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Nakamura, Shoji; Endo, Shunsuke; Kimura, Atsushi; Shibahara, Yuji*
KURNS Progress Report 2022, P. 73, 2023/07
The present study is concerned with the neutron capture cross-sections that contribute to the evaluation of the amount of radionuclides possessing problems in decommissioning. In this study, 
Sc, 
Cu, 
Zn, 
Ag, 
In and 
W were selected among the objective nuclides, and their thermal-neutron capture cross-sections were measured using TC-Pn equipment of the KUR of the Institute for Integrated Radiation and Nuclear Science, Kyoto University. High purity metal samples were prepared. A gold-aluminum ally wire, cobalt and molybdenum foils were used to monitor the neutron flux at the irradiation position of TC-Pn. The flux monitors and metal samples were irradiated for 1 hour at 1-MW operation of the KUR. After irradiation, the irradiation capsule was opened, samples and flux monitors were enclosed in a vinyl bag one by one, and then 
rays emitted from the samples and monitors were measured with a high-purity Ge detector. The thermal-neutron flux component was derived with the reaction rates of flux monitors (
Au, 
Co and 
Mo) on the basis of Westcott's convention, and found to be (5.92
0.10)
10
n/cm
/sec at the irradiation position. The measured reaction rate for each metal sample divided by the evaluated thermal-neutron capture cross-section should give the same value of the thermal-neutron flux component if the cross section is suitable. This time, we found that the cross sections of Sc and 
Zn were consistent with the evaluated one, but those of other nuclides were inconsistent with their evaluated ones; that is, it turned out that their thermal-neutron capture cross-sections should be modified.
Shimada, Taro; Nemoto, Hiromi*; Takeda, Seiji
Hoken Butsuri (Internet), 57(1), p.5 - 29, 2022/03
Of the asbestos-containing wastes arising from the dismantling activities of nuclear facilities, those with radioactive concentrations that do not need to be treated as radioactive substances will be cleared from the nuclear regulatory control. Those will be disposed of or recycled as specially controlled industrial waste based on the Waste Management and Public Cleansing Act. The authors constructed evaluation scenarios according to the treatment manual for asbestos-containing waste and evaluated public exposure doses per year for 33 radionuclides. Based on the evaluated doses, the radioactive concentration corresponding to the dose criteria of 10 
Sv/y for clearance was calculated for each radionuclide and scenario. As a result, the evaluated concentration was equal to or higher than the current clearance level. It was confirmed that the application of the current clearance level for asbestos-containing wastes did not affect safety.
Wakaida, Ikuo; Miyabe, Masabumi
Bunseki, 2004(10), p.585 - 590, 2004/10
no abstracts in English
Kanno, Mitsuhiro*; Takeda, Seiji; Minase, Naofumi; Kato, Hideo; Kimura, Hideo
JAERI-Conf 2004-011, p.131 - 132, 2004/07
no abstracts in English
Yanagihara, Satoshi
Dekomisshoningu Giho, (28), p.2 - 9, 2003/10
Decommissioning of nuclear facilities has been actively progressed in the major member countries participating to OECD/NEA. The NEA has recognized necessity of studying various issues related to decommissioning nuclear facilities and it has made an approach to solve the issues from various ways. In the cooperative program for decommissioning (CPD), information on decommissioning projects has been exchanged among the member countries. In the working party on decommissioning and dismantling (WPDD), recent issues have been studied in terms of regulation, implementation of decommissioning projects and research and development on technologies. Decommissioning cost and regulatory practices were also studies and the reports were published, which will be useful for understanding the present issues on decommissioning in the world. The NEA's activity on decommissioning will be valuable for us to implement decommissioning projects in safe and economical manner in Japan. This report deals with the recent NEA activities on decommissioning.
Takeda, Seiji; Kimura, Hideo
JAERI-Conf 2003-018, p.111 - 112, 2003/10
no abstracts in English
Sakai, Akihiro; Okoshi, Minoru
Radiation Risk Assessment Workshop Proceedings, p.175 - 186, 2003/00
To establish the clearance levels, the Nuclear Safety Commission (NSC) has been discussing the clearance levels since May 1997. The NSC derived the unconditional clearance levels for the solid materials, namely concrete and metal, arising from the operation and dismantling of nuclear reactors and post irradiation examination (PIE) facilities. Two destinations of the cleared materials, namely disposal and recycle/reuse, were considered. Deterministic calculation models were established to assess individual doses resulting from 73 exposure pathways, and realistic parameter values were selected considering the Japanese natural and social conditions. The clearance levels for 21 radionuclides of nuclear reactors and for 49 of PIE facilities were derived as radioactivity concentration equivalent to the individual doses of 10 Sv/y. Most of calculated clearance levels were nearly the same as those shown in IAEA-TECDOC-855. Some, however, were different. It is considered that the major reasons depend on differences of fixed scenarios and of selected values of parameters.
Okamoto, Akiko; Kitami, Yasuo*; Ando, Yoshiaki*; Nakamura, Hisashi; Saito, Kimiaki; Nakashima, Mikio
JAERI-Tech 2002-051, 40 Pages, 2002/06
JAERI-Tech-2002-051.pdf:3.63MB
In order to contribute to safety assessment of recycling products made from dismantling metal wastes, metal ingots containing 
Co were produced and spatial dose rates from the ingots were evaluated by gamma-ray measurement and calculation. Stripping operations were made using detector response functions calculated by Monte Carlo program to derive spatial dose rates from measured gamma-ray spectra. In the computer simulation, Monte Carlo and point kernel calculation codes were used. Agreement between measured and calculated values was satisfactory in spite of an extremely low concentration of Co in the ingots and a complicated geometric condition between detector and samples.
Okoshi, Minoru
KURRI-KR-56, p.39 - 57, 2001/03
no abstracts in English
Okoshi, Minoru
Hoken Butsuri, 34(4), p.353 - 358, 1999/12
no abstracts in English
Okoshi, Minoru; Takahashi, Tomoyuki*; Kimura, Hideo; ; Sakai, Akihiro; Yoshimori, Michiro; Yamamoto, Hideaki
Hoken Butsuri, 34(2), p.187 - 197, 1999/00
no abstracts in English
