Extension and validation of the TRANSURANUS burn-up model for helium production in high burn-up LWR fuels

The TRANSURANUS burn-up model (TUBRNP) calculates the local concentration of the actinides, the main fission products, and (4)He as a function of the radial position across a fuel rod. In this paper, the improvements in the helium production model as well as the extensions in the simulation of (238-242)Pu, (241)Am. (243)Am and (242-245)Cm isotopes are described. Experimental data used for the extended validation include new EPMA measurements of the local concentrations of Nd and Pu and recent SIMS measurements of the radial distributions of Pu, Am and Cm isotopes, both in a 3.5% enriched commercial PWR UO(2) fuel with a burn-up of 80 and 65 MWd/kgHM, respectively. Good agreement has been found between TUBRNP and the experimental data. The analysis has been complemented by detailed neutron transport calculations (VESTA code), and also revealed the need to update the branching ratio for the (241)Am(n,gamma)(242m)Am, reaction in typical PWR conditions. (C) 2011 Elsevier B.V. All rights reserved.