JAEA Abstracts

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

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

November 2008

36001401
International study on the validation of models for the environmental transfer of tritium and carbon-14
Yankovich, T. L.*; Koarashi, Jun; Kim, S. B.*; Davis, P. A.*
Applied Radiation and Isotopes 66(11), p.1726-1729(2008) ; (JAEA-J 04681)

The IAEA's model evaluation program EMRAS (Environment Modelling for Radiation Safety) includes a Tritium and C-14 Working Group (TCWG), the goal of which is to test the performance of environmental tritium and C-14 models. The TCWG has undertaken nine scenarios in which model predictions were compared with experimental data. Two of these scenarios are discussed here, one involving the prediction of time-dependent tritium concentrations in freshwater mussels subject to an abrupt change in ambient tritium levels, and the second involving the prediction of C-14 concentrations in rice grown in the vicinity of continuous atmospheric C-14 sources.

36001402
Quasi-one-dimensional In atomic chains on Si(111) at low temperature studied by reflection high-energy positron diffraction and scanning tunneling microscopy
Hashimoto, Mie; Fukaya, Yuki; Kawasuso, Atsuo; Ichimiya, Ayahiko
Applied Surface Science 254(23), p.7733-7736(2008) ; (JAEA-J 04682)

36001403
Construction of a positron microbeam in JAEA
Maekawa, Masaki; Kawasuso, Atsuo
Applied Surface Science 255(1), p.39-41(2008) ; (JAEA-J 04683)

We have been constructing a positron micro-beam using a conventional scanning electron microscope. The positron source with a titanium window (1 mm diam, 5micron thick) was fabricated by depositing 22-NaCl solution (55.5 MBq) onto a tungsten-copper buckling material. A tungsten mesh moderator or a solid Ne moderator was used to generate a slow positron beam. The positron beam was accelerated up to 25 keV using a multi-electrode array with holes. Subsequently, the positron beam was further focused to approximately 10 micron on the sample. The final beam flux was 1E+3 e+/sec. A beam pulsing section composed of a cylindrical double-gap pre-buncher, an ExB filter and a resonator-cavity-type main buncher. The beam pulse width and SN ratio were approximately 180 ps and 1E+3, respectively. In future, the beam pulsing section will be connected to the microbeam apparatus. At the workshop, several preliminary positron annihilation measurements will be presented.

36001404
Spin-polarization of an electro-static positron beam
Kawasuso, Atsuo; Maekawa, Masaki
Applied Surface Science 255(1), p.108-110(2008) ; (JAEA-J 04684)

It is well known that positrons emitted accompanying beta-plus decay are longitudinally polarized. The polarization (P) increases as the end-point energy of emitted positrons. When positrons meet unpaired electrons both singlet (S=0) and triplet (S=1) states may be formed. Their probabilities depend on the polarizations of positrons and electrons and also external magnetic field. Therefore, it is anticipated that using spin-polarization one can learn magnetic properties of materials. Spin polarized slow positron beam is further useful to probe thin films and interfaces. We measured the spin polarization of a positron beam generated by an electrostatic apparatus with a sodium-22 source and a tungsten mesh moderator. We obtained P=0.3 which is in good agreement with that expected from the end-point energy of sodium-22. We also examined the spin rotation effect using a simple ExB filter.

36001405
Concurrent transformation of Ce(III) and formation of biogenic manganese oxides
Onuki, Toshihiko; Ozaki, Takuo; Kozai, Naofumi; Nankawa, Takuya; Sakamoto, Fuminori; Sakai, Takuro; Suzuki, Yoshinori; Francis, A. J.*
Chemical Geology 253(1-2), p.23-29(2008) ; (JAEA-J 04685)

We examined the changes in the chemical states of Ce(III) during the formation of manganese oxide occasioned by Mn(II)-oxidizing bacteria. The oxidation states of Ce and Mn then were measured by X-ray Absorption Near Edge Structure (XANES). We also determined the elemental distributions in the bacteria and precipitates by Scanning-Proton Induced X-ray Emission (S-PIXE). We found that the precipitation of Ce is preceded by its accumulation by the bacterium, followed by its oxidization to Ce(IV) by the Mn(III, IV)-containing precipitates that the bacteria generate.

36001406
Numerical analysis of forced convection heat transfer of subcooled liquid nitrogen
Tatsumoto, Hideki; Shirai, Yasuyuki*; Hata, Koichi*; Kato, Takashi; Aso, Tomokazu; Otsu, Kiichi; Shiotsu, Masahiro*
IEEE Transactions on Applied Superconductivity 18(2), p.1483-1486(2008) ; (JAEA-J 04691)

The knowledge of forced flow heat transfer of liquid hydrogen is important for cooling design of hydrogen moderator system and HTS superconducting magnets such as MgB₂ magnet. The use of a CFD code is necessary to understand the heat transport phenomena in the practical cooling channel of the magnets. As a first step of the study, forced flow heat transfer of liquid nitrogen in a horizontal tube, instead of liquid hydrogen, was analyzed in this work by using a CFD code. The solutions were compared with the authors' experimental data under the corresponding conditions. The solutions obtained by using the low Reynolds number k-ε model as a turbulent model agreed well with the experimental data for the Reynolds numbers (Re) higher than 1×10⁴. For Re < 1×10⁴, the solutions become lower than the experimental data. The heat transport mechanism in the horizontal tube was also clarified by the analyses.

36001407
Improvement of the quality and stability of electron bunch using countercrossing laser beam
Kotaki, Hideyuki; Daito, Izuru; Kando, Masaki; Hayashi, Yukio; Ma, J.-L.; Chen, L.-M.; Esirkepov, T. Z.; Fukuda, Yuji; Homma, Takayuki; Pirozhkov, A. S.; Koga, J. K.; Nakajima, Kazuhisa; Daido, Hiroyuki; Bulanov, S. V.
IEEE Transactions on Plasma Science 36(4), p.1760-1764(2008) ; (JAEA-J 04692)

The counter-crossing injection, which is a realistic setup for applications, by two sub-relativistic laser pulses colliding is demonstrated in sub-relativistic intensity laser pulse interaction with plasma. The laser pulses in plasma are self-focused to higher intensity when the laser power is above the threshold of a relativistic self-focusing. The collision of self-focused laser pulses generates a high-quality electron beam with high repeatability. The generated monoenergetic electron beam has 14 MeV of the peak energy, 11% of the energy spread, 22 pC of the charge, 1.6πmm mrad of the normalized emittance, and 50% of the repeatability.

36001408
Electronic ferroelectricity from charge ordering in RFe₂O₄
Ikeda, Naoshi*; Matsuo, Yoji*; Mori, Shigeo*; Yoshii, Kenji
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 55(5), p.1043-1045(2008) ; (JAEA-J 04693)

We report our recent discovery of novel ferroelectricity arising from the polar ordering of Fe³⁺ and Fe²⁺ in a mixed valence triangular lattice oxide LuFe₂O₄, where the electric polarization is not a result of ionic displacement. The polar ordering of Fe³⁺ and Fe²⁺ was confirmed with a resonant X-ray scattering study in SPring-8. The origin of such ordering is the competitive interaction between Fe³⁺ and Fe²⁺ in the triangular lattice, i.e., the charge frustration. The polar superlattice of Fe³⁺ and Fe²⁺ develops below 350 K, where the electric polarization appears. The ferroelectricity arising from the polar charge ordering or the polar electron distribution may have great potential for the future application of ferroelectrics.

36001409
Electrochemical and complexation behavior of neptunium in aqueous perchlorate and nitrate solutions
Ikeda, Atsushi; Hennig, C.*; Rossberg, A.*; Funke, H.*; Scheinost, A. C.*; Bernhard, G.*; Yaita, Tsuyoshi
Inorganic Chemistry 47(18), p.8294-8305(2008) ; (JAEA-J 04694)

Electrochemical and complexation properties of neptunium (Np) are investigated in aqueous perchlorate and nitrate solutions by means of cyclic voltammetry, bulk electrolysis, UV-visible absorption and Np L_III-edge X-ray absorption spectroscopies. The redox reactions of Np(III)/Np(IV) and Np(V)/Np(VI) couples are reversible or quasi-reversible, while the electrochemical reaction between Np(III/IV) and Np(V/VI) is irreversible because they undergo the structural rearrangement from spherical coordinating ions (Np³⁺ and Np⁴⁺) to transdioxo neptunyl ions (NpO₂ⁿ⁺, n = 1 for Np(V) and 2 for Np(VI)). A detailed analysis on extended X-ray absorption fine structure (EXAFS) spectra suggests that Np(IV) forms a decaaquo complex of [Np(H₂O)₁₀]⁴⁺ in 1.0 M HClO₄, while Np(V) and -(VI) exist dominantly as pentaaquo neptunyl complexes, [NpO₂(H₂O)₅]ⁿ⁺ (n = 1 for Np(V) and 2 for Np(VI)).

36001410
Feasibility tests on pressure-transmitting media for single-crystal magnetic neutron diffraction under high pressure
Osakabe, Toyotaka; Kakurai, Kazuhisa
Japanese Journal of Applied Physics 47(8), p.6544-6547(2008) ; (JAEA-J 04696)

The hydrostaticity of pressure-transmitting media, such as graphite powder, a mixture of Fluorinert, Fomblin oil, silicone oil, Daphne7373 oil and glycerin, was investigated by high-pressure neutron diffraction experiments on the mosaic spread of NaCl single crystals. The width of the rocking curve of the NaCl single crystal in the medium other than glycerin increases rapidly with increasing pressure below 2.5 GPa, indicating that the medium solidifies below 2.5 GPa. On the other hand, glycerin transmits nearly hydrostatic pressure at least up to 7 GPa. The diffraction profiles of the media were also measured to evaluate the background intensities. Daphne7373 oil and glycerin generate low and flat diffraction profiles particularly at approximately 25°, where the principal magnetic diffraction signals are often present. Thus, glycerin is the most suitable pressure medium for single-crystal magnetic neutron scattering experiments beyond 3 GPa.

36001411
Effect of oxygen vacancies on charge ordered structure in YFe₂O_4-δ
Mori, Shigeo*; Shinohara, Satoshi*; Matsuo, Yoji*; Horibe, Yoichi*; Yoshii, Kenji; Ikeda, Naoshi*
Japanese Journal of Applied Physics 47(9), p.7595-7598(2008) ; (JAEA-J 04697)

We have investigated the electronic ferroelectric material YFe₂O₄by means of electron transmission microscopy. The measurement at room temperature showed the charge-ordered structure of Fe ions in the a-b plane, which is the origin of ferroelectricity. An enlargement of unit cell along the c-axis was also observed. These phenomena were not observed at high temperatures around 600 K. That is, the charge ordering in the a-b plane appeared below about 500 K, whreas the enlargement of unit cell along the c-axis was found at room temperature. Below 100 K, an additional enlargement of unit cell along [119] was observed. This behavior is characteristic of YFe₂O₄. These results are discussed in connection with the dielectric properties.

36001412
Crystal structure and magnetic properties of the new ternary actinide compounds AnPd₅Al₂ (An = U, Np)
Haga, Yoshinori; Aoki, Dai*; Homma, Yoshiya*; Ikeda, Shugo; Matsuda, Tatsuma; Yamamoto, Etsuji; Sakai, Hironori; Tateiwa, Naoyuki; Dung, N. D.*; Nakamura, Akio; Shiokawa, Yoshinobu*; Onuki, Yoshichika
Journal of Alloys and Compounds 464(1-2), p.47-50(2008) ; (JAEA-J 04698)

We report the crystal structure and magnetic properties of new ternary actinide compounds UPd₅Al₂ and NpPd₅Al₂. Both compounds crystallize in the body-center tetragonal ZrAl₅Ni₂ -type tetragonal structure (I 4/mmm). Although the magnetic susceptibility of both compounds follows the Curie-Weiss behavior at high temperature, no magnetic phase transition was observed. UPd₅Al₂ has a nonmagnetic ground state where the magnetic susceptibility saturates at low temperature, while NpPd₅Al₂ superconducts below 4.9 K as reported recently.

36001413
Effect of water density on the absorption maximum of hydrated electrons in sub- and supercritical water up to 400 °C
Jay-Gerin, J.-P.*; Lin, M.; Katsumura, Yosuke; He, H.*; Muroya, Yusa*; Meesungnoen, J.*
Journal of Chemical Physics 129(11), p.114511_1-114511_7(2008) ; (JAEA-J 04699)

In this work, we measure the density dependent absorption spectra of hydrated electron in D₂O at 380, 390, and 400°C, and then compare with the literature data for subcritical water. The results show that at a fixed pressure (25 MPa), E_A-max decreases monotonically with increasing temperature in passing through the liquid-supercritical water (SCW) phase transition at t_c. By contrast, at a fixed density (0.2 and 0.65g/cm³), E_A-max exhibits a minimum near t_c. These behaviors are explained in terms of local density and configurational fluctuations of water structure in SCW.

36001414
Photoabsorption spectra of CF₃I and thermally dissociated CF₃I near the C 1s, I 3d and F 1s ionisation thresholds
Tanaka, Takahiro*; Hoshino, Masamitsu*; Kato, Hideki*; Harries, J.; Tamenori, Yusuke*; Ueda, Kiyoshi*; Tanaka, Hiroshi*
Journal of Electron Spectroscopy and Related Phenomena 164(1-3), p.24-27(2008) ; (JAEA-J 04700)

We report soft X-ray total ion yield and angular-resolved ion yield spectra of CF₃I in the C 1s, I 3d and F 1s ionisation regions, and tentatively assign the observed electronic states. Anisotropy in ion yield is observed only for the C 1s→σ^*_C-I transition, indicating that the dipole moment for this transition is parallel to the C_3v. The effusive source of CF₃I is heated to 800 K to produce a mixture of CF₃ and I, and the resulting spectra are compared to those recorded at room temperature to reveal the first information on the inner-shell excitation of CF₃.

36001415
Carbon-14 transfer into rice plants from a continuous atmospheric source; Observations and model predictions
Koarashi, Jun; Davis, P. A.*; Galeriu, D.*; Melintescu, A.*; Saito, Masahiro*; Siclet, F.*; Uchida, Shigeo*
Journal of Environmental Radioactivity 99(10), p.1671-1679(2008) ; (JAEA-J 04701)

Carbon-14 (¹⁴C) is one of the most important radionuclides from the perspective of dose estimation due to the nuclear fuel cycle. Ten years of monitoring data on ¹⁴C in airborne emissions, in atmospheric CO₂ and in rice grain collected around the Tokai reprocessing plant (TRP) showed an insignificant radiological effect of the TRP-derived ¹⁴C on the public, but suggested a minor contribution of the TRP-derived ¹⁴C to atmospheric ¹⁴C concentrations, and an influence on ¹⁴C concentrations in rice grain at harvest. This paper also summarizes a modelling exercise (the so-called rice scenario of the IAEA's EMRAS program) in which ¹⁴C concentrations in air and rice predicted with various models were compared with observed concentrations. The modelling results showed that Gaussian plume models with different assumptions predict monthly-averaged ¹⁴C concentrations in air well and also that specific activity and dynamic models were equally good for the prediction of inter-annual changes in ¹⁴C concentrations in rice grain.

36001416
Oxygen potential of hypo-stoichiometric Lu-doped UO₂
Osaka, Masahiko; Tanaka, Kosuke
Journal of Nuclear Materials 378(2), p.193-196(2008) ; (JAEA-J 04703)

Equilibrium oxygen partial pressures of oxygen hypo-stoichiometric (U_0.80Lu_0.20)O_2-x were experimentally determined by thermogravimetric analysis using H₂O/H₂ gas equilibria at 1173, 1273 and 1473 K. The equilibrium oxygen partial pressures of (U,Lu)O_2-x were apparently higher than those of other rare earth-doped UO₂, e.g. (U,Gd)O_2-x or (U,Er)O_2-x. Slope analysis of equilibrium oxygen partial pressures versus deviation from stoichiometries indicated the similar defect structure between them in spite of higher equilibrium oxygen partial pressure of (U_0.80Lu_0.20)O_2-x. Consideration on the results with effective ionic radii gave a conclusion that Lu has higher stability in UO₂ fluorite lattice with oxygen hypo-stoichiometry than those of the other rare earth-doped UO₂.

36001417
Historical role of the Tokai reprocessing plant in the establishment of safeguards technologies
Yamamura, Osamu; Yamamoto, Ryuichi; Nomura, Shigeo
Journal of Nuclear Materials Management 36(3), p.36-45(2008) ; (JAEA-J 04707)

This paper describes the role of Tokai Reprocessing Plant (TRP) for the safeguards (SG) technology development by Japan and IAEA and its application to the first large commercial plant in Japan. Through several negotiations between Japan and USA, TRP accepted the full scope application of IAEA's SG, the development of U-Pu mixed conversion process, and the experimental work of IAEA for development of SG activities. Results under the TASTEX, which was research and development program by an agreement made during Japan and USA negotiation on reprocessing, were reflected to the INFCE, which was organized by the change in US atomic energy policy. Most of the current SG technologies being applied by IAEA were developed at this time. Both effectiveness and reliability of such technologies have been validated extensively through the 30 years operation of TRP.

36001418
Mitigation technologies for damage induced by pressure waves in high-power mercury spallation neutron sources, 1; Material surface improvement
Naoe, Takashi; Futakawa, Masatoshi; Shobu, Takahisa; Wakui, Takashi; Kogawa, Hiroyuki; Takeuchi, Hirotsugu*; Kawai, Masayoshi*
Journal of Nuclear Science and Technology 45(7), p.698-703(2008) ; (JAEA-J 04708)

Liquid-mercury target systems for MW-class spallation neutron sources are being developed in the world. At the moment the proton beam hits the target, pressure waves are generated in the mercury because of the abrupt heat deposition. The pressure waves interact with the target vessel leading to negative pressure that may cause cavitation along the vessel wall. Localized impacts by micro-jets and/or shock waves which are caused by cavitation bubble collapse impose pitting damage on the vessel wall. Bubble collapse behavior was observed by using a high-speed video camera, as well as simulated numerically. Localized impact due to cavitation bubble collapse was quantitatively estimated through comparison between numerical simulation and experiment. A novel surface treatment technique which consists of carburizing and nitriding processes was developed and the treatment condition was optimized to mitigate the pitting damage due to localized impacts.

36001419
Neutron irradiation effect on isotopically tailored ¹¹B₄C
Morohashi, Yuko; Maruyama, Tadashi*; Donomae, Takako; Tachi, Yoshiaki; Onose, Shoji
Journal of Nuclear Science and Technology 45(9), p.867-872(2008) ; (JAEA-J 04709)

The present investigation was made to elucidate the effect of neutron irradiation on dimensional change and thermal conductivity of isotopically tailored ¹¹B₄C. The specimens used in the present investigation are 99% ¹¹B enriched ¹¹B₄C, 91% ¹⁰B enriched ¹⁰B₄C and β-SiC. The results of measurements indicated that the changes in dimension and thermal conductivity of neutron irradiated ¹¹B₄C were substantially smaller than those of ¹⁰B₄C and SiC. Post irradiation annealing experiment measurements for ¹¹B₄C showed that dimensional change and thermal conductivity were almost completely annealed out at 1400°C. The changes in thermal conductivity by annealing were analyzed in terms of phonon scattering theory. The onset of recovery in thermal conductivity of ¹¹B₄C well agreed well with irradiation temperature, however the recovery in length did not coincide with irradiation temperature.

36001420
Development of an atmospheric dispersion model for accidental discharge of radionuclides with the function of simultaneous prediction for multiple domains and its evaluation by application to the Chernobyl nuclear accident
Terada, Hiroaki; Chino, Masamichi
Journal of Nuclear Science and Technology 45(9), p.920-931(2008) ; (JAEA-J 04710)

A computational model for an emergency response system, Worldwide version of System for Prediction of Environmental Emergency Dose Information (WSPEEDI), was improved to predict atmospheric dispersion of radionuclides in detail not only around a release point but also on a regional scale during a transboundary nuclear accident. The main improvement described in this paper is simultaneous atmospheric dispersion calculation of two nested domains, achieved by exchanging particle information between the parallel calculations for the domains. The application of the model to the Chernobyl accident remedied the underestimations of surface deposition of ¹³⁷Cs in the calculation only for the local area around Chernobyl, and also predicted the European-scale ¹³⁷Cs depositions precisely. It is concluded that the nesting model developed in this paper is very appropriate for nuclear emergencies in which the prediction of both local and regional scale dispersions are required.

36001421
Development scenario of the iodine-sulphur hydrogen production process to be coupled with VHTR system as a conventional chemical plant
Sakaba, Nariaki; Sato, Hiroyuki; Ohashi, Hirofumi; Nishihara, Tetsuo; Kunitomi, Kazuhiko
Journal of Nuclear Science and Technology 45(9), p.962-969(2008) ; (JAEA-J 04711)

Japan Atomic Energy Agency (JAEA) started design studies of the thermochemical water-splitting Iodine Sulphur (IS) process to be coupled with the HTTR to demonstrate hydrogen production from Very High-Temperature Reactor (VHTR) system. It is important from an economic point of view that a non-nuclear grade, rather than nuclear grade, IS process plant be built based on conventional chemical plant construction standards. In order to construct the IS process as a conventional chemical plant, some critical safety issues must been studied and clarified prior to the application for safety case review from the government. JAEA has launched R&D for non-nuclear grade IS process to be coupled with the HTTR which is the Japan's first VHTR capable of supplying 900 °C secondary helium for process heat application. This paper describes the development scenario for non-nuclear grade hydrogen production system. Utilizing the HTTR-IS system as a reference system, the R&D map is proposed for the VHTR-IS hydrogen production system.

36001422
Densification of molybdenum-cermet fuel by sintering with metal additives
Osaka, Masahiko; Tanaka, Kosuke
Journal of Nuclear Science and Technology 45(9), p.970-974(2008) ; (JAEA-J 04712)

An experimental investigation on densification behavior of molybdenum-cermet fuel was carried out. The Mo-cermet fuel is a candidate for effective transmutation of minor actinides. Tests of UO₂/PuO₂-containing cermet fuels were carried out with Pd or Ni as additive. Only 1 wt.% additive lead to a great increase of sintered densities of cermet fuels. The densification behavior was discussed and a gap-filling effect between oxide and metal phases was revealed to be the main cause for the great increase of sintered density.

36001423
Estimation of generated volume of radiolytic gas voids during prompt criticality with 10% enriched uranium nitrate solution in TRACY
Ogawa, Kazuhiko; Kaminaga, Fumito*
Journal of Nuclear Science and Technology 45(10), p.1028-1035(2008) ; (JAEA-J 04713)

36001424
Voxel-based frog phantom for internal dose evaluation
Kinase, Sakae
Journal of Nuclear Science and Technology 45(10), p.1049-1052(2008) ; (JAEA-J 04714)

A voxel-based frog phantom has been developed for radiation protection of the environment. The voxel-based frog phantom was applied to evaluating self-absorbed fractions (self-AFs), which are defined as the fraction of energy emitted by a radiation source that is absorbed within the source organ. The self-AFs were evaluated for both photons and electrons in the spleen, kidneys and liver using Monte Carlo simulations. Furthermore, self-S values for F-18 and Y-90 in the organs were calculated using the results of the self-AFs. Consequently, the voxel-based frog phantom was found to be useful for the organ dose evaluations which have not been proposed by the International Commission on Radiological Protection (ICRP). It was also confirmed that the self-AFs and self-S values are largely dependent on the size of the source organ.

36001425
Retrospective dosimetry using violet thermoluminescence from natural quartz in soil
Fujita, Hiroki
Journal of Nuclear Science and Technology, Supplement 5 (June 2008) , p.147-150(2008) ; (JAEA-J 04715)

To develop retrospective dosimetry of unexpected radiation accident, the basic studies on violet thermoluminescence (VTL) phenomena were conducted using natural quartz grains. All VTL glowcurves of as-received samples exhibited no peaks below 250 °C, although there remained VTL peaks in the temperature region below 250 °C for artificially irradiated quartz samples. Therefore, accident doses could be estimated without interference of naturally accumulated doses by VTL measurement from natural quartz. The mean lives of VTL were evaluated by the various heating rates method and then the range of values was between some days and ten thousands of years depending on each peak. Furthermore, the lower detection limit was calculated to be tens of mGy from the response curve. This value was lower than that of other methods such as ESR dosimetry. From these results, VTL dosimetry would be preferable for accidental evaluation.

36001426
Development of the neutron calibration fields using accelerators at FRS and TIARA of JAEA
Shikaze, Yoshiaki; Tanimura, Yoshihiko; Saegusa, Jun; Tsutsumi, Masahiro; Shimizu, Shigeru; Yoshizawa, Michio; Yamaguchi, Yasuhiro
Journal of Nuclear Science and Technology, Supplement 5 (June 2008) , p.209-212(2008) ; (JAEA-J 04716)

The neutron calibration fields is necessary to evaluate the energy response of the neutron monitors and dosimeters used in the facility such as J-PARC. The neutron calibration fields using accelerators, for the purpose, have been developed at the Facility of Radiation Standards (FRS) of JAEA-Tokai for neutrons below 20MeV and at Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) of JAEA-Takasaki for those over 20 MeV. At FRS, a 4 MV Van-de-Graaff (Pelletron) accelerator is used. Up until the present, developments of the 8, 144, 250, 565 keV, 5.0 and 14.8 MeV fields have been completed. At TIARA, an AVF cyclotron is used, and three neutron fields of 45, 60 and 75 MeV are planned to be established. For the development, evaluation of the characteristics of the field have been in process.

36001427
An Inter-comparison of the neutron calibration fields by D₂O moderated ²⁵²Cf source at JAEA and KAERI
Kowatari, Munehiko; Fujii, Katsutoshi; Tsutsumi, Masahiro; Kim, B.-H.*; Lee, K.-C.*; Yoshizawa, Michio; Yamaguchi, Yasuhiro
Journal of Nuclear Science and Technology, Supplement 5 (June 2008) , p.217-220(2008) ; (JAEA-J 04717)

36001428
A Remote radiation monitoring system using an autonomous unmanned helicopter for nuclear emergencies
Okuyama, Shinichi; Torii, Tatsuo; Suzuki, Akihiko*; Shibuya, Masanori*; Miyazaki, Nobuyuki*
Journal of Nuclear Science and Technology, Supplement 5 (June 2008) , p.414-416(2008) ; (JAEA-J 04718)

In case of a nuclear emergency when a large amount of radioactive substances and/or radiation is released from a nuclear facility, emergency radiation monitoring is carried out from the sea and air as well as from the ground adjacent to the facility to evaluate the influence of the radiation on the surrounding environment. As a means of radiation monitoring from the air, aerial monitoring using a manned helicopter is conducted. Although a manned helicopter can monitor a large area during a short time, flight at an altitude of 300 m or lower is prohibited by the Aviation Law in Japan. Therefore, it is difficult for a manned helicopter to measure the radiation profile near the ground and to measure the radiation level in a complicated terrain. In recent years, technologies for autonomous flying of industrial unmanned helicopters have been developed and applied to natural disasters. In expectation of the application of unmanned helicopters to aerial radiation monitoring during a nuclear emergency, we have developed a remote radiation monitoring system and investigated its possibilities.

36001429
Monitoring methodologies and chronology of radioactive airborne releases from Tokai reprocessing plant
Koarashi, Jun; Mikami, Satoshi; Nakada, Akira; Akiyama, Kiyomitsu; Kobayashi, Hirohide; Fujita, Hiroki; Takeishi, Minoru
Journal of Nuclear Science and Technology, Supplement 5 (June 2008) , p.462-465(2008) ; (JAEA-J 04719)

Tokai reprocessing plant (TRP) has released radionuclides such as ³H, ¹⁴C, ⁸⁵Kr and ¹²⁹I into the atmosphere since the start of operation in 1977. We have established the monitoring methodologies for these nuclides, to realize an appropriate and continuous radioactive discharge control. The methodologies having various special technical considerations for matching the monitoring of reprocessing off-gas, were summarized in this paper. Briefly, ³H was collected by a cold-trap technique and the concentration was evaluated being independent of the water collection efficiency; ¹⁴C was collected by a monoethanolamine bubbler and then measured by liquid scintillation counting without any interferences from ³H and ⁸⁵Kr; ⁸⁵Kr was continuously measured by combination of two kinds of detectors to cover very wide range of the concentration; and ¹²⁹I was collected by a charcoal filter and a charcoal cartridge in series with a relatively high collecting performance.

36001430
Study on the worldwide estimation of probabilistic effective dose from intake of marine products
Nakano, Masanao
Journal of Nuclear Science and Technology, Supplement 5 (June 2008) , p.598-601(2008) ; (JAEA-J 04720)

The public generally requires worldwide environmental protection. A long-term environmental assessment from nuclear fuel cycle facilities to the aquatic environment also becomes more important to utilize nuclear energy globally. Evaluation of long-term risk including not only in Japan but also in neighboring countries is considered to be necessary in order to develop nuclear power industry. In advance of a multinational assessment of nuclear fuel cycle facilities, a worldwide estimation of probabilistic effective dose due to the atmospheric nuclear tests was carried out as an example. The author successfully simulated the distribution of radionuclides, which was produced by the atmospheric nuclear tests, in seawater and seabed sediment using LAMER (Long-term Assessment ModEl for Radioactivity in the oceans). A part of the LAMER calculated the advection-diffusion-scavenging processes for radionuclides in the oceans in cooperate with an oceanic general circulation model and was already validated for ¹³⁷Cs and ^239,240Pu. The author is challenging to calculate probabilistic effective dose, which is suggested by the International Commission on Radiological Protection, from intake of marine products due to atmospheric nuclear tests using the Monte Carlo method in the other part of LAMER. Although it depended on the deviation of each parameter, the 95th percentile of the probabilistic effective dose was calculated about half of the 95th percentile of the deterministic effective dose in proforma calculation. The probabilistic assessment gives realistic value for the dose assessment of a nuclear fuel cycle facility.

36001431
Experimental constraints on the phase diagram of titanium metal
Zhang, J.*; Zhao, Y.*; Hixson, R. S.*; Gray III, G. T.*; Wang, L.*; Utsumi, Wataru; Saito, Hiroyuki; Hattori, Takanori
Journal of Physics and Chemistry of Solids 69(10), p.2559-2563(2008) ; (JAEA-J 04721)

The phase transformations of titanium metal have been studied at temperatures and pressures up to 973 K and 8.7 GPa using synchrotron X-ray diffraction. An update, more accurate phase diagram is established for Ti metal based on the present observations and previous constraints on the α-β and ω-β phase boundaries.

36001432
Oxidation of xylene and its irradiation byproducts using an electron-beam irradiating a γ-Al₂O₃ bed
Hakoda, Teruyuki; Matsumoto, Kanae*; Mizuno, Akira*; Hirota, Koichi
Journal of Physics D; Applied Physics 41(15), p.155202_1-155202_7(2008) ; (JAEA-J 04722)

The oxidation of xylene and its irradiation byproducts in air using a γ-Al₂O₃ bed was studied under electron-beam irradiation to enhance the decomposition of volatile organic compounds in ventilation gases emitted from paint factories. The use of the γ-Al₂O₃ bed enhanced the oxidation of the irradiation byproducts to CO₂. Furthermore, the oxidation of the byproducts was accelerated by the placement of the γ-Al₂O₃ bed in an irradiation space, because of the interaction of primary electrons with the surface of γ-Al₂O₃ pellets. This combined oxidation process enabled a reduction in the energy consumption for non-toxic CO₂ formation, and improved the selectivity of CO₂ production.

36001433
Properties of a hyperon-quark mixed phase in compact stars
Maruyama, Toshiki; Chiba, Satoshi; Schulze, H.-J.*; Tatsumi, Toshitaka*
Journal of Physics G; Nuclear and Particle Physics 35(10), p.104076_1-104076_4(2008) ; (JAEA-J 04723)

We investigate the property of the hadron-quark mixed phase using the Brueckner-Hartree-Fock model for hadron (hyperon) phase and the MIT bag model for quark phase. To satisfy the Gibbs conditions, charge density as well as baryon number density becomes non-uniform in the mixed phase. Taking into account the density distribution and the Coulomb interaction in a self-consistent way, we clarify the roles of the surface tension and the charge screening effect. We will show that the screened Coulomb interaction makes the EOS similar to the one given by the Maxwell construction. We demonstrate that hyperons are suppressed in the mixed phase, because hadron phase is positively charged. This is a novel mechanism of hyperon suppression in compact stars. Finally we will discuss some consequences of our EOS on the structure and the maximum mass of NS.

36001434
Crystal structure and magnetic properties of new ternary uranium compounds U_2/3Pd₂Al₅
Haga, Yoshinori; Matsuda, Tatsuma; Ikeda, Shugo; Yamamoto, Etsuji; Nguyen, D.; Onuki, Yoshichika
Journal of the Physical Society of Japan 77(Suppl.A), p.365-367(2008) ; (JAEA-J 04724)

We found two ternary intermetallic compounds in the ternary system U-Pd-Al. U_x(Al₃)_1-xPd₂Al₄ (x ∼ 0.67) crystallizes in the hexagonal P6₃/mmc structure with lattice parameters a = 4.3278 and c = 16.2870 Å. Uranium atom occupies one crystallographic site (1/3 2/3 1/4). However, it is randomly replaced by (Al₃), leading to a peculiar magnetic ground state. UPd₅Al₂ has the same structure as the first neptunium-based superconductor NpPd₅Al₂ which consists of a stacking of AuCu₃-type NpPd₃ and Al. UPd₅Al₂ compound is only stable at hight temperature: annealing treatment at 800 °C decomposes it into hexagonal UPd₃ and PdAl. The stability of AnPd₅Al₂ is most likely related to the instability of cubic AnPd₃.

36001435
Pressure-induced superconductivity in antiferromagnet CePd₅Al₂
Honda, Fuminori*; Measson, M.-A.*; Nakano, Yasunori*; Yoshitani, Naohisa*; Yamamoto, Etsuji; Haga, Yoshinori; Takeuchi, Tetsuya*; Yamagami, Hiroshi*; Shimizu, Katsuya*; Settai, Rikio*; Onuki, Yoshichika
Journal of the Physical Society of Japan 77(4), p.043701_1-043701_4(2008) ; (JAEA-J 04725)

Pressure effect on the antiferromagnet CePd₅Al₂ has been investigated. By applying pressure, the antiferromagnetic transition temperature increases up to 5 GPa. Further applying pressure, the antiferromagnetic transition smears out rapidly and finally superconducting region arises around 10 K.

36001436
The de Haas-van Alphen oscillation and fermi surface properties of YCu₂Si₂
Nguyen, D.; Matsuda, Tatsuma; Ikeda, Shugo*; Yamamoto, Etsuji; Haga, Yoshinori; Takeda, Yuji*; Endo, Toyoaki*; Doi, Yusuke*; Settai, Rikio*; Harima, Hisatomo*; Onuki, Yoshichika
Journal of the Physical Society of Japan 77(9), p.094702_1-094702_6(2008) ; (JAEA-J 04726)

We have succeeded in growing a high-quality single crystal of a non-4f reference compound YCu₂Si₂ for a heavy-fermion superconductor CeCu₂Si₂, and observed the de Haas-van Alphen (dHvA) oscillation. The detected dHvA branches in YCu₂Si₂ indicate that the Fermi surfaces are multiply connected, and the dHvA frequencies are in the range from 9×10⁶ to 2×10⁸ Oe. These dHvA branches are found to be well explained by the results of energy band calculations. The corresponding cyclotron masses are light, ranging from 0.4 to 1.5 m₀, and are consistent with the electronic specific heat coefficient of 2.2 mJ/K²·mol.

36001437
As-rich InAs(001)-(2×4) phases investigated by in situ surface X-ray diffraction
Tinkham, B. P.*; Braun, W.*; Ploog, K. H.*; Takahashi, Masamitsu; Mizuki, Junichiro; Grosse, F.*
Journal of Vacuum Science and Technology B 26(4), p.1516-1520(2008) ; (JAEA-J 04727)

Surface X-ray diffraction has been employed, in situ, to measure InAs(001)-(2×4) surface phases under technologically relevant growth conditions. For the As-rich (2×4) phase, the authors obtain good agreement between the data and the β2(2×4) surface reconstruction model. Comparison of our measurements on the (2×4) phase measured close to the metal-rich phase transition to models from density functional theory suggests a mixture of α2(2×4) and β2(2×4) surface structures present on the surface.

36001438
Simulation studies on alpha -particle-driven current in tokamak reactors
Tani, Keiji; Azumi, Masafumi*
Nuclear Fusion 48(8), p.085001_1-085001_9(2008) ; (JAEA-J 04728)

Simulation studies are made for alpha-driven currents in tokamak reactors by using an orbit-following Monte-Carlo code. The finite banana width of alpha particles causes an asymmetry particle trapping and consequently an alpha current is driven by the imbalance of transit particles. The current driven by alpha transit particles (simply referred to as transit current) is greatly enhanced by a collaborative effect of the finite banana-width trajectories and a non-uniformity of alpha particle source. The pitch-angle scattering is also very important for the transit current. Fusion produced alpha particles can drive substantial current to assist the bulk bootstrap current in steady state tokamak reactors.

36001439
Dependence of heat transport on toroidal rotation in conventional H-modes in JT-60U
Urano, Hajime; Takenaga, Hidenobu; Fujita, Takaaki; Kamada, Yutaka; Koide, Yoshihiko; Oyama, Naoyuki; Yoshida, Maiko; JT-60 Team
Nuclear Fusion 48(8), p.085007_1-085007_9(2008) ; (JAEA-J 04729)

Relation between heat transport in the plasma core and toroidal rotation profile was examined in conventional ELMy H-mode plasmas in JT-60U. Energy confinement improvement is observed with toroidal rotation which increases in co-direction with respect to the plasma current. Heat transport in the plasma core varies while sustaining self-similar temperature profile in the variation of toroidal rotation profiles. Large increase in heat conduction imposes the resilient profile of ion temperature, under which local effect of toroidal rotation profile on the scale length of ion temperature gradient is very weak. When the pedestal temperature was fixed between the cases of co and counter-NBI by adjusting the plasma density, the identical temperature profiles were obtained in spite of totally different toroidal rotation profiles.

36001440
MeV γ-ray generation from backward compton scattering at SPring-8
Kawase, Keigo; Arimoto, Yasushi*; Fujiwara, Mamoru; Okajima, Shigeki*; Shoji, Masazumi*; Suzuki, Shinsuke*; Tamura, Kazuhiro*; Yorita, Tetsuhiko*; Okuma, Haruo*
Nuclear Instruments and Methods in Physics Research A 592(3), p.154-161(2008) ; (JAEA-J 04730)

A test experimental line at SPring-8 has been constructed for the generation of backward Compton scattered (BCS) γ-ray by head-on collision between an 8 GeV electron beam and a far-infrared (FIR) laser. For the FIR laser, we use a continuous-wave methanol laser optically pumped by a carbon dioxide (CO₂) laser. The FIR laser output power achieved is 1.6 W at maximum for 118.8 μm lasing; this value is the highest in the case of this type of laser. As a result of the direct measurement, the generated BCS γ-ray flux was found to be about 10³ photons/s. This value is consistent with the estimation calculated by taking into account the input laser power and the transmittance of the laser transport system.

36001441
Ion source development for the on-line isotope separator at JAEA
Osa, Akihiko; Ichikawa, Shinichi; Matsuda, Makoto; Sato, Tetsuya; Jeong, S.-C.*
Nuclear Instruments and Methods in Physics Research B 266(19), p.4394-4397(2008) ; (JAEA-J 04731)

A forced electron beam induced arc discharge (FEBIAD-B2) type ion source and a surface ionization type one with an integrated target have been developed for the on-line isotope separator at JAEA. The ion sources were utilized to produce medium-heavy neutron-rich radioactive ion beams for acceleration with Tokai Radioactive Ion Accelerator Complex (TRIAC). In the FEBIAD-B2 type ion source, a 1 g/cm² ²³⁸UC_x target is directly attached to a plasma chamber. While the surface ionization type ion source, ²³⁸UC_x is located inside ion source as an internal target. With both ion sources, about 100 isotopes produced in the proton-induced fission of ²³⁸U with separation efficiencies of 0.1∼30% have been mass-separated.

36001442
Study of structural change in CeO₂ irradiated with high-energy ions by means of X-ray diffraction measurement
Ishikawa, Norito; Chimi, Yasuhiro; Michikami, Osamu*; Ota, Yasuyuki*; Ohara, Kota; Lang, M.*; Neumann, R.*
Nuclear Instruments and Methods in Physics Research B 266(12-13), p.3033-3036(2008) ; (JAEA-J 04732)

Cerium dioxide films are irradiated with high-energy heavy ions with the energy range of 150 MeV to 2.7 GeV, and X-ray diffraction profile is examined. As a result, the data can be explained by creation of nanometer-size ion track with disordered lattice structure, and the ion track is oxygen deficient.

36001443
Aalpha-ray detection with a MgB₂ transition edge sensor
Okayasu, Satoru; Katagiri, Masaki; Hojo, Kiichi; Morii, Yukio; Miki, Shigenobu*; Shimakage, Hisashi*; Wang, Z.*; Ishida, Takekazu*
Physica C 468(15-20), p.1998-2000(2008) ; (JAEA-J 04733)

We have been investigating for neutron detection with the MgB ₂ transition edge sensor (TES). For the purpose, we have been developing a low noise measurement system for neutron detection. To confirm the usefulness of our detecting system, alpha-ray detection from an ²⁴¹Am source was achieved. To improve the sensitivity, short meander samples with 35 μm length and 1 μm width is used. Samples are fabricated by the Kansai group. Superconducting transition temperature Tc is 23.3 K. The transition width is sharp enough less than 1 K. The detection was achieved under a constant current condition, and the resistivity changes at the sample due to the alpha-ray irradiation were detected. The bias current is 6 μA.

36001444
Controlling the surface chirality of Si(110)
Yamada, Yoichi; Girard, A.*; Asaoka, Hidehito; Yamamoto, Hiroyuki; Shamoto, Shinichi
Physical Review B 77(15), p.153305_1-153305_3(2008) ; (JAEA-J 04735)

A widely well-defined homochiral surface is realized on Si(110), manipulating surface reconstruction by electromigration. Controlled switching of the surface handedness has also been demonstrated. In addition, by means of hydrogen passivation, the surface is sufficiently stabilized while surface chirality is conserved. These findings suggest the possible use of Si(110) as a heterogeneous catalyst for enantioselective chemical reactions.

36001445
Thermal equations of state for titanium obtained by high pressure-temperature diffraction studies
Zhang, J.*; Zhao, Y.*; Hixson, R. S.*; Gray III, G. T.*; Wang, L.*; Utsumi, Wataru; Saito, Hiroyuki; Hattori, Takanori
Physical Review B 78(5), p.054119_1-054119_7(2008) ; (JAEA-J 04736)

We have conducted in situ high-pressure diffraction experiments on titanium metal at pressures up to 8.2 GPa and temperatures up to 900 K. From the pressure-volume-temperature measurements, thermoelastic parameters were derived for titanium based on a modified high-T Birch-Murnaghan equation of state and a thermal pressure approach.

36001446
K^π=8^- isomers and K^π=2^- octupole vibrations in N=150 shell-stabilized isotones
Robinson, A. P.*; Khoo, T. L.*; Ahmad, I.*; Tandel, S. K.*; Kondev, F. G.*; Nakatsukasa, Takashi*; Seweryniak, D.*; Asai, Masato; Back, B. B.*; Carpenter, M. P.*; Chowdhury, P.*; Davids, C. N.*; Eeckhaudt, S.*; Greene, J. P.*; Greenlees, P. T.*; Gros, S.*; Heinz, A.*; Herzberg, R. -D.*; Janssens, R. V. F.*; Jones, G. D.*; Lauritsen, T.*; Lister, C. J.*; Peterson, D.*; Qian, J.*; Tandel, U. S.*; Wang, X.*; Zhu, S.*
Physical Review C 78(3), p.034308_1-034308_6(2008) ; (JAEA-J 04737)

Isomers have been identified in ²⁴⁶Cm and ²⁵²No with quantum number K^π=8^-, which decay through K^π=2^- rotational bands built on octupole vibrational states. For N=150 isotones with atomic number Z=94∼102, the K^π=8^- and 2^- states have remarkably stable energies, indicating neutron excitations. An exception is a singular minimum in the 2^- energy at ²⁴⁶Cm, due to the additional role of proton configurations.

36001447
Flux line lattice melting and the formation of a coherent quasiparticle bloch state in the ultraclean URu₂Si₂ superconductor
Okazaki, Ryuji*; Kasahara, Yuichi*; Shishido, Hiroaki*; Konczykowski, M.*; Behnia, K.*; Haga, Yoshinori; Matsuda, Tatsuma; Onuki, Yoshichika; Shibauchi, Takasada*; Matsuda, Yuji*
Physical Review Letters 100(3), p.037004_1-037004_4(2008) ; (JAEA-J 04738)

We find that in ultraclean heavy-fermion superconductor URu₂Si₂ (T_c0 = 1.45 K) a distinck flux line lattice melting transition with outstanding characters occurs well below the mean-field upper critical fields. We show that a very small number of carriers with heavy mass in this system results in exceptionally large thermal fluctuations even at subkelvin temperatures, which are witnessed by a sizable region of the flux line liquid phase. The uniqueness is further highlighted by an enhancement of the quasiparticle mean free path below the melting transition, implying a possible formation of a quasiparticle Bloch state in the periodic flux line lattice.

36001448
Hole localization in the one-dimensional doped anderson-hubbard model
Okumura, Masahiko; Yamada, Susumu; Taniguchi, Nobuhiko*; Machida, Masahiko
Physical Review Letters 101(1), p.016407_1-016407_4(2008) ; (JAEA-J 04739)

We study an interplay of disorder and correlation in the one- dimensional hole-doped Hubbard-model with disorder (Anderson-Hubbard model) by using the density-matrix renormalization group method. Concentrating on the doped-hole density profile, we find in a large U/t regime that the clean system exhibits a simple fluidlike behavior whereas finite disorders create locally Mott regions which expand their area with increasing the disorder strength contrary to the conventional sense. We propose that such an anomalous Mott phase formation assisted by disorder is easily observable in atomic Fermi gases by setup of the box-shape trap.

36001449
Nature of the structural transformations in B₂O₃ glass under high pressure
Brazhkin, V. V.*; Katayama, Yoshinori; Trachenko, K.*; Tsiok, O. B.*; Lyapin, A. G.*; Artacho, E.*; Dove, M.*; Ferlat, G.*; Inamura, Yasuhiro; Saito, Hiroyuki
Physical Review Letters 101(3), p.035702_1-035702_4(2008) ; (JAEA-J 04740)

We study polyamorphism of B₂O₃ glass using X-ray diffraction up to 10 GPa in the 300-700 K temperature range, in situ volumetric measurements up to 9 GPa, and first-principles simulations. The glass undergoes two-stage transformations under pressure including a gradual increase of the first B-O (O-B) coordination numbers above 5 GPa. The fraction of boron atoms in the fourfold-coordinated state at P<10 GPa is smaller than was assumed from inelastic X-ray scattering spectroscopy data, but is considerably larger than was previously suggested by the classical molecular dynamics simulations. The observed transformations under both compression and decompression are broad in hydrostatic conditions.

36001450
Analysis of effects of posture on organ doses by internal photon emitters using voxel phantoms
Sato, Kaoru; Endo, Akira
Physics in Medicine and Biology 53(17), p.4555-4572(2008) ; (JAEA-J 04741)

In order to clarify the effects of posture on organ doses due to internal exposures, SAFs for photons from 0.01 to 4 MeV were calculated using JM2 (upright) and JM (supine) phantoms whose designs were based on CT images of two postures obtained from the same person. Differences in the SAFs of JM2 and JM are within a factor of 2 in most cases, although significant differences in SAFs exist in several cases for low energy photons. Organ doses due to photons from intake of unit activity of 8 radionuclides with different biokinetics and decay characteristics were calculated from the SAFs of JM2 and JM. It was found the organ doses in the testes, bone marrow, lower large intestine wall, lungs and stomach wall, which are important for calculating effective dose, in the two postures roughly agree, the maximum difference being 14%. These results indicate that the impact of posture on the organ doses and effective doses from internal photon emitters is limited.

36001451
Arabidopsis thaliana Y-family DNA polymerase η catalyses translesion synthesis and interacts functionally with PCNA2
Anderson, H.*; Vonarx, E.*; Pastushok, L.*; Nakagawa, Mayu; Katafuchi, Atsushi*; Gruz, P.*; Rubbo, A.*; Grice, D.*; Osmond, M.*; Sakamoto, Ayako; Nomi, Takehiko*; Xiao, W.*; Kunz, B.*
Plant Journal 55(6), p.895-908(2008) ; (JAEA-J 04742)

We assessed the roles of Arabidopsis thaliana POLH, PCNA1 and PCNA2 in TLS mediated UV resistance. Arabidopsis POLH defective mutants sensitized growth of roots and whole plants to UV radiation indicating AtPolη contributes to UV resistance. POLH alone did not complement the UV sensitivity conferred by deletion of yeast RAD30, although AtPolη exhibited cyclobutane dimer bypass activity and interacted with yeast PCNA in vitro. Co-expression of POLH and PCNA2, but not PCNA1, restored normal UV resistance and mutation kinetics in the rad30 mutant. A single residue difference at site 201, which lies adjacent to the lysine ubiquitylated in PCNA, appeared responsible for the inability of PCNA1 to function with AtPolη in UV treated yeast. PCNA interacting protein boxes and an ubiquitin-binding motif in AtPolη were found to be required for restoration of UV resistance in the rad30 mutant by POLH and PCNA2. These observations indicate AtPolη can catalyse TLS past UV induced DNA damage, and link the biological activity of AtPolη in UV irradiated cells to PCNA2 and PCNA-and ubiquitin-binding motifs in AtPolη.

36001452
Numerical matching scheme for linear magnetohydrodynamic stability analysis
Kagei, Yasuhiro; Tokuda, Shinji
Plasma and Fusion Research (Internet) 3, p.039_1-039_5(2008) ; (JAEA-J 04743)

A new matching scheme for linear magnetohydrodynamic (MHD) stability analysis is proposed in a form that the numerical implementation is tractable. The scheme divides the plasma region into outer regions and inner layers, as in the conventional matching method. However the outer regions do not contain any rational surface as their terminal points; an inner layer contains a rational surface as an interior point. The MHD equation employed in the layers is solved as an evolution equation in time, and the full implicit scheme is used to yield an inhomogeneous differential equation for space coordinates. The matching conditions are derived from the conditions that the radial component of the solution in the layer be smoothly connected to those in the outer regions at the terminal points. The proposed scheme is applied to the linear ideal MHD equation in a cylindrical configuration, and is proved to be effective from the view point of numerical scheme.

36001453
Formation and long term evolution of an externally driven magnetic island in rotating plasmas
Ishii, Yasutomo; Smolyakov, A. I.*
Plasma and Fusion Research (Internet) 3, p.048_1-048_7(2008) ; (JAEA-J 04744)

36001454
Physics mechanisms of toroidal rotation profile and properties of momentum transport in JT-60U
Yoshida, Maiko; Kamada, Yutaka; Takenaga, Hidenobu; Sakamoto, Yoshiteru; Urano, Hajime; Oyama, Naoyuki; Matsunaga, Go; JT-60 Team
Plasma and Fusion Research (Internet) 3, p.S1007_1-S1007_8(2008) ; (JAEA-J 04745)

Toroidal rotation velocity profile plays essential roles in determining confinement and MHD stability at a high pressure in magnetic confined plasmas. Therefore, the critical importance of understanding the physical mechanisms determining the V_t, and controlling V_t has recently been recognized. In JT-60U, the mechanisms of V_t profile for L-mode, H-mode and ITB plasmas are investigated using the perturbative and non-perturbative experiments. The main conclusions are that the elements determining the V_t profile, i.e. the momentum transport, the external momentum input, and the intrinsic rotation (the rotation driven by plasma itself) have been identified, and the roles of these elements on V_t profile are also found.

36001455
Effect of temperature on the absorption spectra of the solvated electron in 1-propanol and 2-propanol; Pulse radiolysis and laser photolysis studies at temperatures up to supercritical condition
Han, Z.*; Katsumura, Yosuke; Lin, M.; He, H.*; Muroya, Yusa*; Kudo, Hisaaki*
Radiation Physics and Chemistry 77(4), p.409-415(2008) ; (JAEA-J 04746)

The absorption spectra of solvated electrons in 1-propanol and 2-propanol have been investigated from 22 to 270 °C at a fixed pressure of 7 MPa, by using both nanosecond pulse radiolysis and laser photolysis techniques. The results show that, even up to supercritical conditions, it is still possible to measure unambiguously the absorption spectra of solvated electron in these two propanols. The peak positions of the absorption spectra show a red-shift (shifts to longer wavelengths) as temperature increases, similar to water and other alcohols, but the temperature efficiency, dE_max/dT, of 1-propanol is larger than that of 2-propanol. In addition, in clear contrast to that of pulse radiolysis, in laser photolysis experiments, an increase in the maximum absorbance of the absorption spectra of solvated electron with temperature up to 200 °C is attributed to the increase of absorbance (CTTS absorption band) of I- anion at 248 nm with increasing temperature.

36001456
Water radiolysis with heavy ions of energies up to 28 GeV, 1; Measurements of primary g values as track segment yields
Yamashita, Shinichi; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*; Miyazaki, Toyoaki*; Murakami, Takeshi*
Radiation Physics and Chemistry 77(4), p.439-446(2008) ; (JAEA-J 04747)

Water radiolysis has been investigated with heavy ions having energies up to 28 GeV provided from the Heavy Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences (NIRS). Beams of ⁴He²⁺, ¹²C⁶⁺, ²⁰Ne¹⁰⁺, ²⁸Si¹⁴⁺, ⁴⁰Ar¹⁸⁺ and ⁵⁶Fe²⁶⁺ with respective energies of 150, 400, 400, 490, 500 and 500 MeV per u corresponding LET values of 2.2, 13, 30, 54, 92 and 183 eV per nm, respectively, were taken for the irradiation. The LET changes in sample solutions can be neglected due to their high energies for the irradiation of 1-cm cells. Primary g values have been determined for three important products, hydrated electron (e^-_aq), hydroxyl radical (^.OH), and hydrogen peroxide (H₂O₂) as track segment yields (differential yields) under the conditions of neutral pH.

36001457
Preface, ASR2007; International Symposium on "Charged Particle and Photon Interactions with Matter", November 6-9, 2007
Katsumura, Yosuke; Lin, M.; Yokoya, Akinari; Hatano, Yoshihiko
Radiation Physics and Chemistry 77(10-12), p.1119(2008) ; (JAEA-J 04748)

As Guest Editors, we publish a special issue of Radiation Physics and Chemistry in conjunction with the ASR2007 Symposium, an international symposium on "Charged Particle and Photon Interactions with Matter" held on November 6-9, 2007 at the Advanced Science Research Center (ASRC), Japan Atomic Energy Agency (JAEA) in Tokai.

36001458
Ultra-fast pulse radiolysis; A Review of the recent system progress and its application to study on initial yields and solvation processes of solvated electrons in various kinds of alcohols
Muroya, Yusa*; Lin, M.; Han, Z.*; Kumagai, Yuta; Sakumi, Akira*; Ueda, Toru*; Katsumura, Yosuke
Radiation Physics and Chemistry 77(10-12), p.1176-1182(2008) ; (JAEA-J 04749)

In order to study radiation-induced fast phenomena, a new pulse radiolysis system with higher time resolution based on pulse-and-probe method was developed and utilized for practical work. A few picosecond electron beam generated from a linear accelerator, in which a laser photocathode RF-gun is introduced, was synchronized with a femtosecond laser pulse which is employed as the analyzing light. The synchronization precision between them was suppressed within 1.6 ps (rms). Converting the fundamental laser into white light continuum or optical parametric amplification allows to measure in the wide wavelength from visible to infrared region.

36001459
Pulse radiolysis of sodium formate aqueous solution up to 400 °C; Absorption spectra, kinetics and yield of carboxyl radical CO₂^·^-
Lin, M.; Katsumura, Yosuke; Muroya, Yusa*; He, H.*; Miyazaki, Toyoaki*; Hiroishi, Daisuke*
Radiation Physics and Chemistry 77(10-12), p.1208-1212(2008) ; (JAEA-J 04750)

Sodium formate neutral aqueous solutions saturated with N₂O were studied by pulse radiolysis techniques from room temperature to 400 °C. The absorption spectra of CO₂^·^- show a red shift from λ_max = 235 nm at 25 °C to 280 nm at 400 °C. The second-order decay of CO₂^·^- is not monotonically temperature-dependent: the rate constant (2k/ε) slightly increases with temperature up to 200 °C, then decreases to a valley at 300 °C, and it sharply increases again for temperature > 350 °C. G × ε(CO₂^·^-) increases with temperature from room temperature to 400 °C. Significant density effect on G × ε(CO₂^·^-) is found at 400 °C. Assumed ε(CO₂^·^-) is independent on temperature, at 400 °C, the density dependence of G(CO₂^·^-) in the presence of N₂O agrees well with that of [G(e_aq^-)+G(H^.)+G(^.OH)].

36001460
Water radiolysis with heavy ions of energies up to 28 GeV, 2; Extension of primary yield measurements to very high LET values
Yamashita, Shinichi; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*; Maeyama, Takuya*; Murakami, Takeshi*
Radiation Physics and Chemistry 77(10-12), p.1224-1229(2008) ; (JAEA-J 04751)

Measurements of primary g-values (at ∼ 10^-7 s after the initial ionizing event) of e^-_aq, ^.OH and H₂O₂ were extended to the very high linear energy transfer (LET) region (∼ 700 eV per nm) near the Bragg peak. Heavy ions (⁴He²⁺, ¹²C⁶⁺, ²⁰Ne¹⁰⁺, ²⁸Si¹⁴⁺, ⁴⁰Ar¹⁸⁺ and ⁵⁶Fe²⁶⁺) of energies up to 28 GeV were provided by the Heavy Ion Medical Accelerator in Chiba (HIMAC) of the National Institute of Radiological Sciences (NIRS) in Chiba, Japan. Energies of the ions were decreased down to about 10 MeV per u for ⁴He²⁺ using an energy absorber made of polymethylmethacrylate (PMMA) plates in order to vary the LET values. Beam was visualized after passing through the energy absorber using agarose gel of aqueous solution containing methyl viologen and sodium formate in order to determine how long ions can penetrate into water. Based on the information of the penetration depth of ions in samples, much attention was paid to dose correction and LET evaluation. The obtained data were plotted as a function of (Z _eff/β)² also instead of LET in order to discuss effects of physical track structures on product yields, resulted in better universality.

36001461
Degradation of hydroxymaleimide in 2-propanol by irradiation of energetic heavy ions, 1; Air-saturated system
Nakagawa, Seiko*; Taguchi, Mitsumasa; Ota, Nobuaki*; Hirota, Koichi
Radiation Physics and Chemistry 77(10-12), p.1230-1232(2008) ; (JAEA-J 04752)

Hydroxymaleimide was irradiated in air-saturated 2-propanol solution by high-energy heavy ions. The differential G-values of the degradation of hydroxymaleimide was smaller than the G-value obtained by γ-irradiation, and decreased with increasing LET value for the same kind of ions. The fitting curve of the differential G-values obtained for He ion is shifted from that for heavier ions. The irradiation effects of the kind and LET value of ions were observed on the degradation of hydroxymaleimide.

36001462
Can Monte Carlo track structure codes reveal reaction mechanism in DNA damage and improve radiation therapy?
Nikjoo, H.*; Emifietzoglou, D.*; Watanabe, Ritsuko; Uehara, Shuzo*
Radiation Physics and Chemistry 77(10-12), p.1270-1279(2008) ; (JAEA-J 04753)

Microdosimetry and track structure have been applied to scrutinize and understand aspects of radiation damage in biological molecules from a theoretical approach. To this end track structure has provided a basis for understanding the mechanism(s) that shape dose-effect relationships. There is a wealth of information and data accumulated from radiation biology that need to be placed in the framework of a general descriptive theory. While there are many classical radiobiology questions remain unanswered new ideas and challenging question are emerging. Among many, simulation of radiation track at molecular level is an emerging tool in radiobiology and theoretical radiotherapy. In this paper we present recent progress in development of low energy electron tracks in condensed media and high energy proton tracks and discuss progress in characterizing DNA damage in terms of types and complexity.

36001463
DNA damage induced by the direct effect of radiation
Yokoya, Akinari; Shikazono, Naoya; Fujii, Kentaro; Urushibara, Ayumi; Akamatsu, Ken; Watanabe, Ritsuko
Radiation Physics and Chemistry 77(10-12), p.1280-1285(2008) ; (JAEA-J 04754)

Ionizing radiation induces a variety of damages in cellular DNA, which is thought to be the critical target of biological effects of radiation, by both direct energy deposition on DNA (direct effect) and reactions with diffusible water radicals (indirect effect). One of the goals of our study is to clarify the nature of DNA damage induced by direct effect. The yields of single- and double-strand breaks, base lesions and clustered damage induced in a plasmid DNA were measured after exposing to various kinds of radiation (ion particles; 20 to 500 keV/ μ, photons; 0.4 keV to 1.3 MeV). Base excision repair enzymes were used to detect the oxidative base lesions. In order to obtain more detailed insights into the physicochemical mechanism of DNA damage induction, short-lived base radicals by applying an EPR spectrometer at a synchrotron ultrasoft X-ray beamline. Experimental evidences obtained by these methods will be discussed in comparison with the previous plasmid data.

36001464
Laser photolysis and pulse radiolysis studies on Silybin in ethanol solutions
Fu, H.*; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*
Radiation Physics and Chemistry 77(10-12), p.1300-1305(2008) ; (JAEA-J 04755)

In the present work, laser photolysis techniques have been used to study the transient species of silybin (abbreviated as SLB) in ethanol solutions. It has been demonstrated that the exposure of silybin to 248 nm excimer laser gives rise to monophotonic ionization with a high quantum yield. The transient species have been identified, and a series of related kinetics parameters have also been obtained. For the sake of comparison, we approached the problem using another way to reduce silybin, i.e. attack of solvated electrons, e_sol^-, produced in pulse radiolysis. The rate constant for reaction of e_sol^- was determined to be 3.8×10⁹ dm³mol^-1s^-1 at 720 nm, which is consistent with 4.6×10⁹ dm³mol^-1s^-1, obtained by laser photolysis.

36001465
Water radiolysis with heavy ions of energies up to 28 GeV, 3; Measurement of G(MV^.+) in deaerated methyl viologen solutions containing various concentrations of sodium formate and Monte Carlo simulation
Yamashita, Shinichi; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*; Miyazaki, Toyoaki*; Murakami, Takeshi*; Meesungnoen, J.*; Jay-Gerin, J.-P.*
Radiation Research 170(4), p.521-533(2008) ; (JAEA-J 04756)

Formation yields of methyl viologen cation radicals G(MV^.+) (100 eV)^-1 have been measured in deaerated aqueous solutions of methyl viologen, MV²⁺, containing various concentrations of formate anion after irradiation with six different ion beams (from ⁴He²⁺ to ⁵⁶Fe²⁶⁺ with incident energies varying from 0.6 to 28 GeV) provided by HIMAC at NIRS in Japan. In parallel to the above measurements, Monte Carlo simulations of the radiolysis of the MV²⁺-formate solutions have been performed to investigate complementarily mechanism from which distinctive irradiation effects of heavy ions are derived from the microscopic viewpoints experimentally non-feasible.

36001466
Hexafluoro complex of rutherfordium in mixed HF/HNO₃ solutions
Toyoshima, Atsushi; Haba, Hiromitsu*; Tsukada, Kazuaki; Asai, Masato; Akiyama, Kazuhiko*; Goto, Shinichi*; Ishii, Yasuo; Nishinaka, Ichiro; Sato, Tetsuya; Nagame, Yuichiro; Sato, Wataru*; Tani, Yuki*; Hasegawa, Hiroko*; Matsuo, Keiji*; Saika, Daisuke*; Kitamoto, Yusuke*; Shinohara, Atsushi*; Ito, Maya*; Saito, Junko*; Kudo, Hisaaki*; Yokoyama, Akihiko*; Sakama, Minoru*; Sueki, Keisuke*; Oura, Yasuji*; Nakahara, Hiromichi*; Schädel, M.*; Brüchle, W.*; Kratz, J. V.*
Radiochimica Acta 96(3), p.125-134(2008) ; (JAEA-J 04757)

Formation of an anionic fluoride-complex of element 104, rutherfordium (Rf) produced in the ²⁴⁸Cm(¹⁸O,5n)²⁶¹Rf reaction was studied by an anion-exchange method based on an atom-at-a-time scale. It was found that the hexafluoro complex of Rf, [RfF₆]^2-, was formed in the studied fluoride ion concentrations of 0.0005 - 0.013 M. Formation of [RfF₆]^2- was significantly different from that of the homologues Zr and Hf, [ZrF₆]^2- and [HfF₆]^2-; the evaluated formation constant of [RfF₆]^2- is at least one-order of magnitude smaller than those of [ZrF₆]^2- and [HfF₆]^2-.

36001467
Development of an electrochemistry apparatus for the heaviest elements
Toyoshima, Atsushi; Kasamatsu, Yoshitaka; Kitatsuji, Yoshihiro; Tsukada, Kazuaki; Haba, Hiromitsu*; Shinohara, Atsushi*; Nagame, Yuichiro
Radiochimica Acta 96(6), p.323-326(2008) ; (JAEA-J 04758)

We developed a new apparatus for the study of electrochemical properties of the heaviest elements. The apparatus is based on a flow electrolytic cell combined with column chromatography. Glassy-carbon fibers modified with Nafion perfluorinated cation-exchange resin are used as a working electrode as well as a cation-exchanger. The elution behavior of ¹³⁹Ce with the number of 10¹⁰ atoms in 0.1 M ammonium α-hydroxyisobutyric acid solution from the column electrode was investigated at the applied potentials of 0.2 - 1.0 V versus the Ag/Agcl reference electrode in 1.0 M LiCl. It was found that ¹³⁹Ce³⁺ is successfully oxidized to ¹³⁹Ce⁴⁺ even with tracer concentration at around the redox potential determined by cyclic voltammetry for the macro amounts of Ce with 10¹⁷ atoms (10^-3 M). The present oxidation reaction and separation of Ce⁴⁺ was accomplished within a few minutes.

36001468
Nuclear liquid drop model revisited (in Japanese)
Oyamatsu, Kazuhiro*; Iida, Kei*; Koura, Hiroyuki
Aichi Shukutoku Daigaku Gendai Shakai Kenkyuka Kenkyu Hokoku (3), p.1-10(2008) ; (JAEA-J 04759)

Liquid drop model is a representative model to describe binding energy and size of nuclei. This model is conventional and well reproduces bulk properties of nuclei even in current studies on nuclei. Nowadays structure of neutron-rich nuclei is paid attention to not only in nuclear physics but also in astrophysics because these nuclei play a quite important role to solve a problem of origin of elements in universe. In this paper, we investigate nuclear symmetry energy and nuclear surface energy by using the nuclear liquid drop model with some higher-order terms. The coefficients of these term are determined so as to reproduce measured nuclear masses of approximately 2200 nuclides. >From this analysis, we find an indication that the fourth-order term of the symmetry energy is required and the curvature term of it is negligible. Regarding a mass-number dependency on nuclear radius, we also find that the dependency of lighter nuclei (typically with mass number, A, less than 50) is larger than that of heavier nuclei.

36001469
Development of high-throughput analysis system using highly-functional organic polymer monoliths (in Japanese)
Umemura, Tomonari*; Kojima, Norihisa*; Ueki, Yuji
Bunseki Kagaku 57(7), p.517-529(2008) ; (JAEA-J 04761)

The growing demand for high-throughput analysis in the current competitive life sciences and industries has promoted the development of high-speed HPLC techniques and tools. As one of such tools, monolithic columns have attracted increasing attention and interest in the last decade due to the low flow-resistance and excellent mass transfer, allowing for rapid separations and reactions at high flow rates with minimal loss of column efficiency. In the present paper, recent progress in the development of organic polymer monoliths is discussed. Especially, the procedure for the preparation of methacrylate-based monoliths with various functional groups is described. Furthermore, the performance of the produced monoliths is demonstrated through the results for (1) rapid separations of alkylbenzenes at high flow rates, (2) flow-through enzymatic digestion of cytochrome c on a trypsin-immobilized monolithic column, and (3) separation of the tryptic digest on a reversed-phase monolithic column.

36001470
Hydrogeological investigations of surface-based investigation phase of Horonobe URL project (in Japanese)
Kurikami, Hiroshi; Takeuchi, Ryuji; Yabuuchi, Satoshi; Seno, Shoji*; Tomura, Goji; Shibano, Kazunori; Hara, Minoru; Kunimaru, Takanori
Doboku Gakkai Rombunshu, C 64(3), p.680-695(2008) ; (JAEA-J 04762)

Japan Atomic Energy Agency has been conducting the Horonobe Underground Research Laboratory (URL) project in Horonobe, Hokkaido, as a part of the research and development program on geological disposal of high-level radioactive waste. This paper shows the results of hydrogeological investigations in the surface-based investigation phase of the project. Hydrological and meteorological investigations show that the infiltration rates of the drainage basins varies and that the infiltration rate depends on the flora and the topography. The hydraulic tests using the deep boreholes reveals that hydraulic conductivity of the scale of a few decameters to a hundred meter varies widely and decreases with depth in the same formation, while the laboratory hydraulic tests suggest that hydraulic conductivity of the intact rock is influenced by the stress history. The hydraulic tests and the long-term monitorings of hydraulic pressure clarify relatively high pressure in the deep underground. Furthermore, groundwater flow analysis shows that the groundwater in and around the URL area flows regionally from the east to the west and depends locally on the geography and geology.

36001471
Geochemistry of the Tono uranium deposit and surrounding area (in Japanese)
Sasao, Eiji; Mizuno, Takashi
Fisshon, Torakku Nyusureta (20), p.27-29(2007) ; (JAEA-J 04763)

36001472
Fission track ages of the Miocene Mizunami, Iwamura and Kani Groups in the eastern part of the Setouchi Province, central Japan (in Japanese)
Sasao, Eiji; Danhara, Toru*; Iwano, Hideki*
Fisshon, Torakku Nyusureta (20), p.42-43(2007) ; (JAEA-J 04764)

36001473
Mutation bleeding of soy sauce brewing microorganisms using ion beams (in Japanese)
Toyoshima, Yoshiyuki*; Tanaka, Hisaki*; Akagawa, Takumi*; Yamazaki, Tatsuo*; Sato, Katsuya; Hase, Yoshihiro; Narumi, Issei
Hoshasen To Sangyo (119), p.22-26(2008) ; (JAEA-J 04765)

36001474
Development of nuclear decay databases used in nuclear medicine and radiation protection (in Japanese)
Endo, Akira
Isotope News (654), p.2-6(2008) ; (JAEA-J 04766)

36001475
Development of digital low level rf system (in Japanese)
Michizono, Shinichiro*; Anami, Shozo*; Katagiri, Hiroaki*; Fang, Z.*; Matsumoto, Toshihiro*; Miura, Takako*; Yano, Yoshiharu*; Yamaguchi, Seiya*; Kobayashi, Tetsuya
Kasokuki 5(2), p.127-136(2008) ; (JAEA-J 04767)

One of the biggest advantages of the digital low level rf (LLRF) system is its flexibility. Owing to the recent rapid progress in digital devices (such as ADCs and DACs) and telecommunication devices (mixers and IQ modulators), digital LLRF system for accelerators becomes popular in these 10 years. The J-PARC linac LLRF system adopted cPCI crates and FPGA based digital feedback system. After the successful operation of J-PARC linac LLRF system, we developed the STF (ILC test facility in KEK) LLRF system. The future R&D projects (ILC and ERL) are also described from the viewpoints of LLRF.

36001476
The Frontiers of condensed matter science advanced by J-PARC (in Japanese)
Fujii, Yasuhiko; Arai, Masatoshi; Kadono, Ryosuke*; Kanaya, Toshiji*; Kamiyama, Takashi*; Niimura, Nobuo*; Nojiri, Hiroyuki*; Noda, Yukio*; Yagi, Takehiko*; Yamada, Kazuyoshi*
Kotai Butsuri 43(7), p.441-450(2008) ; (JAEA-J 04768)

36001477
Fuel cladding materials R&D for high burn-up operation (in Japanese)
Ukai, Shigeharu*; Inoue, Masaki; Kimura, Akihiko*
Materia 47(9), p.450-454(2008) ; (JAEA-J 04769)

Various oxide dispersion strengthened ferritic steels are reviewed in "Materia Japan" issued by the Japan Institure of Metals. The steels have been developed for sodium cooled fast reactors under the Fast Reactor Cycle Technology Development (FaCT) project and for lead-bismuth and super critical water cooled reactors under the innovative nuclear research and development program. Alloy designing, manufacturing process and mechanical properties of the steels are briefly described.

36001478
Structural materials development for sodium cooled fast reactor (in Japanese)
Aoto, Kazumi
Materia 47(9), p.459-463(2008) ; (JAEA-J 04770)

To demonstrate its expected plant performance, now, JAEA is making efforts to develop some new structural materials for advanced sodium cooled loop type fast reactor(JSFR), which is assiduously being developed by also JAEA. SUS316 fast reactor grade and high chromium ferritic steel developed for fast reactor application will be applied to JSFR's reactor vessel and coolant system containing piping system and several main components. In this report, the history, the present status and the remained problems of their developments are introduced.

36001479
Rapid separation of alpha-emitting nuclides in radioactive waste (in Japanese)
Hoshi, Akiko; Watanabe, Koichi; Fujiwara, Asako; Haraga, Tomoko; Kameo, Yutaka; Nakashima, Mikio; Takebe, Shinichi
Nippon Genshiryoku Gakkai Wabun Rombunshi 7(3), p.177-185(2008) ; (JAEA-J 04771)

The simple and rapid separation method was developed for actinides in the low-level radioactive waste. Extraction chromatographic columns were used for the separation of U, Np, Pu, Am, and Cm in the solution of the simulated solidified product and the simulated waste solution. In the investigation of separation procedure, it was tried to construct the scheme with the relatively non-corrosive reagents aiming to apply to the routine analysis of the radioactive waste. Recoveries and decontamination factors of actinides in the solution of simulated waste were high enough to determine of actinides in radioactive waste by alpha-spectrometry, mass spectroscopy. The time required of the separation operation was 2-3 hours. The chromatographic method was applied to analysis of actinide in actual waste solution, high recoveries and decontamination factors were obtained, which indicated that the extraction chromatographic separation method would be adopted as a simple and rapid separation method of actinide in waste.

36001480
Safety assessment of VHTR hydrogen production system against fire, explosion and acute toxicity (in Japanese)
Murakami, Tomoyuki; Nishihara, Tetsuo; Kunitomi, Kazuhiko
Nippon Genshiryoku Gakkai Wabun Rombunshi 7(3), p.231-241(2008) ; (JAEA-J 04772)

Japan Atomic Energy Agency has been developing a nuclear hydrogen production system by using heat from the Very High Temperature Reactor (VHTR). This system will handle a large amount of combustible gas and toxic gas. The risk from a fire, an explosion and an acute toxic exposure caused by an accident of chemical material leakage at the hydrogen production system is assessed. It is an important subject in design to ensure the safety of the nuclear plant and the risk for the public health to be sufficiently small. This report provides the basic policy about the safety evaluation on the accident of the fire, the explosion and the toxic material release from the hydrogen production system near the nuclear plant. Based on this policy, we performed a safety analysis of the GTHTR-300C. This analysis provides us with useful information about a separation distance from the nuclear plant to the hydrogen production system and a prospect that the accident of the hydrogen production system does not significantly increase a risk for the public.

36001481
Hydrogen production by high-temperature gas-cooled reactor; Conceptual design of advanced process heat exchangers of the HTTR-IS hydrogen production system (in Japanese)
Sakaba, Nariaki; Ohashi, Hirofumi; Sato, Hiroyuki; Hara, Teruo; Kato, Ryoma; Kunitomi, Kazuhiko
Nippon Genshiryoku Gakkai Wabun Rombunshi 7(3), p.242-256(2008) ; (JAEA-J 04773)

Nuclear hydrogen production is necessary in an anticipated hydrogen society that demands massive quantity of hydrogen without economic disadvantage. Japan Atomic Energy Agency (JAEA) has launched the conceptual design study of a hydrogen production system with a near-term plan to connect it to Japan's first high-temperature gas-cooled reactor HTTR. The candidate hydrogen production system is based on the thermochemical water-splitting iodine-sulphur (IS) process. The heat of 10 MW that approximately 900°C, which can be provided by the secondary helium from the intermediate heat exchanger of the HTTR, is the energy input to the hydrogen production system. The paper describes the recent progresses made in the conceptual design of advanced process heat exchangers of the HTTR-IS hydrogen production system. A new concept of sulphuric acid decomposer is proposed that integrates three separate functions of sulphuric acid decomposer, sulphur trioxide decomposer and process heat exchanger in the previous design. A new mixer-settler type of Bunsen reactor is also designed that integrates three separate functions of Bunsen reactor, phase separator, and pump in the previous design. The new concepts are expected to result in improved economics through construction and operation cost reductions because the number of process equipment and complicated connections between the equipment has been substantially reduced.

36001482
Development of worldwide version of system for prediction of environmental emergency dose information; WSPEEDI 2nd version (in Japanese)
Terada, Hiroaki; Nagai, Haruyasu; Furuno, Akiko; Kakefuda, Toyokazu; Harayama, Takaya*; Chino, Masamichi
Nippon Genshiryoku Gakkai Wabun Rombunshi 7(3), p.257-267(2008) ; (JAEA-J 04774)

The second version of WSPEEDI (WSPEEDI-II) which has functions to predict the radiological impact of nuclear accident abroad on Japan by quick calculations of air concentration, surface deposition and radiological doses is developed. WSPEEDI-II has the following functions for practical use. (1) High performance prediction of atmospheric dispersion of radionuclides from local to regional ranges with appropriate resolutions by introducing non-hydrostatic atmospheric dynamic model. (2) Source term estimation by coupling calculation results and monitoring data for the case that no source information is available from abroad. (3) On-line prediction data exchanges with major emergency response systems in the United States and Europe with the similar functions as WSPEEDI-II. (4) Web-based graphical user interface system for easy operation of WSPEEDI-II. (5) Preset East-Asian database for the quick start against a nuclear accident in Eastern Asia. This paper describes these new functions.

36001483
Development of fluorescent liquid penetrant test equipment (in Japanese)
Yoshinaka, Kazuyuki; Otsuka, Masahiro*; Hoshino, Masato; Kikuchi, Kenji; Kawata, Tsuyoshi; Taki, Kiyotaka
Nippon Genshiryoku Gakkai Wabun Rombunshi 7(3), p.268-279(2008) ; (JAEA-J 04775)

The fluorescent liquid penetrant test equipment, for welding part in the evaporator for phosphate liquid waste generated by solvent waste treatment at Tokai reprocessing plant, was developed. It is composed of CCD camera and UV light for observation, sprinkling nozzles for fluorescent liquid, washing water and drying air, and positioning mechanism, which could be arranged position of the equipment to inspection object by 3 axes operation, insert length, bending angle and turn angle. Also, the equipment could be inserted by way of the nozzle, which inside diameter is 60 mm, into the evaporator for inspection. It was confirmed that it could be observed the standard faults, which was defined in JIS, by the equipment. Then, fluorescent liquid penetrant test for the evaporator, which has treated phosphate liquid waste for 18 years, and which heating temperature was about 105 centigrade degree, was done. As the result of the test, it was not observed fault in the evaporator.

36001484
Numerical analysis of platinum group particle behavior in vitrification melter (in Japanese)
Kawamura, Takumi*; Ito, Kei; Sakai, Takaaki; Nakajima, Masayoshi; Fujiwara, Koji; Oshima, Hiroyuki
Nippon Genshiryoku Gakkai Wabun Rombunshi 7(3), p.297-307(2008) ; (JAEA-J 04776)

In a vitrification process of high level radio-active liquid wastes, platinum group particles are mixed into molted glass and convected with the glass flow in vitrification melters. Though behaviors of the particles in the melters should be investigated to establish efficient melter operation, difficulties on observations in the high-radioactive melters have prevented enough investigation. In this paper, we present a numerical analysis method to evaluate the particles behaviors. Since thermal convection of the molten glass, electrical potential and particle distribution are interacting each other, we coupled these physical behaviors to evaluate the melter status with high accuracy. The simulation results for ten batches of operation showed that an effective discharge of the particles can be achieved as well as the mock-up experiments did. These results imply that our numerical method can evaluate transient behaviors of the platinum group particles in vitrification melters.

36001485
Toward commercialization of FBR cycle, 2 (in Japanese)
Mizuta, Shunji; Chikazawa, Yoshitaka; Washiya, Tadahiro; Suzuki, Masahiro
Nippon Genshiryoku Gakkai-Shi 50(10), p.624-629(2008) ; (JAEA-J 04777)

36001486
How hot does the wall get? (in Japanese)
Maki, Koichi*; Konno, Chikara
Nippon Genshiryoku Gakkai-Shi 50(10), p.649-653(2008) ; (JAEA-J 04778)

Neutrons produced by the fusion reaction generate secondary neutrons and γ-rays through interaction with materials of divertor, first wall and blanket. Target nuclei are recoiled by the interaction with these neutrons. At the micro level the recoiled nuclei disarray lattice arrangement and cause material damage if the recoil energy is larger than constraint energy of lattice. Here we will explain how the nuclear interactions change to heat and make radiation damage to materials.

36001487
Residual stress measurement with oscillation method of an Aluminum alloy forged part with coarse grains by neutron diffraction (in Japanese)
Saito, Toru*; Suzuki, Hiroshi; Ishibashi, Toshihiro*; Tomota, Yo*
Nippon Kikai Gakkai Rombunshu, A 74(744), p.1118-1125(2008) ; (JAEA-J 04779)

The residual stresses in a forged part made of an aluminum alloy with grain size of approximately 1.0 mm were determined by neutron diffraction where the oscillation method was employed. An optimal range of the oscillation is discussed from the relations between the gauge volume and the number of crystal grain. It is found that the stress measurement could be performed with the oscillation range of ±3 degrees if 1000 grains exist in a gauge volume. The influence of diffraction plane reveals that adoption of (311) requires smaller oscillation angle than (111), (220) or (200). The hydrostatic tensile stress of about 100 MPa was observed inside the part, which was caused by thermal misfit strains caused during cooling after the heat treatment.

36001488
The Nucleosynthetic signatures of the first star survivors among hyper metal-poor stars with [Fe/H] < -4.5
Suda, Takuma*; Komiya, Yutaka*; Nishimura, Takanori*; Iwamoto, Nobuyuki; Aikawa, Masayuki*; Fujimoto, Masayuki*
AIP Conference Proceedings 1016 , p.43-48(2008) ; (JAEA-J 04781)

The first stars in our Universe are the useful probes for the star formation history in the very early Universe. In order to identify these survivors, we should consider the effect of changing surface abundances during their long lives. The surface abundances are modified by the accretion of gas from the interstellar matter and/or the binary mass transfer. The latter can affect the abundance pattern through the evolution of primary star that experienced the internal mixing and dredge-up during thermally pulsating AGB. The top three of the iron deficient stars are reported as the candidates of the first stars. These stars have [Fe/H] < -4.5 and share the common feature of large enhancement of C. We argue that these abundance patterns are testified to the evolutionary characteristics of the first stars with low- and intermediate-mass by trying to constrain the mass of primary under the assumption that they were the survivors of secondary stars in the binary system when they were born.

36001489
Lithium synthesis in low metallicity AGB stars
Iwamoto, Nobuyuki
AIP Conference Proceedings 1016 , p.127-133(2008) ; (JAEA-J 04782)

We evolve thermally pulsing AGB star models in the mass of 1-8M_ʘ. The metallicity is assumed to be [Fe/H] ∼ -3. The 1 and 2M_ʘ AGB models produce Li in an H-flash event. The occurrence of this event is associated with the ingestion of protons from the overlying H-rich envelope into the He-flash driven convective shell during thermal pulse phase. The resulting Li abundances are higher than the primordial one. The present investigation also confirms the efficient production of Li by the HBB in the intermediate-mass AGB stars. If these AGB stars belong to a binary system with a low-mass companion, mass loss from the primary AGB star transfers the materials enriched in Li to the surface of the secondary star and makes the surface composition Li-rich. The nucleosynthesis of the other light elements is also followed until the end of the AGB phase. We find that the yields of the low metallicity AGB stars well reproduce the abundance patterns of extremely metal-poor stars.

36001490
Ultracentrifuge experiment on an Mg-Cd order-disorder alloy
Ono, Masao; Iguchi, Yusuke*; Bagum, R.*; Fujii, Kimio; Okayasu, Satoru; Esaka, Fumitaka; Mashimo, Tsutomu*
AIP Conference Proceedings 973 , p.476-481(2008) ; (JAEA-J 04783)

We had realized atomic-scale graded structures in several miscible alloys by ultracentrifuge experiment. In this study, we performed an ultracentrifuge experiment on a MgCd order-disorder alloy at disordered state of solid solution. The experimental conditions were as follows: maximum acceleration: 610,000 g, temperature: 400°C, composition: Mg:Cd=50:50at%, time duration: 60 h). We investigated the crystal state of the centrifuged sample that had ordered from the disorder state of atomic-scale graded structure. It was found that the graded structure was formed in the centrifuged sample, in which Cd content continuously increased in the direction of gravitational field. It was also found that the different peaks from the starting state appeared in X-ray diffraction patterns of the centrifuged sample. We will present details at the session.

36001491
Forced convection heat transfer of subcooled liquid nitrogen in horizontal tube
Tatsumoto, Hideki; Shirai, Yasuyuki*; Hata, Koichi*; Kato, Takashi; Shiotsu, Masahiro*
AIP Conference Proceedings 985 , p.665-672(2008) ; (JAEA-J 04784)

The knowledge of forced convection heat transfer of liquid hydrogen is important for the cooling design of a material of a cold neutron moderator. An experimental apparatus that obtain forced flow without a pump was developed. As a first step of the study, the forced flow heat transfer of subcooled liquid nitrogen in a horizontal tube, instead of liquid hydrogen, was measured for the pressures (0.3 to 2.5 MPa). The inlet temperature was varied from 78 K to around its saturation temperature. The flow velocity was varied from 0.1 to 7 m/s. The heat transfer coefficients in non boiling region and the DNB heat fluxes were higher for higher flow velocity and higher subcooling. The measured values of Nu/Pr^0.4 in non-boiling region were proportional to Re to the power of 0.8. With decrease in Re, they approached a constant value corresponding to that in a pool of liquid nitrogen. The correlation of DNB derived here can describe the experimental data within 15% difference was derived.

36001492
Thermal stress analysis for a transfer line of hydrogen moderator in J-PARC
Tatsumoto, Hideki; Teshigawara, Makoto; Aso, Tomokazu; Otsu, Kiichi; Maekawa, Fujio; Kato, Takashi
AIP Conference Proceedings 985 , p.1225-1232(2008) ; (JAEA-J 04785)

In JSNS, cryogenic hydrogen at supercritical pressure is selected as a moderator material. Three kinds of hydrogen moderator are installed to provide higher neutronic performance. The transfer lines around the moderators should be changed every 6 years due to its radiation damage. The detachment of the transfer line will be only performed by a hands-on. Therefore, minimum pipe size and elbow-type bend sections are installed to reduce the radiation dose by the radiation streaming. Some spacers are installed so as to avoid touching the hydrogen pipe to the outer vacuum pipe due to thermal shrinkage. In the design, we should consider mechanical stress concentration, deformation, and, touching between the pipes due to the thermal shrinkage at the cryogenic hydrogen temperature. The appropriate locations of spacers to keep the thermal stress below an allowable stress and to avoid touching between the pipes were determined.

36001493
Modeling of radionuclide migration through fractured rock in a HLW repository with multiple canisters
Lim, D.-H.*; Uchida, Masahiro; Hatanaka, Koichiro; Sawada, Atsushi
Materials Research Society Symposium Proceedings, Vol.1107 , p.567-575(2007) ; (JAEA-J 04786)

An integrated numerical model for groundwater flow and radionuclide migration analyses in a water-saturated HLW repository with a multiple-canister configuration is developed by incorporating the heterogeneity of fractured host rock based on the previous multiple-canister model. The current model enables to investigate the effects of heterogeneous fractured host rock on water flow and nuclide migration for the different configurations of multiple canisters, and to optimize the repository design parameters in terms of release of nuclides from the repository.

36001494
Illustration of HLW repository performance; Using alternative yardsticks to assess modeled radionuclide fluxes
Miyahara, Kaname; Kato, Tomoko
Materials Research Society Symposium Proceedings, Vol.1107 , p.673-680(2008) ; (JAEA-J 04787)

Radionuclide fluxes can only be estimated on the basis of models. H12 generic conceptual model for radionuclide transport pathway with conservatively simplified assumptions for geological structures is chosen for this purpose; each waste package is hypothetically assumed to be located 100 m from the downstream major water-conducting fault (MWCF). All radionuclides released from the repository are assumed to migrate upwards through the MWCF, traveling shortest distance to the biosphere. At discharge point from the MWCF to aquifer, these fluxes are compared with fluxes of natural radionuclides in corresponding groundwater flow by conservatively assuming that a groundwater flow rate at the depth of repository is prevail in shallower depth up to the aquifer. This yardstick does not include any geological processes in the surface environment which are practically independent of radionuclide migration processes from the repository up to the discharge point. This paper discusses the relevance of this yardstick to illustrate the effectiveness of barrier performance.

36001495
R&D supporting the technology for safe and practical HLW disposal in Japan
Seo, Toshihiro; Sasao, Eiji; Notoya, Shin; Shimizu, Kazuhiko
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM) , 6p.(2008) ; (JAEA-J 04788)

JAEA has promoted research and development of HLW disposal technology to contribute to both implementation and safety regulation. This R&D covers the geological environment, repository engineering and performance assessment. At two underground laboratories (Mizunami and Horonobe), surface-based investigations have been completed, and the excavation of shafts and drifts is underway. A complementary study of natural disruptive phenomena, such as volcanism and faulting, has also been conducted. In the ENTRY and QUALITY research facilities, the development of engineering technologies with associated advanced models and databases for quantification of the long-term evolution of the near-field has been carried out. To integrate these R&D activities and manage the huge amount of data that they produce, JAEA has initiated a novel project to develop an advanced knowledge management system which will provide a technical knowledge base for supporting both implementers and regulators.

36001496
Radiological assessment of multilateral radioactive effluents in the Pacific Ocean
Nakano, Masanao; Takeishi, Minoru
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM) , 6p.(2008) ; (JAEA-J 04789)

The liquid effluent has been discharged from each nuclear fuel cycle facility in mainly industrially advanced nations with authorization. Since the safety assessment confirms that environmental impact from each facility would be small enough, it was not necessary to assess the effect of the multilateral radioactive effluents. But it will be necessary to quantify the radiological impact between plural countries due to the increase of interest to the global environment and of demand on nuclear energy in the world. In this study, the long-term and multilateral environmental radiological assessment from tritium discharge by effluents from nuclear fuel cycle facilities in the world was carried out. Then, collective and effective doses were evaluated in case of intake of marine products. Additionally, an assessment from the nuclear testing in the atmosphere was carried out. As a result, the concentration and dose level was confirmed not to become an issue for global scale, even if Rokkasho reprocessing plant operates with full scale.

36001497
Advanced LWR concept with hard neutron spectrum (FLWR) for realizing flexible plutonium management
Uchikawa, Sadao; Okubo, Tsutomu; Nakano, Yoshihiro; Kobayashi, Noboru
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM) , 6p.(2008) ; (JAEA-J 04790)

An advanced LWR concept with hard neutron spectrum (FLWR) has been proposed in order to ensure sustainable energy supply in the future based on the well-experienced LWR technologies. The FLWR is essentially a BWR-type reactor, in which the moderation of neutron in the core is reduced by use of the hexagonal-shaped fuel assemblies with the triangular-tight-lattice fuel rod configuration. The core design concept of FLWR is to realize effective and flexible utilization of uranium and plutonium resources by two stages, corresponding to the advancement of the fuel cycle technologies and related infrastructures. The core in the first stage of FLWR aims at intensive utilization and preservation of plutonium based on the experiences of the current LWR and MOX utilization, and the one in the second stage realizes sustainable multiple plutonium recycling with a high conversion ratio over 1.0. The present paper summarizes the recent core design studies of FLWR.

36001498
Development of a neutronics design accuracy evaluation solver for next generation reactor physics analysis code system MARBLE
Yokoyama, Kenji; Numata, Kazuyuki*; Hazama, Taira; Ishikawa, Makoto
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM) , 6p.(2008) ; (JAEA-J 04791)

The new solver for cross section adjustment and design accuracy evaluation has been developed for the new reactor physics analysis code system, MARBLE. In this development, object-oriented design was applied for achieving software extendibility. The new solver was successfully designed to easily add a uncertainty prediction method. This extendibility was confirmed by implementing the extended bias method. The new solver reproduces all functions of the conventional code system and can be used as standard solver for cross section adjustment and design accuracy evaluation in MARBLE.

36001499
Reliability evaluation of SPEEDI's prediction by comparison with calculated results based on meteorological observation data
Rintsu, Yuko*; Serizawa, Shigeru*; Yamazaki, Tetsuo*; Umeyama, Nobuaki*; Moriuchi, Shigeru*; Handa, Hiroyuki*; Onishi, Ryoichi*; Takemura, Morio*; Chino, Masamichi; Nagai, Haruyasu; Yamazawa, Hiromi*
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM) , 6p.(2008) ; (JAEA-J 04792)

36001500
Current status on fuel cycle system of Fast reactor Cycle Technology Development (FaCT) project in Japan
Funasaka, Hideyuki; Nakamura, Hirofumi; Namekawa, Takashi
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM) , 6p.(2008) ; (JAEA-J 04793)

On the FaCT project in Japan, six development issues for the advanced aqueous reprocessing system are identified. Crystallization is the one of the major technologies to recover a large amount of uranium from the dissolver solution. The residual solution is loaded to the extraction process for U, Pu and Np co-recovery. Raffinate solution from the extraction process contains FP and MA, where MA is extracted by chromatography. These processes are expected to be more efficient in costs, wastes management, and the plutonium proliferation. As for the fuel fabrication technology, six development issues are identified. The source powder preparation technology of the conversion and granulation process is the most essential for the simplified pelletizing method technology. Remote operation and remote maintenance technique is essential to handle the low decontaminated TRU fuel in a hot cell. Current development status and plan of this integrated system until around 2015 is reported.

36001501
Nuclear demonstration program of hydrogen production using the HTTR; HTTR-IS program
Sakaba, Nariaki; Sato, Hiroyuki; Ohashi, Hirofumi; Tachibana, Yukio; Kunitomi, Kazuhiko
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM) , 6p.(2008) ; (JAEA-J 04794)

Japan Atomic Energy Agency launched the HTTR-IS program which is a nuclear hydrogen production demonstration program using the Japan's first high-temperature gas-cooled reactor HTTR in 2005. It is expected to be the world's first demonstration of nuclear hydrogen. The candidate system of the hydrogen production is a thermochemical water splitting iodine sulphur process (IS process). The thermochemical water splitting process can produce massive quantity of hydrogen without carbon dioxide greenhouse gas emission. This paper focused on the key issues to be developed for the IS process to couple with the HTTR (HTTR-IS system). The key issues to be established are the safety philosophy for non-nuclear grade system as a conventional chemical system and simplification of the plant for an economic competitiveness. The conceptual safety study for non-nuclear system was carried out. The key elements were proposed which can exempt the IS process from "Prevention System 3" and identify abnormal events initiated from the IS process as external events. Also, the conceptual design study for integration of the components such as a Bunsen reactor and a sulphuric acid decomposer was carried out. Reduction of number of components was proposed by coupling with some of equipment. The proposed philosophy and its supporting technologies are expected to contribute economically for the commercialization of nuclear hydrogen.

36001502
Status and prospects of the FaCT project
Nagaoki, Yoshihiro; Kikuchi, Shin; Ichimiya, Masakazu
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM) , 6p.(2008) ; (JAEA-J 04795)

"Fast Reactor Cycle Technology Development (FaCT)" project has been conducted since 2006. In this project, design study and research and development (R&D) on innovative technologies for fast reactor (FR) cycle system are implemented in order to present the conceptual designs of commercial and demonstration facilities by 2015 and start operating demonstration fast reactor in 2025. The R&Ds has been stepped forward into the development stage to establish the realization of innovative technologies which bring excellent performance to fast reactor cycle system. The purpose of R&D by 2010 is to decide weather innovative technologies shall be adopted. So promoting R&D of FR, the project governance was organized. Furthermore, several possible R&D have been effectively carried out within the frameworks of international cooperation, such as GNEP, GIF, and INPRO.

36001503
"What-if?" calculations to illustrate fault-movement effects on a HLW repository
Miyahara, Kaname; Inagaki, Manabu; Kawamura, Makoto; Ebina, Takanori*
Proceedings of 2008 International High-Level Radioactive Waste Management Conference (2008 IHLRW) (CD-ROM) , p.593-599(2008) ; (JAEA-J 04796)

This paper illustrated how to conduct "what if?" calculations in a transparent manner based on a developed formal procedure in order to treat perturbations of disruptive fault movement on a HLW disposal system. Calculation cases are defined due to stepwise combination of loss of key safety functions as what if? assumptions. The calculation results show effectiveness and robustness of the multibarrier system, even considering the most extreme combination of what if assumptions.

36001504
Active chemistry control for coolant helium applying high-temperature gas-cooled reactors
Sakaba, Nariaki; Hamamoto, Shimpei; Takeda, Yoichi*
Proceedings of 4th International Topical Meeting on High Temperature Reactor Technology (HTR 2008) (CD-ROM) , 7p.(2008) ; (JAEA-J 04797)

Lifetime extension of high-temperature materials utilized, for instance, at the heat transfer tubes of the intermediate heat exchanger of high-temperature gas-cooled reactors is important because high-cost primary equipment will be continued its operation during reactor lifetime without replacing. Since lifetime of high-temperature materials almost depends upon the chemistry conditions in the coolant helium, it is necessary to establish an active chemistry control methods. This technology can maintain adequate chemical conditions during reactor operation. In the past, helium chemistry has been controlled by the passive chemistry control technology in which chemical impurity in the coolant helium removes as low concentration as possible, as does Japan's first high-temperature gas-cooled reactor HTTR. In this study, carbon deposition which could be occurred at the surface of the heat transfer tube and decarburization of the high-temperature material of Hastelloy XR were evaluated by referring the chemistry data obtained by the HTTR. In addition, the chemical composition to be maintained during the reactor operation in order to keep the structural integrity and thermal efficiency of the heat transfer tube was proposed by evaluating not only core graphite oxidation, but also carbon deposition and decarburization. It was also identified when the chemical composition could not keep adequately, injection of 10 ppm carbon monoxide could effectively control the chemical composition to the designated stable area where the high-temperature materials can keep their structural integrity beyond the assumed duration. The proposed active chemistry control technology is expected to contribute economically to the purification systems of the future very high-temperature reactors.

36001505
The Preliminary analysis of the loss of primary coolant flow test in the HTTR
Nakagawa, Shigeaki; Takamatsu, Kuniyoshi; Goto, Minoru; Takeda, Tetsuaki*; Nakao, Yasuyuki*
Proceedings of 4th International Topical Meeting on High Temperature Reactor Technology (HTR 2008) (CD-ROM) , 8p.(2008) ; (JAEA-J 04798)

Loss of primary coolant flow test is under planning by using the HTTR to demonstrate the inherent safety features during the accident condition such as the depressurization accident which is selected as the severest accident in the HTGR. All the gas circulators are tripped in the test and the position of all control rods keeps its initial one. Because the core temperature increases just after the loss of coolant flow, the reactor power decreases according to coolant flow decrease due to negative reactivity feedback effect and the reactor becomes subcritical. The reactor performance after becoming subcritical during the loss of coolant flow is subject to a reactivity balance of core temperature and xenon concentration changes. The loss of primary coolant flow test in the HTTR simulates the depressurization accident and the data obtained from the test is useful for the validation and improvement of the calculation code applied to the safety analysis in the future HTGR.

36001506
Demonstration of nuclear hydrogen production utilizing the Japan's HTTR; Control scheme evaluation of the HTTR-IS nuclear hydrogen production system
Sato, Hiroyuki; Sakaba, Nariaki; Sano, Naoki; Ohashi, Hirofumi; Tachibana, Yukio; Kunitomi, Kazuhiko
Proceedings of 4th International Topical Meeting on High Temperature Reactor Technology (HTR 2008) (CD-ROM) , 10p.(2008) ; (JAEA-J 04799)

One of the key technology requirements to achieve the nuclear hydrogen demonstration is the establishment of control scheme which harmonizes the reactor operation with chemical plant operation. This study focused on developing the control scheme to be considered in the HTTR-IS nuclear hydrogen production system, which are in case of (a) abnormal shut-down and (b) re-start-up of the IS process. The simulation results show that the impact of abnormal events initiated in the IS process on the reactor operation can be effectively minimized by the rapid initiation of diverter valves using model-based fault diagnosis method. Furthermore, the thermal shock to components in the IS process can be prevented in case of re-start-up operation of the IS process by controlling the helium gas flow-rate of primary and secondary cooling system.

36001507
Oxidation behavior of liquid sodium droplet before combustion; Dependency of initial temperature and oxygen fraction
Nishimura, Masahiro; Kamide, Hideki; Sugiyama, Kenichiro*; Shiro, Otake*
Proceedings of 7th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety (NUTHOS-7) (CD-ROM) , 12p.(2008) ; (JAEA-J 04800)

Liquid sodium is used as the coolant of the fast reactor (FR), because of its high thermal conductivity and wide temperature range of liquid phase. It is superior as thermal medium, however the chemical reactivity with water and oxygen is very high. Hence FR plants have been taking safety measures for these reactions. After the "Monju" sodium leak accident, it is desired that more physical and chemical understanding of reaction phenomena and more mechanistic analysis for the sodium fire from the view point of public acceptance. The purpose of this study is to understand oxidation behavior of a liquid sodium droplet precisely, which is a fundamental reaction of spray fire and is easy to observe the reaction interface. This study is also useful for the establishment of safety criterion to handle the remained non-burning sodium after the accident. The oxidation of a liquid sodium droplet was visualized by using a simple experimental setup and a high speed video camera. A sodium single droplet of ca. 50 mg was made at the tip of a nozzle in a combustion chamber. The oxidation was started by supply of oxygen and nitrogen mixture gas. The initial temperature of sodium droplet and the oxygen fraction in the atmosphere were selected as experimental parameters. It was shown that columnar oxides grew longer as initial temperature of sodium droplet was lower and oxygen fraction was lower. In addition, it was observed that sodium combustion with an orange light emission started from the tip of columnar oxides grown out from the droplet surface. These observations suggest the existence of mechanism that liquid sodium is drawn up from droplet to reaction interface by the capillary force caused in the porous oxides which are formed on the droplet surface.

36001508
Numerical calculation of fluid flow within a large-diameter piping with a short-radius elbow in JSFR
Aizawa, Kosuke; Yamano, Hidemasa; Kotake, Shoji; Fujimata, Kazuhiro*
Proceedings of 7th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety (NUTHOS-7) (CD-ROM) , 14p.(2008) ; (JAEA-J 04801)

The present study has numerically investigated using the STAR-CD code the fluid-flow characteristics within a large-diameter piping with a short-radius elbow, which is adopted in an advanced large-sized sodium-cooled fast reactor (named JSFR). This study reports the result of numerical steady-state calculations of the 1/3-scale experiment with 9.2m/s of velocity performed at the first step. Since the experiments have revealed that dominant fluctuating pressures were generated at the boundary of flow separation and reattachment point on the pipe wall, this study focused on the flow separation size as one of the flow characteristics. The calculation has reproduced the flow characteristics, such as the measured velocity profile in the flow separation region, by specifying appropriate analytical models and conditions. With the validated models, the effect of the coolant viscosity has also been investigated as well as the piping scale. In order to examine the disturbance at the piping inlet, the flow dynamics within the reactor vessel were also calculated by modeling an entire upper sodium plenum region including various components within the reactor vessel in the JSFR design. This upper plenum calculation had to reduce the spatial resolution within the hot-leg piping because of numerous computational meshes needed in this calculation. The plenum calculation has shown several vortexes and flow distortion at the hot-leg inlet. The hot-leg inlet flow condition obtained in the plenum calculation was interpolated for the calculation simulating the hot-leg piping, where the spatial resolution was better than in the plenum calculation. The numerical calculation under the reactor condition involving the inlet disturbance has indicated the flow separation size became smaller than that in no disturbance case. This calculation implies that the inlet disturbance may play an important role to mitigate the flow-induced vibration force in the flow separation region.

36001509
Study on thermal striping phenomena in triple-parallel jet; Transfer characteristics of temperature fluctuation in sodium and water based on conjugated numerical simulation
Kimura, Nobuyuki; Kamide, Hideki; Emonot, P.*; Nagasawa, Kazuyoshi*
Proceedings of 7th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety (NUTHOS-7) (CD-ROM) , 17p.(2008) ; (JAEA-J 04802)

A quantitative evaluation on thermal striping, in which temperature fluctuation due to convective mixing between hot and cold fluids causes thermal fatigue in structural components, is of importance for reactor safety. It is necessary for the quantitative evaluation to investigate occurrence and propagate processes of temperature fluctuation, e.g., decay of temperature fluctuation near structures and transfer of temperature fluctuation from fluid to structures. In Japan Atomic Energy Agency, an innovative sodium cooled fast reactor has been designed. The transfer characteristics of temperature fluctuation from fluid to structure in sodium are quite different from that in water. In order to realize the sodium cooled fast reactor, the clarification of the transfer characteristics of temperature fluctuation is of importance for the rational design against the thermal striping phenomena. In this study, sodium and water experiments of parallel triple jets configuration were performed. For these experiments, numerical simulations were carried out to evaluate the transfer characteristics of temperature fluctuation from fluid to structure. The analysis code, called Trio_U, used in the study has been developed at the CEA in France. The large eddy simulation model is incorporated in the code. Furthermore, the code can calculate fluid and structural domains simultaneously. In the simulations, the calculated time-averaged temperature distributions in fluid and structure were close to the experimental results in sodium and water. The power spectrum densities of temperature fluctuation in fluid and structure were also in good agreements between the experiments and calculations. Furthermore the calculated decay characteristics of temperature fluctuation from fluid to structure were in good agreements with the experimental results.

36001510
Flow-induced vibration of a large-diameter elbow piping in high reynolds number range; Random force measurement and vibration analysis
Hirota, Kazuo*; Ishitani, Yoshihide*; Nakamura, Tomomichi*; Shiraishi, Tadashi*; Sago, Hiromi*; Yamano, Hidemasa; Kotake, Shoji
Proceedings of 9th International Conference on Flow-induced Vibrations (FIV 2008) , 6p.(2008) ; (JAEA-J 04803)

The present study is intended to grasp flow-induced vibration characteristics in the piping by newly taken experimental data as well as to verify a vibration analysis tool with its data. It was found that a flow velocity-dependent periodic phenomenon with maximum random vibration force appears in the downstream region of the elbow. The Strouhal number of dominant pressure fluctuations in the downstream of elbow is estimated to be around 0.45. In addition, the validity of the analytical tool was confirmed by comparing between analysis and experiment.

36001511
Validation of Np-237 cross sections by analysis of BFS critical experiments with massively neptunium-loaded cores
Ishikawa, Makoto; Hazama, Taira
Proceedings of International Conference on Nuclear Data for Science and Technology (ND 2007), Vol.2 , p.817-820(2008) ; (JAEA-J 04804)

Three series of BFS critical experiments which loaded approximately 10 kg of ²³⁷Np -dioxide were analyzed to verify the performance of major libraries with ²³⁷Np nuclear data. The latest JENDL-3.3, ENDF/B-VII.0 and JEFF-3.1 showed satisfactory results from the ²³⁷Np data viewpoint; however some other major data such as ²³⁹Pu nu and fission, ²³⁸U μ and/or the sodium inelastic scattering cross-sections of some libraries may need re-evaluation. Further, the effect of integral experimental information to obtain better predictions of reactor core parameters was demonstrated by the cross-section adjustment method.

36001512
TRU recycling in BWR type reactor of FLWR with hard spectrum
Okubo, Tsutomu; Nakano, Yoshihiro; Fukaya, Yuji; Kobayashi, Noboru; Uchikawa, Sadao
Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR '08) (CD-ROM) , 3p.(2008) ; (JAEA-J 04805)

In order to ensure sustainable energy supply in the future based on the well-established LWR technologies, conceptual design studies on the innovative water reactor for flexible fuel cycle (FLWR) have been performed at JAEA. FLWR is a BWR type advanced LWR concept with the triangular tight-lattice core of uranium (U) and plutonium (Pu) mixed oxide (MOX) fuel rods. Accordingly, FLWR can achieve a high conversion ratio from U to Pu in the hard neutron spectrum core. This core characteristic is also suitable for recycling of Pu and/or the minor actinides (MA) based on the fuel recycling strategy. FLWR core consists of two concepts of HC-FLWR and RMWR with different conversion ratios. It has been confirmed that even in HC-FLWR with a lower conversion ratio around 0.85 TRU recycling with about 2% MA would be possible.

36001513
Overview of the activities of the OECD/NEA/NSC working party on nuclear criticality safety
Rugama, Y.*; Blomquist, R.*; Brady Raap, M.*; Briggs, B.*; Gulliford, J.*; Miyoshi, Yoshinori; Suyama, Kenya; Ivanova, T.*
Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR '08) (CD-ROM) , 5p.(2008) ; (JAEA-J 04806)

Over the years, substantial progress has been made in developing nuclear data and computer codes to evaluate criticality safety for nuclear fuel handling. This state-of-the-art knowledge also has an economic impact. Increased understanding of uncertainties in safety margins allow rational and more economical designs for manipulation, storage and transportation of fissile materials. In the mid-nineties, several activities related to criticality-safety were grouped together into the Working Party on Nuclear Criticality Safety. Six expert groups co-ordinate various activities that run the gamut from experimental evaluations to code and data inter-comparisons, for the study of static and transient criticality behaviors. The various reports produced by the expert groups attempt to establish practical rules and identify applicable tools when appropriate.

36001514
First 3-D calculation of core disruptive accident in a large scale sodium-cooled fast reactor
Yamano, Hidemasa; Tobita, Yoshiharu; Fujita, Satoshi; Maschek, W.*
Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR '08) (CD-ROM) , 8p.(2008) ; (JAEA-J 04807)

The present study attempted the first application of SIMMER-IV to a CDA in a large-scale SFR to draw event progression and to grasp key characteristics. Since the 3-D calculation requires much computation time, the SIMMER-IV calculation focused on the early stage of the transition phase in this study. The calculation result indicated mild event progression without recriticality. Compared to a small-scale SFR, it was found that the radial sloshing reactivity was not so significant in a large-scale SFR.

36001515
Development of JENDL actinoid file
Iwamoto, Osamu; Nakagawa, Tsuneo; Otsuka, Naohiko*; Chiba, Satoshi; Okumura, Keisuke; Chiba, Go
Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR '08) (CD-ROM) , 8p.(2008) ; (JAEA-J 04808)

Nuclear data for neutron induced reactions with actinides from Ac to Fm have been evaluated for JENDL Actinoid File (JENDL/AC). Almost all data in JENDL-3.3 have been updated based on available experimental data and using the newly developed theoretical model code CCONE. Integral benchmark tests for fission reactors are in progress using preliminary versions of JENDL/AC. The JENDL/AC will be released in 2008.

36001516
RELAP5 analysis of OECD/NEA ROSA Project experiment simulating a PWR small break LOCA with high-power natural circulation
Takeda, Takeshi; Asaka, Hideaki*; Nakamura, Hideo
Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR '08) (CD-ROM) , 8p.(2008) ; (JAEA-J 04809)

OECD/NEA ROSA Project experiment with the Large Scale Test Facility (LSTF) in JAEA was conducted simulating a PWR 1% cold leg small break LOCA with an assumption of high-power natural circulation due to failure of scram and total failure of high pressure injection system. The core power curve for the LSTF experiment was obtained by PWR analysis with coupled three-dimensional kinetics and thermal-hydraulics code SKETCH-INS/TRAC-PF1. A post-test analysis was performed against the obtained data by using JAEA-modified RELAP5/MOD3.2.1.2 code to validate the code predictability. The JAEA-modified RELAP5/MOD3.2.1.2 code was used by incorporating a break model that employs maximum bounding flow theory with a discharge coefficient of 0.61 for two-phase break flow. In the experiment, flow in hot legs became supercritical during two-phase natural circulation, causing the hot leg liquid level to be quite low. Liquid accumulation in steam generator U-tube upflow-side took place during reflux condensation mode. The RELAP5 code predicted reasonably well the overall thermal-hydraulic phenomena observed in the experiment, while it overpredicted the break flow rate.

36001517
Monju core physics test analysis with JAEA's calculation system
Takano, Kazuya; Sugino, Kazuteru; Mori, Tetsuya; Kishimoto, Yasufumi*; Usami, Shin
Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR '08) (CD-ROM) , 8p.(2008) ; (JAEA-J 04810)

Monju core physics test analysis was performed using JAEA's neutronics calculation system with various nuclear data libraries (JENDL-3.2, JENDL-3.3, JEFF-3.1, ENDF/B-VII) for the purpose to validate the JAEA's neutronics calculation system, which utilizes JENDL-3.3. Subsequent sensitivity analysis was carried out to clarify the cause of differences in calculation results among nuclear data libraries. It is found that the calculation results obtained by JENDL-3.3 and JAEA's neutronics analysis system showed good agreement with the measured values and its accuracy is identical or better than JEFF-3.1, ENDF/B-VII in most core characteristics. Thus, the validity of JAEA's neutronics analysis system with JENDL-3.3 was confirmed. From the sensitivity analysis, it was identified that Monju can be quite valuable for the verification of the cross sections of such high-order Pu isotopes as ²⁴⁰Pu and ²⁴¹Pu and also for the validity of temperature dependency of the self-shielding using its property as a power reactor.

36001518
MARBLE; A Next generation neutronics analysis code system for fast reactors
Yokoyama, Kenji; Hirai, Yasushi*; Tatsumi, Masahiro*; Hyodo, Hideaki*; Chiba, Go; Hazama, Taira; Nagaya, Yasunobu; Ishikawa, Makoto
Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR '08) (CD-ROM) , 8p.(2008) ; (JAEA-J 04811)

A development project of the next generation neutronics analysis code system, MARBLE, has been launched in JAEA. A software platform and common data models for fast reactor neutronics analysis were developed to realize the new system. At present, a fast reactor burnup calculation system, ORPHEUS, has been implemented in the MARBLE system. The new system reproduced benchmark results by the conventional code system and it reduced input data preparation works with the help of the capabilities supported by common data model packages. The new system was validated in an analysis of a burnup reactivity coefficient measured in the experimental fast reactor JOYO. These results show that MARBLE/ORPHEUS can be adopted as a new standard neutronics analysis system for fast reactors.

36001519
Japanese fast reactor program for homogeneous actinide recycling
Ishikawa, Makoto; Nagata, Takashi; Kondo, Satoru
Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR '08) (CD-ROM) , 8p.(2008) ; (JAEA-J 04812)

In Japan, the significance of the development of fast reactor (FR) cycle technology has been seriously recognized in the national fundamental nuclear energy policy. Further, nuclear energy as a whole is indispensable worldwide to meet the expansion of energy demand and the solution of environmental problem such as global climate change. Under such circumstances, Japan launched the FR Cycle Technology Development (FaCT) Project in 2006. In FaCT, the design study and the R&D on innovative technologies regarding the main concept are conducted in order to present the conceptual designs of demonstration and commercial FR cycle facilities by around 2015. The main purpose of the near-term R&Ds by 2010 is to judge whether adoption of innovative technologies is feasible. The R&D program on the innovative technologies will be further extended toward 2015, with the demonstration FR expected to be operated in 2025. The concept of the FR cycle system has various aspects from the viewpoints of safety and reliability, economy, sustainability (consisting of reduction of environmental burden, waste management and efficient utilization of uranium resource), and proliferation resistance. The homogeneous recycling of an entire amount of actinides has a significant advantage from these development targets. In the present paper, we will discuss about our scenario of the homogeneous actinide recycling in the FR cycle system, based on our recent studies in the FaCT Project. The studies on the scenario of nuclear energy policy, the management and development of minor actinide (MA)-bearing fuel, reactor physics related to MA-loaded FR cores, and typical nuclear design of MA-loaded FR cores have shown the feasibility to recycle all MA in the future FR-equilibrium society. Also presented are the R&D programs to demonstrate the homogeneous actinide recycling, which are extensively conducted as one of the key national projects in Japan, as well as utilizing international cooperation.

36001520
Three-dimensional depletion analysis of the axial end of a Takahama fuel rod
DeHart, M. D.*; Gauld, I. C.*; Suyama, Kenya
Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR '08) (CD-ROM) , 9p.(2008) ; (JAEA-J 04813)

Recent developments in spent fuel characterization methods have involved the development of several three-dimensional depletion algorithms based on Monte Carlo methods for the transport solution. However, most validation done to-date has been based on radiochemical assay data for spent fuel samples selected from locations in fuel assemblies that can be easily analyzed using two-dimensional depletion methods. This paper reports on the results of three-dimensional depletion calculations performed using the T6-DEPL depletion sequence of the SCALE 5.1 code system, which couples the KENO-VI Monte Carlo transport solver with the ORIGEN-S depletion and decay code, for a spent fuel sample that was extracted from the end region of the fuel rod.

36001521
Structure, composition and properties of lithium ceramic Li₂TiO₃+5% mole TiO₂ irradiated in WWR-K reactor for solid ceramic blanket of fusion reactor
Tazhibayeva, I. L.*; Kulsartov, T.*; Kenzhin, E. A.*; Maksimkin, O. P.*; Doronina, T. A.*; Silnyagina, N. S.*; Turubarova, L. G.*; Tsai, K. V.*; Zheltov, D. A.*; Kashirskiy, V. V.*; Chikhray, E. V.*; Shestakov, V. P.*; Kuykabaeva, A. A.*; Kawamura, Hiroshi; Tsuchiya, Kunihiko
Questions of Atomic Science and Technology; Series the Thermonuclear Fusion, 1 , p.3-11(2008) ; (JAEA-J 04814)

The paper contains and analyzes the results of integrated material studies of lithium ceramic Li₂TiO₃ + 5% mole TiO₂ irradiated in reactor WWR-K during 5,350 hours under controlled conditions taking into account effects of tritium generated in the course of irradiation. The changes in density, microstructure, phase and chemical composition, strength and microhardness were studies; lithium burn-up level and tritium residual content were defined. The significant influence of radiation-thermal impacts on structure and properties of ceramic samples were observed. It was shown that irradiation resulted in lithium ceramics softening, at that this effect depended on irradiation temperature. It was discovered the radiation change of phase composition of lithium ceramic.

36001522
Unique structures in yttrium trihydride at high pressure
Machida, Akihiko
SPring-8 Research Frontiers 2007 , p.58-59(2008) ; (JAEA-J 04815)

The pressure induced structural transition of yttrium tri-hydride YH₃ has been investigated by X-ray diffraction experiments under hydrostatic pressure at room temperature. The hexagonal metal lattice transforms to a face-centered cubic (fcc) one through an intermediate state, which appears at a wide pressure span of 12∼22 GPa. The high resolution diffraction patterns, which obtained by synchrotron radiation X-ray diffraction experiments, revealed that the intermediate structures are interpreted in terms of long-period stacking structures with the periodic arrangements of hexagonal-type (ABA) and fcc-type (ABC) stacking layers of the yttrium metals. These polytypes gradually transforms toward the fcc metal lattice with a successive increase in the fcc-type component upon compression. The hydrogen-hydrogen and hydrogen-metal interactions likely play a dominant role in the gradual hexagonal-fcc lattice conversion via the long-period polytypic structures.

36001523
Initial stress estimation of diatomaceous mudstone using hydraulic fracturing test (in Japanese)
Nakamura, Takahiro; Kato, Harumi*; Sanada, Hiroyuki; Sugita, Yutaka
Dai-12-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM) , p.297-303(2008) ; (JAEA-J 04816)

This paper shows the results of initial stress obtained from stress relief method, hydraulic fracturing technique and breakout analysis which have been carried out at 140 m niche as a part of the investigation of Horonobe Underground Research Project. The results of investigations are summarized as follows. Initial stress measuring has been tried by stress relief method, but none of the gluing of the gage plugs was successful because clayish slime stuck over the end of the borehole. The direction and value of initial stress obtained from hydraulic fracturing technique and breakout analysis was closely similar.

36001524
Observational construction and behavior measurements for underground research shaft excavation of the Horonobe Underground Research Laboratory project (in Japanese)
Yamazaki, Masanao; Morioka, Hiroshi*; Hatsuyama, Yoshihiro*; Tsusaka, Kimikazu
Dai-12-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM) , p.305-310(2008) ; (JAEA-J 04817)

The underground research shafts and drifts have been constructed in Horonobe by JAEA. The observational construction program to reflect the various data obtained by the shaft excavation for designing and construction was setted on and is being presently applied. The support design was carried out by numerical analysis considering the excavating liberaring power according to the excavation progress. But, it was clear that measurement data of lining stress in G.L.-121m included the influence of extra lining thickness and excavation of drifts in G.L.-140m. We report on the outline of the observational construction program and the result of analyzing the measurement data of the lining stress.

36001525
Estimation of convergence curves through shaft excavation in Horonobe underground research laboratory (in Japanese)
Tsusaka, Kimikazu; Yamazaki, Masanao; Hatsuyama, Yoshihiro*; Yamamoto, Takuya*
Dai-12-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM) , p.311-317(2008) ; (JAEA-J 04818)

Japan Atomic Energy Agency has constructed an underground research laboratory in Horonobe to establish the reliable engineering technologies related to geological disposal. At the end of March 2008, the ventilation and access shafts reached 161 m and 110 m in depth, respectively. During the shaft sinking, measurements of convergence and stress of support members are carried out in order to feed the results to the selection of the appropriate magnitude of support at deeper levels. In this paper, the authors clarified the depth distribution of the strength of rock and frequency of fracture on shaft wall and the relationship between the initial deformation rate and deformation ratio based on the convergence measurement.

36001526
Numerical simulation of rockmass behavior around the shaft excavated by short-step method (in Japanese)
Tani, Takuya*; Shimono, Masato*; Iwano, Masahiro*; Yamamoto, Takuya*; Yamazaki, Masanao; Sanada, Hiroyuki
Dai-12-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM) , p.319-324(2008) ; (JAEA-J 04819)

During the construction of the Horonobe URL shaft, some measurements have been carried out to verify the design and construction method in sedimentary soft-rock. The results obtained from the in-situ measurements at the G.L.-121 m show the unique behavior of surrounding rock masses. This paper reports the result of the numerical simulation of the behavior around the shaft excavation by short step-method. In the analysis using axisymmetric elastic FEM model, construction procedure including the high stiffness lining concrete is accurately followed and the deformation behavior around the shaft is well simulated. Consequently it is found that the excavation release ratio in the short step excavation method is different from one in the typical NATM tunnel excavation.

36001527
Design of management system for large-scale underground development aided intelligent technology, and its mounting (in Japanese)
Xu, Z.*; Matsui, Hiroya; Sato, Toshinori*; Itakura, Kenichi*; Yamachi, Hiroshi*
Dai-12-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM) , p.647-652(2008) ; (JAEA-J 04820)

Various data, such as investigation data, design data and/or field measured data arising during a course of the large-scale underground development are possible and important information, which can contribute to not only design and/or construction work but also maintenance of facilities. However, it is difficult to control and properly operate such enormous data throughout a long term included by an operation period of facilities. Authors developed management system for large-scale underground development system which adopted virtual reality technology and RDBMS as one answer for such problem. In addition, this system was applied experimentally to the Mizunami Underground Research Laboratory construction. This paper asks the validity of proposing technique, while the practice of design and mounting of the system is shown.

36001528
Mechanical property of Horonobe siliceous rock (in Japanese)
Sanada, Hiroyuki; Matsui, Hiroya; Fujii, Yoshiaki*
Dai-12-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM) , p.703-708(2008) ; (JAEA-J 04821)

This paper shows the result of rock mechanical investigations which have been carried out as a part of the investigations of Horonobe Underground Research Project. The results of the investigations are summarized as follows. Uniaxial compression and tensile strength of siliceous rock distributed in Wakkanai formation is larger than diatomaceous mudstone distributed in Koetoi formation. Stress-strain curve shows strain softening behavior from results of tri-axial compression test. Pore pressure and dilatancy behavior show different trends as compared with diatomaceous mudstone and siliceous rock.

36001529
Long-term behaviors of a tuunel in a sedimentary soft rock due to fluid-mechanical interaction (in Japanese)
Aoki, Tomoyuki*; Sanada, Hiroyuki; Jo, Mayumi*; Yamamoto, Takuya*; Matsui, Hiroya
Dai-12-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM) , p.709-716(2008) ; (JAEA-J 04822)

Long-term behaviors of a tunnel at great depth in sedimentary soft rocks are investigated based on pore fluid-mechanical interaction. Poroelastic parameters of diatomaceous and siliceous mudstones at the Horonobe URL site are determined from the tests proposed in this study using a triaxial test apparatus. The test procedures with their theoretical base are described. Coupled fluid-mechanical behaviors on circular and horse-shoe-shaped tunnels supported with shotcrete are numerically analyzed based on the theory of poroelasticity. Some long-term behaviors of rocks and supports peculiar to the fluid-mechanical interaction differing from creep behavior are found from the analysis results.

36001530
Excavation analysis of vertical shaft in sedimentary rock at great depth, taking into account variation in rock physical properties with depth (in Japanese)
Ogawa, Toyokazu*; Kinomura, Koji*; Aoki, Tomoyuki*; Yamamoto, Takuya*; Sanada, Hiroyuki; Matsui, Hiroya
Dai-12-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM) , p.933-940(2008) ; (JAEA-J 04823)

Japan Atomic Energy Agency is planning to conduct researches into geological disposal of high-level radioactive wastes in the Horonobe site located in Hokkaido, Japan. As part of the underground research facilities, two 500m-long vertical shafts have been constructed in tertiary sedimentary rocks since 2005. The surrounding rocks are known to exhibit strain-softening characteristics, necessitating appropriate modelling in the stability analysis. In addition the rocks physical properties often vary with depth. This study shows the results of three-dimensional numerical analysis of the ventilation shaft, taking the construction sequence and the variation of rock properties with depth into consideration.

36001531
Numerical simulation of borehole shape, focusing on strain localization (in Japanese)
Ogawa, Toyokazu*; Kinomura, Koji*; Aoki, Tomoyuki*; Yamamoto, Takuya*; Matsui, Hiroya; Sanada, Hiroyuki
Dai-37-Kai Ganban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM) , p.301-306(2008) ; (JAEA-J 04825)

36001532
Evaluation on stability of shaft during excavation, considerating strain softening behavior surrounding rock mass (in Japanese)
Kinomura, Koji*; Ogawa, Toyokazu*; Aoki, Tomoyuki*; Yamamoto, Takuya*; Matsui, Hiroya; Sanada, Hiroyuki
Dai-37-Kai Ganban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM) , p.307-312(2008) ; (JAEA-J 04826)

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JAEA > JAEA Library > JOPSS > Papers Published in Journals [Back Issues] > November 2008