Document: NUREG-0800
Document ID: 243e1ce7-857c-48e4-9eb7-6125311da9be
Document Type: srp
Title: RESIDUAL HEAT REMOVAL (RHR) SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070437.pdf
Revision Date: 2023-06
Chapter: 5
Section ID: 5.4.7
CFR Part: 
CFR Title: 

Content:
avoid water hammer due to voided line conditions. For RHR systems of BWRs which use the steam condensing mode of operation, the evaluation should include consideration of water hammer due to (a) water entrainment in the steam supply line during startup, (b) formation of steam bubbles in the RHR system pump discharge lines and heat exchangers resulting from leakage past valves in the steam supply line, and (c) water entrainment in the discharge line of the pressure relief valve DRAFT Rev. 4 - April 1996 5.4.7-12 used to prevent over pressurization of the system during operation in the steam condensing mode. Guidance for water hammer prevention and mitigation is found in NUREG-0927 (Reference 26).85 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, 36 hours is considered a reasonable time period. The ASB SPLB is responsible for the review of 86 the initial cooldown phase for PWRs. Therefore, this review effort is to be coordinated with that branch. For the purposes of the review of both PWRs and BWRs, only the operation of safety grade equipment is to be assumed. For PWRs, if the PORVs are relied upon in the performance of a safety-related function such as plant cooldown for compliance with Branch Technical Position RSB 5-1, the PORVs must meet the guidance contained in Generic Letter 90-06 (see References 16 and 24) as reviewed in SRP Section 6.8 (proposed). For new PWRs that utilize PORVs, the valves shall be 87 safety-related.88 7. The cooldown function is to be reviewed to determine if it can be performed from the control room assuming a single failure of an active component, with only