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2021 ANS Winter Meeting and Technology Expo
November 30–December 3, 2021
Washington, DC|Washington Hilton
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Matthew Denman: On Probabilistic Risk Assessment
Probabilistic risk assessment is a systematic methodology for evaluating risks associated with a complex engineered technology such as nuclear energy. PRA risk is defined in terms of possible detrimental outcomes of an activity or action, and as such, risk is characterized by three quantities: what can go wrong, the likelihood of the problem, and the resulting consequences of the problem.
Matthew Denman is principal engineer for reliability engineering at Kairos Power and the chair of the American Nuclear Society and American Society of Mechanical Engineers Joint Committee on Nuclear Risk Management’s Subcommittee of Standards Development. As a college student at the University of Florida, Denman took a course on PRA but didn’t enjoy it, because he did not see its connection to the nuclear power industry. Later, during his Ph.D. study at the Massachusetts Institute of Technology, his advisor was Neil Todreas, a well-known thermal hydraulics expert. Todreas was working on a project with George Apostolakis, who would leave MIT to become a commissioner of the Nuclear Regulatory Commission. The project, “Risk Informing the Design of the Sodium-Cooled Fast Reactor,” was a multi-university effort funded through a Department of Energy Nuclear Energy Research Initiative (NERI) grant. Todreas and Apostolakis were joined in this project by a who’s who of nuclear academia, including Andy Kadak (MIT, ANS past president [1999–2000]), Mike Driscoll (MIT), Mike Golay (MIT), Mike Lineberry (Idaho State University, former ANS treasurer), Rich Denning (Ohio State University), and Tunc Aldemir (Ohio State University).
Educational Session|Panel|Sponsored by Risk Management
Tuesday, August 11, 2020|11:00AM–12:30PM (12:00–1:30PM EDT)|9
Gene Kelly (Exelon)
Timothy Crook (MCR Group)
Robby Christian (INL)
There are substantial benefits and good reasons for incorporating and crediting FLEX equipment in industry PRA models, for all hazard types (not just seismic and external flooding). Reactor safety is improved by allowing operators the flexibility to use FLEX in a variety of scenarios - not just in beyond design basis external event scenarios, which are the subject of the previously issued Mitigation Strategies under Order EA-12-049. The benefits of crediting FLEX - both in procedures and in PRA models, and for risk applications (such as RICT and SDP cases) - outweigh any potential regulatory uncertainties. The NRC’s recent enforcement policy found in Inspection Manual Chapter (IMC) 0609 Appendix A was recently reconsidered for FLEX equipment deficiencies, both in how these are screened, and in how the cases would be quantified (i.e., which hazard models are used) when performing more detailed significance analysis. FLEX component reliabilities and associated deployment actions (HRA) are evolving and being closely studied and evaluated by industry and the NRC. In the meantime, our models should reasonably reflect the as-built/as-operated plant, as required by the ASME Standard and Regulatory Guide 1.200. The option to deploy FLEX strategies is an important defense in depth measure in any/all scenarios when an extended loss of power is present, and is an improvement in reactor safety. It’s acknowledgement in PRA models should not be discouraged or unduly challenged.
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Reference — FLEX Speaker Bios
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