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Due to the large variations of chemical compositions in electronic material, the estimation of the radionuclide inventory following irradiation represents a technical challenge at CERN high-energy particle accelerators. In particular, the activation of printed circuit boards is of concern to the CERN experiments as they are widely used for various purposes ranging from safety systems to sub-detector controls. Because of maintenance operations, part of this equipment has to be removed from the accelerator machines. The literature provides a variety of compositions for electronic materials, leaving the problematic selection of the most appropriate composition for an activation study to the reader. In this article, we discuss two reference chemical compositions on the basis of a statistical analysis of large datasets of gamma spectroscopy results, and on ActiWiz calculations which take into account different activation scenarios at CERN. These results can be extended to electronic material irradiated in other particle accelerators.

In the frame of maintenance, upgrade and dismantling activities, activated equipment are removed from the accelerator complex and require characterization in view of their disposal as radioactive waste. The characterization process consists of a series of radiation measurements, complemented by analytical studies, which quantify the activity of radionuclides inside an object. A fraction of the radioactive waste produced at CERN presents contact dose-rates higher than 100 μSv/h, and can therefore be classified as LILW Waste (“Low and intermediate level radioactive waste”). These objects, due to the activation mechanisms, are often subject to large activity heterogeneities. The quantification of gamma-emitting radionuclides is typically performed by gamma spectrometry, under the assumption of homogeneous distributions of activity within an object. However, this assumption can lead to underestimating the activity value of such radionuclides. In this article we perform a gamma spectrometry qualification in order to quantify the impact of assuming homogenous distribution.

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.

The operation of particle accelerators at CERN requires the use of electromagnets, which are accelerator components used to guide and focus charged particles. In the framework of maintenance activities and machine upgrades or dismantling, a large number of magnets are removed from the accelerator complex and required characterization in view of their disposal as radioactive waste. The present document describes a new characterization methodology, which is applied to radioactive magnets with masses up to 25 tons and lengths up to 6 meters. The characterization of such large electromagnets is challenging due to their heterogeneous composition, variable radiological history, technical constraints related to handling, and the operational complexity of evaluating activity values with gamma spectroscopy . The innovative method proposed in this paper is based on the establishment of transfer functions which convert dose-rate to a radionuclide inventory. This method is validated by comparison with accurate gamma spectroscopy and benchmarking.

The elimination of very low level waste towards the French national repository requires their radiological characterization to estimate the radionuclide inventory and the associated activities within a waste package. Such characterization is performed by means of activation calculations and measurements. Two elimination projects have been identified at CERN, to dispose of bulk metallic waste and cables activated in the CERN accelerator complex. Based on the experience gained over the last 4 years, we develop a large scale elimination process to dispose of such types of activated equipment. A program for quality controls has therefore been developed through a novel software tool whose purpose is to compute the radiological data required by the repository for the acceptance of the waste as well as performing quality controls.

In the framework of maintenance activities in particle accelerators, such as upgrades and dismantling, a large number of activated equipment are removed from the accelerator complex and require characterization in view of their disposal as radioactive waste. In particular, cables can be of different types. This feature induces variations of the efficiency calibration curves due to the variation of the material composition, source distribution and density. Hence, quantifying the activities of the gamma-emitting radionuclides can be quite challenging for mixed cables. In this article, we propose a new qualification methodology, based on gamma spectrometry, in order to assess the activity results uncertainties of gamma-emitting radionuclides. This new methodology is developed to define the envelop efficiency calibration curves and allows for the establishment of more accurate activity values with their corresponding uncertainties.

The gamma spectroscopy technique is commonly used in many applications to evaluate the activity of gamma emitters in a given sample. This assessment of activity is of particular interest for the disposal of radioactive waste or for clearance purposes. However, for these specific applications, one needs to show that the evaluated activities are reasonably conservative. This paper shows an application of a methodology developed to quantify the efficiency calibration curve uncertainties originating from a test case sample and its associated geometry modelling. Therefore, the effects of enclosing geometries on the activity measurement results are discussed. The purpose is to provide an example of uncertainty analysis for an approach that could be applied to other studies in which a conservative estimation of the activity is required.