Exploring Oxalate Co-Precipitation Methods for the Production of Surrogate Americium Oxides for use in European Radioisotope Power Systems

Jones, S. and Boxall, C. and Sanderson, R. and Sarsfield, M. J. and Wilbraham, R. (2024) Exploring Oxalate Co-Precipitation Methods for the Production of Surrogate Americium Oxides for use in European Radioisotope Power Systems. In: Proceedings of Nuclear and Emerging Technologies for Space, NETS 2024 :. Proceedings of Nuclear and Emerging Technologies for Space, NETS 2024 . American Nuclear Society, USA, pp. 501-506. ISBN 9780894487989

Abstract

Following the successful development of Amercium-241 (241Am) power sources for space exploration, further studies by the National Nuclear Laboratory (NNL) in collaboration with the European Space Agency (ESA) are looking to increase the maturity of the technology. Specifically, studies using U and Ce (Ce as a non-active Am surrogate) are looking to identify a suitable route for the production of a mixed U-Am oxide powder from metal nitrate solutions whereby the oxide powder product is compositionally and morphologically homogeneous so that it can be used directly in the pelleting process without further processing or modification. This paper will describe small scale trials for the successful production of homogeneous mixed oxides with target U/(Ce+U) compositions of 5 - 15% U using an oxalate co-precipitation process. Whilst having the drawback of reducing the power density of the AmO2 fuel, a higher U content may be desirable to help stabilize the AmO2 lattice in the cubic fluorite phase, ultimately leading to significant improvements with regards to material properties and safety. A higher U content is additionally expected to help promote grain growth during pellet sintering trials with associated materials structural stability and safety benefits.