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ANSI/ANS-5.1-2014 (R2019)

Decay Heat Power in Light Water Reactors

This standard sets forth values for the decay heat power from fission products and actinides following shutdown of light water reactors (LWRs) using nuclear fuel initially containing 235U and 238U. The decay heat power from fission products is presented in tables and equivalent analytical representations. Contributions from the decay of 239U and 239Np, and the contributions from all other actinides, are represented separately. Methods are described that account for the reactor operating history, for the effect of neutron capture in fission products, and for assessing the uncertainty in the resultant decay heat power. The standard applies to decay times up to 1010 s after shutdown.

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