumors.

36001612
Measurement of derivative of ion temperature using high spatial resolution charge exchange spectroscopy with space modulation optics
Ida, Katsumi; Sakamoto, Yoshiteru; Yoshinuma, Mikiro*; Inagaki, Shigeru*; Kobuchi, Takashi*; Matsunaga, Go; Koide, Yoshihiko
Review of Scientific Instruments 79(5), p.053506_1-053506_6(2008) ; (JAEA-J 04898)

A new technique to measure the first and second derivative of the ion temperature profile has been developed using a charge exchange spectroscopy system with space modulation optics. The space observed is scanned up to ±3 cm with a cosine wave modulation frequency up to 30 Hz by shifting the object lens in front of the optical fiber bundle by 0.5 mm with a piezoelement. The first and second derivatives of ion temperature are derived from the modulation component of the ion temperature measured using Fourier analysis.

36001613
Absolute calibration of microfission chamber in JT-60U
Hayashi, Takao; Nishitani, Takeo; Sukegawa, Atsuhiko; Ishikawa, Masao; Shinohara, Koji
Review of Scientific Instruments 79(10), p.10E506_1-10E506_3(2008) ; (JAEA-J 04899)

In D-D or D-T operation fusion devices, the fusion neutron yield is the most important parameter to estimate the fusion power. We have conducted calibrations of a microfission chamber, 14 mm in diameter and 200 mm in length, by both Cf-252 neutron source and real plasmas in JT-60U. The detector employs both pulse counting and Campbelling modes in the electronics to cover 10⁷ dynamic range of the neutron source strength. The efficiencies were influenced by the various components. The point efficiencies can be integrated and averaged with angle to provide toroidal line efficiencies. The line efficiencies of microfission chamber and the nearest neutron monitor of U-235 fission chamber was 5.38 × 10^-9 and 1.77 × 10^-8, respectively. Then the calibration using real plasma was also performed. The detection efficiency in Campbelling mode was about three-tenth of the nearest neutron monitor, which is consistent with the calibration result using Cf-252 neutron source.

36001614
Buried H monolayer at hetero-interface between highly mismatched Sr films and Si substrates
Yamazaki, Tatsuya; Asaoka, Hidehito; Takeda, Masayasu; Yamazaki, Dai; Taguchi, Tomitsugu; Torikai, Naoya*; Toyoshima, Yasutake*; Shamoto, Shinichi
Transactions of the Materials Research Society of Japan 33(3), p.611-614(2008) ; (JAEA-J 04901)

Strontium and SrO are well-known templates on Si for SrTiO₃, highly-desirable transistor gate material. When stacked on Si, Srlayer becomes amorphous due to its large lattice mismatch of 12%. By introducing a monatomic hydrogen layer on Si, we succeeded in making the Sr (and subsequent SrO) layer(s) grow epitaxially with atomically abrupt interface. However, it is some what mysterious how the monatomic hydrogen layer behaves to manage this large mismatch. In order to identify its behavior, we have employed compound analysis by neutron reflectometer as well as multiple-internal-reflection fourier-transform infrared spectroscopy (MIR-FTIR) to investigate the buried heterointerface of Sr grown on Si(111)1 ×1: monohydride. We have found difference between the H- and D-terminated substrates in the reflectivity profiles, and changes in Si-H bonding features with the Sr growth (mainly at the initial monolayer stage) in the FTIR spectra. From these, existence of buried H layer at the heterointerfaceis confirmed with its bonding environment.

36001615
Fabrication of Ni₂In₃ alloy nanotubes
Kitazawa, Sin-iti
Vacuum 83(3), p.649-652(2008) ; (JAEA-J 04902)

Alloy nanotubes were successfully grown by self-organization. They were produced by annealing of carbon-nickel-indium mixture thin films that were prepared by pulsed laser deposition. The morphology was observed and analysed by both scanning and transmission electron microscope. The diameters were tens of nanometers and the aspect ratios were more than 2500. The growth is suggested to be due to the driving force that originated from supersaturation of alloying liquid indium with solid nickel.

36001616
Fission-track ages of late Pliocene to Pleistocene strata around the eastern margin of the Yokote Basin active fault zone, northeast Japan (in Japanese)
Kagohara, Kyoko; Kosaka, Hideki*; Nohara, Tsuyoshi; Miwa, Atsushi*; Imaizumi, Toshifumi*
Chigaku Zasshi 117(5), p.851-862(2008) ; (JAEA-J 04903)

To understand the development process of the fault zone, fission-track ages of rocks and rock facies are investigated in western margin of the Ou Backbone Range of Northeast Japan. Fission-track dating was carried out for 5 acid volcanic rocks from the late Pliocene to Pleistocene strata which were deposit associated with mountain belt growth. Statistically significant ages obtained are 1.5±0.1 Ma (OB-03) and 1.85±0.1 Ma (YG-01) for the Tazawa Formation, 1.6±0.3 Ma (FT-01) for the Kurisawa Formation,0.93±0.14 Ma (FT-02) and 2.7±0.3 Ma (FT-03) for the Senya Formation. According to the fission-track dating in this study, ages of the mountain belt growth with acid volcanic activity are estimated to before 1 Ma.

36001617
IAEA radioactive waste safety standards; History, current status and future (in Japanese)
Hioki, Kazumasa
Genankyo Dayori (226), p.3-10(2008) ; (JAEA-J 04905)

History, current status and the future of the IAEA Safety Standards on radioactive waste management is explained.

36001618
Current status of adsorbent development for recovery of uranium from seawater (in Japanese)
Tamada, Masao
Genshiryoku eye 54(11), p.13-16(2008) ; (JAEA-J 04907)

Uranium recovery from seawater has been emerging issue since in June, 2007, uranium cost rose suddenly to $136 which was ten times as much as past cost. Though the uranium concentration in seawater is 3.3 ppb, total amount of uranium in seawater is 4.5 billion tons. This amount is 1000 times of mine uranium. An adsorbent which has high affinity to uranium is inevitable to collect the uranium in seawater. Radiation-induced graft polymerization can synthesize such adsorbent having enough strength in seawater, also. Up to now, it was proven that 1kg uranium was collected from seawater by the adsorbent synthesized by grating. Moreover, a braid type adsorbent has been developed for a practicable recovery system. The possibility of 25,000 yen/kg-U in uranium cost is shown in the annual collection scale of 1200 tons uranium by using this adsorbent. Further R&D is expected for the improvement of adsorbent durability and the simultaneous collection of vanadium with uranium.

36001619
IAEA capability on nuclear verification; Does IAEA-nuclear watch-dog function well? (in Japanese)
Kuno, Yusuke
Genshiryoku eye 54(12), p.64-67(2008) ; (JAEA-J 04909)

IAEA International Safeguards by IAEA plays an important role among many nuclear non-proliferation measures. This paper will discuss what is IAEA Safeguards, whether it functions well or not, and potential problems in IAEA Safeguards.

36001620
Neutron calibration fields of high energies (in Japanese)
Shikaze, Yoshiaki
Hokeikyo Nyusu (42), p.2-3(2008) ; (JAEA-J 04910)

36001621
Transition of dose quantities in radiological protection (in Japanese)
Takahashi, Fumiaki
Hoken Butsuri 43(3), p.226-233(2008) ; (JAEA-J 04911)

36001622
Validation of environmental assessment models and assessment of effectiveness of protective measures using data from Chernobyl ¹³¹I releases; IAEA EMRAS programme (in Japanese)
Homma, Toshimitsu
Hoken Butsuri 43(3), p.234-245(2008) ; (JAEA-J 04912)

Since the late 1980s, the International Atomic Energy Agency has sponsored programmes in the area of environmental modelling and assessment. The recent EMRAS programme was started in 2003 and ended in 2007. This paper firstly describes the historical background of international exercises aimed at the testing and validation of models to assess the transfer of radionuclides in the environment and to predict the potential routes and levels of human exposure to the radionuclides. Chernobyl fallout data collected in various regions of Europe have provided a unique opportunity to test the reliability of environmental assessment models for contamination of terrestrial and aquatic environments. The paper also describes the activities undertaken by the ¹³¹I Working Group in the EMRAS programme, which were focused primarily on evaluating the predictive capability of environmental transfer and dosimetry models and on applying models to evaluating the effectiveness of countermeasures.

36001623
Development of the lung set for the JAERI phantom and evaluation of counting efficiencies of a lung monitor (in Japanese)
Kinase, Sakae
Hoken Butsuri 43(3), p.278-281(2008) ; (JAEA-J 04913)

The aim of the present study is the development of the reliable calibration method for lung counting systems. In this study, a lung set that was constructed using a lung equivalent material was developed to simulate various source distributions within the lung. Counting efficiencies of a lung counting system were also evaluated for heterogeneous distributions of ²³⁹Pu and ²⁴¹Am in the lung. The size of the developed lung set is similar to that of the lung for the JAERI phantom, the IAEA Asian torso phantom. The mass density of the lung set is 240 kgm^-3. It was found that counting efficiencies of the lung counting system for ²³⁹Pu/²⁴¹Am loaded lung's apex are one tenth/three tenth of those for the homogenous distributions within the lung.

36001624
Heavy ion-induced bystander effects; Intercellular signaling from irradiated cells to their non-irradiated neighbors (in Japanese)
Hamada, Nobuyuki*; Iwakawa, Mayumi*; Imai, Takashi*; Kobayashi, Yasuhiko
Hoshasen Kagaku 51(8), p.31-41(2008) ; (JAEA-J 04914)

36001625
Superconductivity in CeIrSi₃ realized at the quantum critical point (in Japanese)
Settai, Rikio*; Kawai, Tomoya*; Miyauchi, Yuichiro*; Okuda, Yusuke*; Onuki, Yoshichika; Takeuchi, Tetsuya*; Tateiwa, Naoyuki; Matsuda, Tatsuma; Haga, Yoshinori; Harima, Hisatomo*
Kotai Butsuri 43(8), p.459-474(2008) ; (JAEA-J 04916)

The magnetic transition temperature of an antiferromagnet CeIrSi₃ decreases with increasing hydrostatic pressure, and finally superconductivity appears. An exotic superconducting symmetry is expected because of the absence of the inversion center in the crystal structure. One of the prominent features is the anomalously large upper critical field observed around the quantum critical point.

36001626
Countermeasures planned for reducing water inflow into deep shaft; Contact research at the Mizunami Underground Research Laboratory (in Japanese)
Kuji, Masayoshi*; Asai, Hideaki; Mikake, Shinichiro; Hara, Masato
Maeda Kensetsu Gijutsu Kenkyushoho (CD-ROM) , 8p.(2008) ; (JAEA-J 04917)

The Mizunami Underground Research Laboratory is currently being constructed by Japan Atomic Energy Agency. During its excavation, large amount of water inflow into the shafts has been increasing and affecting the project progress. As countermeasures for reducing water inflow, grouting methods are being considered, one is post-excavation grouting for the area already excavated, and another is pre-excavation grouting for the area excavate in future. Therefore, the field experiment for post-excavation grouting was carried out, and the result show that the applied methods in this field experiment is effective to prevent the draining. And pre-excavation grouting has been undertaken and the applicability of several techniques has been evaluated. This report describes the summary of the Mizunami Underground Research Laboratory and field experiments of post- and pre-excavation grouting method.

36001627
Effects of chemical bonding character on pressure-induced structural changes of liquid metals and semiconductors (in Japanese)
Hattori, Takanori; Tsuji, Kazuhiko*
Materia 47(10), p.507-512(2008) ; (JAEA-J 04918)

We investigate pressure-induced structural changes in liquids of tetrahedrally bonded materials by a synchrotron X-ray diffraction. The liquids show various structural changes, depending on their ionic characters in the chemical bonds. The liquids with a small ionic character, such as GaSb, InSb, InAs, show continuous structural changes over a wide pressure region of about 20 GPa. In contrast, those with a large ionic character, such as CdTe, AgI, show drastic structural changes within a narrow pressure region of ∼ 2 GPa. We discuss the effect of the ionicity on the pressure-induced structural changes in liquid and compare the effect with that in the crystalline phases.

36001628
The Current status of the Russian surplus weapons plutonium disposition and its Japanese contribution (in Japanese)
Funada, Toshio; Kawata, Norio; Senzaki, Masao
Nippon Genshiryoku Gakkai-Shi 50(11), p.33-37(2008) ; (JAEA-J 04920)

36001629
Correlation between tensile property and micro-hardness irradiated RAF/M steel (in Japanese)
Ando, Masami; Wakai, Eiichi; Tanigawa, Hiroyasu; Kawasaki, Yasushi
Nippon Kinzoku Gakkai-Shi 72(10), p.785-788(2008) ; (JAEA-J 04921)

36001630
Classification of water level fluctuation data in wells using linear regression models and genetic algorithm (in Japanese)
Wakamatsu, Naonori*; Watanabe, Kunio*; Takeuchi, Shinji; Saegusa, Hiromitsu
Oyo Chishitsu 49(3), p.126-138(2008) ; (JAEA-J 04922)

A method to evaluate similarities of water level fluctuation between wells is proposed. Linear regression models with independent variable for meteorological condition such as rainfall and atmospheric pressure etc. are developed, and well similarity is estimated from model parameters (regression coefficients and model fitness) calculated by Genetic Algorism. The method was applied to the twelve wells in Tono area, central Japan. Although groundwater level fluctuation is primarily affected by rainfall and pumping conditions, different geological conditions would cause different types of water level response to the factors. Models using preceding rainfalls and atmospheric pressure and models using water level in other wells suggested that water level fluctuation data of the wells are classified into groups which reflect difference in pressure propagation for rain infiltration among the geological units.

36001631
Present status of investigations on ITER neutron streaming (in Japanese)
Ochiai, Kentaro; Iida, Hiromasa; Sato, Satoshi; Takakura, Kosuke; Konno, Chikara
Purazuma, Kaku Yugo Gakkai-Shi 84(9), p.594-599(2008) ; (JAEA-J 04923)

36001632
Use of thermodynamic simulation for preliminary study on electrolyte recycle process by the phosphate conversion technique (in Japanese)
Amamoto, Ippei; Kofuji, Hirohide; Myochin, Munetaka; Terai, Takayuki*
Shimyureshon 27(3), p.189-197(2008) ; (JAEA-J 04925)

Some specific FPs are apt to remain in the medium (electrolyte) used in pyroprocessing even after recovery of uranium and transuranic elements. It is desirable to have the spent electrolyte purified for recycling which in turn, could lead to the reduction of HLW. This study is carried out to evaluate the feasibility of the electrolyte recycle process by the phosphates conversion technique. The evaluation was undertaken mainly by thermodynamic simulation which was especially highlighted the conversion effect at the Spent Electrolyte Generation Step. The obtained computational value and a conceptual idea for recovery of precipitates by this simulation were then reflected to establish the preliminary conceptual flow diagram which would facilitate the next discussion and experiment for the realization of this process.

36001633
Time-of-flight mass spectrometer using an imaging detector and a rotating electric field (in Japanese)
Katayama, Atsushi; Kameo, Yutaka; Nakashima, Mikio
Shitsuryo Bunseki 56(5), p.229-234(2008) ; (JAEA-J 04926)

A new technique is described for minor isotope analysis by using a rotating electric field and an imaging detector. The rotating electric field is generated by cylindrically arranged six plane electrodes with multi-phase sinusoidal wave voltage. When ion packets that are discriminated by time-of-flight enter the rotating electric field, these are circularly deflected and make a spiral image on fluorescent screen of detector. This spiral image represents m/z values data as position of ions and abundance of ions as brightness. For minor isotopes analysis, the micro channel plate detector is used under gate control operation to remove from influence of high intensity of major isotopes.

36001634
Interpretation of extremely metal-poor stars as candidates of first generation stars
Nishimura, Takanori*; Aikawa, Masayuki*; Iwamoto, Nobuyuki; Suda, Takuma*; Fujimoto, Masayuki*; Iben, I. Jr.*
AIP Conference Proceedings 1016 , p.421-423(2008) ; (JAEA-J 04927)

The evolution of extremely metal-poor stars of low- and intermediate-masses is distinct from those of metal-rich stars in that the convection driven by the helium shell flash can extend outward into the hydrogen-rich layer during TP-AGB phase. In the circumstance of [Fe/H]<-2.5, protons are mixed and converted into neutrons in the convective zone to promote nucleosynthesis through neutron and α-captures. We study the nucleosynthesis in the helium-flash convective zone, induced by this hydrogen mixing. In the dearth of the pristine metals, the neutron-recycling reactions ¹²C(n,γ)¹³C(α,n)¹⁶O and in some cases the subsequent ¹⁶O(n,γ)¹⁷O(α,n)²⁰Ne play and important role and catalyze the syntheses of O through Mg and still heavier elements. Based on these results, we assign the origin of two most iron-deficient stars to the Pop III stars, born out of the primordial gas.

36001635
Hydrogeological conceptual model determined from baseline and construction phase groundwater pressure and surface tiltmeter data at the Mizunami Underground Research Laboratory, Japan
Takeuchi, Shinji; Takeuchi, Ryuji; Salden, W.*; Saegusa, Hiromitsu; Arai, Takashi*; Matsuki, Koji*
Proceedings of 11th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM '07) (CD-ROM) , 8p.(2007) ; (JAEA-J 04931)

A hydrogeological conceptual model has been developed based on pressure responses observed at multilevel pressure monitoring zones in seven boreholes and surface tilt data in and around the Mizunami Underground Research Laboratory site. Pressure changes caused by some earthquakes, cross-hole hydraulic testing, and shaft excavation activities are considered. Surface tilt has been measured from the half way of the shaft excavation phase. Continuous monitoring with some numerical analysis during the shaft excavation phase show the existence of the flow barrier fault predicted from the surface-based investigation phase and hydraulic parameter around the shafts.

36001636
Replacement of the criticality accident alarm system in the Tokai reprocessing plant
Sanada, Yukihisa; Nemoto, Makoto*; Suzuki, Kei*; Kawai, Keiichi*; Momose, Takumaro
Proceedings of 12th International Congress of the International Radiation Protection Association (IRPA-12) (CD-ROM) , 7p.(2008) ; (JAEA-J 04932)

The purpose of this study is to show the design principle and the determination procedures for the adequate relocation of the CADs in TRP. When the alarm trip point was 2.0 mGy/h, it is possible to detect a criticality accident even under conservative conditions (i.e. γ: 10 m distances from the equipment to the CAD and 140 cm concrete shield between them; neutron: 15 m distances and both 60 cm concrete shield and 60 cm steel shield). Consequently, it was found the seven CADs at these locations could monitor PCDF adequately. This study was reflected in the determination of the new CAD location.

36001637
Analysis for relocation strategy using the method of probabilistic accident consequence assessment
Takahara, Shogo; Homma, Toshimitsu
Proceedings of 12th International Congress of the International Radiation Protection Association (IRPA-12) (CD-ROM) , 8p.(2008) ; (JAEA-J 04933)

Relocation is one of the long-term protective actions in case of nuclear emergency to mitigate the consequences of an accidental release of radionuclides. The strategy of relocation is characterized by its protective benefit, cost and the corresponding residual dose in planning. This paper describes the application of a probabilistic accident consequence assessment model to the calculation of these quantities and the planning of relocation. Calculations of the consequence have been made of a postulated accident with source terms derived from a generic level 2 PSA. The results provided the insights for the development optimum dose criteria for introducing and terminating relocation.

36001638
Performance test of the electronic personal neutron dosemeter in neutron fields simulating workplaces of MOX fuel fabrication facilities
Tsujimura, Norio; Yoshida, Tadayoshi; Takada, Chie; Nunomiya, Tomoya*; Aoyama, Kei*
Proceedings of 12th International Congress of the International Radiation Protection Association (IRPA-12) (CD-ROM) , 8p.(2008) ; (JAEA-J 04934)

The authors assessed performance of electronic personal neutron dosemeters (EPD). The EPD selected in this study is NRY21, manufactured by Fuji Electric Systems Co., Ltd. This dosemeter uses two silicon semiconductor detectors to provide wide measurable energy ranges from thermal to several tens of MeV. In the test, we focused on the energy and angular dependences of dose equivalent responses because it was of great importance in neutron dosimetry in work environments. Measurements of dose equivalent responses were performed in the moderated neutron field reproducing neutron spectra likely to be encountered in workplaces of MOX fuel facilities. Neutron dose equivalents given by EPD were compared with reference dose values. As a result, dose equivalent responses of this EPD were evaluated to be 0.7 to 1.1 for normal incidence of neutron irradiation. This is satisfactory performance required for personal neutron monitoring.

36001639
Development and characterization of a neutron personal dose equivalent monitor
Tsujimura, Norio; Yoshida, Tadayoshi; Nunomiya, Tomoya*; Aoyama, Kei*
Proceedings of 12th International Congress of the International Radiation Protection Association (IRPA-12) (CD-ROM) , 9p.(2008) ; (JAEA-J 04935)

The authors developed a new neutron-measuring instrument that was designed to measure a neutron personal dose equivalent, H_p(10). This instrument is composed of a conventional moderator-based neutron dose equivalent meter and a neutron shield made of borated polyethylene which covers a backward hemisphere to adjust the angular dependence. The whole design was determined on the basis of MCNP calculations so as to have response characteristics which would generally match both energy and angular dependencies of H_p(10). The verification experiments for energy and angular responses were done using monoenergetic neutrons produced by the accelerator and polyenergetic neutrons from the moderated ²⁵²Cf source. As results of experiments, it is found that this new instrument has reasonably acceptable responses as a reference neutron dosemeter.

36001640
Seismic transient change of natural frequency estimation by adaptive filtering scheme
Kirita, Fumio; Kanazawa, Kenji*; Kitamura, Haruyuki*
Proceedings of 14th World Conference on Earthquake Engineering (WCEE-14) (CD-ROM) , 8p.(2008) ; (JAEA-J 04936)

This paper presents a new system identification procedure for a time-varying system to estimate natural frequency transition of a building from a strong seismic motion record, named as "Adaptive Forward-Backward Kalman Filter (AFB-KF)". The AFB-KF is compared to the conventional Kalman Filter in the below three points: (1) Forgetting factor for covariance functions to track time-varying structural parameters rapidly, (2) Time-backward estimation scheme and global iteration scheme of the forward and backward processes to estimate unknown initial value of structural parameters, (3) The time series renewal algorithm of statistical properties by reflecting the previous analysis information to improve the identification accuracy. It is useful to accurately identify from natural frequency transition of a building during an earthquake for structural health monitoring which evaluates structural integrity.

36001641
Study on enhanced performance sodium-cooled metal fuel core concepts by adopting advanced fuel and flexible design criteria
Kobayashi, Noboru; Ogawa, Takashi; Oki, Shigeo; Mizuno, Tomoyasu; Ogata, Takanari*
Proceedings of 16th International Conference on Nuclear Engineering (ICONE-16) (CD-ROM) , 9p.(2008) ; (JAEA-J 04937)

The metal fuel core is superior to the mixed oxide fuel core because of its higher breeding ratio and compact core size resulting from neutron economics, hard neutron spectrum, and high content of heavy metal nuclides. Utilizing the advantage of the metal fuel core, conceptual sodium-cooled fast breeder reactor designs have been pursued for the attractive core properties of high breeding ratio, small inventory, compact size, low sodium void reactivity, and high transmutation ratio of the minor actinides. Among attractive cores, a conceptual design for a high breeding ratio was performed without blanket fuels. The design conditions were set so a sodium void reactivity of less than 8 $, a core height of less than 150 cm, a maximum cladding temperature of 650 °C, and a fuel pin bundle pressure drop of 0.4MPa. The breeding ratio of the resultant core was 1.34 without blanket fuels.

36001642
Efforts toward the restart of fast breeder reactor Monju
Morizono, Koji; Takeuchi, Norihiko; Takayama, Koichi; Deshimaru, Takehide; Mukai, Kazuo
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM) , 5p.(2008) ; (JAEA-J 04938)

Prototype fast breeder reactor Monju is the first power generating FBR in Japan which is a plant for research & development to demonstrate reliability of fast breeder reactor as a power plant and establish sodium handling technology etc. Monju started construction in 1985, achieved initial criticality in 1994 and attained 40% output in 1995, however the sodium leak accident occurred during the test operation at the end of that year. Since then, the plant remained shut down for 12 years. In this subject, our efforts for the restart of this long term shut down plant will be presented.

36001643
Effects of γ-ray irradiation on the high temperature oxidation of austenitic stainless steel in supercritical water
Nakahara, Yukio; Yamamoto, Masahiro; Karasawa, Hidetoshi*; Kiuchi, Kiyoshi; Katsumura, Yosuke*
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM) , 6p.(2008) ; (JAEA-J 04939)

Three types of commercial-grade austenitic stainless steel, Type 304L, Type 316L, and Type 310S, were immersed in deaerated supercritical water (SCW) of 25 MPa, 550 °C with γ-ray irradiation for 1000 hours in total. Absorbed dose rates in SCW are estimated at 5-15 kGy h^-1. High temperature oxidation experiments resulted in the formation of two-layer oxide film in which the outer layer is porous iron oxide and the inner layer is dense iron-chromium-nickel oxide. Rate constants of parabolic rate law in net weight gains of Type 304L SS and Type 310S SS are decreased as the γ-ray exposure rate is increased. The net weight gain of γ-ray irradiated Type 316L SS is sharply fluctuating and decreasing, because the flaking of the outer layer occurred. Hematite is formed in the outer layer on all irradiated samples of examined alloys. The concentration of chromium on the surface is increased by γ-ray irradiation. A chromium-rich part in the inner layer accompanying a nickel-rich part in the metal is formed along to the oxide/metal interface of γ-ray irradiated Type 304L SS, non-irradiated and γ-ray irradiated Type 316L SS.

36001644
Code development for multi-physics and multi-scale analysis of core disruptive accidents in fast reactors using particle methods
Koshizuka, Seiichi*; Morita, Koji*; Arima, Tatsumi*; Zhang, S.*; Tobita, Yoshiharu; Yamano, Hidemasa; Ito, Takahiro*; Shirakawa, Noriyuki*; Naito, Masanori*; Okada, Hidetoshi*; Uehara, Yasushi*; Nagamine, Yasuo*; Yamamoto, Yuichi*; Himi, Masashi*; Hirano, Etsujo*; Shimizu, Sensuke*; Oue, Masaya*
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM) , 6p.(2008) ; (JAEA-J 04940)

A computer code, named COMPASS, is being developed for various complex phenomena of core disruptive accidents (CDAs) in sodium-cooled fast reactors (SFRs). The COMPASS is designed to analyze multi-physics problems involving thermal hydraulics, structure and phase change, in a unified framework of the MPS (Moving Particle Semi-implicit) method. The project has been carried out by six organizations for five years from FY2005 to FY2009. In this paper, the outcomes of the project in FY2007 are presented. Three validation calculations were completed by following the validation plan: melt freezing and blockage formation, molten pool boiling, and duct wall failure. The COMPASS code development was supported by basic studies of the numerical method, material science for eutectic reaction of the metal fuel, and SIMMER-III analyses.

36001645
Application of PSA to model facility for MOX fuel fabrication
Tamaki, Hitoshi; Yoshida, Kazuo; Hamaguchi, Yoshikane*
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM) , 6p.(2008) ; (JAEA-J 04941)

A PSA is a comprehensive and structured method for assessing the safety of a nuclear facility. This method also provides risk information that could be applied to effective regulatory activities for nuclear facilities and so on. A PSA procedure for MOX fuel fabrication facility has been developed at JAEA. This procedure consists of two steps. One is called as preliminary PSA using simple methods for likelihood and consequence evaluation through whole processes in the facility. The other step is called as detailed PSA and is carried out to evaluate risk of the significant events using methods corresponding to level 1 PSA and level 2 PSA for nuclear power plants. The procedure was applied to a practical model facility based on process information and handling quantities of materials from the planned MOX fabrication plant to understand risks at whole processes in the model facility. A risk-profile, which consisted of dominant accident sequences, was also obtained through this analysis.

36001646
Commissioning status of the rapid-cycling synchrotron at J-PARC
Hayashi, Naoki
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM) , 6p.(2008) ; (JAEA-J 04942)

The J-PARC is a multi purpose research center using neutron/muon sources for research in material and life science, and using hadron or neutrino beams for nuclear and particle physics. Its proton accelerators have been beam commissioned since 2006. The second accelerator RCS (3GeV Rapid-Cycling Synchrotron) was commissioned in early 2008 and the third accelerator MR (Main Ring; 50GeV proton synchrotron) and experimental facilities will follow. This paper describes the beam commissioning of the accelerators, highlighting the RCS, and discusses the outlook of the RCS power up strategy and future plans for the accelerator complex.

36001647
Study on perturbation scenario for uplift and denudation in performance assessment of a HLW disposal system
Kawamura, Makoto; Yasue, Kenichi; Niizato, Tadafumi; Tokiwa, Tetsuya; Ebashi, Takeshi; Oi, Takao; Makino, Hitoshi; Ishimaru, Tsuneari; Umeda, Koji
Proceedings of 2008 East Asia Forum on Radwaste Management Conference (2008 EAFORM 2nd Conference) (USB Flash Drive) , 6p.(2008) ; (JAEA-J 04944)

Japan Atomic Energy Agency (JAEA) had developed a framework to assess the potential impact of natural phenomena (uplift and denudation/climatic and sea-level changes; earthquakes and faulting; volcanism) on a high level radioactive waste (HLW) disposal system as a part of the total system performance assessment. The framework is focused on identifying key T-H-M-C-G (Thermal-Hydrological-Mechanical-Chemical-Geometrical) process associated with potential changes of the geological environment caused by natural phenomena. By using the framework, we could grasp the relationship between characteristic of natural phenomena and geological environmental conditions (T-H-M-C-G) quantitatively, and grasp the relationship between T-H-M-C-G condition and parameters of performance assessment efficiently. In this paper, we tried to develop perturbation scenarios of uplift and denudation by using the framework. As a result, by applying this framework, we could not only grasp the impacts on the geological environmental conditions (T-H-M-C-G) quantitatively, but the excess and deficiency of information resulting from uplift and denudation.

36001648
Effects of earthquakes and faulting on the deep geological environment based on case studies in Japan
Ishimaru, Tsuneari; Niwa, Masakazu; Kurosawa, Hideki; Kagohara, Kyoko
Proceedings of 2008 East Asia Forum on Radwaste Management Conference (2008 EAFORM 2nd Conference) (USB Flash Drive) , 6p.(2008) ; (JAEA-J 04945)

Plate-boundary and intraplate earthquakes occur relative to convergent plate margins in the Japanese Islands. For site selection and design of HLW repositories in Japan, an assessment of the effects of earthquakes and faulting on the deep geological environment is absolutely essential. As a results, it has been determined that consideration of seismic shaking and frictional heating may be unnecessary if repositories are located away from active faults. On the other hand, fracturing along faults could result in the development of fracture zones, which could consequently increase permeability. The number of fracture zone decreases significantly at about 500 m away from the fault, based on the case study of the Atotsugawa Fault System. Therefore, understanding changes in character and spatial distribution of fracture zones through studying the history of fault development is important for long-term changes of regional groundwater flow.

36001649
Behavior of americium in pyrochemical process of the nitride fuel cycle
Hayashi, Hirokazu; Shibata, Hiroki; Akabori, Mitsuo; Arai, Yasuo; Minato, Kazuo
Proceedings of 2008 Joint Symposium on Molten Salts (USB Flash Drive) , p.910-915(2008) ; (JAEA-J 04946)

R&D of the nitride fuel cycle technology is underway at JAEA. Behavior of americium (Am) in the pyrochemical process, which include anodic dissolution of AmN and recovery of Am into liquid Cd cathode by electrorefining in LiCl-KCl eutectic melts, and nitride formation of Am recovered in liquid Cd cathode, are presented.

36001650
Redox equilibria of the U⁴⁺/U³⁺ and U³⁺/U couples in molten LiCl-RbCl eutectic
Nagai, Takayuki; Uehara, Akihiro*; Fujii, Toshiyuki*; Shirai, Osamu*; Sato, Nobuaki*; Yamana, Hajimu*
Proceedings of 2008 Joint Symposium on Molten Salts (USB Flash Drive) , p.927-932(2008) ; (JAEA-J 04947)

Formal redox potentials of the U⁴⁺/U³⁺ and U³⁺/U couples in molten LiCl-RbCl eutectic were determined by cyclic voltammetry. These redox potentials were more negative than those in the LiCl-KCl eutectic but approximately similar to those in the NaCl-CsCl eutectic. These redox potentials in molten alkali chlorides would be correlated with the averaged alkali cationic radius of the melt.

36001651
Reductive extraction of minor actinides from molten chloride into liquid gallium
Toda, Taro*; Maruyama, Takehiro*; Moritani, Kimikazu*; Moriyama, Hirotake*; Hayashi, Hirokazu
Proceedings of 2008 Joint Symposium on Molten Salts (USB Flash Drive) , p.933-938(2008) ; (JAEA-J 04948)

The distribution coefficients of Am and Ce were measured in the LiCl-KCl/Ga system at 773 K. By using ZrCl₄ as the oxide ion scavenger in order to avoid the formation of such oxychlorides as CeO⁺ and AmO⁺, the effect of oxide ion concentration was well controlled on the distribution coefficients of Am and Ce. The separation factor between Am and Ce was then obtained to be about 100. By comparing the present value with the other experimental and the predicted ones, it was confirmed that solvent metals were ordered from the most selective to the less selective one as Al>Ga>Bi>Cd.

36001652
Implementing interoperability between the AEGIS and DIET GridRPC middleware to build an international sparse linear algebra expert system
Caniou, Y.*; Kushida, Noriyuki; Teshima, Naoya
Proceedings of 2nd International Conference on Advanced Engineering Computing and Applications in Sciences (ADVCOMP 2008) (CD-ROM) , p.205-210(2008) ; (JAEA-J 04949)

In this paper, we present the design and architecture of an interoperable solution in order to transparently and securely access French and Japanese computing resources. The aim is to propose an International Sparse Linear Algebra Expert System available through a Web portal where auser can request some analysis on the resolution of a problem involving different kind of matrices, solvers and heuristics, and using different architectures. Hence, numerous validation studies can be performed. The solution mostly relies on the integration of a "protocol" interoperability between the French and Japanese Grid middleware DIET and AEGIS.

36001653
Pressure fluctuation characteristics of the short-radius elbow pipe for FBR in the postcritical reynolds regime
Shiraishi, Tadashi*; Watakabe, Hisato*; Sago, Hiromi*; Kotake, Shoji; Yamano, Hidemasa
Proceedings of 2nd International Conference on Jets, Wakes and Separated Flows (ICJWSF 2008) (CD-ROM) , 11p.(2008) ; (JAEA-J 04950)

For the JAEA sodium-cooled fast reactor, an experimental study on the fluctuating pressure of the hot legs was carried out with tests using a 1/3-scale model. The total resistance coefficient is consistent with the published data, and our research has given some additional data up to the Reynolds number of 8.0 ×10⁶. The flow pattern in the postcritical regime is independent of a Reynolds number. The statistical examination revealed that fluctuating pressures on the pipe wall depend on the mean velocity but not on the viscosity of the fluid. Negative spikes of pressure appeared for high velocity. Based on these experimental data it is revealed that, there are similarity laws for the scale of a model and the property of fluid, but not for the velocity in the pipe. We also discussed how to extrapolate the fluctuating pressure to the actual hot-leg conditions.

36001654
Validation of ecological ¹³¹I transfer models using experimental data of the "Plavsk scenario"
Zvonova, I.*; Krajewski, P.*; Berkovskyy, V.*; Ammann, M.*; Duffa, C.*; Filistovic, V.*; Homma, Toshimitsu; Kanyár, B.*; Nedveckaite, T.*; Simon, S.*; Vlasov, O.*; Webbe-Wood, D.*
Proceedings of 7th International Conference on Nuclear and Radiochemistry (NRC-7) (CD-ROM) , 5p.(2008) ; (JAEA-J 04951)

Environmental Modelling for Radiation Safety (EMRAS) programme was organized by IAEA in 2003. Within this project experimental data of ¹³¹I measurements following the Chernobyl accident in the Plavsk district of Tula region, Russia, This scenario was used to validate the calculation results of some ecological models. Results of model calculations and observed data comparison are presented in the report. Discrepancies between the average thyroid doses estimations produced by most participants did not exceed a factor of ten. The time when cows were brought to the pasture is the most bearing factor for thyroid dose estimations.

36001655
Technical considerations for emergency preparedness with a probabilistic accident consequence assessment model
Homma, Toshimitsu; Kimura, Masanori; Matsubara, Takeshi*; Ishikawa, Jun
Proceedings of 9th International Probabilistic Safety Assessment and Management Conference (PSAM-9) (CD-ROM) , 6p.(2008) ; (JAEA-J 04952)

It is recognized that good preparedness in advance of an emergency can substantially improve the emergency response to a nuclear or radiological accident. This paper presents the methodology and results of the technical considerations for off-site emergency planning using a probabilistic accident consequence assessment model. Calculations of the off-site consequence have been made of postulated accidents with source terms derived from a generic level 2 PSA of the reference plant in Japan. The preliminary results provided the insights of technical guidance for the development of protective actions such as sheltering, evacuation, and administration of stable iodine.

36001656
Use of uncertainty importance measures to complement risk importance measures in PSA
Liu, Q.; Homma, Toshimitsu
Proceedings of 9th International Probabilistic Safety Assessment and Management Conference (PSAM-9) (CD-ROM) , 7p.(2008) ; (JAEA-J 04953)

Fussel-Vesely (FV) and Risk Achievement Worth (RAW) are two commonly used measures in importance ranking of basic events in PSA. Both measures are based on point-estimates of the risk. However, realistic failure characteristics of components are associated with some kinds of uncertainty. The uncertainties of component failures are propagated through the model and bring about the uncertainty of the model risk. Therefore, it is necessary to take uncertainty into consideration when the contribution of a basic event to risk is estimated. By using two fault tree models as examples, the authors calculated the FV and the RAW as well as the uncertainty importance of each basic event. The results show that the uncertainty importance ranking of each basic event does not always agree with the ranking with regard to FV (or RAW). It is argued that uncertainty importance measures provides complementary perspectives of the roles of a basic event in determining the risk.

36001657
Dose evaluation with closed space in vector space composed of radiation detector outputs
Hashimoto, Makoto; Iimoto, Takeshi*; Kosako, Toshiso*
Proceedings of International Symposium commemorating the First Anniversary of the Foundation of GoNERI "Key to the Future; Energy Security and Nuclear Education & Research" , p.247-252(2008) ; (JAEA-J 04957)

Neutron dose evaluation method which flexibly respond to an alteration of neutron field is developing. The mulitidetector method is introduced. The method uses a convex hull in a topological vector space composed of the ratio of multi detector outputs and objective quantities. The convex hull provides range of possible conversion factor to obtain objective quantity based on the circumstance condition. The convex hull is sophisticated with elemental neutron spectra group of respective neutron field. Mixed gas proportional counter is applied to validate the effectively of the dose evaluation method with a convex hull.

36001658
A Large scale simulation for impact and blast loading issues
Nakajima, Norihiro; Araya, Fumimasa; Nishida, Akemi; Suzuki, Yoshio; Ida, Masato; Yamada, Tomonori; Kushida, Noriyuki; Kim, G.; Kino, Chiaki; Takemiya, Hiroshi
Proceedings of International Symposium on Structures under Earthquake, Impact, and Blast Loading 2008 , p.119-123(2008) ; (JAEA-J 04958)

Japan is so said an energy consumption country of the fourth place world, but the energy resources such as petroleum, the natural gas are poor and depend on import for the most, and stable supply becomes a big problem. For the greenhouse gas restraint, the promotion of the energy saving is featured. A nuclear power plant for commerce in Japan has been started in 1966. The supply occupies about 30 percent of the now Japanese electricity generating. Due to the nature of Japan, earthquake proof is an important subject for social infrastructure operation. To encourage its proofing, many approaches have been applied into many infrastructures, not only computational approach. A computational science approach for earthquake proof is suggested with FIESTA(Finite Element Structural analysis for Assembly), a large scale simulation. A methodology is discussed from the point of view of impact and blast loadings. Examples of loadings in the nuclear engineering are introduced.

36001659
Risk analysis of practical model facility for MOX fuel fabrication
Tamaki, Hitoshi; Yoshida, Kazuo; Hamaguchi, Yoshikane*
Proceedings of International Topical Meeting on Probabilistic Safety Assessment and Analysis (PSA 2008) (CD-ROM) , 12p.(2008) ; (JAEA-J 04959)

A Probabilistic Safety Assessment (PSA) procedure for MOX fuel fabrication facilities (MFFF) was developed at Japan Atomic Energy Agency from 2001 to 2005 and some improvement has been continued. The developed procedure consists of two steps. The first step called as preliminary PSA is carried out for selection of significant events with relatively higher risk among abnormal events that cause potentially release of radioactive materials. The second step is carried out to evaluate risks of the selected significant events in more detail. This step includes the accident scenario analysis, the evaluation of accident frequencies and consequences. The latter step is called as detailed PSA, because it is carried out in the same way of level 1 PSA and level 2 PSA for nuclear power plants. To understand a trend of risk-profile of typical MFFF, the developed procedure was applied to a model facility of MFFF that was based on the information of process design and handling quantities of materials obtained from open documents of a planned MOX fabrication plant in Japan. As the results of application of the procedure to the model plant, a risk-profile was obtained that was drawn by the risk of dominant accident sequences anticipated in whole process of the plant.

36001660
Transient behaviour of low enriched uranium silicide plate-type fuel for research reactors during reactivity initiated accident
Yanagisawa, Kazuaki
Transactions of International Topical Meeting on Safety of Nuclear Installations (ENS TOPSAFE 2008) (Internet) , p.A3_035.1-A3_035.13(2008) ; (JAEA-J 04960)

The pulse irradiation tests were conducted on silicide mini-plate fuels. The major findings are: (1) Neither failure nor degradation of dimensional stability of the fuel occurred in the temperature below 400 °C. Beyond that level a dimensional stability was gradually degraded with temperature. (2) The fuels were intact at energy depositions below 82 cal/g but were damaged at energy depositions of above 94 cal/g. A failure threshold must be existed between these two values.

36001661
Radioresistant bacteria (in Japanese)
Narumi, Issei
Biseibutsu No Jiten , p.688-690(2008) ; (JAEA-J 04962)

36001662
Introduction of study on the Atera fault (in Japanese)
Yasue, Kenichi
Myujiamu Rekucha 2008, Atera Danso Ga Yattekita! , 19p.(2008) ; (JAEA-J 04963)

36001663
Applicability of effective stress concept to structural design of tubesheets (in Japanese)
Kasahara, Naoto*; Takasho, Hideki*; Kawasaki, Nobuchika; Ando, Masanori
Nippon Kikai Gakkai M&M 2008 Zairyo Rikigaku Kanfarensu Koen Rombunshu (CD-ROM) , 2p.(2008) ; (JAEA-J 04964)

For design analysis of perforated plates, axi-symmetric models with equivalent solid plates are conventionally adopted to simplify perforated geometries. ASME Sec.III Appendix A-8000 provides elastic constants for equivalent solid plates. To extend applicable area of equivalent solid plates to inelastic analysis, the general determination method of non-linear equivalent material properties for perforated plates was proposed based on the effective stress ratio (ESR). This study examined applicability of effective stress concept to structural design of plat and spherical tubesheet structures.

36001664
Geophysical surveys in uranium exploration (in Japanese)
Shigeta, Naotaka
Saishin No Butsuri Tansa Tekiyo Jireishu , p.61-68(2008) ; (JAEA-J 04965)

Despite of a short history of uranium exploration, many deposits were found during just fifty years or so since the start of survey operations by making full use of geophysical surveys. For the efficient exploration considering the diversity of the deposits, it is indispensable to select an exploration flow based on establishing an appropriate model of physical properties of a uranium deposit and regional characteristics such as surface conditions. In 1990s PNC was establishing or restructuring exploration flows on unconformity-related deposits, of which type has been positioned prior to all in terms of economical merit. Deposit models and exploration flows should be revised constantly by solving various technical issues basing on the latest interpretation of obtained data. On and after 1990s, the deposit discovery rate is strikingly decreasing. This fact indicates that we are in the phase where major revises of models and exploration flows are required.

36001665
Roles of geophysical exploration with regard to the geological disposal of high-level radioactive waste and development of geophysical exploration techniques in the scientific research for deep geological environments (in Japanese)
Shigeta, Naotaka
Saishin No Butsuri Tansa Tekiyo Jireishu , p.257-264(2008) ; (JAEA-J 04966)

Geological environments are required mainly two functions in terms of ensuring the safety for geological disposal of high-revel radioactive waste. One relates to long-term stabilities of a site and the other to properties of host rocks and groundwater that facilitate the emplacement and function as natural barrier. Geophysical surveys are expected to play important roles providing both implementation and safety regulation with information on deep geological environments. Japan Atomic Energy Agency, from the era of its predecessors, is carrying out studies on systematic methodology for evaluating geological environments. Useful knowledge including on geophysical survey has been obtained through the studies.

36001666
Development of geophysical survey technique using the vibration caused by the shafts excavation in the granite; Application of seismic interferometry (in Japanese)
Hodotsuka, Yasuyuki; Matsuoka, Toshiyuki; Tsuruta, Tadahiko; Yamada, Nobuto*; Ishigaki, Koichi*; Yamaguchi, Shinji*
Shadan Hojin Butsuri Tansa Gakkai Dai-119-Kai (Heisei-20-Nendo Shuki) Gakujutsu Koenkai Koen Rombunshu , p.61-64(2008) ; (JAEA-J 04967)

Seismic interferometry using the vibration under the construction works such as borehole drilling, mucking, blasting etc., had been carried out to develop the method that obtain three-dimensional geological image, around the Mizunami Underground Research Laboratory. In this study, we discussed the applicability of this method analytical accuracy depending on vibration resource types.

36001667
Development of geophysical survey technique using the vibration caused by the shafts excavation in the granite; Application of reverse VSP (in Japanese)
Matsuoka, Toshiyuki; Hodotsuka, Yasuyuki; Tsuruta, Tadahiko; Ishigaki, Koichi*; Yamada, Nobuto*; Yamaguchi, Shinji*
Shadan Hojin Butsuri Tansa Gakkai Dai-119-Kai (Heisei-20-Nendo Shuki) Gakujutsu Koenkai Koen Rombunshu , p.65-67(2008) ; (JAEA-J 04968)

A reverse VSP (R-VSP) using the blasting vibration been carried out to obtain three-dimensional geological image around the Mizunami Underground Research Laboratory under the shaft excavation works. In this study, the applicability of this method was discussed.

36001668
Development of know-how and systematic techniques for characterisation of coastal geological environment at Horonobe (in Japanese)
Yamanaka, Yoshiaki; Matsuoka, Toshiyuki; Asamori, Koichi; Ota, Kunio
Shadan Hojin Butsuri Tansa Gakkai Dai-119-Kai (Heisei-20-Nendo Shuki) Gakujutsu Koenkai Koen Rombunshu , p.73-75(2008) ; (JAEA-J 04969)

Characterisation of the coastal geological environment has now been running since July 2007 at Horonobe, northern Hokkaido, with the main aims of establishing a comprehensive coastal site characterisation technology and enhancing its reliability. Work carried out to date involves a survey and interpretation of the existing information, identification of key investigation issues and planning of ground exploration. Development of technical know-how and decision process for the work, in particular the geophysical surveys, has been initiated to provide "knowledge" to support a site characterisation project.

36001669
JAEA Library (in Japanese)
Nakajima, Hidemitsu
Toshokan, Akaibuzu Towa Nanika , p.282-283(2008) ; (JAEA-J 04970)

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