Radiation Protection at the Large Hadron Collider: Problematics, Challenges and Advanced Monte Carlo Simulation Techniques

This paper provides an overview of the problems, challenges, and the advanced simulation techniques used to study and plan complex interventions in radiation areas at CERNs Large Hadron Collider and its future upgrade to the High-Luminosity Large Hadron Collider. The operational radiation protection aspects are supported by state of the art simulations by means of the FLUKA Monte Carlo code and estimates conducted via other tools such as ActiWiz and SESAME, used within the HSE-RP group

In-situ radiological classification and characterization methodology of activated cables in particle accelerators

The estimation of induced radioactivity and radiological classification of activated material is necessary throughout the life cycle of the Large Hadron Collider (LHC) accelerator. As part of the upgrade to HighLuminosity LHC (HL-LHC), radiation protection assessments need to be performed in order to estimate the radiological hazard during the dismantling activities of the LHC cables. The proposed In-situ radiological classification and characterization of the activated cables relies on validated FLUKA.CERN Monte Carlo simulations and analytical computations. The objective is to establish a methodology that allows clearing the material from regulatory control according to the Swiss Radiation Protection Legislation using the total gamma counting (TGC) analysis technique for an envelope set of activation scenarios. The study also includes a preliminary benchmark of the FLUKA geometry model and physics models based on gamma spectrometry laboratory analyses of representative samples

Radiological characterization for the disposal of a decommissioned LHC external beam dump at CERN

During the last Long Shutdown, a scheduled maintenance period between physics runs, the two Large Hadron Collider (LHC) beam dumps were replaced with upgraded spares modules. It was then decided to conduct an in-house autopsy and a post-irradiation examination of the removed dumps to extract information essential for the 3rd LHC physics run and to aid the design of new generations of beam dumps able to cope with future upgrades of the LHC. The need for a postmortem analysis of the dump cores opened the opportunity to combine the autopsy with processes required for the disposal of the dumps as radioactive waste at a dedicated disposal facility in France. This had a direct impact in terms of overall optimization of the interventions (postmortem analysis and prepackaging) to be performed on the dump as well as in terms of minimizing of the radiological risk (ALARA), by reducing the exposure of the personnel by combining two interventions in one. The characterization of the dump as radioactive waste was performed by means of state-of-the-art Monte Carlo and analytical techniques verified experimentally via a series of dedicated radiochemical (using liquid scintillation) analyses, conducted in-house and in external specialized laboratories. Based on these results, the dumps will be disposed of as intermediate–medium-level (FMA-VC) waste at the ANDRA CSA repository in France

PRACTICAL CHALLENGES OF THE LHC MAIN BEAM DUMP UPGRADES

The two Large Hadron Collider (LHC) beam dumps have to withstand arduous operating conditions and are essential for the safe and reliable operation of the collider. During the LHC Long Shutdown 2 (2019-2020), extensive work was carried out to upgrade the dumps to cope with the more demanding future operating conditions of the LHC Run 3. The upgrades included modifications to the dump blocks, dump block supports and their lubrication, beam windows, the beam pipes leading to the dumps, and the nitrogen pressurisation system of the dump blocks. A comprehensive instrumentation system was installed to monitor the behaviour of the dumps. In addition, an internal endoscope inspection was performed on the ex-operational dumps to check their condition. Many of these operations had to be carried out in underground radiation areas, therefore the optimization of the dose-to-personnel according to the ALARA principle was an important consideration. The return on experience for these activities will be provided, including the critical tasks, unexpected events and lessons learnt