A new methodology to obtain the 1D cross-sections for TRAC-BF1 code. Application to Peach Bottom NPP

摘要

In TRAC-BF1 the cross-sections are specified in the input deck in a polynomial form. Therefore, it is necessary to obtain the coefficients of this polynomial expansion. One of the methods proposed in the literature is the KJNPAR methodology. This methodology uses the resultsfrom different perturbations of the original state to obtain the coefficients of the polynomial expansion. The simulations are performed using the SIMULATES code. In this work, a new methodology to obtain the cross-sections sets in ID is presented. The first step consists of the application of the SIMTAB methodology, developed in UPV, to obtain the 3D cross-sections setsfrom CASMO4/SIMULATE3. These 3D cross-sections sets are collapsed to ID using as aweighting factor, the 3D thermal and rapid neutron fluxes obtained from SIMULATE3.With this new methodology it is not necessary to perform simulations of different perturbations ofthe original state, and also the variation range of the moderator density can be higher than usingthe KJNPAR methodology. This is important for the simulation of severe accidents in which thevariables vary in a wide range.This new methodology is applied to the simulation of the turbine trip transient in Peach BottomNPP using the TRAC-BFI code. The results of the steady state in TRAC-BF1 using the KJNPARmethodology and the new methodology are compared with the reference SIMULATE3 results.