Japan’s Nuclear Regulation Authority (NRA) plans to require that high level radioactive waste generated when nuclear reactors are decommissioned should be buried underground at least 70m deep for about 100,000 years until the waste is no longer hazardous, The Mainichi reported on 2 August.
The plan is part of the proposed regulatory standards on disposal sites for radioactive waste from dismantled nuclear reactors, which the NRA approved on 1 August. NRA will consult with power companies operating NPPs and other entities before finalising the new standards.
Low-level waste from reactor decommissioning is graded in descending order from L1 to L3. The proposed new standards cover L1 waste, such as containers for control rods and fuel assemblies. Under the proposed standards for L1 waste, power companies would be required to build disposal sites on stable ground, away from faults of 5km-long or greater. Utilities would be required to confirm from records or geological surveys that there has been no volcanic activity over the past 2.6 million years near planned disposal sites. Companies would also have to avoid building disposal sites near oil or mineral deposits.
The waste must be regularly monitored for 300-400 years following its disposal. The owners of the disposal sites would be banned from digging areas surrounding the facilities without permission from the central government. The proposed standards also require that additional radiation exposure dosages from disposal sites be limited to 0.3mSv/year in accordance with international standards.