Calculation of the residual lifetime of components of the main circulation circuits of Czechoslovak WWER-440 type nuclear power plants, based on a histogram of the actual power plant working loads

A description is given of the theory behind residual lifetime calculations for basic components of the main circulation circuit. Operation parameters, viz. temperature and pressure changes, were measured at the Dukovany nuclear power plant. The computer program produces inputs from archived data and calculates mechanical stresses in selected components of the main circulation circuit and summations of these stresses with non-steady-state temperature stresses. It processes a sequence of voltage extrema by the flowing rain method. The output involves values of fatigue damage of selected components of the main circulation circuit. First experience was gained in 1989. The results will serve as part of the starting data for operation optimization and for the nuclear power plant life extension. (M.D.). 1 fig., 4 refs