Aspects of target optimization for ADS with light ion beams at energies below 0.5 AGeV

• DOI: 10.1016/j.pnucene.2019.103221
• Publication Date: 2019-12-23T20:42:19Z
• Authors: M. Paraipan; V.M. Javadova; S.I. Tyutyunnikov
• Keywords: 03 medical and health sciences; 0302 clinical medicine; 7. Clean energy

Abstract A comparative study about the energy efficiency of proton and light ion beams used for energy production in accelerator driven systems (ADS) is performed. The energy gain G, defined as the ratio of the energy produced to the energy spent to accelerate the beam is used as measure for the energy efficiency. The energy released in the target is obtained through simulation with the code Geant4, and the spent energy is calculated by scaling from the data about the accelerator efficiency for a reference particle. An optimal proton energy of 1.5 GeV is revealed, when the beam is accelerated in a linac. The advantage of light ion beams, especially 7Li at energies below 0.5 AGeV, which allows a reduction of the accelerator length, is substantiated. A study about the target design and the choice of the converter meant to maximize the efficiency of the energy ADS irradiated with light ion beams (7Li) with energies in the range 0.25–0.5 AGeV is presented. The influence of the fuel composition, of the geometry of the target, of the coolant and the converter materials are investigated. The most significant influence on the energy released has the material used for the converter. Cylindrical converters from various materials, from very light (Li, Be) to very heavy (W, Pb, U) are analyzed. The influence of the dimensions of the converter on the energy released in the target is studied and the conditions which maximize the energetic efficiency and ensure a high level of burning of the actinides are determined. Solid fuel with different compositions (metal, oxide, carbide) and liquid fuel (molten salt) are considered. The advantage of a target with beryllium converter for both proton and lithium beams is underlined. The use of a Be converter with length 100–120 cm makes a beam of 7Li with the energy 0.25AGeV (in solid fuel) and 0.275 AGeV (in liquid fuel) equivalent from the point of view of the net power produced with a beam of 1.5 GeV proton, and allow the building of an accelerator 2.2–2.6 times shorter. A comparison between the evolution of the fuel composition during irradiation and its influence on the period of operation without refueling for target with LBE and Be converters is realized. The Be converter allows also to achieve a higher level of burning of the actinides and consequently a larger period between refueling.