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Irisawa, Keita; Komatsuzaki, Toshio; Kawato, Yoshimi; Sakakibara, Tetsuro; Nakazawa, Osamu; Meguro, Yoshihiro
JAEA-Technology 2015-008, 28 Pages, 2015/03
JAEA-Technology-2015-008.pdf:13.63MB
In JAEA, 16,671 drums of intermediate-radioactive bituminized waste products (BWPs) have been stored in asphalt solidification storages. As a way of reduction of uncertainty in assessment of disposal of the BWPs, a processing technique of separation of nitrate salts from the BWP by means of an aqueous leaching method was studied. As elemental techniques for the denitration process, (1) crushing techniques of a BWP and (2) denitration techniques for the crushed BWP by the aqueous leaching method were investigated. In order to promote leaching amounts of nitrates, the BWP was crushed, and the grain size distribution was investigated by sieving. Moreover, leaching behaviors of nitrate, nitrite and elements as radionuclides including in the BWP were investigated.
Ito, Toshimichi; Aramaki, Takafumi*; Otosaka, Shigeyoshi; Suzuki, Takashi; Togawa, Orihiko; Kobayashi, Takuya; Kawamura, Hideyuki; Amano, Hikaru; Senju, Tomoharu*; Chaykovskaya, E. L.*; et al.
Journal of Nuclear Science and Technology, 42(1), p.90 - 100, 2005/01
Times Cited Count：14 Percentile：67.75(Nuclear Science & Technology)During 1996-2002, a wide-area research project on anthropogenic radionuclides was done in the Japanese and Russian EEZ of the Japan Sea to investigate their migration. As the results of expeditions in 2001 and 2002, (1) the concentrations and distributions of radionuclides are similar to the results of previous, (2) inventories of these radionuclides indicate accumulation in the Japan Sea seawater compared to the amounts supplied by global fallout, (3) 
Sr and 
Cs concentrations in intermediate layer show temporal variations, and 4) the variations may reflect the water mass movement in upper part of the Japan Sea.
Nagai, Haruyasu; Terada, Hiroaki; Tsuzuki, Katsunori; Ota, Masakazu; Furuno, Akiko; Akari, Shusaku; Katata, Genki
no journal, ,
In order to assess the radiological dose to the public resulting from the Fukushima Daiichi Nuclear Power Station accident in Japan, the spatial and temporal distribution of radioactive materials in the environment are reconstructed by computer simulations. In this study, by refining the source term of radioactive materials discharged into the atmosphere and modifying the atmospheric dispersion model, the atmospheric dispersion simulation of radioactive materials is improved. Then, a database of spatiotemporal distribution of radioactive materials in the air and on the ground surface is developed from the output of the simulation, and is used for the dose assessment by coupling with the behavioral pattern of evacuees from the nuclear accident. In this year, (1) investigation of the source term, (2) improvement of atmospheric dispersion simulation, and (3) acquisition and organization of measured data have been conducted.
Iijima, Kazuki; Dohi, Terumi; Koma, Yoshikazu; Takahatake, Yoko; Fujiwara, Kenso; Niizato, Tadafumi
no journal, ,
To develop a model to estimate on-site distribution, detailed evaluation of the off-site distribution of radionuclides deposited on the soil and trees in the environment was carried out. Six traces of the radioactive plume, which we defined as NNW, W (divided into W-N and W-S), SW and S (divided into S-W and S-E) from a north to south direction, were clearly identified based on the off-site distribution of air dose rate measured by a car-borne survey within 5 km from the FDNPS. The tendency that the Transport Ratios for Sr and Pu to topsoils obtained in the west direction were higher than those of south direction was consistent with that observed in the previous on-site sampling. Therefore, the data suggest that the estimation of on-site distribution of radionuclides inventory based on the off-site distribution was applicable.
Iijima, Kazuki; Sasaki, Takayuki*; Matoba, Daisuke*; Dohi, Terumi; Fujiwara, Kenso
no journal, ,
In this study, in order to estimate the on-site distribution, the concentrations of several radionuclides in off-site topsoil were evaluated along six traces of the radioactive plumes, and the characteristic of spatial distribution and depth profile was discussed. The tendency of inventories of Sr-90 and Pu-238 observed in off-site was consistent with that of observed in the previous on-site sampling, indicating that the estimation of on-site distribution of radionuclides based on the off-site was applicable. Concentration of Cs-137 drastically decreased from top of the surface to around 10 cm depth, then gradually decreased, suggesting that Cs-137 was strongly adsorbed at upper part. Surprisingly, the profile of Pu-239+240 was quite different from that of Pu-238, while it was similar to Am-241. It was considered that the behavior of Am-241 was strongly reflected by that of Pu-241, a parent of Am-241, and the deposition event of Pu-239+240 and Pu-241 was different from that of Pu-238.
