Document: NRC Regulatory Guide
Document ID: 5f4d6577-6c2a-473a-9a76-4033a95dba4c
Document Type: regulatory_guide
Title: Radiation Embrittlement of Reactor Vessel Materials (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740284.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.99
CFR Part: 
CFR Title: 

Content:
data used to establish the mean. The standard deviation for ARTNDT, a A, is 28 °F for welds and 17 °F for base metal, except that OA, need not exceed 0.50 times the mean value of ARTNDT· 1.2 Charpy Upper-Shelf Energy Charpy upper-shelf energy should be assumed to decrease as a function of fluence and copper content as indicated in Figure 2. Linear interpolation is permitted. 1.3 Limitations Application of the foregoing procedures should be subject to the following limitations: 1. The procedures apply to those grades of SA-302, 336, 533, and 508 steels having minimum specified yield strengths of 50,000 psi and under and to their welds and heat-affected zones. 2. The procedures are valid for a nominal irradiation temperature of 550 °F. Irradiation below 525 °F should be considered to pro- duce greater embrittlement, and irradiation above 590 °F may be considered to produce less embrittlement. The correction factor used should be justified by reference to actual data. 3. Application of these procedures to fluence levels or to cop- per or nickel content beyond the ranges given in Figure 1 and Tables 1 and 2 or to materials having chemical compositions beyond the range found in the data bases used for this guide should be justified by submittal of data. 2. SURVEILLANCE DATA AVAILABLE When two or more credible surveillance data sets (as defined in the Discussion) become available from the reactor in question, they may be used to determine the adjusted reference temperature and the Charpy upper-shelf energy of the beltline materials as described in Regulatory Positions 2.1 and 2.2, respectively. 2.1 Adjusted Reference Temperature The adjusted reference temperature should be obtained as follows. First, if there is clear evidence that the copper or nickel content of the surveillance weld differs from that of the vessel weld, i.e., differs from the average for the weld wire heat number associated with the vessel weld and the surveillance weld, the measured values of