After several years' deliberation, the International Commission on Radiological Protection (ICRP) has decided to reduce its current 30 specified values for various situations to just four, and to focus on sources in setting those rather than dose limits from all sources, which is of less practical use.
Its new dose constraints are the level of dose tolerated from a single source. ICRP is moving towards recommending: • 1mSv/y dose constraint for the general public.
• 20mSv/y dose constraint for workers or for radon in homes.
• 0.01mSv/y as an exclusion or exemption level.
• 500mSv lifetime dose as an intervention level governing evacuation.
The 1mSv/y public level dose constraint is particularly significant as it has been the dose limit, and earlier proposals were for a 0.3mSv/y dose constraint from a single source. The difference has little effect on public exposure to nuclear industry operations, but will mean that decommissioned sites can be cleaned up more cost effectively.
The World Nuclear Association said that the proposed 0.3mSv/y dose constraint, while not impacting on current routine off-site discharges from nuclear industrial sites, would have had practical implications on a wide range of other industry activities, including transportation, mining and milling, and decommissioning and reclamation.
The US Environmental Protection Agency is trying to establish 0.25mSv/y as acceptable for release for unrestricted use. This would save $50 million in decommissioning costs for every nuclear power plant in the USA.
