Document: NUREG-0800
Document ID: 5782f44d-4d34-4048-bf55-d13ffa316faf
Document Type: srp
Title: Revision 3 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0708/ML070850410.pdf
Revision Date: 2023-06
Chapter: 10
Section ID: 10
CFR Part: 
CFR Title: 

Content:
it can function under postulated accident conditions. BTP 10-1-2 Revision 3 - March 2007 Most 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 its control system. The effects of such failures can be minimized by diverse systems with energy sources of at least two different and distinct types. The provision of several independent AFWS flow paths precludes the possibility of a complete loss of function due to a single event either alone or with the failure of an active component. The AFWS is a high-energy system because either the line section connecting to the main feedwater piping or the steam generator is pressurized during plant operation or the entire system is pressurized when in use during startup, hot standby, and shutdown. In the belief that AFWS design guidelines are necessary, the staff has developed guidelines for selection of the minimum diversity acceptable for AFWS pump drives and power supplies. B. BRANCH TECHNICAL POSITION 1. The AFWS should have at least two full-capacity, independent systems with diverse power sources. 2. Other AFWS powered components also should have separate and multiple sources of motive energy (e.g., two separate auxiliary feedwater trains, each capable of removing the reactor system after-heat load, one separate train powered from either of two alternating current sources and the other powered wholly by steam and direct current electric power). 3. The piping arrangements, both intake and discharge, for each train should be designed for the pumps to supply feedwater to any combination of steam generators. This arrangement should be designed for pipe failure, active component failure, power supply failure, or control system failure that could prevent system function. One acceptable arrangement is crossover piping with valves operable by remote manual control from