Neutron data for accelerator driven systems

Different types of accelerator driven systems (ADS) for transmutation of nuclear waste have been proposed. The most promising one is based on a liquid Pb-Bi spallation target. The main components to be investigated are the spallation target, the target-core interface, the core, moderator and coolant, the support structure and shielding.

Characteristic for this system is that the target and the target-core interface, the core and the support structures close to the target are subjected to neutrons of high energies. Energies up to several GeV are possible, the highest energies hitting the target and target support area. Just outside the target area the neutron energies range up to a few tens of MeV, whereas at larger distances from the target the neutron spectrum approaches that of a conventional fast (or thermal) reactor.

IRMM carries out measurements in the energy range up to 20 MeV. For a complex system like an ADS, many cross-sections and reaction parameters are important. The total, capture, elastic and inelastic scattering, and fission cross sections as well as light charged particle production cross-sections (e.g. for hydrogen and helium emission) relevant for damage of structural materials are also of relevance to an ADS.

At IRMM total and capture cross-sections have been measured in the resolved resonance region for ²³²Th, ^207,208Pb, ²⁰⁹Bi and ^235,238U. A new experiment on ²⁰⁶Pb is on-going. Inelastic neutron scattering cross-sections have been measured at IRMM for ²³Na, ²⁷Al, ⁵²Cr, ⁵⁶Fe, ⁵⁸ Ni, ²⁰⁷Pb and ²³⁸U. Also (n,2n) reactions have been measured at GELINA.