Comparison between HELIOS calculations and a PWR cell benchmark for actinides transmutation

This paper shows a comparison between the results obtained with the HELIOS code and other similar codes used in the international community, with respect to the transmutation of actinides. To do this, the international benchmark: “Calculations of Different Transmutation Concepts” of the Nuclear Energy Agency is analyzed. In this benchmark, two types of cells are analyzed: a small cell corresponding to a standard pressurized water reactor (PWR), and a wide cell corresponding to a highly moderated PWR. Two types of discharge burnup are considered: 33 GWd/tHM and 50 GWd/tHM. The following results are analyzed: the neutron multiplication factor as a function of burnup, the atomic density of the principal actinide isotopes, the radioactivity of selected actinides at reactor shutdown and cooling times from 7 until 50,000 years, the void reactivity and the Doppler reactivity. The results are compared with the following codes: KAPROS/KARBUS (FZK, Germany), SRAC95 (JAERI, Japan), TRIFON (ITTEP, Russian Federation) and WIMS (IPPE, Russian Federation). For the neutron multiplication factor, the results obtained with HELIOS show a difference of around 1% δk/k. For the isotopic concentrations: 241Pu, 242Pu, and 242mAm, the results of all the institutions present a difference that increases at higher burnup; for the case of 237Np, the results of FZK diverges from the other results as the burnup increases. Regarding the activity, the difference of the results is acceptable, except for the case of 241Pu. For the Doppler coefficient, the results are acceptable, except for the cells with high moderation. In the case of the void coefficient, the difference of the results increases at higher void fractions, being the highest at 95%. In summary, for the PWR benchmark, the results obtained with HELIOS agree reasonably well within the limits of the multiple plutonium recycling established by the NEA working party on plutonium fuels and innovative fuel cycles (WPPR).