Accuracy assessment of a new Monte Carlo based burnup computer code

This study aims to test for the suitability and accuracy of a new home-made Monte Carlo burnup code, called BUCAL1, by investigating and predicting the neutronic behavior of a “VVER-1000 LEU Assembly Computational Benchmark”, at lattice level. BUCAL1 uses MCNP tally information directly in the computation; this approach allows performing straightforward and accurate calculation without having to use the calculated group fluxes to perform transmutation analysis in a separate code. ENDF/B-VII evaluated nuclear data library was used in these calculations. Processing of the data library is performed using recent updates of NJOY99 system. Code to code comparisons with the reported Nuclear OECD/NEA results are presented and analyzed.

► A new burnup code called BUCAL1 was developed.
► BUCAL1 uses the MCNP tallies directly in the calculation of the isotopic inventories.
► Validation of BUCAL1 was done by code to code comparison using VVER-1000 LEU Benchmark Assembly.
► Differences from BM value were found to be ± 600 pcm for k∞ and ±6% for the isotopic compositions.
► The effect on reactivity due to the burnup of Gd isotopes is well reproduced by BUCAL1.