Document: NUREG-0800
Document ID: a20ea81d-33c2-4a0c-a3b4-216d45d6fccd
Document Type: srp
Title: FEEDWATER SYSTEM PIPE.BREAKS INSIDE AND OUTSIDE CONTAINMENT (PWR)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350148.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.2.8
CFR Part: 
CFR Title: 

Content:
mode. These sensitivity studies may be presented in a generic report and referenced if considered applicable. b. The assumptions as to whether offsite power is lost and the time of loss should be made conservatively. Offsite power may be lost simultaneously with the occurrence of the pipe break, the loss may occur during the accident, or offsite power may not be lost. A study should be made to determine the most conservative assumption appropriate to the plant design being reviewed. The study should take account of the effects that loss of offsite power has on reactor coolant and main feedwater pump trips and on the initiation of auxiliary feedwater, and the resulting modification of the sequence of events. c. The effects of the postulated feedwater line breaks on other systems (piDe whip, jet impingement, reaction forces, temperature, humidity, etc.) should be considered in a manner consistent with the intent of Branch Technical Positions ASB 3-1 and MEB 3-1 (Ref. 5). d. The worst single active component failure should be assumed to have occurred in the systems required to control the transient. e. The maximum rod worth should be assumed to be held in the fully withdrawn position, per GDC 25. An appropriate rod reactivity worth versus rod position curve should be assumed. f. The core burnup (time in core life) should be selected to yield the most limiting combination of moderator temperature coefficient, void coefficlent, Doppler coefficient, axial power profile, and radial power distribution. g. The initial core flow assumed for the analysis of the feedwater line rupture accident should be chosen conservatively. If the minimum core flow allowed by the technical specifications is assumed, the minimum DNBR margin results for the case of a feedwater line rupture inside containment. However, this may not be the most conservative assumption. For example, 15.2.8-4 Rev. 1 - July 1981 maximum initial core flow results in increased reactor coolant system cooldown and