Document: NUREG-0800
Document ID: 5ba2907e-cf47-4a3b-b320-616735faa4cf
Document Type: srp
Title: AUXILIARY FEEDWATER SYSTEM (PWR)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350095.pdf
Revision Date: 2023-06
Chapter: 10
Section ID: 10.4.9
CFR Part: 
CFR Title: 

Content:
nditions. 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 provision of several independent flow paths for the auxiliary feedwater system serves to preclude the possibility of a complete loss of function due to a single event, either occurring alone, or in conjunction with the failure of an active component. The auxiliary feedwater system is categorized as a high energy system, because either that section of line which connects to the main feedwater piping or the steam generator is pressurized during plant operation or else the entire system is pressurized when in use during startup, hot standby, and shutdown. The staff believes that it is necessary to establish design guidelines for the auxiliary feedwater system, and in this regard has developed guidelines that may be used to select the minimum diversity acceptable for auxiliary feedwater system pump drives and power supplies. 10.4.9-11 Rev. 2- - July 1981 B. BRANCH TECHNICAL POSITION 1. The auxiliary feedwater system should consist of at least two full-capacity, independent systems that include diverse power sources. 2. Other powered components of the auxiliary feedwater system should also use the concept of separate and multiple sources of motive energy. An example of the required diversity would be two separate auxiliary feedwater trains, each capable of removing the afterheat load of the reactor system, having one separate train powered from either of two a-c sources and the other train wholly powered by steam and d-c electric power. 3. The piping arrangement, both intake and discharge, for each train should be designed to permit the pumps