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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.
Yoshizawa, Michio; Tanimura, Yoshihiko; Saegusa, Jun; Nemoto, Hisashi*; Yoshida, Makoto
Radiation Protection Dosimetry, 110(1-4), p.81 - 84, 2004/09
Times Cited Count：3 Percentile：23.52(Environmental Sciences)The facility of Radiation Standards (FRS) of JAERI has equipped with the concrete-moderated neutron calibration fields as simulated workplace neutron fields. The fields use an Am-Be (37GBq) neutron source placed in the narrow space surrounded by concrete wall and bricks to produce scattered neutrons. The neutron spectra of the fields were measured with Bonner multi-sphere spectrometer system (BMS), spherical recoil-proton proportional counters (RPCs), and a liquid scintillation counter (NE-213). The results were compared with each other, and the neutron spectra and the ambient dose equivalent rate, 
(10), were agreed well within the uncertainty. The angular distributions of neutron fluence were calculated by the MCNP-4B2 Monte Carlo code to obtain the reference personal dose equivalent rate, 
(10). The calculated results show that the scattered neutrons have a wide variety of incident angles. The reference (10) values considered the angular distribution were found to be 10-18% smaller than those without consideration.
Ishikawa, Hisashi; Nemoto, Norio; Izaki, Kenji; Kobayashi, Hirohide; Tanizawa, Teruaki*; Kanazawa, Yoshito*
JNC TN8400 2004-008, 124 Pages, 2004/05
JNC-TN8400-2004-008.pdf:58.81MB
In order to strengthen the functions of the self moving survey system, the design of the truck and the data transmission system, the investigation of the handling function and the durability test assumed under the disaster environment were executed.As the basic performance of the self moving survey system, it was demanded to have the functions in order to run on the bumpy road, go up and down the stairs and open and shut of the door. And the remote control by the PHS line or the SS wireless is adopted as an operational method. Moreover, as the function that can monitor the disaster situation in the facility, it was assumed the design that make modular the measurement equipments, which mainly measure alpha ray, gamma ray and neutron, and installed it.In consideration of the radiation monitoring under the environment that assumes the critical accident and a fire and the explosion etc. heat test, humidity test, radiation test, and aerosol (smoke) test for monitoring equipments were executed. As a result of the tests, it was confirmed that all equipment except the semiconductor detector operated normally.
Shimizu, Shigeru; Nemoto, Hisashi*; Kurosawa, Koji*; Yoshizawa, Michio
JAERI-Tech 2000-041, 31 Pages, 2000/05
JAERI-Tech-2000-041.pdf:1.35MB
no abstracts in English
Kambara, Toyozo; Uno, Hidero; Shoda, Katsuhiko; Hirata, Yutaka; Shoji, Tsutomu; Kohayakawa, Toru; Takayanagi, Hiroshi; Fujimura, Tsutomu; Morita, Morito; Ichihara, Masahiro; et al.
JAERI 1045, 11 Pages, 1963/03
no abstracts in English
-rays tissue absorbed dose rate in -ray reference fields made by PTBShimizu, Shigeru; Nemoto, Hisashi*; Kajimoto, Yoichi; Tatebe, Yosuke; Takahashi, Hiroshi*
no journal, ,
We were researched and developed in German federal physical engineering laboratory (PTB) and established the standard field of the ray tissue absorbed dose rate corresponding to Series 1 of ISO6980-1(2006) to the Facility of Radiation Standard of Japan Atomic Energy Agency (JAEA) in February, 2010. We measured ray tissue absorbed dose rate of this standard field using an extrapolation ionization chamber made in PTB. By the comparison between this result and standard value of PTB, both agreed well. In this announcement, we speak these evaluation results and comparison result. In addition, we speak that the ray tissue absorbed dose rate at the time of the standard field use comes under a big influence by a change of the air density of the examination environment.
-rays reference field made by PTB, 2; Spectrum measurement and dose evaluation for the photon to be mixed in the irradiation fieldShimizu, Shigeru; Kajimoto, Yoichi; Tatebe, Yosuke; Nemoto, Hisashi*; Takahashi, Hiroshi*
no journal, ,
As a part of the characteristic investigation of the -rays reference field made in PTB which we maintained to a Facility of Radiation Standard of Japan Atomic Energy Agency (JAEA), we evaluated the fluence spectrum of the photon to be mixed in the irradiation field and identified characteristic X-ray, bremsstrahlung radiation and 
-ray from this spectrum distribution and clarified the cause of the outbreak. In addition, we evaluated the H'(0.07) dose equivalent rate of the photon from this spectrum distribution and considered the influence on beta-rays dose equivalent rate of the reference field.
Sato, Satoshi; Kinase, Sakae; Saito, Kimiaki; Takahashi, Tomoyuki*; Kurosawa, Naohiro*; Ryufuku, Susumu*; Hayashi, Hiroko*; Ishibashi, Kazufusa*; Sakamoto, Ryuichi*; Nemoto, Hisashi*
no journal, ,
no abstracts in English
Sato, Satoshi; Kinase, Sakae; Saito, Kimiaki; Sakamoto, Ryuichi*; Nemoto, Hisashi*; Ryufuku, Susumu*
no journal, ,
no abstracts in English
Sato, Satoshi; Kinase, Sakae; Saito, Kimiaki; Takahashi, Tomoyuki*; Kanno, Mitsuhiro*; Hayashi, Hiroko*; Ishibashi, Kazufusa*; Kurosawa, Naohiro*; Sakamoto, Ryuichi*; Nemoto, Hisashi*
no journal, ,
no abstracts in English
