The use of expert opinion in specifying input distributions for use in probabilistic risk analysis of radioactive waste disposal

A methodology has been formulated, on behalf of Her Majesty's Inspectorate of Pollution of the UK Department of the Environment, for using expert opinion in the specification of input probability distributions required within radiological probabilistic risk analysis. Where few measured data are available, use is made of the formal method developed by SRI International for encoding probability distributions from subjective judgements. This is a systematic structured approach which allows the expert judgements to be shaped into fitted beta probability density functions. As the available measured data improve in quality and quantity Bayesian techniques can be adopted to update the subjective probability distributions accordingly. Methods of improving the elicitation procedure are discussed. (author)