Document: NUREG-0800
Document ID: 5d88f9f1-c708-4a51-8593-a2aa484a15f3
Document Type: srp
Title: Revision 4 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0708/ML070850123.pdf
Revision Date: 2023-06
Chapter: 5
Section ID: 5
CFR Part: 
CFR Title: 

Content:
CCS function, the power-operated valve is to be opened upon receipt of a safety injection signal once the reactor coolant pressure has decreased below the ECCS design pressure. iii. Three check valves in series. iv. Two check valves in series, provided that there are design provisions to permit periodic testing of the check valves for leak tightness and the testing is performed at least annually. 3. Pressure Relief Requirements The RHR system shall satisfy the following pressure relief requirements: A. To protect the RHR system against accidental over pressurization when it is in operation (not isolated from the RCS), pressure relief in the RHR system shall be provided with relieving capacity in accordance with the American Society of Mechanical Engineers Boiler and Pressure Vessel Code. The most limiting pressure transient during the plant operating condition when the RHR system is not isolated from the RCS shall be considered when selecting the pressure- relieving capacity of the RHR system. For example, during shutdown cooling in a PWR with no steam bubble in the pressurizer, inadvertent operation of an additional charging pump or inadvertent opening of an ECCS accumulator valve should be considered in the selection of the design bases. BTP 5-4-4 Revision 4 - March 2007 B. Fluid discharged through the RHR system pressure relief valves must be collected and contained such that a stuck open relief valve will not do the following: i. Result in flooding of any safety-related equipment ii. Reduce the capability of the ECCS below that needed to mitigate the consequences of a postulated loss-of-coolant accident iii. Result in a nonisolatable situation in which the water provided to the RCS to maintain the core in a safe condition is discharged outside of the containment C. If interlocks are provided to automatically close the isolation valves when the RCS pressure exceeds the RHR system design pressure, adequate relief capacity shall be provided during the time period