REGULATION |
Allan Carson
CORDEL Project Manager, World Nuclear Association
Byung-Chan Na
Director of CORDEL, World Nuclear Association
Claude Mayoral Chair of CORDEL
Licensing and Permitting Task Force, Edvance
Time for harmony
Why interpretation of regulatory requirements should be harmonised. By Allan Carson, Byung-Chan Na and Claude Mayoral on behalf of the Licensing & Permitting task Force, CORDEL, World Nuclear Association
A NEUTRON IN NORTH AMERICA is the same as a neutron in Europe. But while the physics does not change, national regulators’ interpretation of the risks, and how best to manage them, vary widely. This limits the wide deployment of standardised reactor designs. High-level safety and regulatory requirements have been implemented and agreed through consensus at international level through the Convention of Nuclear Safety and the International Atomic Energy Agency’s (IAEA) safety standards. So why is it that we continue to build different versions of the same reactor design in different countries? In most cases national regulatory requirements were developed using national experience and implemented to support national programmes. During this time little thought was put into aligning approaches between different countries. The international requirements were developed from these national requirements, at such a high level that they can be applied to all existing national regulatory frameworks. Various international activities through organisations
such as the IAEA, Western European Nuclear Regulators’ Association (WENRA), NEA Multinational Design Evaluation programme (MDEP), and World Nuclear Association’s Cooperation in Reactor Design Evaluation
and Licensing (CORDEL) working group, have attempted to further harmonise the application and interpretation of these high-level standards into specific national regulatory standards and guidance. These efforts have not gone far enough, and there is still significant variance between reactor designs deployed in different countries. This variability can be best demonstrated by looking
at the past opportunity for large fleets of Gen III nuclear power plants operating around the world and considering why the design has changed where the same reactor design has been built or licensed in multiple countries.
30 | January 2022 |
www.neimagazine.com The CORDEL report ‘Different Interpretations of Regulatory
Requirements’ examines this in detail, providing examples of when the national regulatory licensing approach has altered the designs of the Westinghouse AP1000, Hitachi-GE ABWR, EDF/Framatome EPR and Rosatom VVER-1200. The differences in national regulatory approaches and the subsequent design changes required to be implemented has resulted in what should be Nth-of-a- kind (NOAK) projects reverting to first-of-a-kind (FOAK). By incurring many of the project and licensing risks and costs associated with such projects, from the project outset there is a great deal of uncertainty regarding the licensing duration and output.
Key conclusions The newly published CORDEL report discusses a wide variety of safety requirements, such as defence-in-depth to heating, ventilation and air conditioning (HVAC) design, and how their implementation varies between national regulations and guidance. The review found that differences in the outcome of design solutions are often driven by differences between the way in which national regulators identify fault scenarios or conditions and acceptance criteria, which ultimately define the design provisions. The differences between the acceptance criteria can
be difficult to distinguish. They are not always part of the established requirements, but in some cases may be strongly influenced by the differing interpretations of national experts. The report also found that the method of demonstrating
a safety case varies widely between national regulators (eg, prescriptive vs non-prescriptive). When reactor vendors wish to license their design in a country with a different regulatory framework, the different levels of prescriptiveness in regulations and guidance can lead to a complete re-framing of the original safety case and a
Different Interpretations of Regulatory Requirements
Cooperation in Reactor Design Evaluation and Licensing – Licensing & Permitting Task Force
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