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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.
Shiba, Tomooki; Maeda, Shigetaka; Sagara, Hiroshi*; Ishimi, Akihiro; Tomikawa, Hirofumi
Energy Procedia, 131, p.250 - 257, 2017/12
Times Cited Count:0 Percentile:0.03In the present paper, the ray source data was developed for the debris composition based on "best estimates", and the subsequent photon transportation calculation was performed to evaluate the leakage ray spectra according to the fuel debris. Since the creation of the line spectrum source requires a great deal, we have developed the relatively simple but accurate enough method to build up ray source, coupling of baseline spectra evaluated by ORIGEN2 code and several line spectra of interest. One of the advantages of the method is taking bremsstrahlung X rays into consideration by utilizing the bremsstrahlung libraries of ORIGEN2. The new ray source was used to calculate the detector response of HPGe detector and the results was compared as a benchmark with experimental measurement results of irradiated fuel pins. As the result, the simulated ray spectrum shape agreed well with the shape of ray spectrum obtained by the experiment.
Nagatani, Taketeru; Komeda, Masao; Shiba, Tomooki; Nauchi, Yasushi*; Maeda, Makoto; Sagara, Hiroshi*; Kosuge, Yoshihiro*; Kureta, Masatoshi; Tomikawa, Hirofumi; Okumura, Keisuke; et al.
Energy Procedia, 131, p.258 - 263, 2017/12
Times Cited Count:8 Percentile:98.37Nagatani, Taketeru; Komeda, Masao; Shiba, Tomooki; Maeda, Makoto; Nauchi, Yasushi*; Sagara, Hiroshi*; Kosuge, Yoshihiro*; Kureta, Masatoshi; Tomikawa, Hirofumi; Okumura, Keisuke; et al.
Proceedings of INMM 57th Annual Meeting (Internet), 10 Pages, 2016/07
Okumura, Keisuke; Sato, Wakaei; Maeda, Hirobumi; Wakaida, Ikuo; Washiya, Tadahiro; Katakura, Junichi*
no journal, ,
In order to develop the evaluation technology of the most probable radiation source and dose rate distributions in the primary containment vessel (PCV), we evaluated the radiation source distribution based on the results of fuel burn-up calculation, activation calculation of structural materials and severe accident analysis. Then, we built a three-dimensional PCV model for the particle transport Monte Carlo calculation code PHITS. From the PHITS calculation, we obtained the response function of the dose rate distribution due to each unit radiation source.
Nagatani, Taketeru; Komeda, Masao; Shiba, Tomooki; Maeda, Makoto; Nauchi, Yasushi*; Sagara, Hiroshi*; Kureta, Masatoshi; Tomikawa, Hirofumi; Okumura, Keisuke; Heinberg, C.; et al.
no journal, ,
no abstracts in English
Okumura, Keisuke; Riyana, E. S.; Sato, Wakaei*; Maeda, Hirobumi*; Katakura, Junichi*
no journal, ,
Based on the results of fuel burn-up calculations and activation calculations for structural materials and on those of severe accident progression analyses and internal investigations by IRID, we predicted a three-dimensional dose rate distribution in the containment vessel of Unit 1 at the Fukushima Daiichi Nuclear Power Station.
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.
Okumura, Keisuke; Riyana, E. S.; Sato, Wakaei*; Maeda, Hirobumi*; Katakura, Junichi*
no journal, ,
The three-dimensional dose rate distribution at the end of 2021 in the primary containment vessel of the Fukushima Daiichi Nuclear Power Station was predicted by combining various numerical calculations such as Monte Carlo calculation and measured data obtained in the internal investigations.