VTESTER analysts manual

Neutron irradiation from reactor operation is known to cause embrittlement in reactor pressure vessel materials. In some nuclear power plants, the effects of irradiation damage could make the reactor pressure vessel the limiting component when considering extended plant life. EPRI has developed the VTester Code as a tool for utilities in addressing the embrittlement issues and choosing possible actions to mitigate the effects of vessel embrittlement on future plant operation. VTester makes use of Decision Analysis techniques in performing a cost/benefit evaluation of various options for managing embrittlement issues. The VTester code and an associated User's Manual has been published by EPRI in the EPRIGEMS format (NP-7020-CCML). This Analyst's Manual is a supporting document which discusses the issues and the mitigative options to address radiation embrittlement of reactor vessels. This report also briefly addresses the development of influence diagrams, decision trees which integrates the uncertainties associated with engineering, regulatory and economic variables into a comprehensive framework for evaluating alternative mitigative actions