Document: NUREG-0800
Document ID: 97b395a8-6e49-47d5-a249-28113b429fe3
Document Type: srp
Title: MASS AND ENERGY RELEASE ANALYSIS FOR POSTULATED SECONDARY
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0706/ML070620010.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.2.1.4
CFR Part: 
CFR Title: 

Content:
ns of mass release should consider the water in the affected steam generator and feedwater line, feedwater transferred to the affected steam generator before the closure of the isolation valves in the feedwater lines, steam in the affected steam generator, and steam coming from the unaffected steam generator(s) as the secondary system is being depressurized before the closure of the isolation valves in the steam generator crossover lines. D. If liquid entrainment is assumed in the steamline 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 steamline breaks should be analyzed, beginning with the double-ended break and decreasing in area until no entrainment is calculated to occur. This will allow selection of the maximum release case. If no liquid entrainment is assumed, a spectrum of the steamline breaks should be analyzed beginning with the double-ended break and decreasing in area until it has been demonstrated that the maximum release rate has been considered. E. Feedwater flow to the affected steam generator should be calculated considering the diversion of flow from the other steam generators, feedwater flashing, and increased feedwater pump flow caused by the reduction in steam generator pressure. An acceptable method for computing feedwater flow is to assume all feedwater travels to the affected steam generator at the pump runout rate before isolation. After isolation, the unisolated feedwater mass should be added to the affected steam generator. Operator action to terminate auxiliary feedwater flow will be reviewed under SRP Section 10.4.9. Any general-purpose thermal-hydraulics computer codes that the responsible reviewing organization for the subject application finds acceptable may be used to compute mass and energy releases from steam and feedwater line break accidents. 3.