Tomita, Jumpei; Takeuchi, Erina
Applied Radiation and Isotopes, 150, p.103 - 109, 2019/08
A rapid analytical method for determining Sr in urine samples (1-2 L) was developed to assess the internal exposure of workers in a radiological emergency. Strontium in a urine sample was rapidly separated by phosphate co-precipitation, followed by extraction chromatography with a tandem column of Pre-filter, TRU and Sr resin, and the Sr activity was determined by ICP-MS/MS. Measurement in the MS/MS mode with an O reaction gas flow rate 1 mL min showed no tailing of Sr at m/z = 90 up to 50 mg-Sr L. The interferences of Ge, Se and Zr at m/z = 90 were successfully removed by chemical separation. This analytical method was validated by the results of the analyses of synthetic urine samples (1.2-1.6 L) containing a known amount of Sr along with 1 mg of each of Ge, Se, Sr and Zr. The turnaround time for analysis was about 10 h, and the detection limit of Sr was approximately 1 Bq per urine sample.
Mohamad, A.*; Nakajima, Kunihisa; Suzuki, Eriko; Miwa, Shuhei; Osaka, Masahiko; Oishi, Yuji*; Muta, Hiroaki*; Kurosaki, Ken*
Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05
In the accident of Fukushima Daiichi Nuclear Power Station, formation of a volatile SrCl could have occurred by the sea-water injection into the core. This can cause the release of non-volatile group Sr from the fuel to induce chemical reactions with reactor structural materials, such as stainless steel and Zircaloy (Zry) cladding. Such reactions could cause the changes in distribution of Sr in the reactor. Chemical reactions between Sr species and Zry were therefore investigated experimentally. As the result, it can be said that Sr vapor species were chemically trapped right after the release from fuel. This trapping effect of Sr by Zry-cladding implies a possibility of preferable Sr retention in the oxide phase of debris.
Horiike, Takumi*; Dotsuta, Yuma*; Nakano, Yuriko*; Ochiai, Asumi*; Utsunomiya, Satoshi*; Onuki, Toshihiko; Yamashita, Mitsuo*
Applied and Environmental Microbiology, 83(20), p.e00855-17_1 - e00855-17_11, 2017/10
Radioactive strontium (Sr) leaked into the ocean from the Fukushima Daiichi Nuclear Power Plant after the nuclear accident. Since the removal of Sr using general adsorbents is not efficient at high salinity, this study investigated removal of soluble Sr from a saline solution by biogenic carbonate minerals. An isolate, Bacillus sp. strain TK2d, from marine sediment removed more than 99 % of Sr in a saline solution. Sr adsorbed at the cell surface and then carbonate minerals containing Sr developed outside the cells.
Takagai, Yoshitaka*; Furukawa, Makoto*; Kameo, Yutaka; Matsueda, Makoto; Suzuki, Katsuhiko*
Bunseki Kagaku, 66(4), p.223 - 231, 2017/04
no abstracts in English
Fujita, Hiroki; Nojima, Takehiro; Nagaoka, Mika; Osawa, Takahito; Yokoyama, Hiroya; Ono, Hironobu*
KEK Proceedings 2016-8, p.168 - 172, 2016/10
An automatic analysis system was developed to analyze Strontium-90 (Sr) radioactivity in environmental sample for 2013-2015. Various kinds of ashed environmental samples were used in performance tests of the automatic system. These tests were successful without any system trouble. However, Sr concentration had not been measured using the samples analyzed by the system. In this research, Sr concentration in seaweed sample was compared by between the system's analysis and worker's one. Moreover, the system was improved in each analysis process.
Sassi, M.*; Rosso, K. M.*; Okumura, Masahiko; Machida, Masahiko
Clays and Clay Minerals, 64(2), p.108 - 114, 2016/04
no abstracts in English
Nojima, Takehiro; Fujita, Hiroki; Nagaoka, Mika; Osawa, Takahito; Yokoyama, Hiroya; Ono, Hironobu*
KEK Proceedings 2015-4, p.111 - 115, 2015/11
Automatic strontium-90 analysis system was developed for environmental sample in this research. The system was successful to do wet ashing, chemical separation and ion exchange processes using robot, automatic heating system and so on. Hand-made control program can operate the system by itself.
Tomita, Jumpei; Yamamoto, Masayoshi*; Nozaki, Teo; Tanimura, Yoshihiko*; Oishi, Tetsuya
Journal of Environmental Radioactivity, 146, p.88 - 93, 2015/08
Otosaka, Shigeyoshi; Amano, Hikaru; Ito, Toshimichi; Kawamura, Hideyuki; Kobayashi, Takuya; Suzuki, Takashi; Togawa, Orihiko; Chaykovskaya, E. L.*; Lishavskaya, T. S.*; Novichkov, V. P.*; et al.
Journal of Environmental Radioactivity, 91(3), p.128 - 145, 2006/00
Distributions of radionuclides (Sr, Cs and Pu) in seabed sediment in the Japan Sea were observed during 1998-2002. Observed inventories of anthropogenic radionuclides in sediment ranged 0.1-86 Bq m for Sr, 23-379 Bq m for Cs and 0.1-86 Bq m for Pu. In the deep part ( 2 km depth) of the western Japan Basin, Pu/Cs inventory ratios were larger than those in the central Yamato Basin although inventories of radionuclides were not different between basins. The higher Pu/Cs ratios in the western Japan Basin were derived by the production of Pu-enriched particle in the surface layer and effective sinking of particulate materials in this region. In the marginal Yamato Basin and the Ulleung Basin, both inventories and Pu/Cs ratios in sediment were larger than those in the central Yamato Basin. In the eastern/southern Japan Sea, it was suggested that the supply of particulate radionuclides by the TWC enhanced accumulation of radionuclides in this region.
Okamoto, Yoshihiro; Yaita, Tsuyoshi; Minato, Kazuo
Journal of Non-Crystalline Solids, 333(2), p.182 - 186, 2004/02
The local structure of solid and molten SrCl was investigated by X-ray absorption fine structure(XAFS) technique. A superionic conduction state was observed below the melting point. The XAFS data at molten state was obtained at 1000C. According to the curve fitting analysis, the nearest Sr-Cl distance and the coordination number are 2.99 and 6.6 in molten state. XAFS functions calculated from molecular dynamics simulation results were copmpared with the experimental XAFS data.
Otosaka, Shigeyoshi; Ito, Toshimichi; Kawamura, Hideyuki; Kobayashi, Takuya; Suzuki, Takashi; Togawa, Orihiko
Dai-45-Kai Kankyo Hoshano Chosa Kenkyu Seika Rombun Shorokushu (Heisei-14-Nendo), p.77 - 78, 2003/12
no abstracts in English
Otosaka, Shigeyoshi; Aramaki, Takafumi*; Suzuki, Takashi; Kobayashi, Takuya; Ito, Toshimichi; Togawa, Orihiko; Chaykovskaya, E. L.*; Dunaev, A. L.*; Karasev, E. V.*; Novichkov, V. P.*; et al.
Proceedings of International Symposium on Radioecology and Environmental Dosimetry, p.390 - 395, 2003/10
Seabed sediments were collected at 22 stations in the Japan Sea, and anthropogenic radionuclides were measured in order to understand distributions and accumulation processes of these materials. Averaged concentrations of Cs in sediment in the Japan Basin and the Yamato Basin were 1.0 Bq/kg and 1.0 Bq/kg, respectively. Although there was no significant difference in mean Cs concentration between the Japan Basin and the Yamato Basin, distributions of radionuclides in these 2 basins showed different features. In the Japan Basin, the spatial variation of concentration of radionuclides was smaller than that at the Yamato Basin. At most stations in the Yamato Basin, significant concentrations of radionuclides were not detected, but remarkable large activities were observed at several stations in the Yamato Basin. For all radionuclides, the highest concentration was observed in the southeastern margin of the Yamato Basin. These results would suggest that there were different accumulation processes of radionuclides between the Japan Basin and the Yamato Basin.
Tanaka, Tadao; Mukai, Masayuki; Li, Z.*; Li, S.*
JAERI-Conf 2003-010, p.142 - 149, 2003/09
An environmental migration test of Sr-85 was carried out in natural unsaturated loess zone at the field test site of China Institute for Radiation Protection, China, and the migratory mobility of Sr was observed during 2 years. As laboratory experiments, the migration experiment of Sr by a column system and the sorption experiment of Sr by a batch system were carried out by using the loess taken from the field test site. We discussed about applicability of sorption data determined from the laboratory experiments to evaluating the Sr migration behavior investigated at the field test site. The Sr migration behavior at the field test site could be expressed by the equilibrium sorption model using distribution coefficients determined from the laboratory experiments. This supports that the valid distribution coefficient for the evaluation of Sr migration in natural environment is predicted from the laboratory experiments.
Tanaka, Tadao; Mukai, Masayuki; Maeda, Toshikatsu; Munakata, Masahiro; Matsumoto, Junko; Ogawa, Hiromichi; Bamba, Tsunetaka*; Wang, Z.*; Yang, Y.*; Zhao, Y.*
Proceedings of International Symposium on Radioecology and Environmental Dosimetry, p.179 - 184, 2003/00
Migration behaviors of stable strontium element and radioactive nuclide strontium 90 in natural aquifer were studied by a field test, which was performed in the aquifer loess zone at 30 m under the ground surface of the field test site of China Institute for Radiation Protection. The migration behavior of stable strontium was a little different from that of Sr. The difference was evaluated by applying the distribution coefficient considering Sr and coexistent ion concentrations. Migration behavior of radionuclide in natural environment has been generally demonstrated on field tests without radioactive tracers and/or large-scale column tests with radioactive tracers. Such tests seem to be valuable to improve reliability of the migratory evaluation.
; Sato, Haruo
JNC-TN8410 2001-028, 36 Pages, 2002/03
For a safety assessment of the high-level radioactive waste disposal, effective diffusion coefficients (D) of radionuclides in bentonite have been accumulated by the through-diffusion method. It has been found recently that experimental results on Ds for several cations (cesium and strontium) by the fairly standard experimental method in JNC differ from those previously reported in several papers. Discrepancy can be considered to be due to different design of diffusion cell and system. In order to confirm influences of the experimental design on cation diffusivities in bentonite, a flow-through diffusion system was developed and several diffusion experiments were conducted.As a result, magnitude of D and its salinity dependence were relatively different between the standard and flow-through diffusion system. Since the latter system can control boundary conditions of the experiment more strictly than the standard method, we can conclude that the flow-through diffusion system provide correct results. In addition, we apply this flow-through diffusion system to a modification of controlling boundary condition during the experiment and to the diffusion experiment under controlled temperature.
Kato, Hiroshige*; Mine, Tatsuya*; Mihara, Morihiro; Oi, Takao; Honda, Akira
JNC-TN8400 2001-029, 63 Pages, 2002/01
Cementitious materials will be used for the TRU waste repository as a component of engineered barrier system. The distribution coefficients which represent the retardation of radionuclides migration for the cementitious materials would be one of the important parameter for the safety assessment. The much information of radionuclide sorption onto the cementitious materials has been accumulated through the study in the world. Therefore it is necessary to compile the information and Kd of the radionuclides reported in previous studies. In this report, the Kd of the important radionuclides, such as C, Ni, Se, Sr, Zr, Nb, Mo, Tc, Sn, I, Cs, Sm, Pb, Ra, Ac, Th, Pa, U, Np, Pu, Am, Cm, for the cementitious materials were compiled as the Sorption Database (SDB). For radionuclides to be sensitive to the redox potential, e.g. Se, Tc, Pa, U, Pu and Np, some Kds measured under the controlled atmosphere had been reported, and few Kds measured under the controlled redox potential had been reported. For Se, Mo, Sm, Cm and Ac, the distribution coefficients had not been reported, therefore distribution coefficients of Se and Mo for OPC (Ordinary Portland Cement) pastes were measured by batch sorption experiments and these data were added into the SDB.
*; *; *
JNC-TJ8400 2000-018, 79 Pages, 2000/02
As a basic research for geological disposal of high-level radioactive wastes, diffusion behavior of radionuclides and corrosion behavior of overpack materials in clay buffer materials (bentonite) were studied. In the study on the diffusion behavior of radionuclides, basal spacing and water content were determined for water saturated, compacted Na-montmorillonite that is major clay mineral of bentonite. The apparent diffusion coefficients of Na, Sr, Cs and Cl ions and their activation energies were also determined at different dry densities of montmorillonite. For all kinds of ions, the activation energies were found to increase as the dry density increased. These findings suggest that the diffusion mechanism of ions in compacted montmorillonite changed with increasing dry density. As a reasonable explanation for the changes in the activation energy, we proposed a multiprocess diffusion model, in which predominant diffusion process is considered to change from pore water diffusion to interlayer diffusion via surface diffusion when the dry density increases. The Na-montmorillonite is expected to alter by the ion exchange with Ca ions, which could be introduced from groundwater and/or cementitious materials in a repository. The apparent diffusion coefficients of Na and Cs ions and their activation energies were studied for Na/Ca montmorillonite mixtures in order to know the effect of this kind of alteration on the diffusion behavior of ions. It was found that the alteration of montmorillonite affected diffusion coefficients and the activation energies for both kinds of cations. These effects cannot be explained only by the pore water diffusion. The multiprocess diffusion model proposed in this study is suggested as the most reasonable explanation for the effects. The oxidation behavior of pyrite in bentonite during drying process was studied for understanding corrosion behavior of overpack materials in bentonite. There ...
Kudo, Akira*; *
JNC-TJ8400 2000-010, 67 Pages, 2000/02
The first and second environmental releases of man-made Pu came from nuclear explosions at Alamagordo and Nagasaki in 1945. The release at Nagasaki was more serious than at Alamagordo, because it happened in an area with a high population density. Unfissioned Pu and various fission products have been interacting here with various environmental materials (soils, sediments, and plants) under wet and temperature conditions for more than 45 years. To assess the environmental mobility of Pu, the distributions of radionuclides from this release were investigated at Nishiyama where heavy black rain containing unfissioned plutonium and fission products fell 30 minutes after the nuclear explosion. The vertical distributions of Cs and Pu were determined in unsaturated soil cores up to 450cm deep. Most radionuclides were found in the soil column 30cm from the ground surface. However, Pu were detected in the groundwater as well below a depth of 200cm. No Cs was found below 40cm from the ground surface or in groundwater. These observations reveal that about 3% of the total Pu have been migrating in the soil at a faster rate than the remaining Pu. Sharp peak of Cs and Pu, indicating heavy deposition from the Nagasaki local fallout of 1945, were found in sediment cores collected from the Nishiyama reservoir. Pu peaks were unexpectedly discovered in pre-1945 sediment core sections. NO Cs was found. By contrast to the distribution in sediment cores, Cs in tree rings had spread by diffusion from the bark to the center of the tree without holding a fallout deposition record. Most of the Pu was distributed in the tree rings following a similar deposition record to that found in sediment cores. Furthermore, a very small amount of Pu (about 1%) was found unexpectedly in pre-1945 tree rings. The only reasonable ...
Mizoguchi, Kenichi*; Yamaguchi, Isoo; Morita, Yasuji; Yamagishi, Isao; ; Kubota, Masumitsu
JAERI-Research 98-026, 29 Pages, 1998/05
no abstracts in English
PNC-TN8410 97-202, 205 Pages, 1998/01
This thesis summarizes the results investigated in order to establish a basic theory on the predictive method of diffusion coefficients of nuclides in compacted sodium bentonite which is a candidate buffer material and in representative rocks for the geological disposal of radioactive waste by measuring the pore structural factors of the compacted bentonite and rocks such as porosity and tortuosity, measuring diffusion coefficients of nuclides in the bentonite and rocks, acquiring basic data on diffusion and developing diffusion models which can quantitatively predict nuclide migration in long-term. This consists of 7 chapters. Chapter 1 is the introduction, in which conventional studies on nuclide migration in buffer materials and rocks for the geological disposal of radioactive waste carried out to date are reviewed, and those problems are summarized as well as the objectives of this study are described. Besides, the difinition of geological disposal is explained. In Chapter 2, it is described on non-steady state diffusion of HTO, Sr-90, Tc-99, I-129, Cs-137, Np-237, Am-241 and Pu in purified sodium bentonite, Kunipia-F, in which the rate of constituent Na-smectite was raised approximately 100wt%. In-diffusion experiments were carried out in a range of bentonite densities of 200 2000 kgm under ambient aerobic conditions at room temperature (20 23C), and apparent diffusion coefficients (Da) were obtained. The apparent diffusion coefficients decreased with increasing dry density of bentonite. It was quantitatively indicated from diffusion experiments using HTO that these Da values include the effect of geometric retardation such as the tortuosity factor of compacted bentonite. It was experimentally clarified that Da is not affected by diffusion time based on diffusion experiments for different experimental periods using Sr and Cs. Moreover, it was also experimentally clarified that Da is not affected by tracer ...