Some observations on NUREG-1150

The U.S. Nuclear Regulatory Commission (USNRC) requested comments on their recently published draft 'Reactor Risk Reference Document' (NUREG-1150). The report concludes that the risk from internal initiators meets USNRC's safety goals. Furthermore, backfitting of U.S. plants is not cost-effective. Although the methodology is basically sound, EPRI believes that the execution was flawed primarily in its use of expert opinions and in providing inadequate time for the performance of supplementary calculations of important physical phenomena. This paper provides an overview of EPRI's comments and recommendations to USNRC for preparation of the next edition of NUREG-1150. (orig.)