Dose Estimate in Treatment and Disposal of Contaminated Materials due to the Accident at the Fukushima Nuclear Power Pla
- PDF / 347,931 Bytes
- 7 Pages / 432 x 648 pts Page_size
- 76 Downloads / 193 Views
Dose Estimate in Treatment and Disposal of Contaminated Materials due to the Accident at the Fukushima Nuclear Power Plant Seiji Takeda1, Takuma Sawaguchi1, and Hideo Kimura1 1 Japan Atomic Energy Agency, Nuclear Safety Research Center, Environmental Safety Research Group, Tokai-mura, Naka-gun, Ibaraki pref., 319-1195, Japan ABSTRACT Some kinds of material in the environment due to the accident at the Fukushima Nuclear Power Plant have been contaminated by radioactive cesium (134Cs and 137Cs), which are represented by dehydrated sludge, surface soil and disaster wastes generated by the Great East Japan Earthquake. Treatment (transportation, temporary storage and incineration) and disposal of the contaminated materials should be carried out while ensuring the safety of radiation for the workers and the public. In this study, in order to provide the technical information for making the criteria, the dose estimation for scenarios on the treatment and disposal is conducted, based on the method used for driving the clearance levels in Japan. Minimum radioactive cesium concentration in contaminated material, that is, limiting activity concentration which is practicable for ordinary treatment and/or disposal, is calculated from the dose results, corresponding to the effective dose criteria indicated by the Nuclear Safety Commission of Japan. From the calculation result, it is suggested that it is necessary to forbid reusing the disposal site as construction, resident and agriculture in which the calculated doses for the public are higher than those in the other exposure pathways. Limiting concentration of radioactive cesium (134Cs and 137Cs) is derived to be 8,900Bq/kg for the external exposure pathway in landfill work under the condition of limited reuse of the site. In the case of the concentration below 8,900Bq/kg, the calculated dose of the resident due to direct and sky-shine radiation scattered in the air and ground from the interim storage place is less than 1mSv/y, irrespective of the distance from the storage place. INTRODUCTION Radionuclides were released to surface environment over Fukushima prefecture due to the severe accident at the Fukushima Nuclear Power Plant. A portion of the disaster wastes such as concrete waste, scrap metal, wood waste and so on, which are generated from the Great East Japan Earthquake, was contaminated by radioactive cesium. Soil particles adsorbing radioactive cesium flow into water resources which are treated at sewage plant or purification plant. Dehydrated sludge containing radioactive cesium of high concentration was also generated through the sewage and water supply processing. Treatment and disposal of thus various contaminated materials should be carried out while ensuring the safety of radiation for the workers and the public. However, in Japan, there was no criterion, namely, limiting activity concentration practicable for ordinary treatment and/or disposal with the contaminated materials. Dose estimation for scenarios on the treatment and disposal was conducted to provide t
Data Loading...
