Uncertainties analysis of fission fraction for reactor antineutrino experiments

TL;DR

This paper improves an open-source reactor simulation code to accurately calculate fission fractions of key isotopes, validating it against benchmarks and applying it to estimate the uncertainty in antineutrino flux measurements.

Contribution

The study enhances the open-source DRAGON code for fission rate calculations and validates it for reactor applications, providing a transparent alternative to commercial codes.

Findings

Fission fraction calculations agree within 5% with existing results.

Uncertainty in antineutrino flux due to fission fraction is estimated at 0.6%.

Correlation coefficients among isotopes were analyzed for uncertainty assessment.

Abstract

Reactor antineutrino experiment are used to study neutrino oscillation, search for signatures of nonstandard neutrino interaction, and monitor reactor operation for safeguard application. Reactor simulation is an important source of uncertainties for a reactor neutrino experiment. Commercial code is used for reactor simulation to evaluate fission fraction in Daya Bay neutrino experiment, but the source code doesn't open to our researcher results from commercial secret. In this study, The open source code DRAGON was improved to calculate the fission rates of the four most important isotopes in fissions, $^{235}$U,$^{238}$U,$^{239}$Pu and $^{241}$Pu, and then was validated for PWRs using the Takahama-3 benchmark. The fission fraction results are consistent with those of MIT's results. Then, fission fraction of Daya Bay reactor core was calculated by using improved DRAGON code, and the fission fraction calculated by DRAGON agreed well with these calculated by SCIENCE. The average deviation less than 5\% for all the four isotopes. The correlation coefficient matrix between $^{235}$U,$^{238}$U,$^{239}$Pu and $^{241}$Pu were also studied using DRAGON, and then the uncertainty of the antineutrino flux by the fission fraction was calculated by using the correlation coefficient matrix. The uncertainty of the antineutrino flux by the fission fraction simulation is 0.6\% per core for Daya Bay antineutrino experiment. The uncertainties source of fission fraction calculation need further to be studied in the future.