Document: NUREG-0800
Document ID: 7a841760-7020-433b-b182-63af2e6f5e72
Document Type: srp
Title: OVERPRESSURE PROTECTION
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340596.pdf
Revision Date: 2023-06
Chapter: 5
Section ID: 5.2.2
CFR Part: 
CFR Title: 

Content:
. To assure that the Appendix G limits of the reactor coolant pressure boundary are not exceeded during any anticipated operational occurrences, technical specification pressure-temperature limits are provided for operating the plant. The primary concern of this position is that during startup and shutdown conditions at low temperature, especially in a water-solid condition, the reactor coolant system pressure might exceed the reactor vessel pressure- temperature limitations in the technical specifications established for protec- tion against brittle fracture. This inadvertent overpressurization could be generated by any one of a variety of malfunctions or operator errors. Many incidents have occurred in operating plants as described in Reference 1. Additional discussion on the background of this position is contained in Reference 1. B. Branch Position 1. A system should be designed and installed which will prevent exceeding the applicable technical specifications and Appendix G limits for the reactor coolant system while operating at low temperatures. The system should be capable of relieving pressure during all anticipated overpressurization events at a rate sufficient to satisfy the technical specification limits, particularly while the reactor coolant system is in a water-solid condition. 2. The low temperature overpressure protection system should be operable during startup and shutdown conditions below the enable temperature, 5.2.2-7 Rev. 1 - November 1988 defined as the water temperature corresponding to a metal temperature of at least RTNT + 900F at the beltline location (1/4t or 3/4t) that is controlling the appendix G limit calculations. 3. The system should be able to perform its function assuming any single active component failure. Analyses using appropriate calculational techniques must be provided which demonstrate that the system will provide the required pressure relief capacity assuming the most limiting single active failure. The cause for