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:
KIR > (2)(24,000)(2.87) + 12,000 = 150,000 psi %ri4 From the KIR curve, a temperature of RTNDT + 1580F is required. With an RTNDT of 1400F (including irradiation effects), the temperature required for operating pressure at a heatup or cooldown rate of 500/hr is then 140 + 158 = 2980F For a pressure of 1/2 of operating (1125 psig), the membrane stress is 1/2 of that at operating pressure, or 12,000 psi. The M can be taken from the 0.5 Cy ratio curve in Figure G-2214.1 (reproduced as Figure 1 herein), so is again 2.87. KIR > (2)(12,000)(2.87) + 12,000 = 81,000 psi 4Jih 5.3.2-8 Rev. 1 - July 1981 From the KIR curve, the minimum temperature is RTNDT + 1000F, or 140 + 100 = 2400F. The same calculation for a pressure of 1/5 operating pressure (450 psig and 4800 psi stress) is similar, but in this case the stress is less than .1 of the yield strength, so the MM (from the .1 ratio curve) is only 2.82. KIR > (2)(4800)(2.82) + 12,000 = 39,000 psi 41iF The KIR curve shows that the minimum temperature is RTNDT + 0F, or 1400F. Three points on a 500/hr operating limit curve for this vessel at this time in its service lifetime have thus been calculated: Pressure Min. Temperature (psig) (Fahrenheit) 450 140 1150 240 2250 298 -A smooth curve drawn through these points will very closely approximate the results using more rigorous methods. d. Core Operation Appendix G, 10 CFR Part 50, specifies pressure-temperature limits for core operation to provide additional margin during actual power production. The pressure-temperature limits for core operation (except for low power physics tests) are that the reactor vessel must be at a tem- perature equal to or higher than the minimum temperature required for the inservice hydrostatic test, and at least 400F higher than the minimum pressure-temperature curve for heatup and cooldown calculated as described in the preceding section. The minimum temperature for the inservice hydrostatic test for the vessel used in the preceding example was 2730F.