395426 - Regulatory Framework for Evaluating Site-Specific Flooding Hazards and Climate Change Impacts to Nuclear Power Plants in the U.S. and U.K.
Wednesday, June 6
8:30 AM - 10:00 AM
Location: Lake Superior B
Taslima Akter, Reston, VA – Bechtel Nuclear, Security & Environmental
The Nuclear Regulatory Commission (NRC) employs a set of requirements and guidance to regulate new nuclear power plant (NPP) licensing activities in the U.S. The regulatory requirements generally led to prescriptive guidance like Regulatory Guides, Interim Staff Guidance, and Standard Review Plans. The NRC encourages deterministic approaches to evaluate site-specific natural hazards. Considerations for long-term climate change in the licensing basis, however, are still based on the requirement that the evaluation includes sufficient margin to account for the limited length of the historical data records. The NRC has recently enhanced its regulatory strategies to address the lessons learned from the beyond-design-basis accident at the Fukushima Daiichi plant.
The Office for Nuclear Regulation (ONR) in the U.K., on the other hand, adopts a goal-setting approach in the permitting process. Under this approach, the ONR defines the regulatory expectations and requires that the design bases are analyzed to justify how regulatory expectations are achieved. The ONR currently attaches 36 conditions to a nuclear site license. The License Conditions are evaluated following the requirements of Safety Assessment Principles, which are then supported by a series of Technical Assessment Guides. The ONR also follows the probabilistic principles of external hazard assessment, an approach which is complementary to the International Atomic Energy Agency guidance. The ONR regulations require that climate change effects are considered for the lifecycle of the plant following the United Kingdom Climate Projections, application of which is rather prescriptive.
In this paper, a comparative assessment of regulatory approaches in the two countries is presented in evaluating flooding hazards to an NPP. The assessment shows that probabilistic risk-informed design in the U.K. often requires additional redundancies to mitigate safety concerns. The treatment of climate projections arguably is the largest differentiator in the regulatory approaches between the two countries.