Current status of radioactive waste disposal in Japan and foreign countries

摘要

Various kinds of wastes are generated from operation and decommissioning of nuclear facilities such as a nuclear power plant, a reprocessing plant and so on. These wastes contain radionuclides and are called "Radioactive Waste". The radionuclides in the wastes vary considerably in amount from small to large and their half-lives differ in length from short-lived to long-lived. The safety principle for radioactive waste management is to prevent human beings and the environment from receiving radiation exposure over the level which the safety authority in each country approve based on the recommendations by international organizations such as the International Commission on Radiation Protection (ICRP). To assure the conformity to this safety principle, each country has examined the safety measures to dispose of radioactive wastes on the basis of their own conditions. For example, high-level radioactive waste (HLW) from reprocessing plant or spent fuel designated as waste and intermediate-and low-level long-lived radioactive wastes, which contain large quantity of long-lived radionuclides, will be disposed of into a deep stable geological formation. The intermediate-and low-level short-lived radioactive wastes, which mainly contain short-lived radionuclides with limited quantity of long-lived radionuclides, have been disposed of in a controlled surface disposal facility or in a rock cavern in the depth of 50-100m. Clearance level has been considered to be applied for the wastes, which contain very small amount of radionuclides and those wastes bellow clearance level will cause negligible hazards only even without taking any radiation control measures. Such wastes could be reused, recycled or disposed of in the same manner as general wastes from the industries, etc.