Impact of Improved Beta-Decay Feedings of ¹⁰⁵Mo on Reactor Decay Heat

Reactor decay heat results from the β decay of fission products back to stability and produces 100% of the power after reactor shutdown. Proper understanding of reactor decay heat is vital to the safe operation of nuclear reactors, and this requires precise and accurate β-feeding intensities for the β decay of fission products. Historical measurements of β-feeding intensities using high-resolution detectors are often troubled by low γ-ray efficiencies, which can result in incomplete β- feeding intensities that generally over-predict low-energy level β feedings and under-predict β feeding to higher energy levels. This can be corrected using high-efficiency total absorption detectors such as the Modular Total Absorption Spectrometer (MTAS). We measured the β-feeding intensity of ¹⁰⁵Mo using MTAS at Argonne National Laboratory. We find substantial discrepancies from previous results for β feedings and average γ-ray energy in ¹⁰⁵Mo. Results and the impact on reactor decay heat will be presented.