Abstract:
Low and intermediate level radioactive solid waste generated from nuclear power plants, is generally disposed in near surface solid waste disposal facilities(NSDF) such as earth trenches, reinforced concrete trenches (R.C.T) and tile holes. The wastes with very low concentration of radionuclide content are disposed off in earth trenches due to economic reason. The radionuclides disposed off in the earth trenches may migrate from the disposal system to the groundwater while interacting with the rainwater and may also reach the groundwater utilization point of the public during the transportation process. Intake of water containing radionuclides concentration above certain levels results in radiation dose to the public. A public dose limit of 0.05mSv/y is apportioned to the near surface solid waste disposal facilities through the terrestrial route including groundwater pathways. This paper is an effort to derive the acceptable/benchmark concentration of the important radionuclides in groundwater based on the terrestrial dose limits. This benchmark concentration can be used to monitor the regulatory compliance and assess the quality of groundwater with respect to radiation safety. The paper also discusses the acceptable distance of the groundwater utilization points of the public from the waste disposal facilities based on easily mobile radionuclides. Efforts are also made to derive the permissible activity limit for the earth trench disposal of radioactive solid waste based on terrestrial dose apportionment, permissible groundwater radionuclide concentration, well groundwater yield and ingestion toxicity index.
