HPA-CRCE-004 - Generalised Derived Constraints for Radioisotopes of Hydrogen, Carbon, Phosphorus, Sulphur, Chromium, Manganese, Cobalt, Zinc, Selenium, Technetium, Antimony, Thorium and Neptunium

Synopsis

The 1990 recommendations of the International Commission on Radiological Protection (ICRP) introduced the concept of the dose constraint and the National Radiological Protection Board (now part of the Health Protection Agency) response to the recommendations introduced the concept of a generalised derived constraint (GDC).

Generalised derived constraints apply to discharges of radionuclides to the environment and are based on the upper value of constraint on effective dose for members of the public of 0.3 mSv y^–1. Generalised derived constraints have been calculated for discharges to atmosphere, rivers and sewers for the radiologically significant isotopes of hydrogen, carbon, phosphorus, sulphur, chromium, manganese, cobalt, zinc, selenium,
technetium, antimony, thorium and neptunium. The methods are as used in calculating GDCs for radioisotopes of other elements, such as caesium and polonium, published previously. The GDCs presented here are intended as convenient reference levels against which proposed discharges can be compared.

Generalised derived constraints are calculated using deliberately cautious assumptions and are in terms of annual discharges, assuming that the releases to the environment are continuous. If a proposed discharge is greater than about 30% of the GDC then the estimated doses corresponding to this discharge should be examined more closely, taking account of site-specific factors.

This report also contains some additional generalised derived limits for environmental materials containing isotopes of technetium, thorium and neptunium, which have not been published previously.

Last reviewed: 8 September 2010