Document: NRC Regulatory Guide
Document ID: 2704425a-c58a-45c4-93ab-8761721c3e7a
Document Type: regulatory_guide
Title: Evaluation of Reactor Pressure Vessels with Charpy Upper-Shelf Energy Less Than 50 Ft-Lb
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740038.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.161
CFR Part: 
CFR Title: 

Content:
1.0, "using Equation 12: K4p -=(S•)p,(. I +R/(2t)](a)O.SF2 (12) F2 = 0.885.0233(a/ft)+0.345(a/t)2 These equations for Kip'"w are valid for 0.05 s at' s 0.5, and include the effect of pressure acting on the flaw faces. If it can be demonstrated that the actual cooldown rate could be bounded by a "constant" cooldown rate, for each crack depth the stress intensity factor arising from radial thermal gradient, including cladding effects (see Example 4 in Appendix A) is given by Equation 13: K,-[-0.012771 *0.549525(- R)-0.611352( )2 1000 1000 +(0.565199,0.046752(.-2-))( 1-.95371("y 1000 t I *1.6287(-a1(t•P t (13) This equation is applicable to 0.05 < a&t' r. 0.5, and 100 g CR < 600TFhour. The CR values less than 100"F/hour are covered under Service Levels A and B (see Equation 8). The cladding thickness ist . -51l6 in., R, = 86.875 in., base metal thickness t = 8.625 in., and RA' ratio = 9.72. Details of the analysis results are given in Appendix A. Equation 13 is based on the current state of knowledge on K solutions for 6:1 asect-ratio flaws subjected to non-uniform stress gradients in the crack-depth direction. The above I. expression can be replaced with an improved accuracy solution if an appropriate justification is provided. Calculate the effective flaw depth for small-scale yielding, a,, using Equation 14: = a + (-L) I(K I Kft) 12 a (14) Step 2 For each flaw size considered, calculate the stress intensity factor arising from internal pressure for small-scale yielding, IC by substituting a. in place of 'a' in Equation 11 for the axial flaws and in Equation 12 for the circumferential flaws. Similarly, calculate the stress intensity factor arising from radial thermal gradients for small-scale yielding, Y, by substituting a. in place of 'a' in Equation 13. The J-integral arising from the applied loads for small-scale yielding is given by Equation 15: JWpphtd = 1000 (K: 7P+ K)2 IE / (15) In an actual transient the cooldown rate initially may vary sigoificantly with