Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Shimada, Asako; Sawaguchi, Takuma; Takeda, Seiji
Health Physics, 120(5), p.517 - 524, 2021/05
Times Cited Count：0 Percentile：0.01(Environmental Sciences)Murata, Chinatsu; Kitahara, Masaru; Tanaka, Kiwamu; Amazawa, Hiroya; Takebe, Shinichi; Yamada, Osamu*; Kameo, Yutaka
Dekomisshoningu Giho, (62), p.20 - 31, 2020/09
On the basis of Act on Special Measures, municipalities stripped surface soil off the playground of park to decontaminate the soil which had been contaminated with radionuclides released from Fukushima Daiichi Nuclear Power Plant. To minimize the exposure dose of the residents, it was essential to decide safe disposal of the contaminated soil which has been stored at temporary storage areas. Therefore, the ministry of the Environment and Tokai-mura office required Japan Atomic Energy Agency (JAEA) to perform demonstration project of burying the contaminated soil generated by decontamination of public facilities in order to provide decision on the enforcement ordinance and guidelines of burying it. In this project, we acquired data of air dose rate and the personal exposure dose during transporting, burying, and storing the contaminated soil. In addition, we measured radioactivity concentration of dust collected from surroundings of the landfill and seepage water through contaminated soil.
Sawaguchi, Takuma; Takai, Shizuka; Takeda, Seiji
JAEA-Research 2020-005, 47 Pages, 2020/06
JAEA-Research-2020-005.pdf:5.09MB
After the Fukushima Daiichi Nuclear Power Station accident, large quantities of radiocesium-contaminated soil were generated from decontamination activities in the Fukushima prefecture. The removed soil has been stored in the prefecture until its final disposal. To complete the final disposal outside Fukushima prefecture, reducing the disposal volume through recycling can prove effective. The Ministry of the Environment, Japan (MOE) has presented a policy to recycle low-radioactive removed soil as recycled materials under the management of public authority. The recycling is limited to civil engineering structures in public projects. In this study, to contribute to guideline development for removed soil recycling by MOE, dose estimation in recycling of removed soil as embankment materials of seaside protection forest was conducted. First, additional doses to workers and the public in construction and service scenarios were evaluated. From the result, the radioactive cesium concentration level of recycled materials, where all additional doses meet the radiation criterion of 1 mSv/y, was derived to be 5,000 Bq/kg. Then, construction conditions were reviewed to reduce additional doses to the public in a service scenario. With the derived radioactivity level of 5,000 Bq/kg, the covered soil thickness of 39 cm or more limited the doses to less than 10 
Sv/y. Finally, additional doses in a disaster scenario were evaluated. The doses were confirmed to be below 1 mSv/y when the removed soil of 5,000 Bq/kg was used.
Takai, Shizuka; Shimada, Asako; Sawaguchi, Takuma; Takeda, Seiji; Kimura, Hideo
Radiation Protection Dosimetry, 188(1), p.1 - 7, 2020/01
Times Cited Count：0 Percentile：0.01(Environmental Sciences)After the Fukushima Nuclear Power Plant accident, most of radiocesium-contaminated soil generated from decontamination activities outside Fukushima prefecture has been stored at decontamination sites such as schools, parks and residential lands (storage at sites) according to the Decontamination Guidelines. However, additional exposure due to the present storage has not been evaluated. Moreover, entering storage sites, which is not restricted for storage at sites, was not considered in safety assessment conducted in the guidelines. To continue the storage and confirm the effectiveness, understanding of present possible exposures is important. In this study, we evaluated exposure doses for residents and users of storage sites based on the present situation. As a result, annual doses due to residence were 10
to 10
mSv y
and doses due to annual entries were of the order of 10 mSv y. Hence, we confirmed that the exposure due to present storage outside Fukushima is significantly less than 1 mSv y.
Shimada, Asako; Nemoto, Hiromi*; Sawaguchi, Takuma; Takeda, Seiji
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 6 Pages, 2019/05
no abstracts in English
Takai, Shizuka; Sawaguchi, Takuma; Takeda, Seiji
Health Physics, 115(4), p.439 - 447, 2018/10
Times Cited Count：4 Percentile：38.11(Environmental Sciences)After the Fukushima Nuclear Power Station accident, large quantities of radiocesium-contaminated soil generated from decontamination activities have been stored in the Fukushima Prefecture. To reduce the disposal volume, the Ministry of the Environment of Japan has presented a policy to recycle low-radioactive decontamination soil limited to civil engineering structures. However, there has been no practical instance or safety assessment of decontamination soil recycling. In this study, the way of ensuring the safety for decontamination soil recycling for road embankments was discussed. First, based on Japanese construction standards, additional doses to workers and the public in construction and service scenarios were evaluated. From the result, the radioactive cesium concentration level of recycled materials, where all additional doses meet the radiation criterion of 1 mSv y, was derived to be 6,000 Bq kg. To confine additional doses to the public in a service scenario below 0.01 mSv y, soil slope protection of 40 cm or more was needed. Finally, additional doses in a disaster scenario were confirmed to be below 1 mSv y.
Takai, Shizuka; Sawaguchi, Takuma; Takeda, Seiji
Proceedings of International Waste Management Symposia 2018 (WM2018) (Internet), 14 Pages, 2018/03
After the Fukushima Nuclear Power Station accident, large quantities of radiocesium-contaminated soil generated from decontamination activities have been stored in the Fukushima prefecture. To complete the final disposal of decontamination soil, the Ministry of the Environment of Japan presented policy to reduce the disposal volume by using low-level decontamination soil as recycled materials. The use will be limited to civil engineering structures in public projects, such as coastal levee and road embankment. However, there has been no example or safety assessment of recycling of decontamination soil. To contribute to guideline development for the recycling by the Ministry of the Environment, we conducted the safety assessment for recycling of decontamination soil as coastal levee. First, we evaluated additional doses to workers and the public in the case of construction and service of coastal levee. From the result, the radioactive cesium concentration level of recycled materials was derived to be 6,800 Bq/kg. For general designs of coastal levee in Japan, additional doses to the public in the case of service were below 0.01 mSv/y with derived radioactivity level. Finally, we confirmed additional doses in the case of disaster to be below 1 mSv/y.
Okada, Takashi; Takeda, Seiji; Nakata, Hisakazu
Nihon Genshiryoku Gakkai-Shi ATOMO
, 59(10), p.603 - 607, 2017/10
Because the reclaimed material is used, quantity of disposal of the removal soil can decrease. It is a strategic key to utilize the reclaimed material. As for this report, it is explained to about the fundamentals of the safe use of the reclaimed materials derived from the removed soil.
Sawaguchi, Takuma; Takai, Shizuka; Umezawa, Katsuhiro; Takeda, Seiji; Okada, Takashi
Nihon Genshiryoku Gakkai-Shi ATOMO, 59(8), p.445 - 447, 2017/08
no abstracts in English
Yui, Mikazu
no journal, ,
no abstracts in English
Nishijima, Shigehiro*; Akiyama, Yoko*; Yukumatsu, Kazuki*; Horie, Hiroki*; Mishima, Fumihito*; Sekiyama, Tomio*; Mitsui, Seiichiro; Kato, Mitsugu
no journal, ,
By the Fukushima Daiichi Nuclear Power Plant accident, a large amount of soil was contaminated by radioactive Cs, and effective volume reduction techniques have been required to optimize final disposal of the contaminated soil outside Fukushima pref. We focused on the phenomenon that Cs ions are strongly adsorbed on paramagnetic 2:1 type clay minerals, and tried to separate 2:1 type clay minerals selectively by the combination of classification and magnetic separation. In this study, we conducted magnetic separation experiments of actual contaminated soil in Fukushima utilizing a superconducting magnet, based on the simulated results of 2:1 type clay minerals with each particle size. Based on the result, we proposed a new method for volume reduction of Cs contaminated soil.
Sawaguchi, Takuma; Takai, Shizuka; Umezawa, Katsuhiro; Takeda, Seiji; Okada, Takashi
no journal, ,
no abstracts in English
Miwa, Kazuji; Takeda, Seiji; Iimoto, Takeshi*
no journal, ,
The Ministry of the Environment has indicated the policy of recycling the contaminated soil generated by decontamination activity after the Fukushima accident as material. By recycling to coastal reclamation which is one of effective recycling application, dissolved radiocesium and absorbed radiocesium on soil particles will flow out to the ocean by construction. It is suggested by previous studies that the both types of radionuclides affect concentration of radionuclides in marine organism. In safety assessment for the recycling, it is necessary to consider transition of nuclides in both types. Therefore, we developed a model to evaluate the radionuclides transition in the ocean considering the both types of radionuclides which flow out during constructing and operation. The concentration of radiocesium in ocean is estimated with time, and the impact of internal exposure dose by sea food ingestion is evaluated through comparison with other major exposure pathway.
Miwa, Kazuji
no journal, ,
There are large amount of radionuclides contaminated soil and debris in Fukushima Prefecture after Fukushima Daiichi Nuclear Power Station accident. It is difficult to dispose the entire amount of soil and debris as radioactive waste from the view point of preparing the disposal site. Therefore, we focused on the recycling as one of the way to reduce the quantity of the radionuclides contaminated materials. In this study, we organised the issues when assuming recycling in the current concept of radiation protection, and propose the way of applying the concept of radiation protection to the regulation in the field. Specifically, we proposed five ways of applying the reference level in radiation protection from radionuclides contaminated material in existing exposure situation. In addition, we calculated radionuclides concentrations for two model case of recycling applying proposed radiation protection concept.
Oba, Kyoko; Yanase, Noboru*; Suzuki, Shigekazu*
no journal, ,
This research is based on the Method of Deliberative Poll regarding Discussion on ALPS Treated Water and Soil from Off site Decontamination Work, which has become a problem due to the decommissioning of the TEPCO Fukushima Daiichi Nuclear Power Plant accident, which is being conducted at universities and national colleges of technology. With an education in mind, the project trains moderators and reporters for group discussions, which are important in discussions. We are also experimenting with an implementation method that includes humanities students and includes on-site visits. We will present the possibilities of education based on the Method of Deliberative Poll.
