Adjoint Sensitivity Analysis of the RELAP5/MOD3.2 Two-Fluid Thermal-Hydraulic Code System—I: Theory

This work presents the implementation of the Adjoint Sensitivity Analysis Procedure for the nonequilibrium, nonhomogeneous two-fluid model, including boron concentration and noncondensable gases, of the RELAP5/MOD3.2 code. The end product of this implementation is the Adjoint Sensitivity Model (ASM-REL/TF), which is derived for both the differential and discretized equations underlying the two-fluid model. The consistency requirements between these two representations are also highlighted.