Radiological Zoning and Clearance Methodology of activated cables in the LHC accelerator at CERN

In the context of upgrading the Large Hadron Collider (LHC) to its High-Luminosity (HL-LHC) configuration, it is essential to conduct a thorough zoning classification and characterization of activated cables within the particle accelerator. To address this need, a methodology was developed to identify regions where materials can be cleared from regulatory control in compliance with the Swiss Radiation Protection Legislation. The study begins with optimizing the elemental composition of cables and validating Monte Carlo FLUKA simulations using high-energy resolution gamma spectrometry (GS) and total gamma counting (TGC) measurements on 19 copper cable samples, collected during the winter shutdown 2023/2024. This methodology enables performing radiological zoning and accurately defines the radiological classification of the cables installed in the LHC Points 1 and 5, including both the accelerator tunnel and service galleries, prior to dismantling. Finally, the study proposes a conservative scaling factor for cable zoning and introduces a TGC figure of merit (FOM), representing a conservative activation scenario for the copper cable types.