Radiation source terms of MYRRHA reactor components and equipment

• MYRRHA the ex-core components and equipment (reactor vessel internal components excluding the reactor core structure) have been modelled by numerous stainless steel samples uniformly distributed inside the vessel.
• Prompt and residual activation, heating, radiation dose and radiation damage were calculated for ex-core equipment and components located inside the reactor vessel.
• The activation calculations were carried out with the ALEPH2 depletion code which invokes the general purpose radiation transport code MCNPX 2.7.0 for the calculation of neutron fluxes and spectra in the activated materials.

In-vessel structural components of nuclear reactors are subject to prompt and residual neutron and photon activation. The MYRRHA fast spectrum facility, when operated in sub-critical mode, suffers additional activation due to a wide range of energetic particles produced in the interactions of 600 MeV-primary protons with matter. The purpose of this work was to assess the source term (activation, heating and induced radiation level) of ex-core equipment and components located inside the reactor vessel. Numerous stainless steel samples uniformly distributed inside the vessel have been used to simulate the activation of equipment in order to take into account the perturbation of the neutron spectrum caused by structural materials of components and equipment. The calculated quantities were prompt and residual activation, heating, radiation dose and radiation damage. The calculations were carried out with the ALEPH2 depletion code which invokes the MCNPX code for radiation transport.