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Sakamoto, Masahiro; Okumura, Keisuke; Kanno, Ikuo; Matsumura, Taichi; Terashima, Kenichi; Riyana, E. S.; Mizokami, Masato*; Mizokami, Shinya*
JAEA-Research 2024-017, 14 Pages, 2025/03
In the TEPCO's Fukushima Daiichi Nuclear Power Station (1F), a trial retrieval of fuel debris with small-amount from Unit 2 is planned. The retrieved fuel debris will be transported out of 1F to Institutes in Ibaraki prefecture for analysis. The analyzed results will be utilized for the improvement of the processes (retrieval, transportation and storage) in the fuel debris management as feedback, and also for the development of technologies necessary in the future. The weight of fuel debris in the trial retrieval is planned to be a few grams. After the trial, the scale of retrieval will be expanded step by step. In the trial retrieval, a rational transportation container should be considered beforehand, according to the laws and regulations associated with the off-site transportation. The transportation container has a classification and the classification is decided according to the radioactivity of the material in the container. In this report, we evaluated the applicability of the Type A transport container to contribute to the safety assessment of retrieved fuel debris.
Matsumura, Taichi; Okumura, Keisuke; Sakamoto, Masahiro; Terashima, Kenichi; Riyana, E. S.; Kondo, Kazuhiro*
Nuclear Engineering and Design, 432, p.113791_1 - 113791_9, 2025/02
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Sakamoto, Masahiro; Okumura, Keisuke; Kanno, Ikuo; Matsumura, Taichi; Terashima, Kenichi; Riyana, E. S.; Kaneko, Junichi*; Mizokami, Masato*; Mizokami, Shinya*
Journal of Nuclear Science and Technology, 10 Pages, 2025/00
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Riyana, E. S.; Okumura, Keisuke; Sakamoto, Masahiro; Matsumura, Taichi; Terashima, Kenichi; Kanno, Ikuo
Journal of Nuclear Science and Technology, 61(2), p.269 - 276, 2024/02
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)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:3 Percentile:42.88(Chemistry, Physical)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:1 Percentile:10.00(Nuclear Science & Technology)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
Riyana, E. S.; Okumura, Keisuke; Terashima, Kenichi
Journal of Nuclear Science and Technology, 56(9-10), p.922 - 931, 2019/09
Times Cited Count:7 Percentile:53.80(Nuclear Science & Technology)Riyana, E. S.*; Suda, Shoya*; Ishibashi, Kenji*; Matsuura, Hideaki*; Katakura, Junichi*; Sun, G. M.*; Katano, Yoshiaki
Journal of Nuclear Science and Technology, 56(5), p.369 - 375, 2019/05
Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)Nuclear reactors produce a great number of electron antineutrinos mainly from beta-decay chains of fission products. Such neutrinos have energies mostly in MeV range. We are interested in neutrinos in a region of keV, since they may have information on fuel burn-up and may be detected in future with advanced measurement technology. We calculate reactor antineutrino spectra especially in the low energy region. In this work we present neutrino spectra from various reactors such as typical PWR reactor and others types of reactors for comparison. Our result shows the electron antineutrino flux in the low energy region increases with burn-up of nuclear fuel by accumulated nuclides with low Q values in beta decay.
Riyana, E. S.; Okumura, Keisuke; Terashima, Kenichi
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 4 Pages, 2019/05
Okumura, Keisuke; Riyana, E. S.; Sato, Wakaei*; Maeda, Hirobumi*; Katakura, Junichi*; Kamada, So*; Joyce, M. J.*; Lennox, B.*
Progress in Nuclear Science and Technology (Internet), 6, p.108 - 112, 2019/01
In order to establish the prediction method of the dose rate distribution in the primary containment vessel (PCV) of the Fukushima Daiichi Nuclear Power Station, a series of calculations were carried out in the following way; (1) burnup calculation to obtain fuel composition at the time of accident, (2) activation calculation for the structural materials including impurities, (3) estimation of Cs contamination in PCV based on the result of severe accident analysis by IRID, (4) decay calculation of radioactive nuclides, (5) photon transport calculation to obtain dose rate distribution. After that, Cs concentration around the dry-well of 1F was modified to be consistent with locally measured dose rates in the PCV-investigation by IRID.
Okumura, Keisuke; Riyana, E. S.
JAEA-Conf 2018-001, p.63 - 68, 2018/12
The decommissioning of the Fukushima Daiichi Nuclear Power Station (1F) is an unexplored field. Although the investigations for inside primary containment vessel (PCV) by robots have been underway by IRID, actual situation inside the PCV and the characteristics of fuel debris have not been sufficiently clarified yet. Under such circumstances, the computational simulation with reliable data is an effective means for solving many problems for the 1F decommissioning. Here, as application examples using nuclear data such as JENDL-4.0, we will introduce some researches and developments on (1) prediction of dose rate distribution in PCV, (2) remotely operated vehicle (ROV) system to explore submerged fuel debris in PCV, (3) non-destructive assay of nuclear fuel materials in a fuel debris canister.
Matsumura, Taichi; Sakamoto, Masahiro; Terashima, Kenichi; Riyana, E. S.; Okumura, Keisuke
no journal, ,
no abstracts in English
Okumura, Keisuke; Riyana, E. S.; Sato, Wakaei*; Maeda, Hirobumi*; Fujita, Manabu*
no journal, ,
In order to contribute to the decommissioning of the Fukushima Daiichi Nuclear Power Station (1F) and characterization of 1F fuel debris, we predicted the decay heat of the fuel debris from the time of accident to future and its contributing nuclides, by considering release of volatile fission products.
Terashima, Kenichi; Matsumura, Taichi; Kaburagi, Masaaki; Sakamoto, Masahiro; Riyana, E. S.; Okumura, Keisuke
no journal, ,
no abstracts in English
Riyana, E. S.; Sakamoto, Masahiro; Matsumura, Taichi; Terashima, Kenichi; Okumura, Keisuke; Kanno, Ikuo
no journal, ,
Terashima, Kenichi; Sakamoto, Masahiro; Matsumura, Taichi; Riyana, E. S.; Kanno, Ikuo; Okumura, Keisuke
no journal, ,
Riyana, E. S.; Sakamoto, Masahiro; Matsumura, Taichi; Terashima, Kenichi; Okumura, Keisuke; Kanno, Ikuo
no journal, ,
Matsumura, Taichi; Okumura, Keisuke; Sakamoto, Masahiro; Terashima, Kenichi; Riyana, E. S.; Kondo, Kazuhiro*
no journal, ,
Kanno, Ikuo; Okumura, Keisuke; Matsumura, Taichi; Riyana, E. S.; Terashima, Kenichi; Sakamoto, Masahiro
no journal, ,
We have developed a method for estimating the Cs-137 contamination distribution behind a constant thickness shield by a gamma-ray pinhole camera. This method is useful for obtaining the contamination distribution at the bottom of the shield plug in TEPCO Fukushima Daiichi Power Plant Unit 2.