actinide fuel NEUTRONIC AND SAFETY ASPECTS OF

We have designed a gas-cooled accelerator-driven system dedicated to transmutation of minor actinides. Thanks to the excellent neutron economy of the uranium-free fuel employed, the pin pitch to diameter ratio (P/D) could be increased to 1.8. The increased coolant fraction allows for decay heat removal at ambient pressure. The large coolant fraction further results in a low pressure loss—26 kPa over the core, 35 kPa in total. Thanks to the large P/D, the elevation of the heat exchanger necessary to remove decay heat by natural circulation is just more than 1 m. The absence of uranium in conjunction with the presence of 35 % (heavy atom) americium in the fuel re-sults in a low effective delayed neutron fraction and a vanishing Doppler feedback, making subcritical opera-tion mandatory. I