Using risk-based regulations for licensing nuclear power plants : case study of gas-cooled fast reactor

Abstract

The strategy adopted for national energy supply is one of the most important policy choice for the US. Although it has been dismissed in the past decades, nuclear power today has key assets when facing concerns on energy dependence and global warming. However, reactor licensing regulations need to be changed to get all the advantages of the most promising technologies. After reviewing the well-known drawbacks of the current regulatory system, the ongoing reforms from the Nuclear Regulatory Commission (NRC) are presented. We argue that full benefice of modem risk analysis methods could not be obtained unless adopting a more ambitious and risk-based regulatory framework. A risk-based licensing framework is then presented, based on previous research from MIT. Probabilistic Risk Assessment (PRA) analyses are used to drive the design toward more safety, and serve as a vehicle for a constructive discussion between designers and the NRC. Mandatory multilevel safety goals are proposed to ensure that adequate safety and adequate treatment of uncertainties are provided. A case-study finally illustrates how this framework would operate. It is based on the Gas- cooled Fast Reactor (GFR) project developed at MIT. We show how PRA provides guidance for the design. Especially, PRA work makes designers consider otherwise overlooked uncertainties and find proper solutions. In a second phase, a simulation of the review by the regulator is conducted. Few new safety concerns are brought. The discussion shows that the proposed risk-based framework has been effective. However, it also highlights that improvements of PRA methodology and clarification over the treatment of key uncertainties are needed.