which may be applied. Delaying return will both decrease the potential health detriment but will also increase the cost of the protective measures. The decision-maker must decide at what level of dose rate people should be allowed to return. In principle the optimum solution to this problem is when the total cost of the health detriment and the cost of protective measures is a minimum.
This concept is illustrated in Figure 9.3.
In order to carry out such an optimization it is necessary to evaluate both the cost of the protective measures and the cost of the health detriment. Calculating the cost of the protective measures is, in principle, straightforward although in practice it may present some problems. In contrast the costing of health detriment, that is putting a monetary value on the unit of collective dose, the man-sievert, may be contentious since it implies a value on the human life. In reality all decisions taken on whether or not to introduce some safety measure can be interpreted as implying a value on a life. Placing a value on the man-sievert simply helps to ensure that decisions are made on a rational basis. The factors which need to be considered when arriving at a value, or more likely a range of values, for the man-sievert are discussed in ICRP Publication 37, (ref 39).
Having carried out this type of analysis for a particular situation, if the resultant optimised solution corresponds to an unacceptably high dose rate, then more remedial action will be required regardless of cost.
In carrying out this type of analysis it must be borne in mind that many of the parameters will be difficult to assess accurately. Sensitivity studies should therefore be carried out on such parameters to see if small changes in their values are likely to affect the final decision.
The Radiological Protection Advisory Group (see Section 12.18) should keep a watching brief on developments in the field of optimization of radiological protection, particularly when applied to post-accident situations. As such they should be able to give advice to the decision-makers in the recovery phase on the use of these techniques.
The recovery phase may extend to some weeks or even months. It is therefore likely that the full emergency organisation as suggested in Chapter 6 will not be required throughout a protracted recovery phase. The appropriate structure of the recovery phase organisation will obviously depend upon the nature of the initial emergency and the subsequent consequences. Some government departments and other agencies will have a diminishing role whilst others will continue to be heavily involved. Other agencies not identified in Chapter 6 may also be required. It is likely that the recovery phase organisation will naturally evolve from the full emergency organisation, however, the Government Committee for Contingency Planning should review, at appropriate intervals, the structure of the organisation to ensure that it reflects the current needs of the situation.
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