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:
wn rate, including the contributions of cladding to thermal stress and the thermal stress intensity factor. For this alternative analysis method (also described in Reference, 4), the main features for computing KY, and Kk., which are applied in examples in Appendix A, are given in. Appendix B.1- The limiting condition should be determined for the transient time at which the material's J-R curve will be greater than or equal to the Jbw for evaluating Equations 1 and 2. The main steps are: a. Determine the temperature gradient across the vessel wall thickness, in 10 to 20 time steps over thefull duration of the tra•sLient; and compute the corresponding thermal stress histozy, taking into account the cladding thickness, t,. b. For each time step. compute K. and uL values as a function of the crack depth in the range 0.05 s a/t s 0.5. c. For Equation 1. calculate the pressure-induced K, and the J... using Equations 9 and 10, at a crack-tip depth of(0.25t' + 0.1 in.) for each time step. d. Use Step a to find crack-tip temperature history at each time step. See Figure A-I in Appendix A for an example. e, For a given material condition, determine the J-R values at the crack extension of 0.1 inch by using the crack-tip temperature history from Step d. See Figure A-2 in Appendix A for an example. f Compare the material's J-R values as a function of time in Step e with the Jý, values in Step c. See Figure A-2 in Appendix A for an example. The time at which the J-R value is just equal to the J,,w determines the critical condition for evaluating Equation 1. g. At the time determined in Step Z evaluate Equation 2 to verify the stability of the predicted flaw growth. 2.1.2 Evaluation of Flaw Stability Flaw stability is evaluated by a direct application of the flaw stability criterion given by Equation 2. The applied J integral is calculated for a series of flaw depths corresponding to increasing amounts of ductile flaw growth. The applied pressure, p, is set equal to the