[en] The D and D industry is a mature industry. In France, this is assessed by the results obtained on the site of Grenoble, and technological breakthroughs such as the implementation of the MAESTRO robotic equipment confirm it.The processes are implemented in complex contexts and are adapted to answer different technical configurations: nuclear reactors, research laboratories, spent fuel reprocessing plants... The efficiency of the processes lies in the control of three generic phases (high-level functions) of the manufacturing industry: 1) the management of the storages, 2) the treatment (put in the physical and radiological template) then 3) the waste produced. The common point is the management of a term source (Bq). Every stage of the process of A and D2 is governed from the evaluation of the radiological levels. Thus the nuclear instrumentation is a major function in the implementation and the control of the processes of A and D2. In operation, the main part of the radiological, chemical and physical characterization devices of the industrial plant at its end of life cycle is concentrated on the waste packages. These equipments are maintained in the phase of A*D2. They are completed by measure and control devices distributed on all the processes, from the integrated standing equipment to the waste package in its final storage. The functional and logical architecture of this instrumentation may be represented by a diagram of instrumentation where the equipments are first used to characterize radiological environments to be dismantled, then, to govern the treatment and dismantling processes and, at the end of line, to control the final waste packages or the plant released from the radiological constraints.The measure of gamma radiations and neutron dominates the non-destructive techniques of analysis. The spectrometry gamma remains the reference technique in A*D2. Its implementation was facilitated thanks to the advent of detectors working at room temperature (CdZnTe, LaBr₃). For the complex hot cells, the result of the gamma spectrum processing is combined with techniques for localization of the hot spots. The combined processing of the measurement results is insured by the exploitation of digital methods to draw the efficiency curves and to estimate the uncertainty associated with the physical quantity of interest.The characterization of the waste of the A*D2 strengthened the use of the coupled methods: chemical and physical analysis, gam-ma spectrometry, gamma imaging and neutron counting. These methods are propagated on the whole waste production line and for the nuclear facility decommissioning. This new concept of complete production line opens numerous technological and scientific working areas. (author)

[en] Project' managers continually seek an ever-greater optimization of time between remote handling operations and those carried out manually; therefore, new technological solutions must be deployed. Robotics offers a great opportunity in this new field of technology to carry out, for example, samplings or remediation in hostile, cluttered surroundings. Teams in charge of dismantling at the CEA have therefore first defined robotizable functions. These functions have been assembled from existing technological blocks to arrive at robots which are operating today [RICAIII, patent: FR 2925702]. Lessons learned, particularly from experience with the RICA robot, have enabled the operating technical specifications to be fine-tuned. A new study phase has been launched applying the same principle of adapting existing, proven means. The growing role of robotics today is unquestioned. Led by research and the academic world; robots such as those equipped with wheels, tracks, feet or even helicopter rotors, are today accessible to the general public, particularly via broadening of the 'open source' concept. Added to these we need tools able to manage large component deconstruction systems, like MAESTRO. Industrialization of such high-potential technological solutions has been aided by: - Easy use, - Increasing reliability, - Flexibility of 'open source' solutions, - Widening skill networks, and therefore greater technical support - Lower costs. Decontamination and dismantling (D and D) projects must be able to meet a number of special demands, increasing the number of unit designs, their costs and delivery times. The complexity of dismantling works sites mean that each is a special case to be dealt with almost independently. Such a way of approaching these projects is not on the same wavelength as industry, with tool and method standardization. The answer to the challenge of operations in difficult environments is an eco-system of functions, performed by a set of inter-connected robots. The first step towards the construction of such robot teams is devoted to functions where strength is not necessary: investigating and clean-up in hostile environments. With this in mind, the CEA Marcoule teams have been given the objective of merging the strengthening commercial robotic world with the needs of D and D, and thus to improve the transversal use of the systems. (authors)

[en] With the development of the dismantling industry in a context of ever-stricter requirements for risk mastery techniques, strengthened means of radiological monitoring are sought. For obvious safety reasons it is, for example, impossible to pilot a dismantling work-site without a good knowledge of the quality and the level of source terms. Source term control is constantly improving throughout the life cycle of nuclear facilities, particularly thanks to new requirements in the dismantling industry. Scenario preparation and nuclear waste management at the factory level, strictly governed by safety rules, provide fertile ground for methodological or technical innovations. This means new combinations of data or the development of special detectors to locate or characterise radioactive sources in hostile environments, and enhanced means for detector positioning, in other words robots. This paper's objective is to illustrate the logic of these developments as implemented for the characterisation of a source term in a pilot reprocessing facility on the CEA's Marcoule site. The objectives of radiological investigations were clearly defined in the early stages of the projects, the methodologies were standardized and the necessary range of tools was available. They therefore enabled confirmation of the special point inventory and the mapping of the source term, essential data for a scenario to be defined. Feedback has shown that implementing these techniques requires many skills: mechanics, calculations, radiation optics and physics, through to integration in an information system. Moreover, the quality of the result largely depends on the quality of the acquisition, and the know-how necessary must not be underestimated, going beyond just the notions of radiation protection, as otherwise information may be overlooked. Certain information remains however difficult to obtain, either because it is hidden under an unfavourable signal to noise level (as is the case for actinides in the presence of FP) or because the carriers are not agile enough to move around in the crowded, small spaces which can exist within cells. As well as these first remarks, the industrialisation of investigation technologies still needs to deal with the issue of coupling characterisation systems to the means of calculation and data traceability in an information system. To conclude, today radiological investigation must not be considered as an occasional operation carried out at different moments during dismantling (e.g. upstream, site release), but must be thought of in an 'on line' mode, using autonomous systems able to analyse the radiological consequences of deconstructing actions in real time.

[en] Commissioned in 1958 on the CEA nuclear site of Marcoule (France) and shut down in 1997, the former UP1 plant was dedicated to reprocess the spent fuel from G1, G2 and G3 GCR reactors. Since 1998, a wide program for cleaning-up and dismantling the plant has been developed in order to dismantle the process equipment, eliminate any radiological risk in all buildings concerned and remove all the resulting waste. Major technical challenges are related to the wide range of complex components and equipment in the facilities such as chemical dissolvers, extractor batteries, evaporators, tanks; and to a high risk of exposure, due to the presence of fission products. To address these challenges, CEA led R and D programs to develop advanced tools for complex dismantling projects: immersive virtual reality, laser cutting techniques, special remote-controlled arms combining dexterity and high resistance to irradiation The purpose of this paper is to provide an overview of a practical implementation and to show first results of these advanced techniques on a real case: the dismantling of dissolver's equipment from the dissolution workshop of UP1 plant. ONET Technologies has been chosen by CEA to design, build and operate the overall dismantling and waste treatment system for this project. ONET Technologies designed two main subsystems to meet all the requirements for this project: first, the 'Remotely-Operated Handling and Cutting Unit' and second the 'Waste Extraction and Conditioning Unit' and the combining innovative technologies. During the design phase, the 'Immersive Virtual Reality' has been used to qualify the kinematics in the final environment and the preliminary dismantling scenario. Following a first R and D program of CEA regarding the laser cutting technique applied to nuclear decommissioning, ONET Technologies and CEA realized elementary inactive tests based on a 6 kW Nd-Yag laser source to qualify the cutting performance according to material and thickness. Main objective was to meet the safety criteria and to check the physical characteristics of waste resulting from the laser cutting operation. The Remotely-Operated Handling and Cutting Unit was equipped with a MAESTRO manipulator, resulting from ten years of research and development cooperation between CEA and Cybernetix. This manipulator, a 6 axis hydraulic manipulator-arm specifically designed to work in harsh environment, entered in its industrial phase. ONET Technologies was responsible for the overall system integration, confinement and performance. A comprehensive qualification program in real conditions has been driven during 2014. The dismantling scenario was tested with a mockup at a full scale of dissolver equipment and confirmed at this stage the expected level of performance and safety. (authors)

[en] During the 1990's, the CEA has developed compact gamma-imaging systems, or gamma cameras, designed to localize irradiating sources quickly. Industrial products have become available, based on prototypes proven by laboratory tests and numerous on-site qualifications: experimental or power reactors, reprocessing facilities, glove boxes, fuel fabrication plants, waste storage area, etc. Gamma imaging was proven to be of significant interest in the following applications: - radiological characterisation of plants before or during decommissioning; - waste sorting; - nuclear material localisation in glove boxes; - radiation protection purposes. The paper will briefly describe the prototypes as well as the main outcomes of on-site operations. The basic performances will be reported as well, namely the detection limit and the operating range. The ability of dose-rate quantification will be also discussed. The second part will focus on new developments related to the extension of the operating range as well as an increased ease of use. The following items will be assessed: - The association of a dense shutter, which leads to a simple and efficient background reduction. - The combination with gamma spectrometry measurements, so as to identify the main radioisotopes of hot spots located by gamma imaging. For this purpose, compact and low cost CdZnTe probes fit with our need, as they provide good quality spectrum while being suitable for measurements under high dose rates. - The ability of replacing the pinhole collimator by a coded-mask aperture. Recent investigations showed that coded masks resulted in the enhancement of both of sensitivity and resolution. The basic principle and performances will be described. Thirdly, medium to long term evolutions will be discussed: one of the most significant expected breakthroughs might be the use of a pixelated CdTe detector, instead of the existing imaging detector (scintillator - MCP image intensifier - CCD). This new configuration should greatly reduce the size of gamma cameras. Developments and new results in this area will be highlighted. Another important issue deals with advanced processing of CdZnTe spectra, which could address one of the main drawback related with these detectors: the photo peaks can be strongly dissymmetrical, which can strongly affects the results. New deconvolution techniques, initially developed for actinides High-Resolution Gamma Spectrometry, might help to overcome this problem. (authors)

[en] Throughout the lifetime of nuclear facilities, radiological inspections are of vital importance, as controlling the radiological state of these facilities is necessary to ensure that their operations remain safe. These inspections are equally important during dismantling and decommissioning (D and D). Inspections of facilities that have contained radionuclides, particularly high activity cells, and very high activity cells are the first step when planning to carry out maintenance and D and D operations. Therefore, the development of investigation robots for hostile environments is a strategic approach in the nuclear field in order to meet these needs. The CEA and CYBERIA have worked together to develop the RICA robot (Robot d'Inspection pour Cellules Aveugles, or blind cell inspection robot), which can locate and measure the activity of radioactive sources. Since 2007, RICA is one of the strategic apparatuses that the CEA has been using for dismantling operations in its nuclear facilities. This small tracked robot was developed to offer a good level of modularity in terms of the onboard equipment able to carry out inspection and sampling missions in extremely hostile environments. To be able to do this, it can be operated either with a complete unit of radiological measurement tools or with a remote-handling arm. The measurement unit consists of a gamma camera, a gamma spectrometer, and a dose rate detector. This innovative radiological measurement unit enables in situ activity quantification and the collection of all the information necessary to interpret the radiological spectra. On the other hand, when equipped with a remote-handling arm, the unit can be used to carry out samplings, which will then be analyzed in a laboratory. This paper first presents the RICA robot, giving its main technical features. The innovative radiological measurement unit is described, explaining each of its bricks. The gamma irradiator tests that qualified the robot's functioning under irradiation are described, and the dose resistance results are analyzed. Lastly, examples of tasks in which RICA has been used in CEA nuclear facilities illustrate the robot's modularity. (authors)

[en] This paper reports a feasibility study, performed by numerical simulation with MCNPX-PoliMi v2.0, for plutonium quantitative assessment in radioactive waste packages by passive neutron coincidence counting with plastic scintillators. Owing to their low cost and good detection efficiency for fast neutrons, plastic scintillators could indeed constitute a good alternative to 3 He proportional counters, which have become too costly because of 3 He global shortage. However, their high-sensitivity to gamma rays and crosstalk are well-known drawbacks that need to be carefully studied. A measurement system for 118 L drums filled either with metallic or organic technological wastes have been modeled with MCNPX-PoliMi, and output data have been processed with ROOT. A 5-cm-thick lead shield is used in front of the detectors to attenuate plutonium and americium gamma radiation. In the studied cases, triple coincidences due to ²⁴⁰Pu spontaneous fissions represent more than 85% of the total signal when using crosstalk rejection algorithms, the 15% remaining coincidences being due to parasitic coincidences caused by (α, n) reactions or Am and Pu gamma rays. Although crosstalk rejection significantly reduces counting statistics, a few thousand triple coincidences are still recorded for 1 g of Pu homogeneously distributed in both metallic and organic matrices in a 25 min acquisition. For higher masses of Pu, a linear evolution of the number of coincidences with the mass is observed up to about 10 g. In addition, a study of Pu localization effects has shown that the triple coincidence difference is smaller than 20% between a point-like fission source and the homogeneous distribution in the drum. (authors)

[en] During cleanup and dismantling programmes, the French Alternative Energies and Atomic Energy Commission (CEA) has undertaken to standardise tools to characterise radiological data on the basis of robotic systems. Each is made up of a mobile robot for work on the floor of the area concerned, and a remote piloting system for the inspection platform. We suggest categorising them with regard to deployability, defined as the way in which the operators can manage the robot at the entrance to the operation zone. Three categories can be defined: - Man-packable: robots that can be handled by one or two operators wearing suitable protective clothing and equipment. The robot's physical features must not upset the handler's centre of gravity. - Man-portable: robots that can be handled by one or two operators wearing suitable protective clothing and equipment. - Maxi: bulky or heavy robots that require an additional handling system to be set up for their management. Each of these robot categories means different environmental constraints concerning the system's entrance and retrieval for the operating zone involved. In collaboration with Cyberia, the CEA has developed a series of three blind cell inspection robots or RICA robots (French abbreviation for 'Robot d'Inspection pour Cellules Aveugles'). RICA 1 and 2 are man-packable. They can be handled by one or two operators when they need to be inserted or retrieved from site, and were developed to investigate cells where access is a major issue. RICA 3 is man-portable. This enables it to carry a set of heavier, larger radiological detectors (dose rate sensor, gamma camera, gamma spectrometer). It is also possible to fit the RICA 3 with a remote arm so the operator can interact with the robot's environment. All three RICA robots use a cable tether rather than wireless linkup to avoid limiting possible inspection duration. In order to keep the number of lines to a minimum, the wires for high and low voltages are multiplexed in a single coaxial cable tether. Each of the platforms is fitted with a cable winder used to manage this coaxial cable. The three platforms all have identical piloting stations. (authors)

[en] The success of clean-up and dismantling projects in end-of-life nuclear facilities is a crucial issue for the nuclear industry, both from a nuclear safety and an economic perspective, which are vital conditions for gaining credibility in the eyes of the public. These projects must overcome several obstacles: i) on a strategic level, they require long-term planning and rigorous management of the risks and priorities, ii) on an operational level, they require a great deal of upstream preparation in terms of inventories, investigations, maps, feasibility studies and data management, iii) on an organisational level, synergy must be created between the professions, operation, project management and R and D. Clean-up and dismantling projects are characterised by a broad range of situations: a reactor, a fuel cycle plant and a damaged nuclear facility are not dismantled in the same way. This monograph provides insight into the techniques used to characterise facilities, carry out clean-up and dismantling operations, and manage the waste resulting from these operations. It also gives several examples of clean-up and dismantling sites led by the CEA, which already boasts a number of successful projects to date, either as project owner for the clean-up and dismantling of its own facilities, or as R and D operator in support of industry players. Content: 1 - Introduction - Clean-up and dismantling: a major challenge for a sustainable nuclear power industry; 2 - Assessment of the radiological, physical and chemical state of the facility to be cleaned up or dismantled - Characterisation techniques: From site history to radiological survey, Neutron activation and dose rate calculations for clean-up and dismantling operations, Nuclear measurements for clean-up and dismantling, Physical and chemical measurements for clean-up and dismantling, Geostatistics applied to clean-up and dismantling, Characterisation of dismantling waste; 3 - Operations in hostile environments: Robots in hostile environments, 3D simulation applied to clean-up and dismantling operations, Laser cutting, an emerging technology for remote-controlled dismantling projects, Containment of clean-up and dismantling sites; 4 - Treatment and decontamination of structures, soils and effluents: Treatment of contaminated solid surfaces, Decontamination of aqueous effluents; 5 - Treatment of clean-up and dismantling waste: Organic waste, Graphite waste, Waste containing magnesium, Special waste - mercury waste, High level sludge or powdery waste, Tritiated waste; 6 - Operating experience in clean-up and dismantling: Operating experience from the Marcoule UP1 fuel processing plant, Dismantling experience from sodium-cooled fast reactors, Dismantling of the Siloe reactor in Grenoble - setting an example; 7 - Dismantling: the special case of severe accidents, Differences between a scheduled dismantling project and unplanned post-accident dismantling, Operating experience from post-accident activities to secure and to dismantle nuclear sites; 8 - Conclusion - Assessment and future prospects for clean-up and dismantling techniques, Glossary-Index.

[en] Historically, nuclear science has developed alongside advances in instrumentation for radioactivity measurement and particle detection. Nuclear installations require a whole panoply of instruments for a precise measurement of quantities which characterize their operation, their control, their safety. This specific instrumentation mainly concerns (but not only) the detection of radioactivity, and it must work in a hostile environment with high requirements of accuracy, robustness and reliability. This monograph provides an overview of the measurement and control instruments used in the various fields of civil nuclear energy, from power reactors to radiation protection, including instrumentation for fuel cycle installations, the management of radioactive wastes or the clean-up and dismantling of nuclear installations. The paper shows the diversity and technical nature of the instruments involved, the importance of data assimilation methods resulting from the measurement, and by the extent of the effort devoted to their development by the nuclear community and the CEA