Document: NRC Regulatory Guide
Document ID: da2e0703-3488-44b0-b6d0-089aac7cae3d
Document Type: regulatory_guide
Title: Format and Content of Plant-Specific Pressurized Thermal Shock Safety Analysis Reports for Pressurized Water Reactors
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740028.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.154
CFR Part: 
CFR Title: 

Content:
tion of Detailed PTS Sequences for Analyses," calculate (or for unimportant sequences, estimate using bounding conditions) the conditional probabi 1 i ty of through-wal 1 crack penetra- tion given the occurrence of the event versus fluence or RTNDT (Although licensees were required to use the method of determining RTNDT (RTpTS) specified in paragraph 50.61(b)(2) when evaluating their vessel properties with respect to the screening limits, in performing these plant-specific calculations, they are encouraged to use any alternative methods/data/correlations for which they provide justification of applicability to their specific plant.) Specific sequences identified in Section 3.5.1 should be calculated individually in detail. Less important events such as the residual groups identified in Sec- tion 3.5.2 may be conservatively bounded without a calculation for each sequence in the group. A good example is provided in Chapter 5 of Reference 3. Input for these calculations includes the primary system pressure, the temperature of the coolant in the reactor vessel downcomer, the fluid-film heat transfer coefficient adjacent to the vessel wall, all as a function of time, and the vessel properties. The calculations should be performed with a probabilistic fracture mechanics code such as OCA-P or VISA-I1 (Refs. 25 arid 26). An acceptable procedure to be followed in the fracture mechanics analysis is as follows: A one-dimensional thermal and stress analysis for the vessel wall should be performed. The effect of cladding should be accounted for in both the thermal and stress analyses. The fracture mechanics model can be based on linear elastic fracture mechanics with a specified maximum value of KIc and I KIa to account for upper-shelf behavior. Plastic instability should be consid- ered in the determination of failure. Warm prestress should not be assumed in evaluations of the postulated transients. Acceptable types of material pro- perties are given in the study of the H. B.