Synthesis of nuclear waste simulants by reaction precipitation: Formation of caesium phosphomolybdate, zirconium molybdate and morphology modification with citratomolybdate complex. (29th March 2015)

• Record Type: Journal Article
• Authors: Paul, Neepa; Hammond, Robert B.; Hunter, Timothy N.; Edmondson, Michael; Maxwell, Lisa; Biggs, Simon
• Is Part Of: Polyhedron. Volume 89(2015)
• Page Start: 129
• Page End: 141
• Publication Date: 2015-03-29
• Subjects: Caesium phosphomolybdate -- Zirconium molybdate -- Zirconium citratomolybdate -- Nuclear waste -- Inorganic compounds; Chemistry, Inorganic -- Periodicals; Chimie inorganique -- Périodiques; Organometaalverbindingen; Anorganische chemie; 546.05
• DOI: 10.1016/j.poly.2014.12.030
• Languages: English
• ISSNs: 0277-5387

Abstract

Graphical abstract: Abstract: Caesium phosphomolybdate (Cs3 PMo12 O40 · x H2 O) and zirconium molybdate ([ZrMo2 O7 (OH)2 ]·2H2 O) solids are known to precipitate out from highly active liquors (HAL) during reprocessing of spent nuclear fuel. Here, a new synthesis for these simulants is reported; with the initial step producing spherical ceasium phosphomolybdate particles, which can then be converted into cubic Zirconium molybdate. Additionally, the addition of citric acid prior to the formation of the zirconium salt is investigated. In this case, a citratomolybdate complex is generated, leading to the synthesis of elongated cuboidal zirconium citratomolybdate ([ZrMo2 O7 (OH)2 ]·2H2 O·[(MoO2 )2 O(cit)2 ]). A key focus of this study is to explore the optimisation of reaction conditions to create a controlled environment for the particles to form with high conversion rates and with desired shape properties. Elemental and structural characterisation of the particles at various points during the synthesis, as well as post-synthesis, was undertaken to provide further insights. Ultimately, it is of importance to determine the mechanism of how these simulants are formed within the components in HAL. Establishing the influence of particle properties on HAL behaviour is key for current processing, post operational clean out (POCO) and life-time assessment of the nuclear waste facilities.