Nuclear data uncertainty propagation analysis for LWR depletion calculation

In order to assess the uncertainties induced by nuclear cross sections in the depletion calculation, a computational code named SUNDEW has been developed based on the home-developed lattice code CACTI. In the SUNDEW, Generalized Perturbation Theory (GPT) is applied to calculate sensitivity coefficient of response functions with respect to the nuclear cross sections. Method of Characteristic (MOC) is employed to solve the transport equation, adjoint and generalized adjoint transport equation. Chebyshev Rational Approximation Method (CRAM) is implemented to solve the depletion equation and adjoint depletion equation. The sensitivity coefficients of K_effand nuclide density with respect to the nuclear cross sections are verified by comparing with the calculation results of direct perturbation calculation (DP). The uncertainties of AT_eff and number density are analyzed for the PWR burn-up pin-cell benchmark proposed by the NEA/OECD. The numerical results with ENDF/B-VII.1 covariance data are compared with those from JENDL4.0 covariance data, which reveal that the uncertainties assessment and the source of covariance data have a strong relationship. In addition, to identify the cross section improvement priority for nuclide, reaction and energy range, the dominant contributors of the K_eff and number density uncertainties are analyzed in different depletions.