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Journal Articles

Seven-year temporal variation of caesium-137 discharge inventory from the port of Fukushima Daiichi Nuclear Power Plant; Continuous monthly estimation of caesium-137 discharge in the period from April 2011 to June 2018

Machida, Masahiko; Yamada, Susumu; Iwata, Ayako; Otosaka, Shigeyoshi; Kobayashi, Takuya; Watanabe, Masahisa; Funasaka, Hideyuki; Morita, Takami*

Journal of Nuclear Science and Technology, 57(8), p.939 - 950, 2020/08

 Times Cited Count:3 Percentile:76.41(Nuclear Science & Technology)

After direct discharges of highly contaminated water of the Fukushima Daiichi Nuclear Power Plant (1F) from April to May 2011, Kanda suggested that relatively small amounts of run-off of radionuclides from the 1F port into the Fukushima coastal region subsequently continued by his estimation method. However, the estimation period was limited to up to September 2012. Therefore, this paper estimates the discharge inventory up to June 2018. In the missing period, the Japanese government and Tokyo Electric Power Company Holdings have continued efforts to stop the discharge, and consequently, the radionuclide concentration in seawater inside the 1F port has gradually diminished. We show the monthly discharge inventory of $$^{137}$$Cs up to June 2018 by two methods, i.e., Kanda method partially improved by the authors and a more sophisticated method using Voronoi tessellation reflecting the increase in the number of monitoring points inside the 1 F port. The results show that the former always yields overestimated results compared with the latter, but the ratio of the former to the latter is less than one order of magnitude. Using these results, we evaluate the impact of the discharge inventory from the 1F port into the coastal area and radiation dose upon fish ingestion.

Journal Articles

Seven-year temporal variation of cesium-137 discharge inventory from the port of Fukushima Dai-ichi Nuclear Power Plant; Continuous monthly estimation of cesium-137 discharge in the period from April 2011 to June 2018

Machida, Masahiko; Yamada, Susumu; Iwata, Ayako; Otosaka, Shigeyoshi; Kobayashi, Takuya; Watanabe, Masahisa; Funasaka, Hideyuki; Morita, Takami*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 18(4), p.226 - 236, 2019/12

After direct discharges of highly-contaminated water from Unit 2 and 3 in Fukushima Daiichi Nuclear Power Plant (1F) in April to May 2011, Kanda suggested that relatively small run-off of radionuclides from 1F port into Fukushima coastal region has subsequently continued by using his estimation scheme. However, the estimation period was limited until September 2012, and there has been no report on the issue since the work. Therefore, this paper focuses on discharge inventory from 1F port until June 2018. In the missing period, the central government and Tokyo Electric Power Company Holdings have done continuous efforts to stop the discharge, and consequently sea water concentration inside 1F port has diminished gradually. We show monthly discharge inventory of Cs-137 until June 2018 by two schemes, i.e., Kanda's scheme partially improved by authors and more sophisticated one using Voronoi tessellation reflecting the increment of the number of monitoring points inside 1F port. The results show that the former always presents overestimated results compared to the latter but the ratio of former to latter is less than one order. Based on these results, we evaluate impact of discharge inventory from 1F port into the coastal area and radiation does via fish digestion.

JAEA Reports

Application to contaminated water management in the Fukushima Daiichi Nuclear Power Station using the plastic scintillation fiber

Sanada, Yukihisa; Yamada, Tsutomu*; Sato, Yoshiharu; Nishizawa, Yukiyasu; Ishibashi, Satoshi*; Watanabe, Masahisa; Torii, Tatsuo

JAEA-Research 2016-011, 52 Pages, 2016/09

JAEA-Research-2016-011.pdf:10.54MB

In the Tokyo Electric Power Co.,Inc. the Fukushima Dai-ichi Nuclear Power Station, management of the contaminated water becomes the social problem, and the situation that severe correspondence is necessary continues to prevent an outflow to the ocean. Plastic scintillation fiber (PSF) can apply as technique to direct measure the concentration of radioactive material in the water at a tank and drainage. In this paper, the results of fundamental test was summarized to apply for monitoring of leakage to the tank and monitoring of drainage in the Fukushima Dai-ichi Nuclear Power Station.

Journal Articles

Groundwater flow modeling focused on the Fukushima Daiichi Nuclear Power Plant site

Saegusa, Hiromitsu; Onoe, Hironori; Kohashi, Akio; Watanabe, Masahisa

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05

Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company is facing contaminated water issues. The amount of contaminated water is continuously increasing due to groundwater leakage into the underground part of reactor and turbine buildings. Therefore, it is important to understand the groundwater flow conditions at the site and to predict the impact of countermeasures taken for isolating groundwater from the source of the contamination, i.e. the reactor buildings. Installations, such as of land-side and sea-side impermeable walls have been planned as countermeasures. In this study, groundwater flow modeling has been performed to estimate the response of groundwater flow conditions to the countermeasures. From the modeling, groundwater conditions and changes in response to implementation of the countermeasures could be reasonably estimated. The results indicate that the countermeasures will decrease the volume of inflow into underground part of the buildings. This means that the countermeasures will be effective in reducing the discharge volume of contaminated groundwater to ocean.

JAEA Reports

Report for "FY 2013 Evaluation of Decontamination Technology Demonstrations Projects for the environmental remediation with radioactive materials discharged from the Fukushima Daiichi Nuclear Power Plant Accident" (Contract research)

Watanabe, Masahisa; Tagawa, Akihiro; Umemiya, Noriko; Maruyama, Noboru; Yoshida, Mami; Kawase, Keiichi; Noguchi, Shinichi; Sakazume, Yoshinori; Watanabe, Masanori; Hiraga, Hayato; et al.

JAEA-Review 2014-028, 184 Pages, 2014/10

JAEA-Review-2014-028.pdf:37.79MB

JAEA received technical proposals from private enterprise about techniques that can be used for decontamination work, and "Decontamination Technology Demonstrations Projects" was commissioned from the Ministry of the Environment to verifies the decontamination effect, economy feasibility, safety, and other factors. By the "FY 2013 Decontamination Technology Demonstrations Projects" JAEA carried out technical advice of demonstration test and evaluation of 11 technologies (e.g., decontamination of soils and green space and wastes and washing of fly ash).

JAEA Reports

Report for "Decontamination Pilot Projects for the environmental remediation of evacuation areas contaminated with radioactive materials discharged from the Fukushima Daiichi Nuclear Power Plant accident; Decontamination Technology Demonstrations Projects" (Contract research)

Watanabe, Masahisa; Tagawa, Akihiro

JAEA-Review 2013-053, 84 Pages, 2014/03

JAEA-Review-2013-053.pdf:48.63MB

To discover technologies that can be utilized for decontamination work and verify their effects, economic feasibility, safety, and other factors, the Cabinet Office, Government of Japan launched the FY2011 Decontamination Technology Demonstrations Project to publicly solicit decontamination technologies that would be verified in demonstration tests and adopted 25 candidates. JAEA was commissioned by the Cabinet Office, Government of Japan to provide technical assistance related to these demonstrations. JAEA carried out a demonstration test and evaluation of 25 technologies (e.g., decontamination technology of soil classifiers, ultra-high pressure water jets and volume reduction of organic materials) to perform decontamination of the environment

JAEA Reports

Report for "FY 2012 Evaluation of Decontamination Technology Demonstrations Projects for the environmental remediation with radioactive materials discharged from the Fukushima Daiichi Nuclear Power Plant Accident" (Contract research)

Watanabe, Masahisa; Umemiya, Noriko; Tagawa, Akihiro; Kawase, Keiichi; Noguchi, Shinichi; Sakazume, Yoshinori; Watanabe, Masanori; Tokizawa, Takayuki

JAEA-Review 2013-052, 232 Pages, 2014/03

JAEA-Review-2013-052.pdf:26.42MB

To discover technologies that can be utilized for decontamination work and verify their effects, economic feasibility, safety, and other factors, the Cabinet Office, Government of Japan launched the FY2012 Decontamination Technology Demonstrations Project to publicly solicit decontamination technologies that would be verified in demonstration tests and adopted 15 candidates. JAEA was commissioned by the Ministry of the Environment, Government of Japan to provide technical assistance related to these demonstrations. JAEA carried out technical advice of demonstration test and evaluation of 15 technologies (e.g., decontamination technology of Burned ash washing and Pond Dredging) to perform decontamination of the environment.

JAEA Reports

Report for "FY 2011 Evaluation of Decontamination Technology Demonstrations Projects for the environmental remediation with radioactive materials discharged from the Fukushima Daiichi Nuclear Power Plant accident" (Contract research)

Watanabe, Masahisa; Tagawa, Akihiro

JAEA-Review 2013-051, 244 Pages, 2014/03

JAEA-Review-2013-051.pdf:34.73MB

To discover technologies that can be utilized for decontamination work and verify their effects, economic feasibility, safety, and other factors, the Cabinet Office, Government of Japan launched the FY2011 Decontamination Technology Demonstrations Project to publicly solicit decontamination technologies that would be verified in demonstration tests and adopted 22 candidates. JAEA was commissioned by the Ministry of the Environment, Government of Japan to provide technical assistance related to these demonstrations. JAEA carried out technical advice of demonstration test and evaluation of 22 technologies (e.g., decontamination technology of Thermal decomposition, Bottom sediment of Pond and volume reduction of organic materials using biomass technologies) to perform decontamination of the environment.

Journal Articles

Demonstration test results of organic materials' volumetric reduction using bio-ethanol, thermal decomposition and burning

Tagawa, Akihiro; Watanabe, Masahisa

Proceedings of 15th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2013) (CD-ROM), 6 Pages, 2013/09

Oral presentation

Three decades of forward steps and prospect in Tokai reprocessing plant, 9; Improvement of accountability/safeguards analysis at Tokai reprocessing plant

Watanabe, Masahisa; Surugaya, Naoki; Kurosawa, Akira; Watahiki, Masaru

no journal, , 

no abstracts in English

Oral presentation

Measurement technology for safeguards analysis at the Tokai reprocessing plant

Yamamoto, Masahiko; Surugaya, Naoki; Taguchi, Shigeo; Ishibashi, Atsushi; Horigome, Kazushi; Yamazaki, Hitoshi; Ogura, Hiroshi; Watahiki, Hiromi; Watanabe, Masahisa; Kurosawa, Akira; et al.

no journal, , 

no abstracts in English

Oral presentation

Result of demonstration tests on decontamination technology, 7; Research of the radioactive cesium pollution in reservoir sediment

Umemiya, Noriko; Tagawa, Akihiro; Watanabe, Masahisa

no journal, , 

no abstracts in English

Oral presentation

Result of demonstration tests on decontamination technology, 5; Effects of water jet decontamination with suction cleaning

Koike, Naoto; Tagawa, Akihiro; Watanabe, Masahisa

no journal, , 

no abstracts in English

Oral presentation

Result of demonstration tests on decontamination technology, 6; Evaluation of cesium elution from ash generated by the biomass power

Kajiyama, Yuichi; Tagawa, Akihiro; Watanabe, Masahisa

no journal, , 

no abstracts in English

Oral presentation

Oral presentation

Result of demonstration tests on decontamination technology, 8; Summary of decontamination techniques demonstration project 2012

Watanabe, Masahisa; Umemiya, Noriko; Tagawa, Akihiro

no journal, , 

no abstracts in English

Oral presentation

Result of demonstration test on decontamination technology, 11; Evaluation result of incineration fly ash washing technique

Umemiya, Noriko; Maruyama, Noboru; Yoshida, Mami; Tagawa, Akihiro; Watanabe, Masahisa

no journal, , 

no abstracts in English

Oral presentation

Hydrodynamic simulation of radionuclides dispersion inside the harbor in Fukushima Daiichi Nuclear Power Plant

Yamada, Susumu; Machida, Masahiko; Watanabe, Masahisa

no journal, , 

no abstracts in English

Oral presentation

Environmental analysis of sea water inside the harbor in Fukushima Daiichi Nuclear Power Plant, 2; Numerical simulation inside the haber

Yamada, Susumu; Machida, Masahiko; Watanabe, Masahisa

no journal, , 

no abstracts in English

Oral presentation

32 (Records 1-20 displayed on this page)