In-situ nuclear measurement for decommissioning: recent trends and needs

摘要

On-site nuclear measurements are indispensable at various stages of decommissioningprojects. This paper will firstly describe the trends that can be drawn up from recent experience in France. Atechnical description of recently developed measurements techniques will be reported, as well as lessons learnedthrough in-situ operations. This mainly includes gamma imaging, gamma spectrometry and calculation codes:Calculation codes are increasingly used in association with nuclear measurements. The paper will summarisehow they are generally operated, as well as recent trends in this area. Gamma imaging techniques have beenoperated for almost 10 years in many french decommissioning projects. Typical operations in various plants willbe described, as well as the main outcomes which can be expected from this technology. Regarding gammaspectrometry, the paper will firstly discuss compact CdZnTe probes, which usually fit with decommissioningrequirements, especially in highly irradiating conditions. Recent achievements in this area will be reported. Lowlevel measurements of concrete structures with high resolution gamma spectrometry will also be assessed. Theseitems will be illustrated by various examples of recent operations: final control of buildings, radiologicalcharacterisation of cells, components or vessels in different kinds of shutdown facilities, such as reactors,reprocessing plants and waste storage area. Limitations as well as improvement possibilities will be addressed aswell. The last part of the paper will focus on technical needs that might be identified in this field.