Abstract
Recent developments in the nuclear data libraries used by the ORIGEN-S isotope generation and depletion code have enabled the extension of the code to accurately predict the delayed energy release rates from nuclear decay (decay heat) at very short cooling times of interest to reactor accident analysis. Historically this time domain has required integral methods, such as the ANS-5.1 decay heat standard, because isotopic summation codes could not be reliably applied due to incomplete nuclear data. This paper describes work to validate ORIGEN-S against experimental measurements for decay times that extend down to about 1 second after fission. Benchmarks using measured gamma ray spectra following fission are also included because these results are important to predicting spatial energy deposition from delayed gamma energy release.
