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Journal Articles

Preliminary study of the criticality monitoring method based on the simulation for the activity ratio of short half-life noble-gas fission products from fuel debris

Riyana, E. S.; Okumura, Keisuke; Sakamoto, Masahiro; Matsumura, Taichi; Terashima, Kenichi; Kanno, Ikuo

Journal of Nuclear Science and Technology, 8 Pages, 2024/00

Journal Articles

Relationship between internal stress distribution and microstructure in a suspension-sprayed thermal barrier coating with a columnar structure

Yamazaki, Yasuhiro*; Shinomiya, Keisuke*; Okumura, Tadaharu*; Suzuki, Kenji*; Shobu, Takahisa; Nakamura, Yuiga*

Quantum Beam Science (Internet), 7(2), p.14_1 - 14_12, 2023/05

Journal Articles

Applicability of differential die-away self-interrogation technique for quantification of spontaneous fission nuclides for fuel debris at Fukushima Daiichi Nuclear Power Plants

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:0 Percentile:33.72(Nuclear Science & Technology)

Journal Articles

Proposal on how to proceed with Verification and Validation of radiation shielding analyses

Okumura, Keisuke; Sakamoto, Yukio*; Tsukiyama, Toshihisa*

Shahei Kaiseki No V&V Gaidorain Sakutei Ni Mukete, p.4 - 8, 2023/03

no abstracts in English

Journal Articles

Development of a method for the determination of plutonium in fuel debris by dual times neutron measurements

Nagatani, Taketeru; Sagara, Hiroshi*; Kosuge, Yoshihiro*; Nakaguki, Sho; Nomi, Takayoshi; Okumura, Keisuke

Dai-43-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 3 Pages, 2022/11

Journal Articles

Journal Articles

Preliminary measurement of prompt gamma-ray from nuclear material for the classification of fuel debris and waste

Shiba, Tomooki; Kaburagi, Masaaki; Nomi, Takayoshi; Suzuki, Risa; Kosuge, Yoshihiro*; Nauchi, Yasushi*; Takada, Akira*; Nagatani, Taketeru; Okumura, Keisuke

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR2022) (Internet), 3 Pages, 2022/10

Journal Articles

Study on identification of materials in fuel debris and waste by neutron induced gamma ray spectroscopy

Nauchi, Yasushi*; Nomi, Takayoshi; Suzuki, Risa; Kosuge, Yoshihiro*; Shiba, Tomooki; Takada, Akira*; Kaburagi, Masaaki; Okumura, Keisuke

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR2022) (Internet), 4 Pages, 2022/10

Journal Articles

Characterization of bremsstrahlung and $$gamma$$-rays of fuel debris

Matsumura, Taichi; Okumura, Keisuke; Fujita, Manabu*; Sakamoto, Masahiro; Terashima, Kenichi; Riyana, E. S.

Radiation Physics and Chemistry, 199, p.110298_1 - 110298_8, 2022/10

 Times Cited Count:1 Percentile:33.72(Chemistry, Physical)

Journal Articles

Depletion calculation of subcritical system with consideration of spontaneous fission reaction

Riyana, E. S.; Okumura, Keisuke; Sakamoto, Masahiro; Matsumura, Taichi; Terashima, Kenichi

Journal of Nuclear Science and Technology, 59(4), p.424 - 430, 2022/04

 Times Cited Count:0 Percentile:16.97(Nuclear Science & Technology)

Journal Articles

Comparison of photon spectra emitted from fuel debris using different decay data libraries

Matsumura, Taichi; Okumura, Keisuke; Fujita, Manabu*

JAEA-Conf 2021-001, p.144 - 149, 2022/03

We require reliable nuclear data that can appropriately evaluate the radiation characteristics of fuel debris for the purpose such as development of new sensors, non-destructive assay technologies and optimization of radiation shielding. In the past, even if different results were obtained depending on calculation codes, it was difficult to clarify what caused the differences. To overcome it, we have developed a new reliable code to calculate radiation decay and radioactive source spectra that can accurately treat with large amounts of nuclides and all decay modes in the decay data file. As the first step, we compared the photon spectra of fuel debris by using the recent decay data files: JENDL/DDF-2015, decay sub-libraries of ENDF/B-VIII.0 and JEFF-3.3. In the presentation, we will report requests for the modifications on the decay scheme and branching ratio of decay mode for the next JENDL decay data file.

Journal Articles

Evaluation of radionuclide inventory

Okumura, Keisuke

Fission Product Behavior under Severe Accident, p.70 - 72, 2021/05

no abstracts in English

Journal Articles

Estimation of the dose rate distribution in the primary containment vessel of Fukushima Daiichi Nuclear Power Plants

Okumura, Keisuke

Fission Product Behavior under Severe Accident, p.116 - 121, 2021/05

no abstracts in English

Journal Articles

Feasibility study on tritium recoil barrier for neutron reflectors of research and test reactors

Kenzhina, I.*; Ishitsuka, Etsuo; Ho, H. Q.; Sakamoto, Naoki*; Okumura, Keisuke; Takemoto, Noriyuki; Chikhray, Y.*

Fusion Engineering and Design, 164, p.112181_1 - 112181_5, 2021/03

Tritium release into the primary coolant during operation of the JMTR (Japan Materials Testing Reactor) and the JRR-3M (Japan Research Reactor-3M) had been studied. It is found that the recoil release by $$^{6}$$Li(n$$_{t}$$,$$alpha$$)$$^{3}$$H reaction, which comes from a chain reaction of beryllium neutron reflectors, is dominant. To prevent tritium recoil release, the surface area of beryllium neutron reflectors needs to be minimum in the core design and/or be shielded with other material. In this paper, as the feasibility study of the tritium recoil barrier for the beryllium neutron reflectors, various materials such as Al, Ti, V, Ni, and Zr were evaluated from the viewpoint of the thickness of barriers, activities after long-term operations, and effects on the reactivities. From the results of evaluations, Al would be a suitable candidate as the tritium recoil barrier for the beryllium neutron reflectors.

Journal Articles

A Prediction method for the dose rate of fuel debris depending on the constituent elements

Terashima, Kenichi; Okumura, Keisuke

Journal of Advanced Simulation in Science and Engineering (Internet), 8(1), p.73 - 86, 2021/03

Journal Articles

Evaluation of tritium release into primary coolant for research and testing reactors

Kenzhina, I.*; Ishitsuka, Etsuo; Okumura, Keisuke; Ho, H. Q.; Takemoto, Noriyuki; Chikhray, Y.*

Journal of Nuclear Science and Technology, 58(1), p.1 - 8, 2021/01

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The sources and mechanisms for the tritium release into the primary coolant in the JMTR and the JRR-3M containing beryllium reflectors are evaluated. It is found that the recoil release from chain reaction of $$^{9}$$Be is dominant and its calculation results agree well with trends derived from the measured variation of tritium concentration in the primary coolant. It also indicates that the simple calculation method used in this study for the tritium recoil release from the beryllium reflectors can be utilized for an estimation of the tritium release into the primary coolant for a research and testing reactors containing beryllium reflectors.

Journal Articles

Gamma detector response simulation inside the pedestal of Fukushima Daiichi Nuclear Power Station

Riyana, E. S.; Okumura, Keisuke; Terashima, Kenichi; Matsumura, Taichi; Sakamoto, Masahiro

Mechanical Engineering Journal (Internet), 7(3), p.19-00543_1 - 19-00543_8, 2020/06

JAEA Reports

Development of inventory calculation modules using ORIGEN-S for decommissioning

Matsuda, Norihiro; Konno, Chikara; Ikehara, Tadashi; Okumura, Keisuke; Suyama, Kenya*

JAEA-Data/Code 2020-003, 33 Pages, 2020/03

JAEA-Data-Code-2020-003.pdf:1.85MB

Data handling modules for the radioactivity calculation code, ORIGEN-S, are developed for the reliable evaluations of radioactivity inventory. By using these modules, an activation cross-section data library for the ORIGEN-S code is updated easily and effectively based on a facility-specific neutron spectrum and multi-group neutron activation cross-section library for decommissioning of nuclear facilities, MAXS2015. In order to guarantee the reliability of the radioactivity calculations, functions of data verification in a visual way and numerical comparison between before and after the data processing are also prepared.

Journal Articles

Sensitivity analysis of activation

Okumura, Keisuke

Hoshasen Shahei Handobukku; Oyohen, p.78 - 83, 2020/03

no abstracts in English

260 (Records 1-20 displayed on this page)