TNAG-1776-FCO40-2530-Daya-Bay-nuclear-power-station-project-safety-concerns-in-Ho-1988 — Page 148

(i)

(ii)

(iii)

There is an overall need for more and better information for members of the public living near nuclear facilities (within a few kilometres) about possible accidents, their consequences, and action that may need to be taken in the event of an accident occurring.

If an accident occurs, the public and a wide range of interested organisations will require accurate and comprehensive information about radiation levels and possible contamination of foodstuffs. Well-planned monitoring networks and rapid methods of analysing and disseminating the resulting information are

needed.

Nothing has emerged from these studies to suggest that evacuation needs to be considered or planned for Hong Kong.

5.6 Radiological Protection Principles

There are a number of organisations which have considered the actions to be taken following a nuclear reactor accident, and have offered advice. These include the World Health Organisation, the International Atomic Energy Agency, The International Commission on Radiological Protection and the UK National Radiological Protection Board, (refs 9 16). In general the views of these organisations are in agreement and their advice forms the basis for emergency planning worldwide. The advice given in this report is based upon the principles recommended by these organisations.

The three basic principles upon which emergency planning decisions are based are as follows:

(i)

(ii)

(iii)

Serious early (non-stochastic) health effects should be avoided by the introduction of countermeasures to limit individual doses to levels below the thresholds for these effects.

The risk from late (stochastic) health effects should be limited by the introduction of countermeasures which achieve a positive net benefit to the individuals involved.

The overall incidence of late health effects should be limited, as far as reasonably practicable, by reducing the collective dose to the affected population.

5.7 Categorisation of Accident Time Phases

The actual sequence of events following any major reactor accident will depend upon a number of factors, and no two accidents are likely to be exactly similar. However, with most postulated accidents it is possible to divide the subsequent events into three time phases. These time phases, usually referred to as 'Early', 'Intermediate' and 'Recovery', will not be clearly defined but are typified by conditions at the reactor and by the decisions being taken at that time. The categorisation of the time phases can be useful since in each phase the potential routes of exposure may differ and therefore require different countermeasures. Each of the three time phases will be now briefly discussed.

Early Phase

The early phase can be considered to be the period from when the first threat of a serious release of radioactive material has been identified until a few hours after the commencement of that release. During this early phase decisions on countermeasures may be taken on advice received from the operators of the Daya Bay reactor or on readings from fixed monitoring stations and the initial results from radiological surveys.

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