Abstract
Engineering assessment that supports the safety basis for a reactor plant operating license is defined as:
“An assessment of a system to determine its adequacy to successfully perform its safety-related function(s) when required.”
The approach to engineering assessment of systems at the Leningrad Nuclear Power Plant (LNPP), as part of its in-depth safety assessment (ISA), is unique. The content and format of engineering assessments for western Safety Analysis Reports (SARs) have evolved over time and current requirements are somewhat scattered in the governing documents (USNRC, 1978). Many regulatory guides and requirements (western or eastern) have not kept up with changes in safety analysis technology. Performance of the ISA for LNPP affords the opportunity to rethink the approach to engineering assessments, and to incorporate current methods and latest technology in safety analysis. As an example, for many systems, information about system reliability obtained from a modem Probabilistic Safety Assessment is more comprehensive than that from a Single Failure Analysis as prescribed in SAR content and format guides.
Overall, the engineering assessment of LNPP systems looks at five major assessment elements: 1) assessment of regulatory compliance, 2) assessment of operability, 3) assessment of vulnerability, 4) assessment of environmental qualifications, and 5) assessment of reliability. By reorganizing the approach to meeting regulatory requirements, and by looking at engineering assessment in various ways, information can be obtained that goes beyond simply demonstrating regulatory compliance to more fully supporting the safety basis for a plant operating license.