Document: NUREG-0800
Document ID: 087cef2c-a084-4143-84b9-9f1ba68e1851
Document Type: srp
Title: MASS AND ENERGY RELEASE ANALYSIS FOR POSTULATED SECONDARY SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340662.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.2.1.4
CFR Part: 
CFR Title: 

Content:
ll power. Only the 102% power condition need be analyzed provided the applicant can demonstrate that the feedwater flows and fluid inventory are greatest at full power. 2. Mass and Energy Release Rate Calculations In general, calculations of the mass and energy release rates during a steam or feedwater line break accident should be done in a manner that is conservative from a containment response standpoint; i.e., that maximizes the post-accident containment pressure and temperature. The following criteria indicate the degree of conservatism that is desired. Mass release rates should be calculated using the Moody model (Ref. 16) for saturated conditions, or a model that is demonstrated to be equally conservative. Calculations of heat transfer to the water in the affected steam generator should be based on nucleate boiling heat transfer. Calculations of mass release should consider the water in the affected steam generator and feedwater line, the feedwater transferred to the affected steam generator prior to the closure of the isolation valves in the feedwater lines, the steam in the affected steam generator, and the steam coming from the unaffected steam generator(s) as the secondary system is being depressurized prior to the closure of the isolation valves in the steam generator crossover lines. If liquid entrainment is assumed in the steam line breaks, experimental data should support the predictions of the liquid entrainment model. The effect on the entrained liquid of steam separators located upstream from the break should be taken into account. A spectrum of steam line breaks should be analyzed, beginning with the double-ended break and decreasing in area until no entrainment is calculated to occur, to allow selection of the maximum release case. 6.2.1.4-2 Rev. 1 - July 1981 If no liquid entrainment is assumed, a spectrum of the steam line breaks should be analyzed beginning with the double-ended break and decreasing in area until it has been demonstrated that