Nickel Electrodeposition over Powder Compact for Irradiation Target

Abstract:

rradiation targets with 20% of ²³⁵U (Low Enriched Uranium - LEU) have been studied to replace HEU (Highly Enriched Uranium) targets in future nuclear reactors. These are used to produce the pair of radionuclides ⁹⁹Mo / ^99mTc, used for diagnostics in nuclear medicine. This work aims to develop an alternative route to produce LEU targets. It consists in hydrogenating and powdering metallic uranium and compacting the produced powder, followed by sealing it with nickel by electrodeposition. The deposited nickel should suppress the release of fission gases, and avoid a reactive contact of uranium with aluminum from the enclosure. In order to obtain the best conditions for deposition over uranium, in this work iron powder was compacted into small discs, with a diameter of 22mm and weight of 14g, simulating an equivalent volume of 10g of LEU uranium powder. As well, aluminum discs were used to ensure adhesion and uniformity of the nickel layer. Pulsed nickel electrodeposition was carried out over the compacts, employing current frequency of 900Hz, -0.84A/cm² of peak current and duty cycle of 0.5 in Watts Bath. The electrical resistance of pulse Ni-plated layer was checked by experiments with impedance spectroscopy in plated samples using aluminum substrate, held in KCl (pH=6), giving EIS results after resting the discs in solution for 0h, 4h and 24h. The physical strength was evaluated qualitatively by treating the Ni covered compact at 600°C, developing a bump deformation on the original planar layer, up to the point to open the Ni-layer for gas relief. These results suggest an adequate mechanical strength of the Ni-layer for using under neutronic irradiation, sealing the radioactive gases, mainly ¹⁴⁰Xe, produced during fission of ²³⁵U.

• Periodical: Materials Science Forum (Volumes 727-728)
• Pages: 14-19
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.727-728.14
• Online since: August 2012
• Authors: Adonis M. Saliba-Silva, R.H.L. Garcia, I.C. Martins, E.F. Urano de Carvalho, M. Durazzo
• Keywords: EIS, Electro-Deposition, Irradiation Target, LEU, Nickel

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