Nonprescriptive nuclear safety regulation: example of loss of offsite power

The US approach to nuclear safety regulation has been criticized as highly prescriptive, burdensome, and unpredictable - much more so than are such systems in other countries. The work reported here illustrates the feasibility and potential benefits of an alternate, nonprescriptive approach to nuclear safety regulation. In the example investigated, a nonprescriptive regulation for treatment of the problem of loss of offsite power at a pressurized-water reactor is formulated, and its implementation in a set of power-station cases is explored. The results of this work have been reviewed by representative groups from the US nuclear power industry and the Nuclear Regulatory Commission. The responses indicate a consensus that nonprescriptive regulation would be beneficial and that the exercise summarized in this article represents a credible first step toward its realization. Nevertheless, there remain significant reservations concerning specific aspects of implementation, such as those involving data-base manipulation, uncertainty, and the standardization of assessment methods. The extension of the work reported here to treatment of the full range of issues encountered in regulation of an entire power station would be necessary before the complete case for use of nonprescriptive regulation could be established