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Nakase, Masahiko*; Mishima, Ria; Abe, Takumi; Okamura, Tomohiro*; Asano, Hidekazu*
Annals of Nuclear Energy, 224, p.111569_1 - 111569_14, 2025/12
Takeshita, Kenji*; Okamura, Tomohiro*; Nakase, Masahiko*; Abe, Takumi; Nishihara, Kenji
Progress in Nuclear Science and Technology (Internet), 8, p.52 - 57, 2025/09
Takeshita, Kenji*; Okamura, Tomohiro*; Nakase, Masahiko*; Nishihara, Kenji; Abe, Takumi
Proceedings of International Conference on Nuclear Fuel Cycle (GLOBAL2024) (Internet), 2 Pages, 2024/10
Using the dynamic nuclear fuel cycle simulator NMB4.0, the mass balance analysis of the nuclear fuel cycle assuming the introduction of the metal fuel fast reactor in the second half of this century was evaluated. The impact of the introduction of the fast reactor cycle on the back-end including final disposal was discussed.
Arai, Yoichi; Watanabe, So; Hasegawa, Kenta; Okamura, Nobuo; Watanabe, Masayuki; Takeda, Keisuke*; Fukumoto, Hiroki*; Ago, Tomohiro*; Hagura, Naoto*; Tsukahara, Takehiko*
Nuclear Instruments and Methods in Physics Research B, 542, p.206 - 213, 2023/09
Times Cited Count：1 Percentile：19.80(Instruments & Instrumentation)Okamura, Tomohiro*; Katano, Ryota; Oizumi, Akito; Nishihara, Kenji; Nakase, Masahiko*; Asano, Hidekazu*; Takeshita, Kenji*
Journal of Nuclear Science and Technology, 60(6), p.632 - 641, 2023/06
Times Cited Count：3 Percentile：35.97(Nuclear Science & Technology)The Okamura explicit method (OEM) for depletion calculation was developed by modifying the matrix exponential method for dynamic nuclear fuel cycle simulation. The OEM suppressed the divergence of the calculation for short half-life nuclides, even for long time steps. The computational cost of the OEM was small, equivalent to the Euler method, and it maintained sufficient accuracy for the fuel cycle simulation.
Okamura, Tomohiro*; Nishihara, Kenji; Katano, Ryota; Oizumi, Akito; Nakase, Masahiko*; Asano, Hidekazu*; Takeshita, Kenji*
JAEA-Data/Code 2021-016, 43 Pages, 2022/03
JAEA-Data-Code-2021-016.pdf:3.06MB
The quantitative prediction and analysis of the future nuclear energy utilization scenarios are required in order to establish the advanced nuclear fuel cycle. However, the nuclear fuel cycle consists of various processes from front- to back-end, and it is difficult to analyze the scenarios due to the complexity of modeling and the variety of scenarios. Japan Atomic Energy Agency and Tokyo Institute of Technology have jointly developed the NMB code as a tool for integrated analysis of mass balance from natural uranium needs to radionuclide migration of geological disposal. This user manual describes how to create a database and scenario input for the NMB version 4.0.
Okamura, Tomohiro*; Katano, Ryota; Oizumi, Akito; Nishihara, Kenji; Nakase, Masahiko*; Asano, Hidekazu*; Takeshita, Kenji*
Bulletin of the Laboratory for Advanced Nuclear Energy, 6, p.29 - 30, 2022/02
Takeshita Laboratory, Tokyo Institute of Technology, has been developing Nuclear Material Balance code version 4.0 (NMB4.0) in collaboration with Japan Atomic Energy Agency (JAEA). This report summarized the outline and functions of NMB4.0.
Okamura, Tomohiro*; Katano, Ryota; Oizumi, Akito; Nishihara, Kenji; Nakase, Masahiko*; Asano, Hidekazu*; Takeshita, Kenji*
EPJ Nuclear Sciences & Technologies (Internet), 7, p.19_1 - 19_13, 2021/11
Nuclear Material Balance code version 4.0 (NMB4.0) has been developed through collaborative R&D between Tokyo Institute of Technology and JAEA. Conventional nuclear fuel cycle simulation codes mainly analyze actinides and are specialized for front-end mass balance analysis. However, quantitative back-end simulation has recently become necessary for considering R&D strategies and sustainable nuclear energy utilization. Therefore, NMB4.0 was developed to realize the integrated nuclear fuel cycle simulation from front- to back-end. There are three technical features in NMB4.0: 179 nuclides are tracked, more than any other code, throughout the nuclear fuel cycle; the Okamura explicit method is implemented, which contributes to reducing the numerical cost while maintaining the accuracy of depletion calculations on nuclides with a shorter half-life; and flexibility of back-end simulation is achieved. The main objective of this paper is to show the newly developed functions, made for integrated back-end simulation, and verify NMB4.0 through a benchmark study to show the computational performance.
Okamura, Tomohiro*; Oizumi, Akito; Nishihara, Kenji; Nakase, Masahiko*; Takeshita, Kenji*
JAEA-Data/Code 2020-023, 32 Pages, 2021/03
JAEA-Data-Code-2020-023.pdf:1.67MB
Nuclear Material Balance code (NMB code) have been developed in Japan Atomic Energy Agency. The NMB code will be updated with the function of mass balance analysis at the backend process such as reprocessing, vitrification and geological disposal. In order to perform its analysis with high accuracy, it is necessary to expand the number of FP nuclides calculated in the NMB code. In this study, depletion calculation by ORIGEN code was performed under 3 different burn-up conditions such as spent uranium fuel from light water reactor, and nuclides were selected from 5 evaluation indexes such as mass and heat generation. In addition, the FP nuclides required to configure a simple burnup chain with the same calculation accuracy as ORIGEN in the NMB code was selected. As the result, two lists with different number of nuclides, such as "Detailed list" and a "Simplified list", were created.
Okamura, Tomohiro*; Oizumi, Akito; Nishihara, Kenji; Nakase, Masahiko*; Takeshita, Kenji*
Bulletin of the Laboratory for Advanced Nuclear Energy, 5, P. 31, 2021/02
The Takeshita Laboratory at Tokyo Institute of Technology has started to develop a Nuclear Material Balance code (NMB code) in collaboration with Japan Atomic Energy Agency. This report summarized the results of the joint research conducted in 2019.
Takeshita, Kenji*; Okamura, Tomohiro*; Nakase, Masahiko*; Nishihara, Kenji; Abe, Takumi
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Database of nuclear power plant and dry reprocessing required for the metal fuel fast reactor cycle was maintained in the nuclear fuel cycle simulator NMB4.0. In addition, the introduction scenario of metal-fueled fast reactors was verified using sample scenarios.
Okamura, Tomohiro*; Abe, Takumi; Nishihara, Takahiro*; Suzuki, Taiga*; Nakase, Masahiko*; Takeshita, Kenji*; Nishihara, Kenji
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Yamamura, Tomoo*; Harigai, Miki*; Shimada, Takashi*; Okamura, Tomohiro*; Nakase, Masahiko*; Takeshita, Kenji*; Konishi, Yuki*; Nishimura, Keisuke*; Tsukamoto, Taisuke*; Ishida, Hitomi*; et al.
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no abstracts in English
Shimada, Takashi*; Yamamura, Tomoo*; Harigai, Miki*; Takeshita, Kenji*; Nakase, Masahiko*; Okamura, Tomohiro*; Ban, Yasutoshi; Tsukamoto, Hiroki*; Nishimura, Keisuke*; Gima, Hiromichi*
no journal, ,
no abstracts in English
Abe, Takumi; Suzuki, Taiga*; Okamura, Tomohiro*; Nakase, Masahiko*; Nishihara, Kenji; Takeshita, Kenji*
no journal, ,
Shimada, Takashi*; Yamamura, Tomoo*; Harigai, Miki*; Nishimura, Keisuke*; Fukuda, Yuki*; Yamashina, Kazuhisa*; Nakase, Masahiko*; Okamura, Tomohiro*; Takeshita, Kenji*; Ban, Yasutoshi
no journal, ,
no abstracts in English
Ono, Koki*; Okamura, Tomohiro*; Abe, Takumi; Nishihara, Takahiro*; Nakase, Masahiko*; Nishihara, Kenji; Suzuki, Taiga*
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no abstracts in English
Okamura, Tomohiro*; Nishihara, Takahiro*; Nakase, Masahiko*; Nishihara, Kenji; Abe, Takumi
no journal, ,
NEUChain (New Chain), a research and development project aiming at the digitization of the nuclear fuel cycle, is being implemented. The basic concept of NEUChain, its application, and the use of distributed ledger technology in the nuclear field will be discussed.
Abe, Takumi; Suzuki, Taiga*; Okamura, Tomohiro*; Nakase, Masahiko*; Nishihara, Kenji; Takeshita, Kenji*
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no abstracts in English
Mishima, Ria; Okamura, Tomohiro*; Abe, Takumi; Nakase, Masahiko*
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no abstracts in English
