Document: NRC Regulatory Guide
Document ID: 5f799693-27fd-4e13-a5e1-4c02f393d90a
Document Type: regulatory_guide
Title: Best-Estimate Calculations of Emergency Core Cooling System Performance + HISTORY –HISTORY 04/2013 – Periodic Review of Revision 0 – Reviewed with issues identified for future consideration 03/1987 – Draft RS 701-4, Proposed Revision 0
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003739584.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.157
CFR Part: 
CFR Title: 

Content:
e appropriate for the facility's operating history. Best-estimate models will be con sidered acceptable provided their technical basis is demonstrated with appropriate data and analyses. 3.2.4 Fission Product Decay Heat The heat generation rates from radioactive decay of fission products, including the effects of neutron capture, should be included in the calculation and should be calculated in a best-estimate manner. The energy release per fission (Q value) should also be calculated in a best-estimate manner. Best-estimate methods will be considered acceptable provided their technical basis is demonstrated with appropriate data and analyses. The model in Reference 10 is consid ered acceptable for calculating fission product decay heat. 3.2.4.1 Model Evaluation Procedure for Fission Product Decay Heat. The values of mean energy per fission (Q) and the models for actinide decay heat should be checked against a set of relevant data. 3.2.5 Metal-Water Reaction Rate The rate of energy release, hydrogen generation, and cladding oxidation from the reaction of the zir caloy cladding with steam should be calculated in a best-estimate manner. Best-estimate models will be considered acceptable provided their technical basis is demonstrated with appropriate data and analyses. For rods calculated to rupture their cladding during the loss-of-coolant accident, the oxidation of the in side of the cladding should be calculated in a best estimate manner. 3.2.5.1 Model Evaluation Procedure for Metal-Water Reaction Rate. Correlations to be used to calculate metal-water reaction rates at less than or equal to 1900'F should: a. Be checked against a set of relevant data, and b. Recognize the effects of steam pressure, pre oxidation of the cladding, deformation dur ing oxidation, and internal oxidation from both steam and U0 2 fuel. The data of Reference 11 are considered accept able for calculating the rates of energy release, hydro gen generation, and cladding oxidation for cladding