Benchmarking 235U independent fission yields using electron spectra data measured at ORNL to quantify nuclear decay heat for Loss of Coolant Accident scenarios

The current best estimates of the antineutrino spectrum produced by nuclear reactors are obtained from the Huber-Mueller model, which for 235U are derived from the integral electron spectra measured at the Institut Laue-Langevin (ILL). However, the latest generation of nuclear reactor antineutrino experiments – Daya Bay, Double Chooz, NEOS and RENO – have revealed a 6% deficit with respect to this model, a finding which has become known as the Reactor Antineutrino Anomaly. An alternate method to calculate the antineutrino spectrum is to use fission yields and nuclear decay databases, which has become even more relevant in view of the normalization issue with the ILL measurements brought to light in a recent publication of the 235U spectra ratio by Kopeikin and collaborators. The electron spectrum data measured at ORNL was used to benchmark the JEFF-3.3 fission yields, and these data are sensitive to both the fission products' electron spectrum and their half-lives. 235U was specifically examined because it has the biggest contribution to the overall antineutrino spectrum, and we were able to identify about ten key fission products whose fission yields would merit a precise re-evaluation and eventually a measurement.