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Hayashi, Hirokazu; Okada, Shota; Izumo, Sari; Hoshino, Yuzuru; Tsuji, Tomoyuki; Nakata, Hisakazu; Sakai, Akihiro; Amazawa, Hiroya; Sakamoto, Yoshiaki
Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 7 Pages, 2017/04
A near surface disposal for low-level radioactive waste (LLW) generated from commercial nuclear power plants (NPP) is operating in Japan. However, the disposal of LLW from other nuclear facilities and radioisotope utilization facilities has not yet been implemented. Japan Atomic Energy Agency (JAEA) plans to implement the near surface disposal. In order to be disposed of these wastes, it must be confirmed by the regulator that each waste package (radioactive waste solidified with filling materials, such as cement, in a container by a regulated method is termed a waste package) conforms to technical standards that aim for safe disposal. JAEA has studied reasonable confirmation methods to demonstrate the conformity of the waste package to the technical standard as NPP operators have studied it. This report describes the outline of our activities focused on development of the confirmation method applicable to radioactive wastes from research facilities.
Hoshino, Yuzuru; Sakamoto, Yoshiaki; Muroi, Masayuki*; Mukai, Satoru*
JAEA-Technology 2015-015, 96 Pages, 2015/07
JAEA-Technology-2015-015.pdf:20.34MB
In order to dispose of the radioactive waste which generates from post-irradiation examination (PIE) facilities, the common evaluation method of radioactivity in wastes from PIE should be established by the actual data such as radioactivity values and the theoretical calculation. In this study, the radioactivity concentrations of 17 nuclides (H-3, C-14, Co-60, Ni-63, Sr-90, Tc-99, Cs-137, Eu-154, U-234, U-235, U-238, Pu-238, Pu-239, Pu-240, Pu-241, Am-241, Cm-244) in combustible wastes stored in NUCLEAR DEVELOPMENT CORPORATION were measured from 3 samples and the radioactivity was calculated by ORIGEN-2 based on initial contents and operation record of the spent fuel. From the comparison of the obtained data by the radiological measurement with the calculated values, the subject to be solved for establishment of the radioactivity evaluation method for PIE was extracted.
Hayashi, Hirokazu; Mizui, Hiroyuki; Sano, Kazuya; Kitamura, Koichi
no journal, ,
no abstracts in English
Kawamura, Hideyuki; Kobayashi, Takuya; Kamidaira, Yuki
no journal, ,
This study aims to validate accuracies of forecast of the Short-Term Emergency Assessment system of Marine Environmental Radioactivity (STEAMER) developed at JAEA by using forecast and reanalysis ocean current data. Oceanic dispersion simulations were carried out in the northwestern Pacific Ocean for 30 days from first day of every month between 2015 and 2017. It was assumed that 
Cs was continuously released into the ocean from the Fukushima Daiichi Nuclear Power Plant. The released Cs was inclined to disperse by mesoscale eddies in the northern part and by the Kuroshio Extension in the southern part. The simulation results with forecast ocean current data were similar to those with reanalysis ocean current data in the early periods and differences between them were remarkable after that. The cause must be accuracies of variable ocean current in the coastal ocean rather than phenomena with long time scale such as the Kuroshio Extension.
Matsuda, Norihiro
no journal, ,
no abstracts in English
Kawamura, Hideyuki
no journal, ,
The Japan Atomic Energy Agency (JAEA) performed oceanic dispersion simulations of radionuclides released from the Fukushima Daiichi Nuclear Power Plant. It was suggested that a part of the Fukushima-derived radionuclides was transported in the east by the Kuroshio Extension and was diluted by mesoscale eddies. JAEA also performed drift simulations of tsunami debris released by the Great East Japan Earthquake. It was suggested that a part of tsunami debris would be transported clockwise in the North Pacific and would be concentrated near the Hawaiian Islands. Recently, JAEA developed STEAMER that receives the forecast data of oceanic condition and forecasts the oceanic dispersion of radionuclides. STEAMER is in temporary operation at JAEA. STEAMER will be upgraded in the future.
Cs derived from Fukushima Dai-ichi Nuclear Power Plant using the short-term emergency assessment system of marine environmental radioactivityIkenoue, Tsubasa; Kawamura, Hideyuki; Kamidaira, Yuki
no journal, ,
In this study, we analyzed the characteristics and trends of oceanic dispersal of Cs by performing the oceanic dispersion simulations using past oceanographic data received on the Short-Term Emergency Assessment system of Marine Environmental Radioactivity (STEAMER) developed at JAEA. Oceanic dispersion simulations in 1461 cases were carried out in the northwestern Pacific Ocean for 60 days from every day between 2015 and 2018. It was assumed that Cs was released into the ocean from the Fukushima Dai-ichi Nuclear Power Plant. In all calculation cases, the maximum concentration in 30 days at each computational grid (maximum concentration distribution) was calculated. Cs in the ocean surface in winter tended to be not dispersed so much. In the ocean surface, the seasonal variation was greater than the annual variation though the maximum concentration distributions have little annual variation. The average of the maximum concentration distribution in all calculation cases was inclined to be high from the coast of Fukushima to the offshore (140
E-145E) and near the Kuroshio Extension.
Izumo, Sari; Nakamura, Mizuki; Nakata, Hisakazu; Sakai, Akihiro
no journal, ,
no abstracts in English