Item C-5: Decay Heat Update

DESCRIPTION

Historical Background

As identified in NUREG-0471,[1] this issue involved following the work of research groups in determining best estimate decay heat data and associated uncertainties for use in LOCA calculations.

Safety Significance

No significant change in public risk is attributed to this issue.

CONCLUSION

In accordance with a DSI memorandum,[2] the staff has determined that the 1979 ANSI/ANS Standard 5.1[3] is technically acceptable and has allowed the use of this data to justify relaxation of non-required conservatisms in

current ECCS evaluation models.[4] In addition, the proposed ECCS rule change being developed by the staff will allow the use of this new data. Thus, this issue is a resolved Regulatory Impact issue.


 

 



[1] NUREG-0471, "Generic Task Problem Descriptions (Categories B, C, and D)," U.S. Nuclear Regulatory Commission, June 1978.

[2] Memorandum for W. Minners from B. Sheron, "Generic Issues C-4, C-5, C-6," May 29, 1985. [8506100882]

[3] ANSI/ANS 5.1, "Decay Heat Power in Light Water Reactors," American National Standards Institute, 1979.

[4] SECY-83-472, "Emergency Core Cooling System Analysis Methods," U.S. Nuclear Regulatory Commission, November 17, 1983. [8401060169]

Page Last Reviewed/Updated 06/24/2025