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Tokushima, Kazuyuki; Shirasu, Noriko; Hoshino, Kuniyoshi*; Ohara, Hiroshi*; Kurata, Masaki
Proceedings of Annual Topical Meeting on LWR Fuels with Enhanced Safety and Performance (TopFuel 2016) (USB Flash Drive), p.1055 - 1063, 2016/09
At the fuel assembly degradation stage in severe accidents, chemical features of the intermediate products are expected to be changed depending upon the accident progressions. These differences are originated from the differences in oxygen potential and temperature, and are highly important for evaluating the relocation and stratification progress of the fuel debris. Two types of sim-test with the different oxygen potentials were performed to investigate these tendencies. The chemical features of the intermediate materials used in the tests were determined from the observations for the control blade and channel box degradation in our previous study. The present results indicate that the U concentration in the metallic layer is largely varied depending upon the oxygen potential of the atmosphere. Also, when the B
C-Fe alloy, as of a typical intermediate product, coexists with UO
and Zr, the apparent red-ox reaction rate between UO and Zr are mitigated.
Hoshino, Takanori; Kitagaki, Toru; Yano, Kimihiko; Okamura, Nobuo; Ohara, Hiroshi*; Fukasawa, Tetsuo*; Koizumi, Kenji
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 6 Pages, 2015/05
Shibata, Akira; Ito, Masayasu; Takemoto, Noriyuki; Nakatsuka, Masafumi*; Ohara, Hiroshi*; Kodama, Mitsuhiro*; Tanimoto, Masataka; Tsuchiya, Kunihiko
JAEA-Technology 2011-034, 67 Pages, 2012/02
JAEA-Technology-2011-034.pdf:6.94MB
Reflector elements made from metal beryllium is widely used as neutron reflectors to increase neutron flux in test reactors. When beryllium reflector elements are irradiated by neutron, bending of reflector elements caused by swelling occurs, and beryllium reflector elements must be replaced in several years. In this report, investigation for non-destructive inspection method of metal Beryllium and experiments for Preliminary inspection to establish post irradiation examination method for research of characteristics of metal beryllium under neutron irradiation were reported.
Watahiki, Shunsuke; Saito, Takashi; Tsuchiya, Kunihiko; Ohara, Hiroshi; Iimura, Koichi
JAEA-Technology 2008-044, 42 Pages, 2008/06
JAEA-Technology-2008-044.pdf:5.43MB
This report is described for the development of nicrosil-nisil type multi-paired thermocouple which was usable at over 1000 degrees under the neutron irradiation environment. Developed nicrosil-nisil type multi-paired thermocouple has maximum 7 hot junctions in axial direction in a sheath. Though the design, trial production and out-pile tests, its productivity and electric performances were confirmed, and the production method was established.
Hoshino, Takanori; Yano, Kimihiko; Kaji, Naoya; Washiya, Tadahiro; Fukasawa, Tetsuo*; Ohara, Hiroshi*
no journal, ,
no abstracts in English
Yano, Kimihiko; Hoshino, Takanori; Kaji, Naoya; Washiya, Tadahiro; Fukasawa, Tetsuo*; Ohara, Hiroshi*
no journal, ,
A part of study on the management of fuel debris in unit 1-3 at Fukushima Dai-ichi Nuclear Power Station, it is suggested that solubilization of fuel debris for nitric acid by solution treatment with UO. It was experimentally confirmed that this process made insoluble (U,Zr)O, one of the major components, be dissoluble.
Tokushima, Kazuyuki; Shirasu, Noriko; Hoshino, Kuniyoshi*; Ohara, Hiroshi*; Kurata, Masaki
no journal, ,
At the fuel assembly degradation stage in severe accidents, chemical features of the intermediate products are expected to be changed depending upon the accident progressions. These differences are originated from the differences in oxygen potential and temperature, and are highly important for evaluating the relocation and stratification progress of the fuel debris. Two types of sim-test with the different oxygen potentials were performed to investigate these tendencies. The chemical features of the intermediate materials used in the tests were determined from the observations for the control blade and channel box degradation in our previous study. The present results indicate that the U concentration in the metallic layer is largely varied depending upon the oxygen potential of the atmosphere. Also, when the BC-Fe alloy, as of a typical intermediate product, coexists with UO and Zr, the apparent red-ox reaction rate between UO and Zr are mitigated.