A TALE OF TWO EPISTEMOLOGIES: THE EVOLUTION OF NUCLEAR SAFETY IN THE US AND FRENCH NUCLEAR INDUSTRY

Abstract

This paper traces the evolution of the distinctive epistemologies of nuclear safety regulation in the United States and France with an examination of the use and evolution of probabilistic risk assessments and the “defense-in-depth” principle in each country. The analysis offers insights into how each nation’s industrial and historical contexts have shaped their distinct regulatory approaches for assessing nuclear safety.

In the United States, a “risk-informed” approach to nuclear safety has become prevalent, shaped by the historical development from the Atomic Energy Commission to the Nuclear Regulatory Commission (NRC). The NRC has favored a methodology that emphasizes transparency, repeatability and the use of quantitative assessments over qualitative judgment in its regulatory decision-making, although “defense-in-depth” has, over time, become a complementary qualitative criterion.

In contrast, the French nuclear regulator, the Autorité de Sûreté Nucléaire (ASN), adheres to “defense-in-depth” as a foundational principle. The French model maintains a qualitative and flexible approach that aligns with public expectations for continuous safety improvement, avoiding a firm commitment to quantitative safety targets and allowing the ASN to exercise its discretion in safety enhancements.

Despite these differing safety philosophies, no significant disparities in the operational safety records of the nuclear reactors in both countries are apparent. However, these epistemologies may influence the design and technology choices for future reactors. By analyzing regulatory reports and the trade press, the paper highlights the role and interplay of “epistemic cultures”, revealing the complex ways in which expert communities shape and interpret nuclear safety paradigms within shifting technological and societal contexts.