Radiological clearance of equipment from high-energy electron accelerators: The example of LEP superconducting acceleration system

The lifespan of a particle accelerator includes its final decommissioning and the disposal of potentially activated materials, one of the major challenges faced at accelerator laboratories. This paper discusses the computational and experimental techniques adopted for clearing from regulatory control the superconducting acceleration system of the former CERN Large Electron Positron collider (LEP), consisting of nearly 450 tons of valuable metals. The paper first briefly recalls the major sources of activation at high-energy electron accelerators and then discusses the general process, the computational tools employed, the methods to determine the amount of radionuclides that cannot be measured by γ -spectrometry, the selection of samples representative of the whole equipment and the outcome of the operational phase. The process ended up with the clearance of 95% of the material. The aim of this work is to provide a practical example of an approach that could be applicable to similar projects targeting radiological clearance of high-energy particle accelerator equipment.