Calculation of predicted lifetime of nuclear power plant vessels by deterministic and probabilistic methods

Various deterministic and one probabilistic life-prediction methods for nuclear power plant pressure vessels are discussed. It is shown that the use of a nonlinear deterministic model instead of the linear Palmgren-Miner method prescribed by several nuclear vessel codes leads to a more conservative estimate. The effect of a linear approximation of the nonlinear low-cycle fatigue curves and their simple extension up to 108 loading cycles on the predicted lifetime is discussed. A probabilistic-statistical analysis of service loads together with a comparison with the design loading maxima also can be used to estimate the lifetime quantitatively. Results of a numerical example are presented.

Keywords:

• Fatigue Life
• Nuclear Power Plant Vessels