In-toto non-destructive assay methodology for the elimination of metallic waste from particle accelerators after melting.

Melting of metallic waste reduces the waste volume, allows more accurate radiological characterization, and minimizes handling at the waste production site. This paper proposes a new non-destructive assay methodology to radiologically characterize low- and intermediate-level (LILW) waste before melting. A non-destructive assay technique is developed and qualified using geometry optimization technique and sample analysis after melting. Additionally, we present an operational methodology to predict the activity values of the major gamma emitters based on the average dose rate measurements.

Radiation protection challenges in the upgrade, autopsy and disposal of the LHC beam dump.

The upgrade of the Large Hadron Collider spare beam dumps (Target Dump External, TDE) and the autopsy of the old operational TDE required to perform several activities in a high-radiation environment posing significant radiation protection challenges due to the residual activation of the equipment. To ensure high safety standards and to respect the ALARA principle, these challenges were addressed using the advanced Monte Carlo techniques to predict the residual ambient dose equivalent rate and the radionuclide inventory at different steps of the interventions. The CERN HSE-RP group makes extensive use of the FLUKA and ActiWiz codes to produce accurate estimates. This work aims to provide an overview of the radiation protection studies to optimise the interventions (ALARA) and to reduce the radiological risk for personnel and environment.

Radiological characterisation for the clearance of burnable waste produced at CERN.

Burnable waste produced at CERN during upgrading, maintenance and dismantling campaigns may be contaminated with radioactive nuclides produced through activation of accelerator components. Here, we present a methodology for the radiological characterisation of burnable waste, which takes into account the wide range of potential activation conditions (beam energy, material composition, location, irradiation and waiting time). Waste packages are measured using a total gamma counter, with the sum of clearance limit fractions estimated using the fingerprint method. Gamma spectroscopy was found to be unsuitable for classifying this waste due to the long counting times required to identify many expected nuclides, but was retained for quality control purposes. Using this methodology, a pilot campaign was performed in which we were able to clear 13 m3 of burnable waste as conventional non-radioactive waste.

Classification of radiological objects at the exit of accelerators with a dose-rate constraint.

Maintenance activities and operations of high-energy particle accelerators can lead to the collection of radioactive equipment as well as waste materials. In order to ensure their proper classification as radioactive or non-radioactive, one has to quantify the activities of radionuclides produced. According to the regulatory requirements in Switzerland, these activities need to be compared with nuclide-specific clearance limits. In particular, a new set of clearance limits was introduced by the Swiss authorities in January 2018, leading to more conservative values for a number of relevant radionuclides. We describe in this paper a new methodology based on dose-rate measurements to classify potentially radioactive objects at the exit of the CERN accelerator complex. This methodology concerns the specific material compositions typically found at CERN and takes into account the latest clearance limits introduced by the Swiss authorities.

INTEGRATED OPERATIONAL DOSIMETRY SYSTEM AT CERN.

CERN, the European Organization for Nuclear Research, upgraded its operational dosimetry system in March 2013 to be prepared for the first Long Shutdown of CERN's facilities. The new system allows the immediate and automatic checking and recording of the dosimetry data before and after interventions in radiation areas. To facilitate the analysis of the data in context of CERN's approach to As Low As Reasonably Achievable (ALARA), this new system is interfaced to the Intervention Management Planning and Coordination Tool (IMPACT). IMPACT is a web-based application widely used in all CERN's accelerators and their associated technical infrastructures for the planning, the coordination and the approval of interventions (work permit principle). The coupling of the operational dosimetry database with the IMPACT repository allows a direct and almost immediate comparison of the actual dose with the estimations, in addition to enabling the configuration of alarm levels in the dosemeter in function of the intervention to be performed.