Uncertainties on radiation source terms of MINERVA (MYRRHA Phase 1) beam dump

Abstract

In the framework of Phase I of the MYRRHA project implementation, the superconducting linear accelerator with proton beam parameters 100 MeV, 4 mA is going to be built. To stop the beam, a beam dump based on Al-6061 alloy is designed. The evaluation of radiological impact of an accidental radioactivity release requires the reliable estimates of primary radiation source terms with associated uncertainties. The article addresses the propagation of nuclear data uncertainties through beam dump activation calculations. The Total Monte Carlo approach was used to generate large number of random excitation functions for residual products of proton interactions with materials of Al-6061 alloy. The residual products do not impose any feedback on proton and neutron spectra in the beam dump, moreover the calculation of the production rates is sufficient to obtain uncertainties on final activities. This significantly accelerates the uncertainty quantification allowing to study the convergence of mean and higher moments (variance, variance of variance) for individual nuclides.