The perspectives of accelerator driven subcritical reactors (ADSR) can be not only a solution for the problem of nuclear waste, but also an efficient source of energy. A core with low enrichment, optimal keff 0.985-0.988 maintained during exploitation with control rods, the use of light ion beams, especially ⁷Li and ⁹Be at low energy (0.25-0.3 GeV/n) are optimal.

The LETASUR (LEad Target for the study of Accelerator driven SUbcritical Reactors) target is dedicated to the comparative study of the energy efficiency of proton and ion beams used to drive a subcritical core. A lead block with dimensions 80x80x150 cm, surrounded by a steel blanket with thickness 10 cm is used as substitute for the lead-bismuth coolant. The target has a central hole with radius 10 cm, length 120 cm for the placement of the converter, and horizontal and vertical holes with radius 1.5 cm at 4 radii (15, 20, 25 and 30 cm) for detectors. Converters from Be and Pb with total length 110 cm are placed in the central hole, ensuring a beam window with length 10 cm, and holes with length 150 cm in horizontal and vertical directions, at different radii for the placement of the detectors.

Proton beams with energies in the range 0.5-2 GeV and ion beams with masses until 12C and energies from 0.25 to 0.75 GeV/n will be tested. The fission distribution obtained in foils of natural and enriched uranium is analysed. Expected results predicted by GEANT4 and MCNP simulation codes for different beams and converter materials are presented.