A review of the entire seismic design process risk and conservatism assessment

This paper reviews the basic steps involved in the entire seismic design process of a nuclear power plant. Noting that the currently instituted conservatism in each of these steps is reasonable, and that it is compounded from one step to the next, the paper discourages the tendency to use upper bound inputs in any one of the steps. The paper also shows that reducing the seismic risk will not significantly affect the overall risk associated with a nuclear power plant. In the discussion thereafter, it was noted that when the OBE was about one-half the SSE, the OBE could constitute a greater constraint in the calculation, owing to the stricter limits on deformations and the lower degree of damping used