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:
ce with the NRC regulations. 1. Sources of Energy. The sources of energy that should be considered in the analyses of steam and feedwater line break accidents include the stored energy in the affected steam generator’s metal, including the vessel tubing, feedwater line, and steamline; stored energy in the water contained within the affected steam generator; stored energy in the feedwater transferred to the affected steam generator before closure of the isolation valves in the feedwater line; stored energy in the steam from the unaffected steam generator(s) before the closure of the isolation valves in the steam generator crossover lines; and energy transferred from the primary coolant to the water in the affected steam generator during blowdown. The steamline break accident should be analyzed for a spectrum of pipe break sizes and various plant conditions from hot standby to 102 percent of full power. The applicant need only analyze the 102-percent power condition if it can demonstrate that the feedwater flows and fluid inventory are greatest at full power. 2. Mass and Energy Release Rate. In general, calculations of the mass and energy release rates during a steam or feedwater line break accident should be performed in a conservative manner from a containment response standpoint (i.e., the postaccident 6.2.1.4-4 Revision 2 - March 2007 containment pressure and temperature are maximized). The following criteria indicate the degree of conservatism that is desired: A. Mass release rates should be calculated using the Moody model (Ref. 1) for saturated conditions or a model that is demonstrated to be equally conservative. B. Calculations of heat transfer to the water in the affected steam generator should be based on nucleate boiling heat transfer. C. Calculations 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