Enhancement of the methodology of repository design and post-closure performance assessment for preliminary investigation stage, 2; Progress report on NUMO-JAEA collaborative research in FY2012 (Joint research)

Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Hayano, Akira; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.

JAEA-Research 2013-037, 455 Pages, 2013/12

JAEA-Research-2013-037.pdf:42.0MB

Following FY2011, JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, the tree diagram of methodology of groundwater travel time has been extended for crystalline rock, in addition, tree diagram for sedimentary rock newly has been organized. With regard to (2) study on scenario development, the existing approach has been improved in terms of a practical task, and applied and tested for near field focusing on the buffer. In addition, the uncertainty of some important processes and its impact on safety functions are discussed though analysis. With regard to (3) study on setting radionuclide migration parameters, the approaches for parameter setting have been developed for sorption for rocks and solubility, and applied and tested through parameter setting exercises for key radionuclides.

Enhancement of the methodology of repository design and post-closure performance assessment for preliminary investigation stage; Progress report on NUMO-JAEA collaborative research in FY2011 (Joint research)

Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Hayano, Akira; Mitsui, Seiichiro; Taniguchi, Naoki; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.

JAEA-Research 2012-032, 298 Pages, 2012/09

JAEA-Research-2012-032.pdf:33.68MB

JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation phase. The topics and the conducted research are follows; (1) Study on selection of host rock: in terms of hydraulic properties, items for assessing rock property, and assessment methodology of groundwater travel time has been organized with interaction from site investigation. (2) Study on development of scenario: the existing approach has been embodied, in addition, the phenomenological understanding regarding dissolution of and nuclide release from vitrified waste, corrosion of the overpack, long-term performance of the buffer are summarized. (3) Study on setting nuclide migration parameters: the approach for parameter setting has been improved for sorption and diffusion coefficient of buffer/rock, and applied and tested for parameter setting of key radionuclides. (4) Study on ensuring quality of knowledge: framework for ensuring quality of knowledge has been studied and examined aimed at the likely disposal facility condition.

Performance of a 4 Ge spectrometer for neutron capture cross section measurements

Oshima, Masumi; Hori, Junichi*; Harada, Hideo; Furutaka, Kazuyoshi; Koizumi, Mitsuo; Kitatani, Fumito; Toh, Yosuke; Kimura, Atsushi; Nakamura, Shoji; Igashira, Masayuki; et al.

Proceedings of International Conference on Nuclear Data for Science and Technology (ND 2007), Vol.1, p.603 - 606, 2008/05

Neutron capture cross sections of minor actinides and long-lived fission products are important for the R&D of innovative nuclear reactors. However, those data are rather poor both in quality and in quantity at present. Thus, we have started projects for neutron cross section measurements. We will construct an innovative -ray spectrometer consisting of Ge crystals and BGO shields. The neutron cross section measurements will be done at KUR linac and JAEA JRR-3M facilities, which will be extended at the high-intensity neutron source at J-PARC.

Coulomb excitation experiments at JAEA Tandem facility for the study of nuclear structure

Koizumi, Mitsuo; Toh, Yosuke; Osa, Akihiko; Kimura, Atsushi; Utsuno, Yutaka; Oshima, Masumi; Hayakawa, Takehito; Hatsukawa, Yuichi; Katakura, Junichi; Matsuda, Makoto; et al.

Proceedings of the International Workshop on Quark Nuclear Physics 2006, p.245 - 252, 2006/00

no abstracts in English

Hydrogen retention in divertor tiles used in JT-60 for hydrogen discharge period

Hirohata, Yuko*; Shibahara, Takahiro*; Tanabe, Tetsuo*; Arai, Takashi; Goto, Yoshitaka*; Oya, Yasuhisa*; Yoshida, Hajime*; Morimoto, Yasutomi*; Yagyu, Junichi; Masaki, Kei; et al.

Journal of Nuclear Materials, 337-339, p.609 - 613, 2005/03

https://doi.org/10.1016/j.jnucmat.2004.10.078

no abstracts in English

Transmission electron microscopy of redeposition layers on graphite tiles used for open divertor armor of JT-60

Goto, Yoshitaka*; Arai, Takashi; Yagyu, Junichi; Masaki, Kei; Kodama, Kozo; Miya, Naoyuki

Journal of Nuclear Materials, 329-333(1), p.840 - 844, 2004/08

https://doi.org/10.1016/j.jnucmat.2004.04.314

TEM and Selected Area Diffraction (SAD) were made on nm-structures of redeposition layers on graphite tiles used in the lower-X-point divertor of JT-60. The tiles were used in the 1988 experimental campaign in which 300 divertor discharges and 1500 limiter discharges were made. TEM observations were made at poloidal and/or toroidal sections at two positions on the inboard side of the inner-separatrix strike point. Layer structures in 0-6micron depths were correlated to the last 40-shots in the campaign. Columnar structures corresponded to divertor discharges of additional heating power below 10MW. Lamellar structures were due to limiter discharges or to the higher power divertor discharges. Carbon-Mo, Ti or carbon-Ni, Fe, Cr, Ti codeposition layers were ascribed to disruptive shots. From analyses on poloidal orientation of the column axes and graphene sheets composing columns, the observed columnar structures were ascribed to both low adatom-migration due to the low deposition temperatures and also to self-shadowing effects due to inclined incidence of carbon impurity ions.

Horonobe Underground Research laboratory Project Plans for Surface-based Investigations (Phase I)

Goto, Junichi; Hama, Katsuhiro

JNC TN5510 2003-002, 18 Pages, 2003/10

JNC-TN5510-2003-002.pdf:1.19MB

The Horonobe Underground Research Laboratory Project is an investigation project which is planned over 20 years. The investigations are conducted in three phases: investigations from the surface (PhaseI), investigations during construction of the underground facility (Phases2) and investigations using the facility (Phase3). Taking into account the results from the Second Progress Report on Research and Development for the Geological Disposal of HLW in Japan, research and development goals for the Horonobe URL project were re-defined.

Horonobe Underground Research Laboratory Project Plan of the Investigation Program for the 2003 Fiscal Year (2003/2004)

Goto, Junichi; Hama, Katsuhiro

JNC TN5510 2003-001, 19 Pages, 2003/08

JNC-TN5510-2003-001.pdf:3.79MB

The Horonobe Underground Research Laboratory Project is an investigation project which is planned over 20 years. The investigations are conducted in the three phases, investigations from surface (Phase 1), investigations during construction of the underground facility (Phase 2) and investigations using the facility (Phase 3). The 2003 fiscal year is the fourth year of the Phase 1 surface-based investigations.In the development of techniques to investigate the geological environment, geophysical, geological, surface hydrogeological and borehole investigations are carried out. Models of geological environment are constructed and revised based on the acquired data. In the development of monitoring techniques of the geological environment, long-term monitoring of groundwater pressure is continued in the previously equipped borehole. The long-term monitoring systems are also installed in the remaining boreholes, and measurement is subsequently started. Development of the remotely operated monitoring system (ACROSS) is continued. In the study on long-term stability of the geological environment, monitoring with seismographs, GPS and electromagnetic survey equipment is carried out. In the development of basis for engineering techniques in deep underground, basic design of the underground facility is defined. In the research and development on geological disposal, laboratory tests are continued on the transportation and emplacement equipment of engineered barrier, and on the reinforcement material to make detailed plans of the Phase 2 and 3 investigations. In the improvement of reliability on safety assessment methods, suitability of safety assessment methods is examined using the field and laboratory data. Design of the facility on the ground is defined, and development of the site for the underground laboratory is started. In the environmental survey, environmental monitoring is continued. Cooperation with domestic and overseas research institutes is proceeded.

Analyses of erosion and re-deposition layers on graphite tiles used in the W-shaped divertor region of JT-60U

Goto, Yoshitaka*; Yagyu, Junichi; Masaki, Kei; Kizu, Kaname; Kaminaga, Atsushi; Kodama, Kozo; Arai, Takashi; Tanabe, Tetsuo*; Miya, Naoyuki

Journal of Nuclear Materials, 313-316, p.370 - 376, 2003/03

https://doi.org/10.1016/S0022-3115(02)01354-5

Erosion and re-deposition were studied for graphite tiles from W-shaped divertor region of JT-60U in Jun. 1997 - Oct. 1998 periods in which more than 3000 D-D discharges were made with all-carbon wall with boronizations and inner-private flux pumping. On the outer divertor targets, erosion was dominant: maximum erosion depth of around 20 micrometers was measured, while on the inner targets, re-deposition was dominant: columnar structure layers and laminar/columnar-layered structures of maximum thickness around 60 micrometers were found. Through XPS analysis, compositions of the re-deposition layers at a around mid point on the inner target were 94 - 95 at% C, 3 - 4 at% B, and less than 0.6 at% O, Fe, Cr, and Ni. Boron is mainly bound to Carbon. No continuous deposition layers on the dome top/outer wing, while deposition layers were found on the inner wing. Observed in/out asymmetry is attributable to in/out asymmetry of plasma particle conditions in the divertor region.

Fracture side observation of the plasma facing material by SEM

Miyo, Yasuhiko; Goto, Yoshitaka*; Yagyu, Junichi; Masaki, Kei; Miya, Naoyuki

Heisei-15-Nendo Kiki, Bunseki Gijutsu Kenkyukai Hokoku, p.117 - 120, 2003/00

no abstracts in English