A fuzzy decision support system for the economic calculus in radioactive waste management

Abstract

A methodology has been elaborated to derive contingency factors for evaluating in a realistic way the costs of first-of-the-kind projects in radioactive waste management (RWM). The paper describes the practical implementation of the fuzzy decision support system (FDSS) and its interface to assist economists in charge of the economic calculus. Uncertainties to be added on top of basic cost evaluations are represented by two contingency factors, respectively, called the P- and the T-factors. The P-factor represents the uncertainties of the project induced by its still incomplete advancement; the T-factor represents the uncertainties caused by the still insufficient technological maturity on which the project is based. Progressive implication rules of the Goguen type are used with the two contingency factors as outputs. Input variables for P and T are given on relative [0,1] scales. Fuzzy logic is also used as front-end for obtaining the two inputs in the course of peer reviews of technology-experts and project-specialists. To that aim, the semantic opinions and past experience of the latter are expressed in the form of conditional and unconditional rules. The credibility of T-experts and P-specialists are taken into account by using the Kleene-Dienes inference. A numerical example on the cost of disposal of high-level radioactive waste in a deep repository is used to illustrate the practical use of the FDSS. This approach is also applicable to other economic assessments inside or outside the nuclear field.