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Shiina, Hidenori; Ono, Katsuto; Nishi, Masahiro; Uno, Kiryu; Kanazawa, Hiroyuki; Oi, Ryuichi; Nihei, Yasuo
Dekomisshoningu Giho, (61), p.29 - 38, 2020/03
The Research Hot Laboratory (RHL) in Japan Atomic Energy Agency (JAEA) was constructed in 1961, as the first one in Japan, to perform the examinations of irradiated fuels and materials. RHL consists of 10 heavy concrete cells and 38 lead cells. RHL contributed to research and development program in or out of JAEA for the investigation of irradiation behavior for fuels and nuclear materials. However, RHL is the one of target as the rationalization program for decrepit facilities in former Tokai institute. Therefore the decommissioning works of RHL started on April 2003. The dismantling of 12 lead cells has been progressing since 2010. The dismantling procedure of lead cells was performed in the following order. The peripheral equipment in lead cells were removed and contamination survey of the inner surface of the cells. Then, the backside shield doors were extracted. The lifting frame for the isolation tent was set on the cells. After that, the ceiling plates, isolation walls and lead blocks were removed. The strippable paint was used to remove permeable contamination on the inner surface of structural steel of the cells. The dismantling work will be continued to mention the efficiency of decommissioning works and reduction of radioactive waste with ensuring safety.
Shiina, Hidenori; Ono, Katsuto; Nishi, Masahiro; Nihei, Yasuo
Proceedings of 54th Annual Meeting of Hot Laboratories and Remote Handling (HOTLAB 2017) (Internet), 7 Pages, 2017/00
The Research Hot Laboratory (RHL) in Japan Atomic Energy Agency (JAEA) is the first facility in Japan for the post irradiation examination (PIE) on reactor fuels and structural materials, which had contributed to advancement of the fuels and materials since 1961. The building of RHL consists of two stories above ground and a basement, in which 10 heavy concrete and 38 lead cells were installed. In RHL, all operations for PIE had been completed in 2003. Then the decommissioning program has been implemented in order to promote the rationalization of research facilities in JAEA. As the first step of the program, PIE apparatuses and irradiated samples were removed from the cells, which have been managed as radioactive wastes. The dismantling of lead cells was initiated in 2005. At present 26 lead cells are successfully dismantled. This paper shows technical review of dismantling operations for the lead cells.
Uehara, Hiroyuki; Komuro, Kazuma; Usami, Koji; Nihei, Yasuo; Nakata, Masahito
Proceedings of 52nd Annual Meeting of Hot Laboratories and Remote Handling Working Group (HOTLAB 2015) (Internet), 5 Pages, 2015/09
For the accurate measurement of the released FP gas during RIA, Gas Chromatograph was improved with the hardware approach and the software one. As the hardware approach, PDD was added to the gas detector of GC and it can detect 50 times higher sensitivity compared with the TCD. As the software approach, ETG function was adopted to deconvolute the overlapped Kr peak from N
one. With ETG estimation, Kr volume can be evaluated with the deconvolution from N peak in neither the long measurement time nor the changing measurement condition.
Koya, Toshio; Nozawa, Yukio; Hanada, Yasushi; Ono, Katsuto; Kanazawa, Hiroyuki; Nihei, Yasuo; Owada, Isao
Dekomisshoningu Giho, (42), p.41 - 48, 2010/09
The Research Hot Laboratory (RHL) in Japan Atomic Energy Agency (JAEA) had been contributed to R&D program for fuels and nuclear materials in or out of JAEA. However, the decommissioning work of RHL has been started on April 2003 as the rationalization program for decrepit facilities in former Tokai institute. This work will be progressing, dismantling the lead cells and decontamination of concrete caves then release in the regulation of controlled area. The partial area of RHL will be used for the central storage of un- irradiated fuel and for temporary storage of radioactive device generated by J-PARC. The 18 lead cells had been dismantled and the preparing work for remained 20 lead cells has been finished including the removal of the applause from the cells, survey of the contamination revel in the lead cells and prediction of radio active waste. The future plan of decommissioning work has been prepared to incarnate the basic vision and dismantling procedure.
Shirasu, Noriko; Kuramoto, Kenichi; Nakano, Yoshihiro; Yamashita, Toshiyuki; Kimura, Yasuhiko; Nihei, Yasuo; Ogawa, Toru
Journal of Nuclear Materials, 376(1), p.88 - 97, 2008/05
Times Cited Count：13 Percentile：64.63(Materials Science, Multidisciplinary)The concept of the rock-like oxide (ROX) fuel has been developed for the annihilation of excess plutonium in light water reactors. Irradiation tests and post-irradiation examinations were carried out on candidate ROX fuels. The ternary fuel of YSZ-spinel-corundum system, the single-phase fuels of YSZ, the particle dispersed fuels of YSZ in spinel or corundum matrix, and the blended fuels of YSZ and spinel or corundum matrix were fabricated and submitted to irradiation tests. The fuels containing spinel showed chemical instabilities with the vaporization of MgO component, which caused fuel restructuring. The swelling behavior was improved with the particle-dispersed fuels. However, the particle-dispersed fuels showed higher fractional gas release (FGR) than blended type fuels. The FGR of YSZ single-phase fuels were comparable to what would be expected for UO fuels. The YSZ single-phase fuel showed the best irradiation performance among the ROX fuels investigated.
Shirasu, Noriko; Kuramoto, Kenichi*; Yamashita, Toshiyuki; Ichise, Kenichi; Ono, Katsuto; Nihei, Yasuo
Journal of Nuclear Materials, 352(1-3), p.365 - 371, 2006/06
Times Cited Count：4 Percentile：30.68(Materials Science, Multidisciplinary)To evaluate irradiation behavior of the ROX fuel, irradiation experiment was carried out using 20% enriched U instead of Pu. Three fuels were prepared; a single phase fuel of YSZ containing UO (U-YSZ), two particle-dispersed fuels of U-YSZ particle in spinel or corundum matrix. The U-YSZ particles were prepared by crashing presintered U-YSZ pellets and by sieving them. These fuels were irradiated in Japan Research Reactor No.3 for 13 cycles, about 300 days. Though many cracks were observed in the pellets by X-ray photographs, significant appearance changes were not observed for all fuel pins. Distribution of typical FPs was analyzed by the 
scanning over the fuel pin. Non-volatile nuclide remained in the fuel pellet. On the other hand, a part of Cs moved to the gaps between the pellets and to the insulators. 
Cs and 
Cs showed different distributions at the plenum. Fuel pellets were taken out from fuel pins without bonding. Spinel decomposition and subsequent restructuring were not observed probably due to low irradiation temperature.
Harada, Katsuya; Nakata, Masahito; Harada, Akio; Nihei, Yasuo; Yasuda, Ryo; Nishino, Yasuharu
JAERI-Tech 2004-034, 13 Pages, 2004/03
JAERI-Tech-2004-034.pdf:0.69MB
The Department of Hot Laboratories has been aiming the establishment of the melting temperature measuring technique for small samples obtained from the micro-region of irradiated fuel pellet. Due to the modification of the shape of tungsten capsule contained sample and the improvement of the detection method for melting temperature from indistinct thermal arrest point owing to small sample, it is possible to determine the melting temperature of small sample and to utilize effectively for the irradiated fuel pellet by using the existing apparatus. This paper describes the technique of the melting temperature measurement for small sample and the experimental results by using tantalum, molybdenum, hafnium oxide and un-irradiated UO pellet.
Arai, Yasuo; Iwai, Takashi; Nakajima, Kunihisa; Nagashima, Hisao; Nihei, Yasuo; Katsuyama, Kozo*; Inoue, Masaki*
Proceedings of GLOBAL2003 Atoms for Prosperity; Updating Eisenhower's Global Vision for Nuclear Energy (CD-ROM), p.1686 - 1693, 2003/00
no abstracts in English
14 PWR type fuel rod prior to pulse irradiation in NSRRYanagisawa, Kazuaki; Sasajima, Hideo; Katanishi, Shoji; ; ; Nihei, Yasuo; Mimura, Hideaki; ; Yamahara, Takeshi; *
JAERI-M 91-218, 199 Pages, 1992/01
no abstracts in English
Kaminaga, Norihisa; Nihei, Yasuo; Kimura, Yasuhiko; Kikuchi, Hiroyuki; Takahashi, Ishio; Matsuura, Takanobu; Suzuki, Kazuhiro; Kitamura, Toshikatsu; Sato, Yasuo; Hatanaka, Kazuo*
no journal, ,
no abstracts in English
