The intensive exploitation of multi-particle accelerators – more specifically medical cyclotrons – leads to activation of systems, structures and components (SSC) involving considerable future decommissioning costs for both industrial companies and universities/hospitals. Material evacuation routes are comparable to those for industrial nuclear installations such as nuclear power reactors, e.g. reuse, conditional and unconditional release in some cases after melting and disposal as radioactive waste. The elimination of an SSC item according to a specific route requires the knowledge of the radionuclide inventory to prove accordance with radiological acceptance criteria, and therefore of the induced activation source term. However, the inventory and the specific activities of the radionuclides found in the irradiated materials of accelerators differ considerably from those found in nuclear reactors because the activation mechanisms and activating particles are generally different.
Today, preliminary assessment of the radiological inventory is mainly supported by sampling and analysis, a costly and labour-intensive approach subjected to several uncertainties among which the heterogenous activation of SCC, the potential presence of difficult to measure pure β- emitters and the extrapolation to larger volume/mass. Moreover, in the framework of making provisions for future decommissioning of new installations, this partly destructive approach is useless for newly installed cyclotrons for which the activation level is limited at the start of the exploitation.
This means that relying solely on a sampling approach can lead to unexpected delays and costs. Past years some initiatives [2,3] were taken to use Monte Carlo tools to characterise particle transport and neutron fluxes in the framework of shielding design, but long-term activation of SSC materials was poorly addressed. For this reason, the need for a reliable methodology based on computational tools and validated by nuclide-specific measurements should be studied.
 IAEA Safety Report Series No.95, Methodologies for Assessing the Induced Activation Source Term for Use in Decommissioning Applications, 2019.
 Brad D.Jeffries et al. Characterization of the neutron flux during production of 18F at a medical cyclotron and evaluation of the incidental neutron spectrum for neutron damage studies. Applied Radiation and Isotopes (154), 2019.
 D.Alloni et al. Characterisation of the secondary neutron field generated by a compact PET cyclotron with MCNP6 and experimental measurements. Applied Radiation and Isotopes (128), 2017.