Document: NUREG-0800
Document ID: e2737d9a-8e56-46cb-a97d-aaf62a442c6c
Document Type: srp
Title: PRESSURE-TEMPERATURE LIMITS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340637.pdf
Revision Date: 2023-06
Chapter: 5
Section ID: 5.3.2
CFR Part: 
CFR Title: 

Content:
produced here as Fig. 2), a temperature of at least RTNDT + 120'F is necessary for a KI of this level. If, for example, an original RTNDT of 400F is assumed, the required temperature is then 40 + 120, or 1600F. b. Inservice Leak and Hydrotest. The temperatures for the inservice leak and hydrotest, performed at operating pressure and about 1.1 operating pressure, respectively, are calculated in essentially the same way. The differences are that a factor of 1.5 must be applied to the calculated KI to provide extra margin, and the stress levels are lower, so the value of Mm is taken from a lower ratio curve. Using the same vessel as an example, with a normal operating pressure (PO) of 2250 psi, the membrane stress for the leak test can be approximated as: design pressure x allowable stress or 250 x 26,700 = 24,000 psi This is about half of the minimum yield strength, so the Mm is taken from the 0.5 ratio curve, and is 2.87. The calculated K1 that must be assumed is then: KI = (1.5) (M. ) (Membrane Stress) or K1 = (1.5) (2.87) (24,000) = 103,500 psi Jig. From the KIR curve, a temperature of about RTNDT + 125?F is required. As this is an inservice test, the RTNDT would probably have been increased from its original value of + 400F 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 Po) is determined in exactly the same way, and requires a minimum temperature of about RTNDT + 133?F, or 2730F. c. Heatup, Cooldown, and Normal Operation. For normal operation, which includes upset conditions and startup and shutdown procedures, operating limit curves must be provided 5.3.2-7 Rev. 1 - July 1981 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,