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Togawa, Orihiko; Okura, Takehisa; Kimura, Masanori
JAEA-Review 2022-049, 76 Pages, 2023/01
JAEA-Review-2022-049.pdf:3.74MB
Before construction and after operation of nuclear facilities, environmental consequence assessments are conducted for normal operation and an emergency. These assessments mainly aim at confirming safety for the public around the facilities and producing relief for them. Environmental consequence assessments are carried out using observations/ measurements by environmental monitoring and/or model predictions by calculation models, sometimes using either of which and at other times using both them, according to the situations and necessities. First, this report investigates methods, roles, merits/demerits and relationship between observations/measurements and model predictions which are used for environmental consequence assessments of nuclear facilities, especially holding up a spent nuclear fuel reprocessing plant at Rokkasho, Aomori as an example. Next, it explains representative examples of utilization of data on observations/measurements and results on model predictions, and considers points of attention at using them. Finally, the report describes future direction, for example, improvements of observations/measurements and model predictions, and fusion of both them.
Callen-Kovtunova, J.*; Homma, Toshimitsu
International Journal of Disaster Risk Reduction (Internet), 70, p.102746_1 - 102746_10, 2022/02
Times Cited Count：2 Percentile：34.55(Geosciences, Multidisciplinary)This paper presents key lessons on protecting the public during an emergency at a nuclear power plant (NPP) that have been identified from the accident at the Fukushima Daiichi NPP. The paper describes what emergency arrangements were in place prior to the accident, what occurred during the emergency and then the ascertained lesson. The paper highlights the failings of dose project models, emphasizes several lessons identified from past emergencies, such as the importance of predetermined criteria and emergency zones for determining protective actions. It also presents an essential lesson previously overlooked: the need for arrangements to ensure the safe evacuation of patients from hospitals and care homes.
Kobayashi, Takuya; Kawamura, Hideyuki; Kamidaira, Yuki
Nihon Genshiryoku Gakkai-Shi ATOMO
, 62(11), p.635 - 639, 2020/11
It is important to predict the dispersion of radioactive materials released into the ocean due to nuclear accidents in the surrounding ocean of the east Asian countries. The Japan Atomic Energy Agency developed a Short-Term Emergency Assessment system of Marine Environmental Radioactivity (STEAMER) based on an oceanic dispersion model. STEAMER quickly predicts the oceanic dispersion of radioactive materials in the surrounding ocean of the east Asian countries using the online prediction data of oceanic condition. We validated the predictability of the oceanic dispersion and demonstrated the improvement of the predictability using an ensemble prediction method. Moreover, we developed a high resolution model in the coastal region using a Regional Ocean Modeling System (ROMS).
Iwasaki, Toshiki*; Sekiyama, Tsuyoshi*; Nakajima, Teruyuki*; Watanabe, Akira*; Suzuki, Yasushi*; Kondo, Hiroaki*; Morino, Yu*; Terada, Hiroaki; Nagai, Haruyasu; Takigawa, Masayuki*; et al.
Atmospheric Environment, 214, p.116830_1 - 116830_11, 2019/10
Times Cited Count：6 Percentile：26.43(Environmental Sciences)The utilization of numerical atmospheric dispersion prediction (NDP) models for accidental discharge of radioactive substances was recommended by a working group of the Meteorological Society of Japan. This paper is to validate the recommendation through NDP model intercomparison in the accidental release from the Fukushima Dai-ichi Nuclear Power Plant in 2011. Emission intensity is assumed to be constant during the whole forecast period for the worst-case scenario unless time sequence of emission is available. We expect to utilize forecasts of surface air contaminations for preventions of inhalations of radioactive substances, and column-integrated amounts for mitigation of radiation exposure associated with wet deposition. Although NDP forecasts have ensemble spread, they commonly figure out relative risk in space and time. They are of great benefit to disseminating effective warnings to public without failure. The multi-model ensemble technique may be effective to improve the reliability.
Saito, Kimiaki; Nagai, Haruyasu; Kinase, Sakae; Takemiya, Hiroshi
Nihon Genshiryoku Gakkai-Shi ATOMO, 59(6), p.40 - 44, 2017/06
no abstracts in English
Hayashi, Nobuhiko; Honda, Mitsuru; Shiraishi, Junya; Miyata, Yoshiaki; Wakatsuki, Takuma; Hoshino, Kazuo; Toma, Mitsunori; Suzuki, Takahiro; Urano, Hajime; Shimizu, Katsuhiro; et al.
Europhysics Conference Abstracts (Internet), 39E, p.P5.145_1 - P5.145_4, 2015/06
Ono, Tomio*; Subekti, M.*; Kudo, Kazuhiko*; Takamatsu, Kuniyoshi; Nakagawa, Shigeaki; Nabeshima, Kunihiko
Nihon Genshiryoku Gakkai Wabun Rombunshi, 4(2), p.115 - 126, 2005/06
Control-rod withdrawal tests simulating reactivity insertion are carried out in the HTTR to verify the inherent safety features of HTGRs. This paper describes pre-test analysis method using artificial neural networks to predict the changes of reactor power and reactivity. The network model applied in this study is based on recurrent neural networks. The inputs of the network are the changes of the central control rods position and other significant core parameters, and the outputs are the changes of reactor power and reactivity. Furthermore, Time Synchronizing Signal(TSS) is added to input to improve the modeling of time series data. The actual tests data, which were previously carried out in the HTTR, were used for learning the model of the plant dynamics. After the learning, the network can predict the changes of reactor power and reactivity in the following tests.
Shibata, Yasushi*; Yamamoto, Kazuyoshi; Matsumura, Akira*; Yamamoto, Tetsuya*; Hori, Naohiko; Kishi, Toshiaki; Kumada, Hiroaki; Akutsu, Hiroyoshi*; Yasuda, Susumu*; Nakai, Kei*; et al.
JAERI-Research 2005-009, 41 Pages, 2005/03
JAERI-Research-2005-009.pdf:1.99MB
The measurement of neutron flux and boron concentration in the blood during medical irradiation is indispensable in order to evaluate the radiation in boron neutron capture therapy. It is, however, difficult to measure the blood boron concentration during neutron irradiation because access to the patient is limited. Therefore we prospectively investigated the predictability of blood boron concentrations using the data obtained at the first craniotomy after infusion of a low dosage of BSH. When the test could not be carried out, the blood boron concentration during irradiation was also predicted by using the 2-compartment model. If the final boron concentration after the end of the infusion is within 95% confidence interval of the prediction, direct prediction from biexponential fit will reduce the error of blood boron concentrations during irradiation to around 6%. If the final boron concentration at 6 or 9 hours after the end of infusion is out of 95% confidence interval of the prediction, proportional adjustment will reduce error and expected error after adjustment to around 12%.
Sawa, Kazuhiro; Ueta, Shohei; Sumita, Junya; Verfondern, K.*
Journal of Nuclear Science and Technology, 38(6), p.411 - 419, 2001/06
Times Cited Count：17 Percentile：74.85(Nuclear Science & Technology)no abstracts in English
Nagai, Haruyasu; Chino, Masamichi; Yamazawa, Hiromi
Nihon Genshiryoku Gakkai-Shi, 41(7), p.777 - 785, 1999/07
Times Cited Count：13 Percentile：68.53(Nuclear Science & Technology)no abstracts in English
P.J.Barry*; B.M.Watkins*; Y.Belot*; P.A.Davis*; O.Edlund*; D.Galeriu*; W.Raskob*; S.Russell*; Togawa, Orihiko
Journal of Environmental Radioactivity, 42(2-3), p.191 - 207, 1999/00
Times Cited Count：19 Percentile：45.67(Environmental Sciences)no abstracts in English
Rn concentration model using a hydrodynamic meteorological model,1; One dimensional practical modelChino, Masamichi; Yamazawa, Hiromi; Iida, Takao*
Health Physics, 70(1), p.47 - 54, 1996/01
Times Cited Count：3 Percentile：32.72(Environmental Sciences)no abstracts in English
Honda, Fumiya*; Kinase, Sakae
no journal, ,
Yamashita, Takuya
no journal, ,
JAEA has been conducting decontamination simulations and calculating the future air dose rates for the purpose of providing information to the government and local governments that are in the process of reconstruction. The restoration support system for environment "RESET" is used for decontamination simulation, and "two component model of air dose rate attenuation" is used for prediction of future air dose rate after decontamination. Since the "two-component model of air dose rate attenuation" has not been sufficiently confirmed for the measurement data after decontamination, the applicability to the area after decontamination was verified. Since the prediction by the two-component model has good agreement with the measured air dose rate after the decontamination model demonstration project conducted by the Ministry of the Environment and the variation of the parameters, it is judged that there is no problem in applying to prediction.
