Document: NUREG-0800
Document ID: 16afcc26-09c8-4627-8906-8c56ffe8434b
Document Type: srp
Title: LOSS OF NORMAL FEEDWATER FLOW
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070683.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.2.7
CFR Part: 
CFR Title: 

Content:
REVIEW RESPONSIBILITIES Primary - Reactor Systems Branch (RSB)SRXB1 Secondary - None I. AREAS OF REVIEW A loss of normal feedwater flow could occur from pump failures, valve malfunctions, or a loss of offsite power (LOOP). The sequence of events for the loss of feedwater transient differs 2 between a boiling water reactor (BWR) and a pressurized water reactor (PWR). A PWR has a backup (auxiliary or emergency) feedwater system while a BWR relies on the emergency core cooling system (ECCS) and reactor core isolation cooling (RCIC) system for backup core cooling. In either case, loss of feedwater flow results in an increase in reactor coolant temperature and pressure which eventually requires a reactor trip to prevent fuel damage. For both PWRs and BWRs, fission product decay heat must be transferred from the reactor coolant system following a loss of normal feedwater flow. This can be accomplished by actuation of one or several of the following systems: steam relief system, steam bypass to the condenser, reactor core isolation cooling system (BWR), emergency core cooling system (BWR) and auxiliary or emergency feedwater system (PWR). DRAFT Rev. 2 - April 1996 15.2.7-2 The review of the loss of feedwater transient includes: 1. the sequence of events, 2. the analytical model, 3. the values of parameters used in the analytical model, and 4. the predicted consequences of the transient. 3 The sequence of events described in the applicant's safety analysis report (SAR) is reviewed by both RSBSRXB and the Instrumentation and Control Systems Branch (ICSB)HICB. The 4 RSBSRXB reviewer concentrates on: 1. the need for the reactor protection system, 2. the engineered safety systems, and 3. operator action to secure and maintain the reactor in a safe condition. 5 The analytical methods are reviewed by RSBSRXB to ascertain whether the mathematical modeling and computer codes have been previously reviewed and accepted by the staff. If a referenced analytical method has not been