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Tonoike, Kotaro; Okubo, Kiyoshi; Takada, Tomoyuki*
Proceedings of International Conference on Nuclear Criticality Safety (ICNC 2015) (DVD-ROM), p.292 - 300, 2015/09
The damaged Unit 1-3 reactors of the Fukushima Daiichi Nuclear Power Station may contain fuel debris of a significant amount that is in a form of molten-core-concrete-interaction (MCCI) product with porous structure. Such low density MCCI product including fissile material is a great concern for its criticality control, especially under submerged condition, due to its fairly good neutron moderation. This report shows computation results of basic criticality characteristics of the MCCI product, which will facilitate criticality risk assessments during decommissioning of the reactors. The results imply that water bound in concrete may raise the risk from the viewpoints of possibility of criticality events and of effectiveness of mitigation measures such as neutron poison injection into coolant water.
Shibata, Yasushi*; Yamamoto, Kazuyoshi; Matsumura, Akira*; Yamamoto, Tetsuya*; Hori, Naohiko; Kishi, Toshiaki; Kumada, Hiroaki; Akutsu, Hiroyoshi*; Yasuda, Susumu*; Nakai, Kei*; et al.
JAERI-Research 2005-009, 41 Pages, 2005/03
JAERI-Research-2005-009.pdf:1.99MB
The measurement of neutron flux and boron concentration in the blood during medical irradiation is indispensable in order to evaluate the radiation in boron neutron capture therapy. It is, however, difficult to measure the blood boron concentration during neutron irradiation because access to the patient is limited. Therefore we prospectively investigated the predictability of blood boron concentrations using the data obtained at the first craniotomy after infusion of a low dosage of BSH. When the test could not be carried out, the blood boron concentration during irradiation was also predicted by using the 2-compartment model. If the final boron concentration after the end of the infusion is within 95% confidence interval of the prediction, direct prediction from biexponential fit will reduce the error of blood boron concentrations during irradiation to around 6%. If the final boron concentration at 6 or 9 hours after the end of infusion is out of 95% confidence interval of the prediction, proportional adjustment will reduce error and expected error after adjustment to around 12%.
Shibata, Yasushi*; Matsumura, Akira*; Yamamoto, Tetsuya*; Akutsu, Hiroyoshi*; Yasuda, Susumu*; Nakai, Kei*; Nose, Tadao*; Yamamoto, Kazuyoshi; Kumada, Hiroaki; Hori, Naohiko; et al.
Research and Development in Neutron Capture Therapy, p.1055 - 1060, 2002/09
We prospectively investigated the predictability of blood boron concentrations using the data obtained at the first craniotomy after infusion of a low dose of sodium undecahydroclosododecaborate (BSH). Nine patients with malignant glial tumors underwent Boron neutron capture therapy (BNCT) at the Japan Atomic Energy Research Institute (JAERI) between 1995 and 2001. In 7 patients, 1g of BSH was infused before the first tumor removal and boron concentrations were determined using prompt gamma ray analysis (PGA). Then, 12 hours before BNCT, patients were infused at a dose of 100mg/kg BSH, and the boron concentrations were determined again. The boron biodistribution data showed a biexponential pharmacokinetic profile. If the final boron concentration at 6 or 9 hours after the end of the infusion is within the 95% confidence interval of the prediction, direct prediction from biexponential fit will reduce the error of blood boron concentrations during irradiation to around 6%.
Hayashi, Takafumi*; Suyama, Kenya; Mochizuki, Hiroki*; Nomura, Yasushi
JAERI-Tech 2001-041, 158 Pages, 2001/06
JAERI-Tech-2001-041.pdf:5.15MB
no abstracts in English
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Nuclear Technology, 78(8), p.140 - 150, 1987/08
no abstracts in English
Yoshikawa, Tomoki; Araki, Shohei; Arakaki, Yu; Izawa, Kazuhiko; Gunji, Satoshi; Suyama, Kenya
no journal, ,
In order to clarify the criticality characteristics of fuel debris, we plan experiments in the Static Experiment Critical Facility (STACY) by using concrete and steel simulating the structural materials of the core of the Fukushima Daiichi Nuclear Power Plant. In order to carry out the experiments, it is necessary to obtain a construction permit for the core with the debris structural material simulant mentioned above. In this presentation, we present the analysis results and the feasible core configuration for obtaining the certification from the regulatory body.