New Monte Carlo-based method to evaluate fission fraction uncertainties for the reactor antineutrino experiment

Abstract

Uncertainties of fission fraction is an important uncertainty source for the antineutrino flux prediction in a reactor antineutrino experiment. A new MC-based method of evaluating the covariance coefficients between isotopes was proposed. It was found that the covariance coefficients will varying with reactor burnup and which may change from positive to negative because of fissioning balance effect, for example, the covariance coefficient between 235 U and 239 Pu changes from 0.15 to -0.13. Using the equation between fission fraction and atomic density, the consistent of uncertainty of fission fraction and the covariance matrix were obtained. The antineutrino flux uncertainty is 0.55% which does not vary with reactor burnup, and the new value is about 8.3% smaller.

Investigation of antineutrino spectral anomaly with reactor simulation uncertainty

“…However, the fission fraction uncertainty as a function of burnup was not reported. To investigate this question and determine the correlation coefficient of the fission fraction of different isotopes, a new Monte Carlo-based method was proposed using the one-group fission cross section and concentration of each isotope [19]. That paper also discussed a coefficient to correlate the results with the burnup function.…”