Document: NUREG-0800
Document ID: 26aca061-b0de-4983-bbca-3fccb00afc2f
Document Type: srp
Title: PRESSURE-TEMPERATURE LIMITS AND PRESSURIZED THERMAL SHOCK1
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070431.pdf
Revision Date: 2023-06
Chapter: 5
Section ID: 5.3.2
CFR Part: 
CFR Title: 

Content:
r example, an original RT of 40 F is assumed, the required temperature is NDT then 40 + 120, or 160 F. b. Inservice Leak and Hydrotest. The temperatures for the inservice leak and hydrotest, performed at operating pressure and about 1.1 times the operating pressure, respectively, are calculated 56 in essentially the same way. The differences are that a factor of 1.5 must be applied to the calculated K to provide extra margin, and the stress levels are I lower, so the value of M is taken from a lower ratio curve. m Using the same vessel as an example, with a normal operating pressure (P ) of 0 2250 psi, the membrane stress for the leak test can be approximated as: operating pressure x allowable stress design pressure or 2250 x 26,700 = 24,000 psi 2500 DRAFT Rev. 2 - April 1996 5.3.2-12 This is about half of the minimum yield strength, so the M is taken from the 0.5 m ratio curve, and is 2.87. The calculated K that must be assumed is then: I K = (1.5) (M )(Membrane Stress) I m or K = (1.5)(2.87)(24,000) = 103,5300 psi in. I 57 From the K curve, a temperature of about RT + 125 F is required. As this IRa NDT 58 is an inservice test, the RT would probably have been increased from its NDT original value of + 40 F by some shift caused by radiation. Assume this shift is 100 F, thus the temperature for the leak test must be at least: 40 + 100 + 125 = 265 F The inservice hydrotest temperature (at 1.1 P ) is determined in exactly the same 0 way, and requires a minimum temperature of about RT + 133 F, or 273 F. NDT c. Heatup, Cooldown, and Normal Operation. For normal operation, which includes upset conditions and startup and shutdown procedures, operating limit curves must be provided that show the maximum permissible pressure at any temperature from cold shutdown conditions to full pressurization conditions. Reactor vendors have developed computer codes to perform the necessary calculations, because thermal stresses must be included, and hand calculations of even moderate