No abstract

No abstract

No abstract

No abstract

Irradiation embrittlement of reactor pressure vessel beltline materials is currently evaluated using U.S. Nuclear Regulatory Commission Regulatory Guide 1.99 Revision 2 (RG1.99/2), which presents methods for estimating the shift in Charpy transition temperature at 30 ft-lb (TTS) and the drop in Charpy upper shelf energy (ΔUSE). The purpose of the work reported here is to improve on the TTS correlation in RG1.99/2 using the broader database now available and current understanding of embrittlement mechanisms.The key areas expanded in the current database are low-flux, low-copper, and long-time, high-fluence exposures, previously sparse areas. The model incorporates both physically motivated features and empirical calibration to the U.S. power reactor surveillance data. It contains two terms, corresponding to the best-understood radiation damage features, matrix damage and copper-rich precipitates. The new model includes the variables copper, nickel, and fluence that are in RG1.99/2, but also includes irradiation temperature, neutron flux, phosphorus, and manganese.