Document: NUREG-0800
Document ID: 33a67dd5-21e3-4458-9085-803f75466a73
Document Type: srp
Title: OVERPRESSURE PROTECTION
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070540076.pdf
Revision Date: 2023-06
Chapter: 5
Section ID: 5.2.2
CFR Part: 
CFR Title: 

Content:
normal operating range, including uncertainties and technical specification limits that produce the highest anticipated pressure. iii. The second safety-grade signal from the reactor protection system initiates the reactor scram. iv. The discharge flow is based on the rated capacities specified in ASME III for each type of valve. v. The design of the safety valves should have sufficient capacity to limit the pressure to less than 110 percent of the RCPB design pressure during the most severe infrequent event, as specified by ASME Code Article NB- 7000. C. A single malfunction or failure of an active component should not preclude safety-related portions of the system from functioning as required during normal operations, adverse environmental occurrences, and accident conditions, including loss of offsite power. Full credit is allowed for spring-loaded safety valves designed in accordance with the requirements of ASME Code Article NB-7511.1. 3. Design Requirements for PWRs Operating at Power A. For overpressure protection during power operation of the PWR reactor, the design of the PORVs or the pressurizer should have sufficient capacity to preclude actuation of safety valves during normal operational transients, when assuming the following conditions at the plant: i. The reactor is operating at the licensed core thermal power level. 5.2.2-7 Revision 3 - March 2007 ii. All system and core parameters have values within normal operating range that produce the highest anticipated pressure. iii. All components, instrumentation, and controls function normally. B. The designs of the safety valves should have sufficient capacity to limit the pressure to less than 110 percent of the RCPB design pressure during the most severe AOO with reactor scram, as specified by ASME Code Article NB-7000. Also, sufficient available margin should account for uncertainties in the design and operation of the plant assuming: I. The reactor is operating at a power level that will produce the