Perspective on Trend Curve Models and Their Role in RPV Integrity

Abstract

The use of nuclear energy is critical for achieving carbon neutrality in 2050 and beyond as well as energy security worldwide. For this, the safe operation of nuclear power plants must be guaranteed. Material aging issues of safety-significant components are of primary concern, and particularly the neutron irradiation embrittlement of reactor pressure vessels (RPVs) must be appropriately evaluated and managed to protect RPVs from failure during normal operation as well as postulated accident conditions. The amount of embrittlement is estimated using embrittlement trend curves (ETCs), and thus the accuracy and reliability of the ETCs are critical for the continued operating safety of RPVs. In this paper, we discuss how the reliable prediction of RPV embrittlement using ETCs can be enabled. The role and history of ETCs are briefly summarized followed by three topics on ETCs from the viewpoints of accuracy, margin, and database.