Westinghouse Electric Company and Stevenson & Associates have entered into a teaming agreement to provide seismic probabilistic risk assessment (SPRA) model development and fragility estimation services for nuclear power plants.
The Westinghouse/Stevenson team will provide expertise and methodologies to address the U.S. Nuclear Regulatory Commission's (NRC's) Regulatory Guideline 1.200, Rev. 2, which became effective April 1, 2010, and requires that risk-informed applications demonstrate compliance with American Society of Mechanical Engineers/American Nuclear Society RA-Sa-2009 and with the Regulatory Guideline revision. This includes high-level requirements and supporting technical requirements for performing SPRAs and seismic margin assessments (SMAs). The team is also prepared to assist nuclear power plant operators in addressing issues recently identified in NRC Information Notice 2010-18, "Generic Issue 199, Implications of Updated Probabilistic Seismic Hazard Estimates in Central and Eastern United States on Existing Plants."
Although the NRC guideline applies to U.S. plants, some international regulators follow U.S. regulations.
Westinghouse is a proven global leader and recognized expert in probabilistic risk assessment (PRA) model development and application services, with more than three decades of experience and more than 70 dedicated PRA professionals around the world. Westinghouse has access to critical data for nuclear steam supply components, equipment and electrical relays required to successfully perform a seismic risk assessment. Stevenson & Associates is a world-recognized expert at providing structural and mechanical engineering consulting services to the commercial nuclear power industry since 1981. The firm has more than 40 engineering professionals performing more seismic risk and margins assessments than any other firm currently practicing in the United States.
"This is an exciting opportunity to help our customers understand the impact of these new, more robust seismic hazard curves and to fully comply with the regulatory changes," said Doug Holderbaum, director, Westinghouse Engineering Services Systems and Risk Applications. "The team's expertise will be invaluable to our global utility customers in understanding both PRA concerns and regulatory issues, and also in anticipating future PRA developments."
Walter Djordjevic, president of Stevenson & Associates, noted, "By virtue of our long experience and many seismic PRA and margins assessments, we maintain and have ready access to seismic engineering and fragility data for many nuclear power plants, information that is still current and applicable to performing future probabilistic risk assessments."
The Westinghouse/Stevenson team is uniquely qualified to incorporate new risk information currently being evaluated by the nuclear industry, and can address issues associated with new hazard curves and their impact on plant seismic design margins and risk. This is important because several groups are now addressing the need to obtain a more accurate understanding of seismic risk at nuclear power plants. The revised Central and Eastern United States Seismic Source Characterization for Nuclear Facilities project currently under development by the Electric Power Research Institute and the NRC is demonstrating the need for significant changes in seismic hazard curves. In the future, updates of SMAs and SPRAs performed in the framework of the Individual Plant Examination for External Events will reflect these new seismic source characterizations.