Preliminary identification of contaminating alpha and beta emitting radionuclides in nuclear installations to be decommissioned through Digital Autoradiography

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How Digital Autoradiography Technique can be useful for D&tD projects ?

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Radiological mapping of nuclear facilities under dismantlement drawn up by Digital Autoradiography technique

International audienceDigital Autoradiography (DA) is a conventional technique for the detection and quantification of radioactivity, commonly used in molecular biology research. It consists of the exposure of a radiosensitive flexible screen (a few hundred cm$^2$) to $\beta$ sources, such as mice sections with radioactive tracers ( $^3$H, $^{14}$C etc.) in it. After partial ionization, screens are scanned in a dedicated apparatus, which provides a quantitative image of the radioactivity distribution in the sample, in the form of black spots, shadows... Since 2011, this technique has been rerouted from molecular biology research to characterization of nuclear facilities to be dismantled. In this application, floors, walls, ceilings of the facility to investigate are fully or partially covered by batches of screens. After screen scanning and data processing, a radiological mapping of the facility can be obtained, in a reasonable time (roughly a few weeks for areas, often larger than 100 m$^2$); moreover, the implementation of geostatistical tools can dramatically shorten this duration. This approach should systematically be inserted in the range of common methods of contamination detection and quantitation used in dismantlement projects, such as wipe tests, insitu probe counting, and destructive laboratory analyses of samples from the facility. Indeed, DA is quantitative, sensitive to both labile and fixed contamination, and to both penetrating and nonpenetrating radiations ($\alpha$ and low-energy $\beta$, such as $^3$H). Besides, it does not involve nuclear matter transportation, nor does it produce wastes (reusable screens), it requires neither power supply, nor operator presence during acquisition. Thanks to the accurate localization of potential contamination spots, it enables relevant and representative sampling for further destructive laboratory analyses of drilled cores, broken pieces and powders of facility construction material

Digital Autoradiography technique an efficient tool for sampling procedure

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Development of different analytical techniques to investigate radionuclides difficult to measure and to improve detection limits.

International audienceThe radioactive waste management is a challenging task faced by nuclear powercountries and is a prime concern for the public and therefore for control authorities. In France,several nuclear facilities were shut down few years ago and are now under dismantling. In thesefacilities, after the disposal of different equipments (glove boxes etc.) and a cleaning-up step,laboratories are subject to decommissioning and sometimes demolition. In order to establish theworking procedure of dismantling, an inventory on the radioactive level of the various materialsand areas is essential. Furthermore, correct waste classification is crucial to define the appropriatefinal disposal repository and also to keep disposal cost down to a minimum. For all thesecharacterizations, the laboratory in CEA Saclay (LASE) develops radiochemical procedures andanalytical techniques to provide results with high confidence level and with very low detectionlimits

Evaluation of tetrafunctional block copolymers as synthetic vectors for lung gene transfer

International audienceIn the present study, we evaluated, in mice, the efficacy of the tetrafunctional block copolymer 704 as a nonviral gene delivery vector to the lungs. SPECT/CT molecular imaging of gene expression, biochemical assays, and immunohistochemistry were used. Our dataset shows that the formulation 704 resulted in higher levels of reporter gene expression than the GL67A formulation currently being used in a clinical trial in cystic fibrosis patients. The inflammatory response associated with this gene transfer was lower than that induced by the GL67A formulation, and the 704 formulation was amenable to repeated administrations. The cell types transfected by the 704 formulation were type I and type II pneumocytes, and transgene expression could not be detected in macrophages. These results emphasize the relevance of the 704 formulation as a nonviral gene delivery vector for lung gene therapy. Further studies will be required to validate this vector in larger animals, in which the lungs are more similar to human lungs