APPLICATION OF SENSITIVITY ANALYSIS TO A SIMPLIFIED COUPLED NEUTRONIC THERMAL-HYDRAULICS TRANSIENT IN A FAST REACTOR USING ADJOINT TECHNIQUES

In this paper a method to perform sensitivity analysis for a simplified multi-physics problem is presented. The method is based on the Adjoint Sensitivity Analysis Procedure which is used to apply first order perturbation theory to linear and nonlinear problems using adjoint techniques. The multi-physics problem considered includes a neutronic, a thermo-kinetics, and a thermal-hydraulics part and it is used to model the time dependent behavior of a sodium cooled fast reactor. The adjoint procedure is applied to calculate the sensitivity coefficients with respect to the kinetic parameters of the problem for two reference transients using two different model responses, the results obtained are then compared with the values given by a direct sampling of the forward nonlinear problem. Our first results show that, thanks to modern numerical techniques, the procedure is rela-tively easy to implement and provides good estimation for most perturbations, making the method appealing for more detailed problems. Key Words: Uncertainty Analysis, ASAP, multi-physics problems 1