6.81. In view of the overall goals of the decision making process, it is evident that it influences all parts of the development of the safety case. In particular, all key components of the methodology for post-closure radiological impact assessment presented in Section 5 will be affected by considerations derived from the goals and requirements of the decision making process. The following are important considerations:@@- As the basis for definition of the context for the assessment, the necessary decisions and potential factors of influence that have to be addressed in the safety case should be identified.@@- A decisive part of establishing the context for the assessment consists of definition of the assessment philosophy. This encompasses, inter alia, the approach to the assessment of relevant end points, the nature of the assumptions to be adopted (e.g. realistic or conservative), the type of data to be used (site specific or generic) and the approach to the treatment of uncertainties. It is evident that inappropriate specification of these boundary conditions of the assessment with regard to decision making requirements would preclude the ability to make adequate and justifiable decisions.@@- Apart from the range of decisions to be made, the context for assessment will also be determined by the decision making methodology adopted. If quantitative decision aiding methodologies are to be applied to compare options, requirements for addressing specific end points arise (such as requirements on collective doses12 if a cost-benefit analysis is to be used). Other components of the assessment philosophy, such as the treatment of uncertainties, may also depend on the decision making methodology eventually selected.@@12) With regard to the use of collective doses in such assessments, the following statement from Ref. [21] should be taken into account: “Both the individual doses and the size of the exposed population become increasingly uncertain as the time increases. Furthermore, the current judgements about the relationship between dose and detriment may not be valid for future populations. ...[F]orecasts of collective dose over periods longer than several thousand years and forecasts of health detriment over periods longer than several hundred years should be examined critically.”@@- Scenarios should be set up by considering all features, events and processes that could directly or indirectly influence the system and the radioactive inventory. To the extent that non-radiological factors are relevant, these will also need to be considered in the development of scenarios. Examples for such non-radiological factors are risks from chemically toxic or carcinogenic substances, or physical risks associated with mining activities. If such aspects are relevant for the decisions to be made, it has to be ensured that the conditions that could possibly lead to such risks are adequately covered by the scenarios.@@- The models to be used and their calibration and validation should be carefully planned in the light of the actual requirements of the decision making process. In application of the graded approach, efforts invested should be in accordance with the importance of the results for making and justifying decisions.@@- The results need to be analysed and interpreted in view of their relevance with regard to the decision making requirements. If the results are not considered to be sufficient for this purpose, refinement of scenario definitions and/or models and possibly the collection of additional data will be necessary.