Sensitivities of the proton beam current resulting from variations in the source term for a Pb–Bi cooled accelerator driven system with a Pb–Bi Target

Numerical simulations of a subcritical reactor coupled to a neutron spallation source, 600 MeV protons impinging on a Pb–Bi target, have been performed using the deterministic code system ERANOS. The investigations are focussed on the sensitivity of the subcriticality parameters resulting from variations in the external source term, the same neutron yield per source proton being assumed in each calculation. The analysis is performed using a detailed three-dimensional model representative of the experimental accelerator driven system being designed by Ansaldo. The reactor is based on a pool-type liquid metal fast critical reactor with a thermal output of about 80 MW and has been currently considered with the option of using existing Superphénix MOX fuel (Ansaldo Nucleare, 2001. XADS Pb–Bi cooled eperimental accelerator driven system reference configuration, Summary Report by Division of Ansaldo Energia SpA, ADS 1 SIFX 0500, Rev. 0, June 2001.). In the paper, it is highlighted that for such Pb–Bi cooled systems the proton beam current required in order to obtain the foreseen operational power level is not significantly sensitive to the source characteristics. Clearly, this result is hoped to facilitate the further overall optimisation of the Ansaldo design.