Safety Control of Prestressing in Nuclear Plants

Programs for the safety control of nuclear power plants include those that check the prestressing forces in the containment by pullout testing. The selection of the range of tolerance for stresses may be approached as a decision problem in a context of uncertainty. A priori analysis of this decision is made by assuming several simplifications of both the possible actions and the random states that may arise. This analysis shows that the pullout tests, carried out to check the state of prestressing of the containment structure of nuclear power plants, may show to be excessively costly if the ranges of tolerance are strict; if they are wide, these tests are unlikely to fulfill their purpose. This analysis also reveals that the position of nuclear authorities with regard to technically unjustified shutdowns of plants can influence significatively the optimal range of tolerance for stresses in pullout tests of tendons.