Document: NUREG-0800
Document ID: 2925ed14-c49b-459b-8786-e6bffd2c43c4
Document Type: srp
Title: AUXILIARY FEEDWATER SYSTEM (PWR)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070603.pdf
Revision Date: 2023-06
Chapter: 10
Section ID: 10.4.9
CFR Part: 
CFR Title: 

Content:
CR-2815, "Probabilistic Safety Analysis Procedures Guide", January 1984.83 21. IE Bulletin, "Steam Binding of Auxiliary Feedwater Pumps," October 29, 1985.84 10.4.9-17 DRAFT Rev. 3 - April 1996 BRANCH TECHNICAL POSITION ASB 10-1 (Currently the responsibility of the Plant Systems Branch - SPLB)85 DESIGN GUIDELINES FOR AUXILIARY FEEDWATER SYSTEM PUMP DRIVE AND POWER SUPPLY DIVERSITY FOR PRESSURIZED WATER REACTOR PLANTS A. BACKGROUND Heat removal from pressurized water reactor plants following reactor trip and a loss of offsite power is accomplished by the operation of several systems including the secondary system via the steam relief system. Similar capability is required to mitigate the consequences of certain postulated piping breaks. Such heat removal involves heat transfer from the reactor to the steam generators, resulting in the production of steam which is then released to the atmosphere. In this process it becomes necessary to supply makeup water to the steam generators. This is accomplished by the use of an auxiliary feedwater system, which generally consists of redundant components that are powered by both electrical and steam-driven sources. The auxiliary feedwater system functions as an engineered safety system because it is the only source of makeup water to the steam generators for decay heat removal when the main feedwater system becomes inoperable. It must, therefore, be designed to operate when needed, using the principles of redundancy and diversity in order to assure that it can function under postulated accident conditions. The majority of current systems are powered by electrical or steam-driven sources. Operating experience demonstrates that each type of motive power can be subject to a failure of the driving component itself, its source of energy, or the associated control system. The effects of such failures can be minimized by the utilization of diverse systems that include energy sources of at least two different and distinct types. The