European collaborative efforts to achieve effective, safe, and cost-controlled dismantling of nuclear facilities

This paper aims to give an overview of very recent European coordinate efforts to implement technologies of the “4.0 Industry” in the nuclear deconstruction sector. This objective aims to benefit from the lever of efficiency and reliability represented by innovative technologies on all the value chain of the dismantling, from early characterization to the dismantling operations themselves through engineering studies, waste management, project management and coordination of multiple stakeholders of each project. The outcomes of five projects (INNO4GRAPH, LD-SAFE, PLEIADES, CLEANDEM and INSIDER) are summarized here. They result in a unique data and knowledge common base, as well as in a significant sharing of experience based on dismantling projects already carried out or to come. They also result in designing new tools or methods natively taking into account the needs of a maximum of dismantling operators, as well as new test facilities. This will allow the undertaken joint work and collaboration to be continued. All of this paves the way to further collaborative projects and developments, in order to continue to implement reliable new technologies and processes in European dismantling projects to make future dismantling operations more efficient, safer and more cost-effective

Étude de l’induction optique d’une émission laser DFB dans les scintillateurs organiques en vue d’une mesure active des rayonnements ionisants.

Transducers used for nuclear measurements are divided into two groups. The first one is made of detectors based on the movement of charged carriers created during the interaction of ionizing radiation with materials (ionization chambers, semiconductors, etc.). The second comprises scintillating materials which emit light following such interaction.The present work aims at shifting the current paradigm in order to achieve an active measurement of the interactions between particles and sensor. The aim of this thesis is to investigate the response of nanostructured scintillators when excited by a primary laser beam while in the presence of ionizing radiations. It consists more precisely in optically inducing a laser emission in scintillators so as to benefit from the inherent sensitivity of this kind of wave to any kind of change in its environment.This study is at first focused on controlling the propagation of the electromagnetic waves in nanostructured media. This nanostructuration allows the channeling of the electromagnetic energy in a particular direction and at a precise wavelength and thus to amplify the transduction signal.The second part of this study is dedicated to the attempts at observing any change in the emission in an amplified regime while exposed to ionizing radiations (alpha, beta). The limitation of these sources requires the use of an electron accelerator. The conclusion of this part lays the foundation for future work and provides hypotheses regarding the effects that could be expected from the irradiation with high electron fluxes.Les transducteurs utilisés pour la mesure nucléaire se divisent en deux groupes. Le premier groupe est formé par les détecteurs exploitant la collecte des porteurs de charges créées lors de l'interaction des rayonnements ionisants (RI) avec les matériaux (chambres à ionisation, semi-conducteurs, etc.). Le second est formé des matériaux scintillants qui émettent de la lumière suite à cette interaction.Les travaux présentés portent sur le changement du paradigme actuel afin de parvenir à une mesure active des interactions entre particules et senseur. L’objectif de cette thèse est d'étudier la réponse de scintillateurs nanostructurés excités par un faisceau laser primaire en présence de RI. Il s'agit plus précisément d'induire optiquement une émission laser dans les scintillateurs de façon à bénéficier de la sensibilité inhérente de ce type d'onde à toute modification de leur environnement.L’étude est dans un premier temps focalisée sur le contrôle de la propagation des photons dans des milieux nanostructurés. Cette nanostructuration permet de canaliser l'énergie électromagnétique dans une direction et à une longueur d'onde donnée et donc d'amplifier un signal de transduction.La seconde partie de l’étude est quant à elle consacrée aux tentatives d'observation de la perturbation de l’émission en régime amplifié en présence de RI (alpha, bêta). Les limitations de ces sources imposent de travailler avec un accélérateur d’électrons. La conclusion de cette partie jette les fondations pour de futurs travaux et formule des hypothèses quant aux effets qui pourront être attendus en présence de hauts flux d’électrons

Update on the cleandem project

International audiencePrésentation de l'avancée des travaux du projet EURATOM CLEANDEM, coordonné par le LIST. Au moment de la conférence, les essais finaux (internes au consortium) seront en cours ou très proches

Amplification of the luminescence response in organic materials exposed to ionizing radiation: A new method for ionizing radiation detection

International audiencePolymer-based scintillators present interesting features for the field of ionizing radiation detection, related to the high sensitivity of fluorescence techniques coupled to the manufacturing advantages of such materials. Organic materials can indeed be manufactured into large sensing areas with different geometrical conformations through low-cost fabrication techniques. While results herein presented focus on liquids, the same phenomena would occur in solid samples. Widely used for sensing applications because of its high sensitivity, fluorescence has yet been further improved using technologies yielded by research in photonics. It has already been shown that the use of nanostructuration for sensing applications enables previously unattained precision. Herein we propose a new technique based on the manipulation of light using nanostructuration of the detection medium in order to enable the amplification of the sensitive material emission. This amplification of the luminescence signal is aimed at reducing the detection limit of low-energy beta emitters such as tritium, wellknown issue of major importance. The first step of our study, presented here, consists in demonstrating the ability of well-known scintillators to emit in laser regime when optically excited in a Distributed Feedback scheme. They are, to our knowledge, the first of their kind. The technique here presented, being usable, whatever the sample maximum emission wavelength, should also enable a simplification of the devices based on scintillators

Benchmark study of TRIPOLI-4 through experiment and MCNP codes

International audienceReliability on simulation results is essential in nuclear physics. Although MCNP5 and MCNPX are the world widely used 3D Monte Carlo radiation transport codes, alternative Monte Carlo simulation tools exist to simulate neutral and charged particles' interactions with matter. Therefore, benchmark are required in order to validate these simulation codes.For instance, TRIPOLI-4.7, developed at the French Alternative Energies and Atomic Energy Commission for neutron and photon transport, now also provides the user with a full feature electron-photon electromagnetic shower. Whereas the reliability of TRIPOLI-4.7 for neutron and photon transport has been validated yet, the new development regarding electron-photon matter interaction needs additional validation benchmarks. We will thus demonstrate how accurately TRIPOLI-4's "deposited spectrum'' tally can simulate gamma spectrometry problems, compared to MCNP's "F8'' tally. The experimental setup is based on an HPGe detector measuring the decay spectrum of an $^{152}$Eu source. These results are then compared with those given by MCNPX 2.6d and TRIPOLI-4 codes.This paper deals with both the experimental aspect and simulation. We will demonstrate that TRIPOLI-4 is a potential alternative to both MCNPX and MCNP5 for gamma-electron interaction simulation

A Comprehensive Survey of Visual SLAM Algorithms

Simultaneous localization and mapping (SLAM) techniques are widely researched, since they allow the simultaneous creation of a map and the sensors’ pose estimation in an unknown environment. Visual-based SLAM techniques play a significant role in this field, as they are based on a low-cost and small sensor system, which guarantees those advantages compared to other sensor-based SLAM techniques. The literature presents different approaches and methods to implement visual-based SLAM systems. Among this variety of publications, a beginner in this domain may find problems with identifying and analyzing the main algorithms and selecting the most appropriate one according to his or her project constraints. Therefore, we present the three main visual-based SLAM approaches (visual-only, visual-inertial, and RGB-D SLAM), providing a review of the main algorithms of each approach through diagrams and flowcharts, and highlighting the main advantages and disadvantages of each technique. Furthermore, we propose six criteria that ease the SLAM algorithm’s analysis and consider both the software and hardware levels. In addition, we present some major issues and future directions on visual-SLAM field, and provide a general overview of some of the existing benchmark datasets. This work aims to be the first step for those initiating a SLAM project to have a good perspective of SLAM techniques’ main elements and characteristics

CLEANDEM, a Cyber physicaL Equipment for unmAnned Nuclear DEcommissioning Measurements

International audienceHuman intervention is still required nowadays for most operations conducted during the Dismantling & Decommissioning (D&D) steps, which cover a wide range of radiological conditions: from the harsh initial conditions, nearly identical to when operating, to the final decommissioning steps where radioactivity has been removed.The goal of the three years EU-funded CLEANDEM project (Horizon 2020 Euratom Nuclear Fission and Radiation Protection Research call), led by CEA List with the support of ARTTIC, is to deliver a unique platform which will support the end-users' operations, from the initial radiological assessment to the final characterization of the facility, while enabling their continuous monitoring during the D&D operations.Ten leading actors from four European countries' nuclear industry (CAEN, ORANO, ANSALDO, RINA, TECNALIA, SOGIN, AiNT) and research (CEA, INFN, ENEA), have joined their expertise and efforts in the CLEANDEM consortium to develop a mobile unmanned ground platform (UGV), equipped with upgraded highly-mature detection technologies for 3D-localized radiological measurements. These will complete the facilities' available data into a 3D and fully detailed Digital Twin of the surveyed area, thus improving the planning and traceability of the D&D operations.The project started in March 2021 with the end-users' and stakeholder' input collection by ORANO leading to the concepts of operations and technical specifications, starting point for the technical developments.The first developments concern the upgrade of radiological sensors with* the improvement of low-cost sensors for rapid neutron and gamma (INFN's developments on the MiniRadMeter gamma counters/spectrometers and gamma-blind MiniSiLiF neutron counters), and distributed dose rate mapping (CEA List's OSL optical fibers technology coupled to 3D shape-sensing to access narrow spaces).* Then, neutron/gamma detection and identification sensors improvements (CAEN's PSD Phoswich alpha/beta large surface contamination monitor, and CEA List's upgrade of coded-aperture Nanopix gamma imager for hotspot localization);* And, last: air and surface contamination monitoring (with ENEA's cryogenic system for radioactive radiocarbon dioxide monitoring 14CO2, and CEA List's pixelated plastic scintillators for beta/gamma surface contamination).Most of the sensors will be embedded on the RB-VOGUI unmanned platform equipped with a UR 5e robotic-arm upgraded by TECNALIA and ANSALDO, for remote and autonomous operations.All gathered data are then to be passed for the continuous update of the Digital Twin containing all available radiological information, developed by RINA-CSM.The use cases selected by SOGIN for in-situ demonstration at the EUREX Saluggia plant, based on the scenarios defined by end-users shall also be presented; as well as AiNT's development of the concept for the training programme targeted at the end-users network

A Comprehensive survey of visual SLAM algorithms

International audienceSimultaneous localization and mapping (SLAM) techniques are widely researched, since they allow the simultaneous creation of a map and the sensors’ pose estimation in an unknown environment. Visual-based SLAM techniques play a significant role in this field, as they are based on a low-cost and small sensor system, which guarantees those advantages compared to other sensor-based SLAM techniques. The literature presents different approaches and methods to implement visual-based SLAM systems. Among this variety of publications, a beginner in this domain may find problems with identifying and analyzing the main algorithms and selecting the most appropriate one according to his or her project constraints. Therefore, we present the three main visual-based SLAM approaches (visual-only, visual-inertial, and RGB-D SLAM), providing a review of the main algorithms of each approach through diagrams and flowcharts, and highlighting the main advantages and disadvantages of each technique. Furthermore, we propose six criteria that ease the SLAM algorithm’s analysis and consider both the software and hardware levels. In addition, we present some major issues and future directions on visual-SLAM field, and provide a general overview of some of the existing benchmark datasets. This work aims to be the first step for those initiating a SLAM project to have a good perspective of SLAM techniques’ main elements and characteristics

Evaluation of delayed neutron yields and time spectra from photofission of ²³⁸U induced by Bremsstrahlung photons below 9 MeV

International audienceFew data exist regarding the yields and time spectra of delayed neutrons from the photofission reaction on actinides. In this paper, we report the characteristics of both six-group and eight-group delayed neutron time models for the photofission of U-238 induced by a Bremsstrahlung photon spectrum with an end-point energy at 9 MeV. This study was conducted using a 9 MeV linear electron accelerator housed at the SAPHIR platform located at CEA Paris-Saclay, France. A reference sample of depleted uranium was positioned inside a neutron detection block, previously designed and optimized by Monte Carlo simulation, made of high-density polyethylene covered by cadmium and including ten one meter-long He-3 proportional counters. Based on the consistent set of half-lives proposed by Spriggs et al. as early as 1999 for neutron induced fission, our description in eight delayed neutron groups for U-238 at 9 MeV is the first published for photofission. These new results bring valuable information to the scarce data available in the literature and represent useful inputs for the development of photofission-based nuclear measurement systems as they meet a significant interest in the fields of nuclear data, radioactive waste package characterization and for security-related applications

European collaborative efforts to achieve effective, safe, and cost-controlled dismantling of nuclear facilities

International audienceThis paper aims to give an overview of very recent European coordinate efforts to implement technologies of the “4.0 Industry” in the nuclear deconstruction sector. This objective aims to benefit from the lever of efficiency and reliability represented by innovative technologies on all the value chain of the dismantling, from early characterization to the dismantling operations themselves through engineering studies, waste management, project management and coordination of multiple stakeholders of each project. The outcomes of five projects (INNO4GRAPH, LD-SAFE, PLEIADES, CLEANDEM and INSIDER) are summarized here. They result in a unique data and knowledge common base, as well as in a significant sharing of experience based on dismantling projects already carried out or to come. They also result in designing new tools or methods natively taking into account the needs of a maximum of dismantling operators, as well as new test facilities. This will allow the undertaken joint work and collaboration to be continued. All of this paves the way to further collaborative projects and developments, in order to continue to implement reliable new technologies and processes in European dismantling projects to make future dismantling operations more efficient, safer and more cost-effective