Evaluation of sediment and Cs redistribution in the Oginosawa River catchment near the Fukushima Dai-ichi Nuclear Power Plant using integrated watershed modeling

Sakuma, Kazuyuki; Malins, A.; Funaki, Hironori; Kurikami, Hiroshi; Niizato, Tadafumi; Nakanishi, Takahiro; Mori, Koji*; Tada, Kazuhiro*; Kobayashi, Takamaru*; Kitamura, Akihiro; et al.

Journal of Environmental Radioactivity, 182, p.44 - 51, 2018/02

https://doi.org/10.1016/j.jenvrad.2017.11.021

The Oginosawa River catchment lies 15 km south-west of the Fukushima Dai-ichi nuclear plant. The General-purpose Terrestrial Fluid-flow Simulator (GETFLOWS) code was used to study sediment and Cs redistribution within the catchment. Cesium-137 input to watercourses came predominantly from land adjacent to river channels and forest gullies. Forested areas far from the channels only made a minor contribution to Cs input to watercourses, total erosion of between 0.001-0.1 mm from May 2011 to December 2015. The 2.3-6.9% y decrease in the amount of Cs in forest topsoil over the study period can be explained by radioactive decay (approximately 2.3% y), along with a migration downwards into subsoil and a small amount of export. The amount of Cs available for release from land adjacent to rivers is expected to be lower in future than compared to this study period, as the simulations indicate a high depletion of inventory from these areas.

Establishment of experimental system for Mo/Tc production by neutron activation method

Ishida, Takuya; Shiina, Takayuki*; Ota, Akio*; Kimura, Akihiro; Nishikata, Kaori; Shibata, Akira; Tanase, Masakazu*; Kobayashi, Masaaki*; Sano, Tadafumi*; Fujihara, Yasuyuki*; et al.

JAEA-Technology 2015-030, 42 Pages, 2015/11

JAEA-Technology-2015-030.pdf:4.82MB

The research and development (R&D) on the production of Mo/Tc by neutron activation method ((n, ) method) using JMTR has been carried out in the Neutron Irradiation and Testing Reactor Center. The specific radioactivity of Mo by (n, ) method is extremely low compared with that by fission method ((n,f) method), and as a result, the radioactive concentration of the obtained Tc solution is also lowered. To solve the problem, we propose the solvent extraction with methyl ethyl ketone (MEK) for recovery of Tc from Mo produced by (n, ) method. We have developed the Mo/Tc separation/extraction/concentration devices and have carried out the performance tests for recovery of Tc from Mo produced by (n, ) method. In this paper, in order to establish an experimental system for Mo/Tc production, the R&D results of the system are summarized on the improvement of the devices for high-recovery rate of Tc, on the dissolution of the pellets, which is the high-density molybdenum trioxide (MoO) pellets irradiated in Kyoto University Research Reactor (KUR), on the production of Tc, and on the inspection of the recovered Tc solutions.

Mo-Tc production process by (n,) reaction with irradiated high-density MoO pellets

Tsuchiya, Kunihiko; Nishikata, Kaori; Tanase, Masakazu*; Shiina, Takayuki*; Ota, Akio*; Kobayashi, Masaaki*; Yamamoto, Asaki*; Morikawa, Yasumasa*; Takeuchi, Nobuhiro*; Kaminaga, Masanori; et al.

Proceedings of 6th International Symposium on Material Testing Reactors (ISMTR-6) (Internet), 9 Pages, 2013/10

http://www.invap.com.ar/ismtr/images/stories/trabajos/Tsuchiya-Paper.pdf

http://www.invap.com.ar/ismtr/images/stories/trabajos/Tsuchiya-Presentation.pdf

no abstracts in English

Development of Mo-Tc domestic production with high-density MoO pellets by (n,) reaction

Tsuchiya, Kunihiko; Tanase, Masakazu*; Takeuchi, Nobuhiro*; Kobayashi, Masaaki*; Hasegawa, Yoshio*; Yoshinaga, Hideo*; Kaminaga, Masanori; Ishihara, Masahiro; Kawamura, Hiroshi

Proceedings of 5th International Symposium on Material Testing Reactors (ISMTR-5) (Internet), 10 Pages, 2012/10

http://www.murr.missouri.edu/ismtr/papercall/Papers/JAEA/Tsuchiya_K=PAPER_Dev%20of%20Mo99-Tc99m%20Domestic%20Prod%20with%20HighDens%20MoO3%20Pellets.pdf

As one of effective uses of the JMTR, JAEA has a plan to produce Mo by (n, ) method, a parent nuclide of Tc. In case of Japan, the supplying of Mo depends only on imports from foreign countries. The R&D on production method of Mo -Tc has been performed with Japanese industrial users under the cooperation programs. The main R&D items for the production are (1) Fabrication of irradiation target such as the sintered MoO pellets, (2) Separation and concentration of Tc by the solvent extraction from Mo solution, (3) Examination of Tc solution for a medicine, and (4) Mo recycling from Mo generator and solution. In this paper, the status of the R&D is introduced for the production of Mo -Tc.

Study on construction technology for repository

Tanai, Kenji; Iwasa, Kengo; Hasegawa, Hiroshi; Miura, K.*; Okutsu, Kazuo*; Kobayashi, Masaaki*

JNC TN8400 99-046, 177 Pages, 1999/11

JNC-TN8400-99-046.pdf:6.03MB

For the construction of underground facilities comprising access tunnels, connecting tunnels, main tunnels and disposal tunnels, a large number of tunnels will be excavated in deep rock formations. These excavations will extend hundreds kilometers in total length. Therefore, special attention must be paid, to transporting large volume of debris, ventilation, emergency escape routes in case of accident, and other factors. In addition, special attention must also paid to potential accidents which might in underground excavations, including unstable facing phenomena (such as collapse and swelling of facing at weak layer sections), spring water flow resulting collapse of rock, gas eruption, and rock burst. While considering these factors to be emphasized during the construction of geological disposal facilities, the investigation reviewed the existing working methods on individual construction technologies of access tunnels, main tunnels, connecting tunnels, disposal tunnels, and disposal pit, based on the recognition that the present state deals with a wide range of geological environments, and conducted investigation about the construction methods for each tunnel on the basis current technologies, and described the outline of these methods. Furthermore, for the items to be particulaly emphasized on site characterization koko and siting data such as ground pressure and spring water, the investigation reviewed the current countermeasure works, and made survey on the phenomena appeared during actual tunnel construction works and their countermeasres, and carried out a study on effectiveness of these countermeasures. This constructing of disposal site in deep geological formations is basically possible by applying, or confirming, current excavation technologies for tunnels and underground facilities, A systematic construction system combines separate technologies relating to construction, (excavation technology, tunnel support work method, etc.). Such systems ...

Comparison of calculated alues with measured values on the amount of TRU and FP nuclides accumulated in gadolinium bearing PWR spent fuels

Adachi, Takeo; Nakahara, Yoshinori; Kono, Nobuaki; Gunji, Katsubumi; ; ; ; Kato, Kaneharu; Tachikawa, Enzo; *; et al.

Journal of Nuclear Science and Technology, 31(10), p.1119 - 1129, 1994/10

https://doi.org/10.3327/jnst.31.1119

no abstracts in English

Investigation of modification on JRR-3 heavy water tank to produce a large diameter (12 inch) NTD-Si, 2; Thermal-hydraulic analysis

Araki, Masaaki; Kobayashi, Tetsuya; Oba, Toshinobu; Takeuchi, Masaki

no journal, , 

no abstracts in English

Development of Mo-Tc domestic production with high-density MoO pellets by (n,) reaction

Tsuchiya, Kunihiko; Tanase, Masakazu*; Shiina, Takayuki*; Ota, Akio*; Kobayashi, Masaaki*; Morikawa, Yasumasa*; Yamamoto, Asaki*; Kaminaga, Masanori; Kawamura, Hiroshi

no journal, , 

no abstracts in English

Extraction Properties of Tc from irradiated High-density MoO Pellets Solution

Shibata, Akira; Ishida, Takuya; Shiina, Takayuki*; Kobayashi, Masaaki*; Tanase, Masakazu*; Kato, Yoshiaki; Kimura, Akihiro; Ota, Akio*; Yamamoto, Asaki*; Morikawa, Yasumasa*; et al.

no journal, , 

Tc, a daughter nuclide of Mo, is commonly used as a radiopharmaceutical. In case of Japan, all of Mo are imported from foreign countries. R&D for domestic production of Mo by the (n, ) method has been being performed in JMTR from viewpoints of nuclear proliferation resistance and waste management. In this study, experiments of Mo/Tc production were performed to enhance recovery yields of Tc. High-density MoO pellets were irradiated in the Kyoto University Reactor (KUR). Solvent extraction method with MEK was used to extract Tc from Mo/Tc solution and the maximum recovery yields as high as 80% was achieved. Quality tests were performed, and impurities in Tc solution were evaluated and were efficiently low. It is concluded that Tc solution produced by this method is suitable for a raw material of radiopharmaceutical.

Evaluation of Mo/Tc production with irradiated MoO pellets

Ishida, Takuya; Shiina, Takayuki*; Ota, Akio*; Suzuki, Yoshitaka; Shibata, Akira; Nishikata, Kaori; Kimura, Akihiro; Tanase, Masakazu*; Kobayashi, Masaaki*; Sano, Tadafumi*; et al.

no journal, , 

Technetium-99m (Tc) is one of the radioisotopes which are used most as radiopharmaceuticals, and it is obtained from the parent nuclide of Molybdenum-99 (Mo). However, the specific radioactivity of Mo by (n, ) method is extremely low compared with that by fission method ((n,f) method), and as a result, the radioactive concentration of the extracted Tc solution is also low. Thus, it is necessary for the high radioactive concentration of the Tc solution to develop the Mo/Tc separation/extraction/concentration method. In this study, the experiments of Mo/Tc production were performed to enhance recovery yields of Tc and to get a high quality of Tc product. The procedures are described as follows. (1) High-density MoO pellets were irradiated in the Kyoto University Research Reactor (KUR). (2) Tc was extracted with MEK. (3) Tc extracted in MEK was purified and concentrated with acidic alumina column. (4) Product of Tc solution was checked in several factors such as radionuclidic and radiochemical purities. The irradiated MoO pellets were dissolved in 6M-NaOH and the Mo/Tc solution was treated with the devices. From the results, the Tc recovery yields achieved 805% of our goal. Finally, the extracted Tc solution passed the quality inspection of six items.