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Nagatani, Taketeru; Sagara, Hiroshi*; Kosuge, Yoshihiro*; Nomi, Takayoshi; Okumura, Keisuke
Journal of Nuclear Science and Technology, 60(4), p.460 - 472, 2023/04
Times Cited Count：1 Percentile：31.61(Nuclear Science & Technology)Shiba, Tomooki; Sagara, Hiroshi*; Tomikawa, Hirofumi
Proceedings of International Nuclear Fuel Cycle Conference (GLOBAL 2017) (USB Flash Drive), 3 Pages, 2017/09
Since the removal of fuel debris from the Fukushima Daiichi Nuclear Power Plant is planned to commence in 2021, measurement technologies for quantification of the nuclear material in fuel debris will be required for appropriate nuclear material management. In this paper, an outline of a passive gamma technique as one of the measurement technologies is briefly described, and the results of phase 1 and 2 of the so-called common set of simulation models for fuel debris and canisters are reported. The newly developed coupling method is applied to produce a gamma ray source for simulation. As the result of phase 1, it is revealed that the variation in the composition of fuel debris does not affect the gamma ray leakage behavior from canisters. According to the result of phase 2, the primary peak of Eu-154 at 1.27 MeV is clearly observable, although the debris is centrally located in canister. In addition, rotational scanning is effective for correcting the deviation in detection efficiency due to debris located off-center in canisters.
Sagara, Hiroshi; Kawakubo, Yoko; Inoue, Naoko
JAEA-Review 2013-011, 54 Pages, 2014/01
JAEA-Review-2013-011.pdf:3.05MB
The Generation IV (GEN IV) International Forum Proliferation Resistance and Physical Protection (PR & PP) Working Group is in charge of developing a methodology for evaluating PR & PP of potential GEN IV options. The present report, published in Oct. 2009, was used as a supporting study for development of the evaluation methodology for PR & PP, summarizing the case study of the PR & PP evaluation of Example Sodium Fast Reactor (ESFR) co located with a dry fuel storage facility and a pyrochemical spent-fuel reprocessing facility, a hypothetical nuclear energy system, consisting of nine main system elements, and it provides for designers the practical experience of applying the PR&PP evaluation methodology to a nuclear energy system. The development of the future nuclear fuel cycle system with sufficient PR & PP features is a crucial task in Japan. With the usefulness the report, it was translated and published here as a Japanese-language edition with the concurrence of the OECD-NEA.
spectrometry of molten core material from Fukushima Daiichi Nuclear Power Station unit 1, 2 and 3 cores for special nuclear material accountancy; Low-volatile FP and special nuclear material inventory analysis and fundamental characteristics of -rays from fuel debrisSagara, Hiroshi; Tomikawa, Hirofumi; Watahiki, Masaru; Kuno, Yusuke
Journal of Nuclear Science and Technology, 51(1), p.1 - 23, 2014/01
Times Cited Count：9 Percentile：57.19(Nuclear Science & Technology)Feasibility study of spectrometry of molten core material from Fukushima Daiichi Nuclear Power Station Unit 1, 2 and 3 cores for special nuclear material accountancy has been performed, focusing on the low-volatile fission product and heavy metal inventory analysis, and fundamental characteristics of -ray from fuel debris for passive measurement. The inventory ratio of low-volatile lanthanides, 
Eu and 
Ce, to special nuclear material were evaluated by whole core inventory in unit 1, 2 and 3 cores as reference value for homogenized molten fuel material, and also as a function of burnup for specific fuel debris, considering the sensitivity of enrichment, specific power, water void fraction, cooling time, calculation tool accuracy and release ratio. The same indices could be applied to unit 3, while the uncertainty of specific fuel debris of separated MOX fuel would be increased significantly. Source photon spectrum results showed the detectability of low-volatile high energy -rays emitted from Eu at least in 20 years after the accident, that from Ce/Pr in 10 years, and volatile 
Cs and 
Cs at least in 20 years with 99% or more release ratio. Mass attenuation coefficients of fuel debris was evaluated to be insensitive to its compositions in high energy region. Leakage photon ratio was evaluated with variety of parameters and significant impact was confirmed with certain size of fuel debris, its correlation was summarized with respect to the photopeak ratio of source Eu. Finally, preliminary study with hypothetical canister model of fuel debris based on TMI-2 experience, and future plan were introduced.
Sagara, Hiroshi; Tomikawa, Hirofumi; Watahiki, Masaru; Kuno, Yusuke
Transactions of the American Nuclear Society, 107(1), p.803 - 804, 2012/11
Fission products(FPs) such as Eu, Ce, Ru have low release ratio in case of core melting event in severe accident to co-exist inside fuel debris in oxide or metallic phase, based on TMI-2 experience and source term experiments. Passive spectroscopy of Ce-144/Pr-144 was utilized in quantifying special nuclear material in fuel debris of TMI-2 historically, and the same methodology might be applied to high energy emitter, Eu-154 and Ru-106. Passive neutron measurement has been also utilized for quantifying nuclear material practically. Different from conventional spent fuel, however, fuel debris would be lost in information of irradiated profile, release ratio of volatile FPs, and so on. In the present paper, sensitivity analysis of low-volatile FPs and Cm-244 inventory in irradiated nuclear fuel in light water reactor was performed numerically to clarify the uncertainty of low-volatile FP and Cm inventory regarding fuel irradiation parameters and calculation methodology, and to derive applicable index to quantify nuclear material in fuel debris.
spectroscopy of low-volatile FPs for special nuclear material accountancy in molten core materialSagara, Hiroshi; Tomikawa, Hirofumi; Watahiki, Masaru; Kuno, Yusuke
Proceedings of INMM 53rd Annual Meeting (CD-ROM), 10 Pages, 2012/07
Reviewing the technologies applied to TMI-2, feasibility study of spectroscopy of low-volatile FPs for special nuclear material accountancy in molten core material or debris has been performed numerically, and the sensitivity of low-volatile FP nuclides on fuel contents, especially 
Pu, was studied with parameters of typical BWR fuel such as enrichment, burnup and neutron spectrum, heat density. Comparing TMI-2, a PWR reactor, broader neutron spectrum axial profile and irradiation cycle complexity of typical BWR fuel assemblies make more variance in the accumulation of daughter nuclides by neutron capture reactions. As results, Pu quantification, by burnup dependent Eu/Pu index has accuracy of 15-18% in 1-sigma level mainly affected by burnup uncertainty, and Pu quantification by Ce/Pu has accuracy of 20% as long as Ce released photon could be observed within 10 years, within the scope of inventory survey except for measurement uncertainty. Finally systematic image of fuel quantification by passive spectroscopy and, as future study, FPs quantification by passive measurement tests by mockup debris measurement with self-attenuation correction are introduced.
Sagara, Hiroshi; Inoue, Naoko; Kawakubo, Yoko; Watahiki, Masaru
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-32-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2011/11
The Generation IV (GEN IV) Nuclear Energy Systems International Forum (GIF) Proliferation Resistance and Physical Protection Working Group (PRPP WG) was established in December 2002 in order to develop the PR&PP evaluation methodology for GEN IV nuclear energy systems. In the final report of "PR&PP Evaluation; Example Sodium Fast Reactor (ESFR) Full System Case Study," issued in October 2009, the demonstration study of PR&PP evaluation with the qualitative approach are summarized using ESFR with four scenario threats. The present paper reviews and analyzes some results of the ESFR case study, and identifies the challenges and direction for the PR&PP evaluation methodology with quantitative approach.
Nagatani, Taketeru; Komeda, Masao; Shiba, Tomooki; Nauchi, Yasushi*; Sagara, Hiroshi*; Kosuge, Yoshihiro*; Okumura, Keisuke; Maeda, Makoto; Toh, Yosuke; Hori, Keiichiro
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no abstracts in English
Nagatani, Taketeru; Komeda, Masao; Shiba, Tomooki; Nauchi, Yasushi*; Sagara, Hiroshi*; Kosuge, Yoshihiro*; Okumura, Keisuke; Maeda, Makoto; Toh, Yosuke; Hori, Keiichiro
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Nagatani, Taketeru; Komeda, Masao; Shiba, Tomooki; Nauchi, Yasushi*; Sagara, Hiroshi*; Kosuge, Yoshihiro*; Miyaji, Noriko; Okumura, Keisuke
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no abstracts in English
techniqueShiba, Tomooki; Sagara, Hiroshi*; Tomikawa, Hirofumi
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no abstracts in English
Asano, Hidekazu*; Sakuragi, Tomofumi*; Hamada, Ryo*; Han, C. Y.*; Nakase, Masahiko*; Matsumura, Tatsuro; Chiba, Go*; Sagara, Hiroshi*; Takeshita, Kenji*
no journal, ,
no abstracts in English
