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:
tin, in minutes. Heat transfer coefE = 320 BTU/br-t-OF; Thermal diffusivity = 0.98 in.2/min Elastic modulus, E = 28E3 ksi; Poisson's ratio, v =0.3; a f S&IE-6 inlm.-0F Yield stress, oy = 80 ksi; Flow stres, of-85 ksi J-R curve: J = (SF).[CI.(Aa)c. cxpfC3.(Aa)"4] in.-kipr/ 2 where. ln(Cl) = [-2.89+1.22 ln(CVN,) - 0.0027 T + 0.014 ((t)] C2 = [0.077 + 0.116 ln(Cl)] C3 = [- 0.0812 - 0.0092 ln(Cl)] C4 -0.417 SF = 0.741 forLevelC events The VISA-i code was used to determine thermal stress and temperature history for the Level C transient specified in the problem. It was found that at time tm = 20 minutes, the peak thermal stresses occur. The corresponding peak thermal strews intensity factor as a function of crack depth to vessel thickness ratio, a/, of semi-elliptical flaws is given as: Kj- [21.026+374.22(a/t)-1593.56(aA)0+2912.1(a/t)-2029.7(a/)] ksih"m. with 0.05 ! at • 0.5 Therefore, at a = I inch, K, - 46.6 ksi-"in. At an internalpressure, p - I ksi, the pressure induced K, - 18.9 ksi-fin. Now, ifthe pressure, p, is increased, then at a pressure of 6.75 ksi, the J-applied at a = (0.It + t. + 0.1) inch becomes equal to the material's J-R curve as shown in Figure A-4. This will mark an "initiation" of ductile flaw growth. The temperature at the crack-tip (a= 0.It + t,) for time tmn= 20 minutes is 400OF. If internal pressure p is further increased, in Figure A-4 it can be seen that at pressure p = 7.56 ksi the crack growth becomes unstable. That is, the slope of the J-applied curve becomes greater than the slope of the material's J-R curve. Example 3 (Levels C and D Loading, BWR Vessel) The problem statement is the same as in Example 2, except for a BWR vessel geometlry. The vessel geometric details are: BWR vessel internal radius, R. = 120.0 inch; A-533B plate material Thickness, t = t, - 6.0 in.; Cladding thickness, t., = 0, M - 20 Flaw orientation - Axial, in plate material; Flaw aspect ratio - 6 to I The VISA-il code was used to determine thermal stress and