Document: NUREG-0800
Document ID: c755e557-3a72-423f-92bc-0f0270936e27
Document Type: srp
Title: RESIDUAL HEAT REMOVAL (RHR) SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1006/ML100680577.pdf
Revision Date: 2023-06
Chapter: 5
Section ID: 5.4.7
CFR Part: 
CFR Title: 

Content:
the pump(s) under all conditions. B. The miniflow system should be designed such that the miniflow function can be performed assuming a single failure. A single failure should not result in conditions causing no flow through the RHR pumps. C. In cases where only the miniflow return line is available for pump testing, flow instrumentation must be installed on the miniflow return line. This instrumentation is necessary to provide flow rate measurements during pump testing so these data can be evaluated with the measured pump differential pressure to monitor for pump hydraulic degradation. 5. The staff reviews the RHR system to evaluate the adequacy of design features and procedures that have been provided to prevent damaging water hammer and degradation or loss of RHR pumps because of such mechanisms as voided lines. NUREG-0927 provides guidance for water hammer prevention and mitigation and Generic Letter 88-17 provides guidance for shutdown operation. 6. Using the system process diagrams, P&IDs, failure modes and effects analysis, and component performance specifications, the reviewer determines that the system(s) has the capacity to bring the reactor to conditions permitting operation of the RHR system in a reasonable period of time, assuming a single failure of an active component with only either onsite or offsite electric power available. For the purposes of this review, the NRC considers 36 hours a reasonable time period. The organization responsible for the review of steam and feedwater systems evaluates the initial cooldown phase for PWRs, so this review effort should be coordinated with that reviewer. For the purposes of the cooldown review of both PWRs and BWRs, the reviewer should only assume the operation of safety-grade equipment. For PWRs, if the PORVs are relied upon in the performance of a safety-related function such as plant cooldown for compliance with BTP 5-4, the PORVs must meet the guidance contained in Generic Letter 90-06 (see also