New antineutrino energy spectra predictions from the summation of beta decay branches of the fission products

TL;DR

This study updates antineutrino energy spectra predictions for key fissile isotopes by incorporating recent beta decay measurements, highlighting the importance of new data for accurate reactor neutrino modeling.

Contribution

It introduces new antineutrino spectra predictions based on recent beta decay data, especially for $^{238}$U, and emphasizes the need for further TAS measurements to enhance accuracy.

Findings

Improved spectra predictions for $^{235}$U, $^{239}$Pu, $^{241}$Pu, and $^{238}$U.

Beta decay data significantly affect the gamma component of decay heat.

New measurements help resolve previous spectral discrepancies.

Abstract

In this paper, we study the impact of the inclusion of the recently measured beta decay properties of the $^{102;104;105;106;107}$Tc, $^{105}$Mo, and $^{101}$Nb nuclei in an updated calculation of the antineutrino energy spectra of the four fissible isotopes $^{235, 238}$U, and $^{239,241}$Pu. These actinides are the main contributors to the fission processes in Pressurized Water Reactors. The beta feeding probabilities of the above-mentioned Tc, Mo and Nb isotopes have been found to play a major role in the $\gamma$ component of the decay heat of $^{239}$Pu, solving a large part of the $\gamma$ discrepancy in the 4 to 3000\,s range. They have been measured using the Total Absorption Technique (TAS), avoiding the Pandemonium effect. The calculations are performed using the information available nowadays in the nuclear databases, summing all the contributions of the beta decay branches of the fission products. Our results provide a new prediction of the antineutrino energy spectra of $^{235}$U, $^{239,241}$Pu and in particular of $^{238}$U for which no measurement has been published yet. We conclude that new TAS measurements are mandatory to improve the reliability of the predicted spectra.