Issue |
EPJ Web Conf.
Volume 288, 2023
ANIMMA 2023 – Advancements in Nuclear Instrumentation Measurement Methods and their Applications
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---|---|---|
Article Number | 07005 | |
Number of page(s) | 6 | |
Section | Decommissioning, Dismantling and Remote Handling | |
DOI | https://doi.org/10.1051/epjconf/202328807005 | |
Published online | 21 November 2023 |
https://doi.org/10.1051/epjconf/202328807005
Gamma-ray spectroscopy for the characterization of uranium contamination in nuclear decommissioning
1 CEA, DES, IRESNE, DTN, SMTA, Nuclear Measurement Laboratory, F-13108 Saint-Paul-Lez-Durance, France
2 CEA, DES, IRESNE, Nuclear Technology Department, 13108 Saint-Paul-Lez-Durance, France
3 CEA, DES, ISEC, DMPE, SEIP, LNPA, Univ. Montpellier, Marcoule, F-30207 Bagnols-sur-Cèze Cedex, France
4 Laboratory of Subatomic Physics and Cosmology, CNRS/IN2P3, Grenoble Alpes University, 38026 Grenoble, France
* Francisco.SALVADORBARBA@cea.fr
Published online: 21 November 2023
Decommissioning is the last step in the life cycle of a nuclear facility. After the evacuation of the facility components, the remaining structures such as concrete walls and floors must be surveyed to ensure that no residual contamination remains. It is a costly and time consuming activity, for which CEA develops fast alpha and beta detection methods allowing a full scanning of very large areas (hundreds of thousands of square meters) in legacy uranium enrichment plants. To support these developments, we present here complementary high-resolution gamma-ray spectroscopy analyses of a contaminated area at the gaseous diffusion uranium enrichment facility UDG, currently under decommissioning at Pierrelatte nuclear plant, France. Long measurements are performed with a High-Purity Germanium (HPGe) detector on the contaminated surface, and in a clean area to assess the natural gamma background of the concrete ground. The surface activity of uranium is 16.6 ± 6.0 Bq.cm-2, mainly due to 234U and 238U, most of the uncertainty coming from the non-uniform distribution of the contamination on the ground. This measurements also allowed us estimating the uranium enrichment of the contamination, which amounts to (0.80 ± 0.13) % of 235U mass fraction, consistently with the range of the Low Enrichment Plant where this measure was performed. Eventually, the background spectrum allowed us to determine the mass fractions of natural uranium, thorium and potassium in the concrete ground, which respectively amount to 3.8 ± 0.2. ppmU (i.e. 3.8 mg of uranium per kg of concrete), 7.4 ± 0.7 ppmTh, and (2.6 ± 0.1) %K of potassium.
Key words: HPGe detector / gamma-ray spectroscopy / MCNP simulation / uranium contamination / Decommissioning / Dismantling / UDG
© The Authors, published by EDP Sciences, 2023
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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