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INSIDER is an EU Horizon 2020 research project, within the topic NFRP-7 of the EURATOM programme, that aims to develop and validate a new and improved integrated characterization methodology and strategy for the nuclear decommissioning and dismantling operations (D&D) of nuclear power plants, and post-accidental land remediation of nuclear facilities under constrained environments. In line with this general objective, the definition and implementation of the practical considerations surrounding the radiological characterization of nuclear/radioactive facilities subject to a D&D programme is under development.. In-situ measurements are key for this radiological characterization. However, in some cases these measurements have to be carried out under constrained conditions, which poses some challenges to their realization. A constrained environment is a general term that includes all types of environment that hinder the choice of a non-destructive in-situ measurement method. In the context of this paper, it is applied to different situations: radioactive levels of the area to be characterised, difficult accessibility of this area, type and properties of the materials contained in it, as well as the possible presence of other environmental hazards, such as asbestos, chemical and/or organic/biological ones. In this context, an analysis of the suitability of existing methodologies for in-situ measurements in constrained environment is being carried out. The first step to accomplish this task is to describe the constrained environments that could appear in the different nuclear/radioactive facilities and their respective challenges. This paper includes a description of the different constrained environments, showing their corresponding challenges and a classification of the constraints, and it provides a series of tables linking the installations and areas inside them with the different constraints that appear. In the case of the radioactive constraints, a description of the expected level of their impact depending on the different D&D steps also appears. [ABSTRACT FROM AUTHOR]

In this paper, in-situ radiological characterisation by means of non-destructive techniques is studied and analysed in the context of the different constrained environments (identified as radioactivity, materials, accessibility and other hazards) that may be encountered in the nuclear facilities undergoing decommissioning and dismantling. As a complement to a previous paper (Aspe et al., 2020), the present one gives a global guidance to assist with the decision making process regarding the selection of in-situ measurement techniques that could be applied in such constrained environments. In addition, from the definition of the investigation objectives, and for each one of the most common in-situ measurement techniques, a brief description is given about the impact of the above constraints and how to integrate them onto the system definition, including the experimental design, the mechanical integration and the data management, to properly define the best radiological characterization methodology. Moreover, complementing this general view, all the phases – from initial to final – of a D&D programme were taken into account to provide basic recommendations, together with some particular dispositions, for the appropriate implementation of the chosen instruments. Strengths and weaknesses of the common detectors used for the different in-situ measurement techniques, as well as their recommended applications in nuclear facilities are also outlined. • Analysis on in-situ radiological characterisation by means of non-destructive techniques under constrained environments. • Guidance to assist with the decision for the selection of in-situ measurement techniques under constrained environments. • Description of the impact of the constraints and its integration to define the radiological characterization methods. • Provision of basic recommendations for the implementation of the chosen instruments. • Strengths and weaknesses of the common detectors used for in-situ measurement and their recommended applications. [ABSTRACT FROM AUTHOR]

Nearly all decommissioning and dismantling (D&D) projects are steered by the characterisation of the plant being dismantled. This radiological characterisation is a complex process that is updated and modified during the course of the D&D. One of the tools for carrying out this characterisation is the performance of in-situ measurements. There is a wide variety of equipment and methodologies used to carry out on-site measurements, depending on the environment in which they are to be carried out and also on the specific objectives of the measurements and the financial and personnel resources available. The extent to which measurements carried out with different types of equipment or methodologies providing comparable results can be crucial in view of the D&D strategy development and the decision-making process. This paper concerns an on-site benchmarking exercise carried out at the activated biological shield of Belgian Reactor 3 (BR3). This activity allows comparison and validation of characterisation methodologies and different equipment used as well as future interpretation of final results in terms of uncertainties and sensitivities. This paper describes the measurements and results from the analysis of this exercise. Other aspects of this exercise will be reported in separate papers. This paper provides an overview of the on-site benchmarking exercise, outlines the participating organisations and the measurement equipment used for total gamma, dose rate and gamma spectrometry measurements and finally, results obtained and their interpretations are discussed for each type of measurement as a function of detector type. Regarding the dose measurements, results obtained by using a large variety of equipment are very consistent. In view of mapping the inner surface of the biological shield the most appropriate equipment tested might be the organic scintillator, the BGO or even the ionisation chamber. In addition, for mapping this surface, the most appropriate total gamma equipment tested might be the LaBr 3 (Ce), the thick organic scintillator or the BGO. These measurements can only be used as a secondary parameter in a relative way. Results for the gamma spectrometry are very consistent for all the equipment used and the main parameters to be determined. • On-site intercomparison in real nuclear facilities. • Performance of dose rate probes. • Performance of total gamma probes. • Performance of gamma spectrometry systems and tools. [ABSTRACT FROM AUTHOR]