Development of Cumulative Fission Yield Covariances for Uncertainty Quantification
This study by A.A. Sonzogni and E.A. McCutchan focuses on developing cumulative fission yield covariances for uncertainty quantification in nuclear reactors. The research involves calculating cumulative fission yields, using decay data and nuclear databases, to improve accuracy in predicting fission observables and related quantities. Correlations among cumulative fission yields are found to be essential for more realistic uncertainty assessments in nuclear reactions.
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Development of Cumulative Fission Yield Covariances for Uncertainty Quantification A.A. Sonzogni, E.A. McCutchan National Nuclear Data Center A.A. Sonzogni WANDA 2020
Cumulative fission yields In a reactor, the fission products form a decay network satisfying dNi / dt = - i Ni + r IFYi + k pki Nk, Decay probability from k to I product ln(2)/T1/2i Independent fission yield Fission rate Under equilibrium, that is dNi / dt = 0, then Ni= r CFYi / i A.A. Sonzogni WANDA 2020
Summation Method Using nuclear databases, the IBD antineutrino yield under equilibrium conditions can be calculated as Unfortunately, the fission yield databases don t contain any correlation data. The GEF1 code will be used to obtain Y(Z,A) correlations, which will be converted to Y(Z,A,FPS) correlations, and then using decay data, we will obtain Cor(Ci,Cj) 1 "General Description of Fission Observables: GEF Model Code", K.-H. Schmidt, B. Jurado, C. Amouroux, C. Schmitt, Nucl. Data Sheets 131, 107 (2016). A.A. Sonzogni WANDA 2020
Summation Method Using ENDF/B-VIII.0 decay data, we can calculate cumulative yield correlations: Ci = Ii + bik Ik, where bik are decay probabilities and Ik are independent yields. For instance, C(92Rb) = I(92Rb) + I(92Kr)+ 0.0195 xI(93Kr) + 0.67xI(92Br) + 0.68xI(93Br) A.A. Sonzogni WANDA 2020
Summation Method Yield results (10-43 cm2) using ENDF/B-VIII.0 decay data, JEFF-3.3 yields and GEF IFY correlations. Sum. Yield Sum. yield No Corrs. Nucleus Summation Yield 235U 6.37 2.58% 1.76% 238U 9.69 2.51% 2.04% 239Pu 4.39 3.19% 2.08% 241Pu 6.25 3.27% 2.36% Conclusion: summation calculations must include correlations among Cumulative Fission Yields! We have also obtained more realistic uncertainties in other quantities, such as decay heat, delayed neutrons and energy release following fission A.A. Sonzogni WANDA 2020
