An environmental factor approach to account for reactor water effects in light water reactor pressure vessel and piping fatigue evaluations

This paper summarizes past and current studies of the environmental fatigue effects in LWR applications. Current Argonne and Japanese research efforts are reviewed and an approach to calculate an environmental correction factor is described. A description of how the proposed approach can be implemented in Section III, NB-3600 and NB-3200-type fatigue evaluations, is presented along with examples of applying the approach to piping (NB-3600) and safe-end fatigue evaluations. These procedures were applied to several BWR and PWR example cases. The results of these case studies indicated that there is a modest increase in calculated fatigue usage, which is considerably less than the results obtained when the NUREG/CR-5999 curves are applied directly.