Abstract:

A synthesis of the research developed in the frame of E&T collaboration aimed to identify the conditions which maximise the efficiency of an accelerator driven subcritical reactor (ADSR) are presented. Experiments performed in the extended U target “Quinta” irradiated with deuteron and ¹²C beams with energies 0.5-4 AGeV and simulations realised with the toolkit Geant4 in enriched targets were meant to find on one hand, the optimal beam and energy for ADSR, and on the other hand, the core characteristics that maximise the energy gain G and the actinides incineration. Aspects related with the core geometry, the optimal value of the criticality coefficient k_eff, the material used for the converter, the enrichment were analysed. A core with k_eff 0.985-0.988, Be converter and low enrichment ensure deep actinides burning during a cycle (20-25 % from the initial actinides mass). The optimal proton energy is in the range 1-1.5 GeV, depending on the accelerator type (linear accelerator or cyclotron) with G values 12-14. Ion beams starting with ⁷Li realise significantly higher G, from 20-25 for 0.25 AGeV ⁷Li to 35-45 for ¹⁶O and ²⁰Ne with energy 0.75-1 AGeV. The influence of the fuel type on the ADSR performance was also, analysed. Metallic, oxide and nitride fuels with various enrichment distributions were taken into account. The use of nitride fuel is preferable in ADSR because allows to accommodate high power densities.