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Gunji, Satoshi; Tonoike, Kotaro; Clavel, J.-B.*; Duhamel, I.*
Journal of Nuclear Science and Technology, 58(1), p.51 - 61, 2021/01
Times Cited Count：1 Percentile：0.01(Nuclear Science & Technology)The new critical assembly STACY will be able to contribute to the validation of criticality calculations related to the fuel debris. The experimental core designs are in progress in the frame of JAEA/IRSN collaboration. This paper presents the method applied to optimize the design of the new STACY core to measure the criticality characteristics of pseudo fuel debris that simulated Molten Core Concrete Interaction (MCCI) of the fuel debris. To ensure that a core configuration is relevant for code validation, it is important to evaluate the reactivity worth of the main isotopes of interest and their k
sensitivity to their cross sections. In the case of the fuel debris described in this study, especially for the concrete composition, silicon is the nucleus with the highest k sensitivity to the cross section. For this purpose, some parameters of the core configuration, as for example the lattice pitches or the core dimensions, were adjusted using optimization algorithm to find efficiently the optimal core configurations to obtain high sensitivity of silicon capture cross section. Based on these results, realistic series of experiments for fuel debris in the new STACY could be defined to obtain an interesting feedback for the MCCI. This methodology is useful to design other experimental conditions of the new STACY.
Nakayoshi, Akira; Jegou, C.*; De Windt, L.*; Perrin, S.*; Washiya, Tadahiro
Nuclear Engineering and Design, 360, p.110522_1 - 110522_18, 2020/04
Times Cited Count：14 Percentile：91.63(Nuclear Science & Technology)Kitagaki, Toru; Ikeuchi, Hirotomo; Yano, Kimihiko; Brissonneau, L.*; Tormos, B.*; Domenger, R.*; Roger, J.*; Washiya, Tadahiro
Journal of Nuclear Science and Technology, 56(9-10), p.902 - 914, 2019/09
Times Cited Count：7 Percentile：66.48(Nuclear Science & Technology)Nakayoshi, Akira; Ikeuchi, Hirotomo; Kitagaki, Toru; Washiya, Tadahiro; Bouyer, V.*; Journeau, C.*; Piluso, P.*; Excoffier, E.*; David, C.*; Testud, V.*
Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05
Kitagaki, Toru; Ikeuchi, Hirotomo; Yano, Kimihiko; Ogino, Hideki; Haquet, J.-F.*; Brissonneau, L.*; Tormos, B.*; Piluso, P.*; Washiya, Tadahiro
Progress in Nuclear Science and Technology (Internet), 5, p.217 - 220, 2018/11
Gunji, Satoshi; Tonoike, Kotaro; Izawa, Kazuhiko; Sono, Hiroki
Progress in Nuclear Energy, 101(Part C), p.321 - 328, 2017/11
Times Cited Count：3 Percentile：21.14(Nuclear Science & Technology)Criticality safety of fuel debris, particularly MCCI (Molten-Core-Concrete-Interaction) products, is one of the major safety issues for decommissioning of Fukushima Daiichi Nuclear Power Station. Criticality or subcriticality condition of the fuel debris is still uncertain; its composition, location, neutron moderation, etc. are not yet confirmed. The effectiveness of neutron poison in cooling water is also uncertain for use as a criticality control of fuel debris. A database of computational models is being built by Japan Atomic Energy Agency (JAEA), covering a wide range of possible conditions of such composition, neutron moderation, etc., to facilitate assessing criticality characteristics once fuel debris samples are taken and their conditions are known. The computational models also include uncertainties which are to be clarified by critical experiments. These experiments are planned and will be conducted by JAEA with the modified STACY (STAtic experiment Critical facilitY) and samples to simulate fuel debris compositions. Each of the samples will be cladded by a zircalloy tube whose outer shape is compatible with the fuel rod of STACY and loaded into an array of the fuel rods. This report introduces a study of experimental core configurations to measure the reactivity worth of samples simulating MCCI products. Parameters to be varied in the computation models for the experimental series are:(1) Uranium dioxide with 
U enrichments of 3, 4, and 5 wt.%; (2) Concrete volume fraction in the samples of 0, 20, 40, 60, and 80%; and (3) Porosity of the samples filled from 0 to 80% where the sample void is filled with water. It is concluded that the measurement is feasible in both under- and over-moderated conditions. Additionally, the required amount of samples was estimated.
Kitagaki, Toru; Yano, Kimihiko; Ogino, Hideki; Washiya, Tadahiro
Journal of Nuclear Materials, 486, p.206 - 215, 2017/04
Times Cited Count：27 Percentile：94.39(Materials Science, Multidisciplinary)Gunji, Satoshi; Tonoike, Kotaro; Izawa, Kazuhiko; Sono, Hiroki
Proceedings of International Conference on the Physics of Reactors; Unifying Theory and Experiments in the 21st Century (PHYSOR 2016) (USB Flash Drive), p.3927 - 3936, 2016/05
Criticality safety of fuel debris including MCCI products is one of the major safety is-sues for decommissioning of Fukushima Daiichi Nuclear Power Station. Criticality or subcriticality condition of the fuel debris is still uncertain since its composition, location, neutron moderation, etc. are not confirmed. Also uncertain in criticality control of fuel debris is the effectiveness of neutron poison in cooling water. A database is being built by computation in JAEA, covering a wide range of possible conditions of such composition, neutron moderation, etc., to facilitate assessing criticality characteristics when fuel debris samples are taken and their conditions are known. The computation also has uncertainties to be clarified by critical experiments, which is planned by JAEA to be conducted with the modified STACY and samples simulating fuel debris compositions. This report introduces a study of experimental core configurations for reactivity worth measurements of samples simulating MCCI products. It is concluded that the measurement is feasible in both under- and over-moderated conditions. Additionally, required amount of samples was estimated.
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.
Nariai, Hideki*; Sugiyama, Kenichiro*; Kataoka, Isao*; Mishima, Kaichiro*; *; Monde, Masanori*; Sugimoto, Jun; ; Hidaka, Akihide; *; et al.
Nihon Genshiryoku Gakkai-Shi, 39(9), p.739 - 752, 1997/00
Times Cited Count：1 Percentile：13.16(Nuclear Science & Technology)no abstracts in English
Sugimoto, Jun
Dennetsu Kenkyu, 34(133), p.52 - 59, 1995/04
no abstracts in English
Sugimoto, Jun; Yamano, N.; Maruyama, Yu; Kudo, Tamotsu; Soda, Kunihisa
Safety Options for Future Pressurized Water Reactors, 0, 14 Pages, 1994/00
no abstracts in English
Hidaka, Akihide; Soda, Kunihisa; Sugimoto, Jun; Yamano, N.; Maruyama, Yu
KfK-5108; NEA/CSNI/R(92)10, p.211 - 225, 1992/00
no abstracts in English
Fink, J. K.*; Corradini, M.*; Hidaka, Akihide; Honta
n, E.*; Mignanelli, M. A.*; Schr
dl, E.*; Strizhov, V.*
KfK-5108; NEA/CSNI/R(92)10, p.533 - 546, 1992/00
no abstracts in English
Takano, Masahide; Onozawa, Atsushi; Sudo, Ayako
no journal, ,
no abstracts in English
Sudo, Ayako; Onozawa, Atsushi; Takano, Masahide
no journal, ,
no abstracts in English
Tonoike, Kotaro; Okubo, Kiyoshi; Takada, Tomoyuki*
no journal, ,
no abstracts in English
Kitagaki, Toru; Yano, Kimihiko; Washiya, Tadahiro; Haquet, J.-F.*; Boulin, A.*; Piluso, P.*
no journal, ,
Yano, Kimihiko; Kitagaki, Toru; Ogino, Hideki; Washiya, Tadahiro; Pascal, P.*; Jean-Fran
ois, H.*; Patricia, C.*; Anne, B.*; Brissonneau, L.*; Brigitte, T.*; et al.
no journal, ,
In a collaborative agreement with Commissariat 
l'
nergie atomique et aux nergies alternatives (CEA), the characterization of MCCI products was carried out using the materials that CEA produced in its past large-scale MCCI test. Samples of a corium oxide phase and an interface of corium/concrete phases were selected. They were observed by SEM/EDS and measured by Vickers Hardness Tester.
Kitagaki, Toru; Ikeuchi, Hirotomo; Yano, Kimihiko; Ogino, Hideki; Washiya, Tadahiro
no journal, ,
