Journal article
Chemical stability of zirconolite for proliferation resistance under conditions typically required for the leaching of highly refractory uranium minerals
Metals, Vol.9(10), 1070
2019
Abstract
In this study, synthetic zirconolite samples with a target composition Ca0.75Ce0.25ZrTi2O7, prepared using two different methods, were used to study the stability of zirconolite for nuclear waste immobilisation. Particular focus was on plutonium, with cerium used as a substitute. The testing of destabilisation was conducted under conditions previously applied to other highly refractory uranium minerals that have been considered for safe storage of nuclear waste, brannerite and betafite. Acid (HCl, H2SO4) leaching for up to 5 h and alkaline (NaHCO₃, Na2CO3) leaching for up to 24 h was done to enable comparison with brannerite leached under the same conditions. Ferric ion was added as an oxidant. Under these conditions, the synthetic zirconolite dissolved much slower than brannerite and betafite. While the most intense conditions were observed previously to result in near complete dissolution of brannerite in under 5 h, zirconolite was not observed to undergo significant attack over this timescale. Fine zirconolite dissolved faster than the coarse material, indicating that dissolution rate is related to surface area. This data and the long term stability of zirconolite indicate that it is a good material for long-term sequestration of radioisotopes. Besides its long term durability in the disposal environment, a wasteform for fissile material immobilisation must demonstrate proliferation resistance such that the fissile elements cannot be retrieved by leaching of the wasteform. This study, in conjunction with the previous studies on brannerite and betafite leaching, strongly indicates that the addition of depleted uranium to the wasteform, to avert long term criticality events, is detrimental to proliferation resistance. Given the demonstrated durability of zirconolite, long term criticality risks in the disposal environment seem a remote possibility, which supports its selection, above brannerite or betafite, as the optimal wasteform for the disposition of nuclear waste, including of surplus plutonium.
Details
- Title
- Chemical stability of zirconolite for proliferation resistance under conditions typically required for the leaching of highly refractory uranium minerals
- Authors/Creators
- A.N. Nikoloski (Author/Creator)R. Gilligan (Author/Creator)J. Squire (Author/Creator)E.R. Maddrell (Author/Creator)
- Publication Details
- Metals, Vol.9(10), 1070
- Publisher
- MDPI
- Identifiers
- 991005540159607891
- Copyright
- © 2019 by the authors. Licensee MDPI, Basel, Switzerland.
- Murdoch Affiliation
- Centre for Water, Energy and Waste; College of Science, Health, Engineering and Education
- Language
- English
- Resource Type
- Journal article
UN Sustainable Development Goals (SDGs)
This output has contributed to the advancement of the following goals:
Source: InCites
Metrics
61 File views/ downloads
50 Record Views
InCites Highlights
These are selected metrics from InCites Benchmarking & Analytics tool, related to this output
- Collaboration types
- Industry collaboration
- Domestic collaboration
- International collaboration
- Citation topics
- 2 Chemistry
- 2.78 Photoluminescence
- 2.78.1729 Pyrochlore
- Web Of Science research areas
- Materials Science, Multidisciplinary
- Metallurgy & Metallurgical Engineering
- ESI research areas
- Materials Science