Document: NRC Regulatory Guide
Document ID: a2b67b51-f5fe-4c86-a879-f0e439601f7f
Document Type: regulatory_guide
Title: Format and Content of Report for Thermal Annealing of Reactor Pressure Vessels
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740052.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.162
CFR Part: 
CFR Title: 

Content:
he "lateral shift" method, the reem brittlement trend is the same as the embrittlement trend used for the pre-anneal operating period, regard less of whether the embrittlement was determined using the procedures of the PTS Rule (10 CFR 50.61(c)) for embrittlement of RTNDT, or the proce dures of Revision 2 of Regulatory Guide 1.99 (Ref. 21) for embrittlement of Charpy upper-shelf energy, or whether embrittlement was determined from "cred ible" surveillance data. The assurance program should describe the pro gram to estimate reembrittlement trends prior to the development of "credible" data from the reembrittle ment surveillance program and should describe the surveillance program to be used for post-anneal plant operation. 3.2.1 Lateral Shift Method 3.2.1.1 Description of the Lateral Shift Meth od. As illustrated in Figure 1 for both RTNDT and Charpy upper-shelf energy, the lateral shift method re sults in a shift of the initial irradiation embrittlement curve along the fluence axis, using the post-anneal properties (ARTNDT and Charpy upper-shelf energy) as the basis point. This method has been found to be conservative in bounding subsequent embrittlement. 3.2.1.2 Reembrittlement of RTNDT. The reem brittlement of RTNDT is established using the same embrittlement trend as the pre-anneal operating peri od, with a lateral shift. For the pre-anneal operating period, RTNDT is given by: RTNDT = RTNDT(U) + ARTNDT + M (Equation 7) where RTNDT = reference temperature, RTNDT, of the material in the irradiated condition in OF, RTNDT(U) = reference temperature, RTNDT, of the material in the preservice or unirradiated condition in OF, ARTNDT = mean value of the transition temperature shift, or change in RTNDT, from irradiation in OF, and M = margin term in OF to account for uncertainties in the values of RTNDT(U), nickel and copper content, fluence and the calculational procedures, as determined from Equation 8. M - 2 Ja12 + a,2 (Equation 8) where al = standard deviation of