Intervention levels for protective measures in nuclear accidents. International intervention policy and Nordic status on intervention

A radiation protection philosophy for exposure situations following an accident has been developed by international organisations such as the ICRP, IAEA, NEA/OECD, FAO/WHO, and the CEC during the last decade. After the Chernobyl accident, the application of radiation protection principles for intervention situations such as exposure from accidental contamination or radon in dwellings were further developed and this work is still in progress. The present intervention policy recommended by the international organisations as well as by the Nordic radiation protection authorities is reviewed. The Nordic Intervention levels for foodstuff restrictions, both for the Chernobyl and post-Chernobyl periods, have been based on dose limits and they are therefore in conflict with international intervention policy. Illustrative examples on intervention level setting for relocation and foodstuff restrictions are derived for Nordic conditions from the optimisation principle recommended by the international organisations. Optimised Generic Intervention Levels have been determined to be about 10 mSv·month⁻¹ for relocation/return and 5,000−30,000 Bq·kg⁻¹ for restrictions on various foodstuffs contaminated with ¹³⁷Cs and ¹³¹L.