Simulation of irradiation history in combined annular multi-tube fuel element of BR2

The impact of strong non-uniformity of neutron fluxes in the Belgian High Flux Materials Testing Reactor BR2 on the spatial distributions of the fuel burn-up and heat fluxes in complex annular fuel elements and on the irradiation conditions in various experiments performed in BR2 is discussed in the paper. The purpose was to develop a calculation approach for predicting 3-D fuel burn-up in multi-tube annular fuel elements. In the method presented here the spatial 3-D distribution of the fuel burn-up in plates of the multi-tube fuel element is calculated using the 3-D distributions of the power peaking factor calculated in the registration mesh using the MCNP code linked with the burn-up module ORIGEN-S in the SCALE code. The presented approach permits to predict effectively the dependence of the fuel burn-up distribution in the fuel plates versus their position inside the core and versus their azimuth orientation. (author)