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Tomimoto, Hiroshi; Kato, Yasushi; Owada, Hiroyuki; Sato, Nao; Shimazaki, Yosuke; Kozawa, Takayuki; Shinohara, Masanori; Hamamoto, Shimpei; Tochio, Daisuke; Nojiri, Naoki; et al.
JAEA-Technology 2009-025, 29 Pages, 2009/06
JAEA-Technology-2009-025.pdf:21.78MB
The first driver fuel of the HTTR (High Temperature Engineering test Reactor) was loaded in 1998 and the HTTR reached first criticality state in the same year. The HTTR has been operated using the first driver fuel for a decade. In Fuel elements assembling, 4770 of fuel rods which consist of 12 kinds of enrichment uranium are loaded into 150 fuel graphite blocks for HTTR second driver fuel elements. Measures of prevention of fuel rod miss loading, are employed in fuel design. Additionally, precaution of fuel handling on assembling are considered. Reception of fuel rods, assembling of fuel elements and storage of second driver fuels in the fresh fuel storage rack in the HTTR were started since June, 2008. Assembling, storage and pre-service inspection were divided into three parts. The second driver fuel assembling was completed in September, 2008. This report describes concerns of fuel handling on assembling and storage work for the HTTR fuel elements.
Hamamoto, Shimpei; Iigaki, Kazuhiko; Shimizu, Atsushi; Sawahata, Hiroaki; Kondo, Makoto; Oyama, Sunao; Kawano, Shuichi; Kobayashi, Shoichi; Kawamoto, Taiki; Suzuki, Hisashi; et al.
JAEA-Technology 2006-030, 58 Pages, 2006/03
JAEA-Technology-2006-030.pdf:10.69MB
During normal operation of High Temperature engineering Test Reactor (HTTR) in Japan Atomic Energy Agency (JAEA), the reactivity is controlled by the Control Rods (CRs) system which consists of 32 CRs (16 pairs) and 16 Control Rod Drive Mechanisms (CRDMs). The CR system is located in stand-pipes accompanied by the Reserved Shutdown System (RSS). In the unlikely event that the CRs fail to be inserted, the RSS is provided to insert B
C/C pellets into the core. The RSS shall be designed so that the reactor should be held subcriticality from any operation condition by dropping in the pellets. The RSS consists of BC/C pellets, hoppers which contain the pellets, electric plug, driving mechanisms, guide tubes and so on. In accidents when the CRs cannot be inserted, an electric plug is pulled out by a motor and the absorber pellets fall into the core by gravity. A trouble, malfunction of one RSS out of sixteen, occurred during a series of the pre-start up checks of HTTR on February 21, 2005. We investigated the cause of the RSS trouble and took countermeasures to prevent the issue. As the result of investigation, the cause of the trouble was attributed to the following reason: In the motor inside, The Oil of grease of the multiplying gear flowed down from a gap of the oil seal which has been deformed and was mixed with abrasion powder of brake disk. Therefore the adhesive mixture prevented a motor from rotating.
Nojiri, Naoki; Shimakawa, Satoshi; Takamatsu, Kuniyoshi; Ishii, Yoshiki; Kawano, Shuichi; Kobayashi, Shoichi; Kawamoto, Taiki; Iyoku, Tatsuo
JAERI-Tech 2003-086, 136 Pages, 2003/11
JAERI-Tech-2003-086.pdf:8.67MB
To provide a basis for determination of the actual core power distribution, The power distribution experiments by measuring gross gamma ray emitted from fission products in the fuel assemblies were performed. The fuel assemblies were not spent condition but in-service condition. The averaged burn up was about 4,400 MWD/t. The gamma ray of a fuel assembly was measured with a GM counter under a temporary fuel withdrawing situation from the core during shutdown state. Uncertainties of the determination were from 3 to 6 percent in axial distribution per one fuel compact and within about 4 percent in radial and axial distribution of the core per one fuel assembly. It was concluded that the power distribution of the HTTR is almost equivalent to the expected power-profile shaping. Calculation of gamma ray distribution was performed by ORIGEN-2 code based the power distribution obtained by the Monte Carlo MVP code. The calculation results show good agreement with the experimental ones. The method, procedure, analysis, correction, determination and comparison are described in this report.
Kono, Taiki*; Fujio, Kazuki*; Minato, Futoshi; Ishizuka, Chikako*; Chiba, Satoshi*
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no abstracts in English