Yamamoto, Masahiko; Shirozu, Hidetomo; Mori, Eito; Surugaya, Naoki
JAEA-Technology 2016-009, 58 Pages, 2016/05
The panels of glove box installed at Tokai Reprocessing Plant have been deteriorated and transparencies have been decreased due to the long-term use. Therefore, the panels have been replaced from the view point of preventive maintenance. In the new regulation formulated since the Fukushima Daiichi Nuclear Power Plant accident, it is demanded that the glove box consists of incombustible or inflammable materials. In this replacement, new panels have been manufactured with polycarbonate which satisfied the UL94 V-0 incombustible class. The inside of glove box has been contaminated with radioactive materials. Thus, the contamination and operator's exposure have been investigated. Then radiation protection equipment have been selected. Also, it is necessary to maintain the glove box enclosure during the replacement. The replacement has been conducted by covering the opening parts with vinyl sheets. The enclosure function has been verified by the inspection of the new panels and glove box.
Nakano, Takafumi; Sato, Fuminori; Shirozu, Hidetomo; Nakanishi, Ryuji; Fukuda, Kazuhito; Tachibana, Ikuya
Nippon Genshiryoku Gakkai-Shi, 57(1), p.14 - 20, 2015/01
no abstracts in English
Sakaguchi, Shinobu; Tachibana, Ikuya; Koshino, Katsuhiko; Shirozu, Hidetomo; Shirai, Nobutoshi; Imamoto, Nobuo; Tomita, Tsuneo; Tobita, Hiroo; Yamanaka, Atsushi; Kobayashi, Daisuke; et al.
JAEA-Technology 2011-006, 24 Pages, 2011/03
In the Niigataken Chuetsu-oki Earthquake on 2007, observed earthquake motion exceeded design base at the Kashiwazaki Kariwa nuclear plant. However, there was no earthquake damage in safety important equipments to stop reactor, to cool reactor, and to contain radioactive materials. One of this reason is said that many safety margin are included in the design and the permissible value. To know more accurate safety margin, shearing force examinations for the base bolts were conducted. In examinations, delegate test-bolts were made; the test bolts were selected from heavier equipment in Tokai Reprocessing Plant. In this report, the shearing strength obtained from the examinations shows more accurate safety margin.
Okano, Masanori; Kuno, Takehiko; Takahashi, Ichiro*; Shirozu, Hidetomo; Charlton, W. S.*; Wells, C. A.*; Hemberger, P. H.*; Yamada, Keiji; Sakai, Toshio
JAEA-Technology 2006-055, 38 Pages, 2006/12
The amount of Pu in the spent fuel was evaluated from Xe isotopic ratio in off-gas in reprocessing facility, is related to burnup. Six batches of dissolver off-gas at spent fuel dissolution process were sampled from the main stack in Tokai Reprocessing Plant during BWR fuel reprocessing campaign. Xenon isotopic ratio was determined with GC/MS. Burnup and generated amount of Pu were evaluated with Noble Gas Environmental Monitoring Application code (NOVA), developed by Los Alamos National Laboratory. Inferred burnup evaluated by Xe isotopic measurements and NOVA were in good agreement with those of the declared burnup in the range from -3.8% to 7.1%. Also, the inferred amount of Pu in spent fuel was in good agreed with those of the declared amount of Pu calculated by ORIGEN code in the range from -0.9% to 4.7%. The evaluation technique is applicable for both burnup credit to achieve efficient criticality safety control and a new measurement method for safeguards inspection.
Shimizu, Ryo; Takaya, Akikazu; Shirozu, Hidetomo; Uchida, Naoki; Tanaka, Kosuke; Yamaguchi, Akira; Aoto, Kazumi; Watahiki, Masaru
Nippon Genshiryoku Gakkai Wabun Rombunshi, 4(3), p.203 - 212, 2005/09
It was occurred that process solution leaked from the steam jet in the acid recovery process of Tokai reprocessing plant. So we retrieved the jet from the cell and observed the inside. As a result, it was revealed that a defect by corrosion, which penetrated the inside of the structure, arose from the steam nozzle root in the suction room of the jet. To ascertain why such failure occurred, we carried out observation of metallurgical structure of the jet, an analysis of temperature distribution of the structure involving verification using mock-ups and evaluation of material by corrosion test. Consequently, the origin of the corrosion defect was pin hole which was occurred on the surface of the end of the material at the steam nozzle root, where nitric acid fluid was contacted, and then the defect progressed along the temperature of about 120 of the structure. Anisotropy of the material, possibly originating in the manufacturing process, was observed from the result of evaluation of material by corrosion test. Finally, we devised a new design of improved corrosion resistance on the result of the whole investigations.
Shirozu, Hidetomo; Shimizu, Ryo; Takaya, Akikazu; Uchida, Naoki; Tanaka, Kosuke; Yamaguchi, Akira; Aoto, Kazumi
Saikuru Kiko Giho, (21), p.41 - 55, 2003/00
The cause of the failure, which had occurred in the steam jet (273J202) in the acid recovery process of Tokai reprocessing plant, was investigated .
Shirai, Nobutoshi; ; ; Shirozu, Hidetomo; ; Hayashi, Shinichiro;
JNC-TN8410 2000-006, 116 Pages, 2000/04
Criticality limits for equipments in Tokai Reprocessing Plant which handle fissile material solution and are under shape and dimension control were reevaluated based on the guideline No.10 "Criticality safety of single unit" in the regulatory guide for reprocessing plant safety. This report presents criticality safety evaluation of each equipment as single unit. Criticality safety of multiple units in a cell or a room was also evaluated. The evaluated equipments were ones in dissolution, separation, purification, denitration, Pu product storage, and Pu conversion processes. As a result, it was reconfirmed that the equipments were safe enough from a view point of criticality safety of single unit and multiple units.
Koshino, Katsuhiko; Shirai, Nobutoshi; Sakaguchi, Shinobu; Shirozu, Hidetomo; Otaki, Miyuki*; Kosaka, Ichiro; Nakano, Takafumi; Nagasato, Yoshihiko; Tachibana, Ikuya
no journal, ,
no abstracts in English
Miyamoto, Masanori; Shirozu, Hidetomo; Morita, Minoru; Fujisaku, Sakae; Kurita, Tsutomu; Kimura, Yuichi; Kataoka, Satoshi; Seya, Katsunori*; Sasaki, Shunichi
no journal, ,
no abstracts in English