Document: NRC Regulatory Guide
Document ID: 3df13dae-14ee-4f25-95b4-1cedf617ae15
Document Type: regulatory_guide
Title: Regulatory Guidance on the Alternate Pressurized Thermal Shock Rule + HISTORY - HISTORY 03/2015 – DG-1299 , Proposed Revision 0
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1405/ML14056A011.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.230
CFR Part: 
CFR Title: 

Content:
of Step C are satisfactory, or (if applicable) the results of Step F are acceptable, the plant-specific flaw data should be compared to Tables 2 and 3 of 10 CFR 50.61a. A specific example of how this step may be performed, including how the plant-specific flaw data is categorized into weld or plate flaws, is shown in Section 6.3 of NUREG-2163. Step E: If the results of Step B indicate that any axial flaws with through-wall extents greater than 0.075 inch are connected to the RPV inner surface, or (if applicable) the results of Step “F” are not acceptable, other plant-specific assessment is required and the provisions of 10 CFR 50.61a may not be used. Step F: If the evaluation associated with Step C is not successful (i.e., if any flaws exceed ASME Code, Section XI, Table IWB-3510-1 flaw acceptance standards), the flaws should be evaluated and found to be acceptable in accordance with ASME Code, Section XI flaw evaluation methods, and the flaws should be evaluated for acceptability according to 10 CFR 50.61a (see Step I). Step G: If the results of Step D are not acceptable, NDE uncertainties may be accounted for in the evaluation. Appendix C of NUREG-2163 describes the development and application of one methodology acceptable to the NRC that accounts for uncertainties in NDE data. This method may be used for the purpose of developing more realistic vessel-specific flaw depth and density distributions for comparison to Tables 2 and 3 of 10 CFR 50.61a, as well as for use in a plant-specific PFM analysis. The methodology considers flaw sizing errors, a flaw detection threshold, probability of detection (POD), and a prior flaw distribution assumption. It uses a Bayesian updating methodology to combine the observed NDE data with the available flaw data and models used as part of the PTS re-evaluation effort. The licensee must submit the adjustments made to the volumetric test data to account for NDE-related uncertainties as described in (c)(2) of 10 CFR 50.61a. Step