Optimal ion beam, target type and size for accelerator driven systems: Implications to the associated accelerator power

摘要

In interactions of different energetic ions with extended targets hydrogen isotopes are the most effective projectiles for the production of spallation neutrons. It is shown that for every target material and incident ion type and energy there is an optimal target size which results in the escape of a maximum number of spallation neutrons from the target. Calculations show that in an ADS, combination of a beam of 1.5 GeV deuteron projectiles and a uranium target results in the highest neutron production rate and therefore highest energy gain. For fast 1.5 GeV d + ~(238)U ADS with lead or lead-bismuth eutectic moderator, the required ion beam current is only 38% of that for 1 GeV proton projectiles on lead target. It is shown that for a modular ADS with uranium target and output power of 550 MW_(th) a 1.5 GeV deuteron beam of current 1.8 mA is required, which is easily achievable with today's technology. For an ADS with K_(eff) 0.98 and output power of 2.2 GW_(th), the required beam currents for (a) 1 GeV p + Pb and (b) 1.5 GeV d + U systems are 18.5 and 7.1 mA, respectively. 【keyworks】Accelerator driven systems;Energy gain;Target types;Optimal target size;ADS power;MCNPX code