Document: NUREG-0800
Document ID: 2cb61281-91f4-400a-8eda-41e187e51d77
Document Type: srp
Title: AUXILIARY FEEDWATER SYSTEM (PWR)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070570007.pdf
Revision Date: 2023-06
Chapter: 10
Section ID: 10.4.9
CFR Part: 
CFR Title: 

Content:
and cool-down of the remaining units. The AFWS safety function is emergency heat removal from and the shutdown and cool-down of the reactor coolant system to low-pressure residual heat removal system cut-in conditions. If the AFWS is shared between units, its ability to accomplish these functions for both units simultaneously must be demonstrated. GDC 5 provides assurance that equipment failures and events occurring in one unit will not propagate to the other units of the site. 6. GDC 19 establishes requirements for design of control room instrumentation and controls for prompt hot shutdown and subsequent cold shutdown of the reactor. BTP 5-4 provides guidance for compliance with GDC 19 for achieving cold shutdown from the control room with only safety grade equipment. The AFWS is required for safe shutdown of the reactor during normal and accident conditions, including cool-down of the reactor to the cut-in conditions for low-pressure residual heat removal. GDC 19 and BTP 5-4 ensure the availability of adequate instrumentation and controls for the required safety function under all anticipated conditions. 7. GDC 34 and 44 establish the requirements to assure the capability to transfer heat from the reactor to a heat sink under normal and accident conditions with sufficient redundancy and isolation capability to accomplish the safety function with a single failure of an active component with or without a coincident loss of offsite power. The capability to transfer heat loads during normal and accident conditions is necessary to maintain fuel, reactor pressure boundary, and containment integrity. The AFWS transfers the heat from the reactor coolant system via the steam generators. Suitable redundancy adds assurance of system capability to perform the safety function in the event of system or component failures. The capability to isolate components, subsystems, or piping if required provides assurance that the AFWS will accomplish the safety function of reactor