Document: NUREG-0800
Document ID: ec8e8c49-ea1e-4b46-a508-500ea11caad2
Document Type: srp
Title: ULTIMATE HEAT SINK
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350549.pdf
Revision Date: 2023-06
Chapter: 9
Section ID: 9.2.5
CFR Part: 
CFR Title: 

Content:
n regulations. Implementation schedules for conformance to parts of the method discussed herein are contained in the referenced regulatory guides. VI. REFERENCES 1. 10 CFR Part 50, Appendix A, General Design Protection Against Natural Phenomena." 2. 10 CFR Part 50, Appendix A, General Design tures, Systems, and Components." 3. 10 CFR Part 50, Appendix A, General Design System." 4. 10 CFR Part 50, Appendix A, General Design Cooling Water System." 5. 10 CFR Part 50, Appendix A, General Design Water System." 6. Regulatory Guide 1.27, "Ultimate Heat Sink Criterion 2, "Design Bases for Criterion 5, "Sharing of Struc- Criterion 44, "Cooling Water Criterion 45, "Inspection of Criterion 46, "Testing of Cooling for Nuclear Power Plants." I I 7. Regulatory Guide 1.29, "Seismic Design Classification." 8. Regulatory Guide 1.72, "Spray Pond Plastic Piping." 9. Branch Technical Position ASB 9-2, "Residual Decay Energy for Light Water Reactors for Long-Term Cooling." I 9.2.5-7 Rev. 2 - July 1981 BRANCH TECHNICAL POSITION ASB 9-2 RESIDUAL DECAY ENERGY FOR LIGHT-WATER REACTORS FOR LONG-TERM COOLING A. BACKGROUND The Auxiliary Systems Branch has developed acceptable assumptions and formula- tions that may be used to calculate the residual decay energy release rate for light-water-cooled reactors for long-term cooling of the reactor facility. Experimental data (Refs. 1 and 2) on total beta and gamma energy releases for long half-life (> 60 seconds) fission products from thermal neutron fission of U-235 have been considered reliable for decay times of 103 to 107 seconds. Over this decay time, even with the exclusion of short-lived fission products, the decay heat rate can be predicted to within 10% of experimental data (Refs. 3, 7, and 8). The short-lived fission products contribute appreciably to the decay energy for decay times less than 103 seconds. Although consistent experimental data are not as numerous (Refs. 4 and 5) and the results of various calculations differ, the effect of