Localization of nuclear materials in large concrete radioactive waste packages using photofission delayed gamma rays - Archive ouverte HAL Accéder directement au contenu
Communication Dans Un Congrès Année : 2021

Localization of nuclear materials in large concrete radioactive waste packages using photofission delayed gamma rays

Résumé

The characterization of radioactive waste packages is mandatory for their transport, interim storage and final disposal. In this framework, the Nuclear Measurement Laboratory of CEA DES IRESNE Institute, at Cadarache, France, uses a high-energy electron linear accelerator (LINAC) to produce an interrogating bremsstrahlung beam with endpoint energies ranging from 9 to 21 MeV to perform X-ray imaging and high-energy photon interrogation on large concrete packages. In particular, highenergy photon beam induces photofission reactions in both fissile (235U, 239Pu, 241Pu) and fertile (238U, 240Pu, 232Th, etc.) actinides possibly present in the radioactive waste. In order to assess their mass, we use delayed gamma rays emitted by their photofission products, which are measured with a 50 % relative efficiency High-Purity Germanium (HPGe) detector. Actinide differentiation, which is important for the fissile mass estimation, is based on the ratios of gamma rays emitted by different photofission products and requires appropriate corrections for the gamma attenuation in concrete. To this aim, we report here a localization method of point-like nuclear materials in the concrete matrix, based on the differential attenuation of several gamma rays emitted by a same photofission product. We use here the 1435.9 and 2639.6 keV lines of 138Cs, with both experimental data and MCNP numerical simulations to determine the (r,θ) coordinates of nuclear materials. Then, the depth inside the concrete matrix, which is determined with a precision of a few percent, mainly depending on counting statistics on 1435.9 and 2639.6 keV net peak areas, is used to correct for the different gamma ratios used in the actinide identification method. Experimental tests with uranium samples have been performed to validate the localization method.Key words: Photofission / Uranium / Delayed gamma rays / Bremsstrahlung / MCNP / Concrete matrix / Nuclear material localization

Dates et versions

hal-03552913 , version 1 (02-02-2022)

Identifiants

Citer

Manon Delarue, Eric Simon, Bertrand Pérot, Pierre-Guy Allinei, Nicolas Estre, et al.. Localization of nuclear materials in large concrete radioactive waste packages using photofission delayed gamma rays. The 7th International Conference on Advancements in Nuclear Instrumentation Measurement Methods and their Applications, Jun 2021, Prague, Czech Republic. pp.08003, ⟨10.1051/epjconf/202125308003⟩. ⟨hal-03552913⟩
32 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Mastodon Facebook X LinkedIn More