Pressurized thermal shock screening criteria re-evaluation effort — US industry activities

A joint project is under way between the US nuclear power industry and the US Nuclear Regulatory Commission (NRC) to re-evaluate the pressurized thermal shock (PTS) screening criteria as presently defined in title 10 of the Code of Federal Regulations, 10 CFR 50.61. Advances in probabilistic risk assessment (PRA), probabilistic fracture mechanics (PFM), thermal hydraulics (TH), and overall plant risk assessment are being incorporated into a comprehensive program to establish a technical basis for revising the present screening criteria. US industry activities are being coordinated through the Reactor Pressure Vessel Integrity Issue Task Group (RPV Integrity ITG) of the EPRI Materials Reliability Project (MRP). The EPRI MRP was formed in 1998 to identify and address issues that could affect operability of major components in pressurized water reactor (PWR) plants. Major activities are coordinated with the nuclear steam supply system (NSSS) vendors, the vendor owner's groups, The Nuclear Energy Institute (NEI), and the NRC. The MRP provides for a unified industry approach to resolution of technical and regulatory issues related to PWR materials degradation. A major task under the Reactor Pressure Vessel Integrity Issue Task Group (RPV Integrity ITG) is to support industry activities associated with the pressurized PTS re-evaluation effort. This paper provides a brief overview of the EPRI MRP program, the RPV Integrity ITG, and industry activities associated with the PTS re-evaluation effort.