Replace "defense-in-depth" with risk-informed approach to design & regulation -- the only way to make n-plants competitive

Shortly after initiating this project, team members established the principal strategies required to achieve the project's cost-reduction goals. It was agreed that a very basic and significant change to the current method of design and regulation was needed. That is, it was believed that the cost-reduction goal could not be met by fixing the current system (i.e., an evolutionary approach) and a new, more advanced approach for this project would be needed. It is believed that a completely new design and regulatory process would have to be developed-a "clean sheet of paper" approach. This new approach would start with risk-based methods, would establish probabilistic design criteria, and would implement defense-in-depth only when necessary to (1) meet public policy issues (e.g., use of a containment building no matter how low the probability of a large release) and (2) address uncertainties in probabilistic methods and equipment performance. This new approach is significantly different from the Nuclear Regulatory Commission's (NRC's) current risk-informed program for operating plants. For the new approach, risk-based methods are the primary means for assuring plant safety, whereas in the NRC's current approach, defense-in-depth remains the primary means of assuring safety.

[Source: Stanley E. Ritterbusch (ABB-Combustion Engineering) et al., "Risk Informed Assessment of Regulatory and Design Requirements for Future Nuclear Power Plants" NERI Project Number 99-058, NERI Ñ 2002 Annual Report, p. 27]