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:
ions between the K determined directly and results of simpler fracture Ic toughness tests are not exact, but may be used if appropriate allowances are made for variations in material behavior and data scatter. The Code gives values of K as a function of temperature relative to a conservative determination of the IRa 22 reference temperature of the material. This reference temperature, RT , is NDT determined for the ferritic materials of components for which operating and testing limit curves must be calculated. The effects of radiation on the fracture toughness of the material in the beltline region of the reactor vessel is accounted for by adjusting the RT of the affected material upward. The amount of NDT upward shift depends on the composition of the steel (especially its copper and phosphorousnickel content), and the neutron fluence. Conservative predictions 23 of the effect of radiation on the RT based on datathe methods in Regulatory NDT 24 Guide 1.99, are factored into the original limit curves. The continued conservatism of these predictions throughout plant life is verified by a mandatory material surveillance program described in Appendix H of 10 CFR Part 50. d. The Code specifies the stress components that must be used for the KI calculations, and the factors that must be applied to each to provide adequate safety margins. The Code, by reference to WRC Bulletin- 175 (Reference 15) , 25 26 specifies the expression to use for calculating the K , using the applied stresses I and the postulated flaw geometry. Although calculations are usually made by a computer, curves are provided in the Code to facilitate the use of conservative hand calculations if desired. 3. Pressure-Temperature Requirements The requirements for the pressure-temperature limits are as follows: a. Pressure-Temperature Limits for Preservice Hydrostatic Tests During preservice hydrostatic tests (if fuel is not in the vessel), the K must be IRa 27 greater than the K caused by pressure. The