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:
f fracture toughness follow ing the thermal anneal and the reembrittlement rate with subsequent plant operation. 3.1 Fracture Toughness Recovery Program This section of the assurance program should de scribe the method planned to determine the percent recovery, including any computations or tests. The methods discussed below provide experimental and computational means for determining the percent re covery of ARTNDT, Rt, and the percent recovery of Charpy upper-shelf energy, RUSE. As provided in the thermal annealing rule (10 CFR 50.66), one of three methods may be used to evaluate the recovery in fracture toughness following the thermal annealing. One method requires the use of surveillance specimens from "credible" surveillance programs (as defined in the PTS rule, 10 CFR 50.61) to develop material-specific data, if such specimens are available. The most accurate, but difficult, second method uses material removed from the reactor pres sure vessel beltline to develop plant-specific data. The third method uses generic computations to estimate > the recovery. These three methods are described be low. Values of percent recovery (RUSE and RI) may not exceed 100 percent. 3.1.1 Vessel Surveillance Program Method If the plant's surveillance program has resulted in "credible" data (as defined in the PTS rule, 10 CFR 50.6 1), and broken specimens from that program have been retained (as recommended in NRC Information Notice No. 90-52, "Retention of Broken Charpy Specimens," Reference 17), the thermal annealing rule (10 CFR 50.66) requires that broken specimens from surveillance specimens and any remaining untest ed surveillance specimens be used to evaluate anneal ing recovery on a material-specific basis. The broken specimens should be reconstituted (see Section 3.1.4 of this guide) to form new, full-size specimens with the insert material being the only material from the original surveillance specimen. These reconstituted specimens, and any untested specimens from the