Abstract
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.
Highlights
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
Easy-To-Measure nuclides (ETM) (IAEA Nuclear Energy Series) are radionuclides which can be measured via non-destructive assay techniques
Examples of ETM radionuclides are Co-60 or Na-22. These radionuclides have typi cally a Minimum Detectable Activity (MDA) which is below the ANDRA declaration thresholds for the counting times considered in the charac terization process of LILW waste
Summary
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. In view of the elimination of LILW waste in the French national re pository (ANDRA1), radiological characterization has to be performed in order to comply with ANDRA’s acceptance criteria (ANDRA, 2018). These criteria require the estimation of the radiotoxicity levels, based on the radionuclide inventory. The radiological characterization of LILW waste has the purpose to establish the radionuclide inventory and the associated activity values of the candidate waste items (Zaffora et al, 2019; IAEA, 2009; ISO 21238, 2007; Zaffora, 2017). This document describes the qualification of a measurement calibration of LILW waste Due to their specific activation mechanisms in accelerator machines, LILW waste can have heterogeneous activation patterns.
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