RADIOLOGICAL CRITERIA FOR THE PROTECTION OF THE PUBLIC FROM RADIONUCLIDES IN THE ENVIRONMENT

摘要

The advice on public protection given by the National Radiological Protection Board for application in the United Kingdom is broadly in line with recent international recommendations. For practices, the system of protection is based on the principles of justification, optimization and limitation of dose or risk. However, application of the principles of justification and constrained optimization in practical circumstances has provoked some debate. The paper discusses some of the issues raised. There may be situations where land is contaminated with radioactive material from previous practices but, whilst access is prohibited, there is no exposure of the public. However, if a change of use of the land is proposed, such as de-licensing a nuclear site or sale of premises contaminated with radionuclides, this may lead to a situation where members of the public may be exposed. It seems appropriate to judge this situation according to the same criteria as those applied for practices. Development of advice on appropriate criteria is described. If an accidental release of radionuclides occurs, intervention may be required in order to avoid or reduce doses. At the time of the accident, or in its immediate aftermath, it may be necessary to implement urgent countermeasures to avoid short term relatively high doses. However, in the event of a very serious accident, there may be a need to consider long term countermeasures. Drastic countermeasures, such as relocation, would be considered only for the purpose of avoiding substantial doses and only if other methods of reducing doses were not effective. For small dose savings, other procedures such as decontamination would be considered so as to reduce doses, avoid restriction on individuals' lifestyles and so promote a return to normality. Similar considerations apply to situations where contamination from past practices is discovered on land to which the public has access.