Unification of risk concepts for radiation protection and nuclear safety

Concepts of risk used in radiation protection (RP) and nuclear safety (NS) are not the same. Probability is used for the former, and mathematical expectation is used for the latter. It is well known that the people's fear against nuclear facilities eventually reduced to the fear of exposure to radiation, certain exposure and possible future exposure. Safety issues are mainly treated for the daily tangible exposure in RP while in NS for the future possible exposure. It is shown, the quantity 'expectation value of shortening in the residual life-span' can be used as a unified concept of risk to both RP and NS, which was proposed by one of the authors (K.K.) at IRPA-9 in the paper 'A Mathematical Formulation of Radiation Risk'. Some results of pilot calculations will be shown, too. (author)