Emma Perry
ICO CDT
Department of Earth Sciences
University of Cambridge
Sponsor: EPSRC
Oxidative dissolution of mixed uranium thorium oxides under ‘in canister' reducing conditions
Geological disposal, hundreds of metres underground, offers the safest long-term solution for the disposal of spent nuclear fuel. Despite use of multiple barriers, groundwater will eventually reach spent nuclear fuel. To understand the rate of radioactive release, it is important to understand the mechanism by which different nuclear fuels dissolve. Dissolution is reasonably well understood for uranium dioxide in the reducing conditions expected underground. Less is known about the behaviour of mixed oxide fuels in these environments.
To separate out competing effects of radioactivity, microstructure and chemistry, this project comprises of a series of single effect dissolution studies with mixed uranium thorium oxide under an argon atmosphere. U0.75 Th0.25 O2 has been produced using an oxalic co-precipitation, pressed into 5mm diameter pellets and sintered to 6% porosity. The contribution of an additional actinide to the passivation of the surface is being studied by XRD, EDS and NMR by comparison with pure UO2 and ThO2 pellets. Radiolytic oxidants produced by uranium-plutonium mixed oxides can be simulated for these lower activity samples by the addition of hydrogen peroxide. Use of a peristaltic pump will allow a realistic assessment of the effect of alpha-radiolysis on the anoxic dissolution of mixed oxide fuels.
Achievements
Best ‘Chemistry and Corrosion’ poster in the Uranium Science conference.
Winner of the Famelab Cambridge regional final.
Highlights
The main highlights are those moments when something clicks and I finally understand a research question or a concept or a result. I particularly remember when I first managed to refine my own XRD spectra. But also it was really fun to stay at that amazing hotel for the York winterschool.
Future plans
I would like to work in France for a year or two, maybe in a postdoc position, and then work in industry in the UK in spent fuel waste management or maybe as a technician at a light source/university lab.