Faculty of Natural and Agricultural Sciences
Department of Chemistry
Materials Chemistry
The most unique feature of the PBMR are the fuel pebbles or spheres (thousands of them) that produce the nuclear reaction. Each 60-mm diameter, billiard ball size, sphere is coated with a 5-mm thick graphite layer that is fuel free. The graphite can withstand temperatures of 2,800 degrees Celsius which is much higher than the maximum 1,600 degrees Celsius that the reaction can produce – this is why the PBMR is considered to be intrinsically safe nuclear reactor. Within this graphite layer are approximately 15,000 coated particles that are embedded in a graphite mix. Each particle is about 1 mm diameter, containing several layers of coatings and the 0.5-mm diameter, uranium dioxide fuel kernel. The porous carbon buffer maintains the shape of the fuel kernel as it goes through deformation caused by density change from the fission products produced. It accommodates the fuel products without over-pressurizing the particle. The role of the remaining pyrolytic and silicon carbide coatings is to prevent fission products from leaving the particle thereby preventing radiation leakage during normal operation and, worst case, accident. In particular, the silicon carbide barrier is so dense that ideally no radiological significant quantities of gaseous or metallic fission products should be released from the fuel elements at temperatures of up to 1,650 degrees Celsius. All the above is a dream scenario of the safest reactor. Our Research Group is focusing on very reach and mostly unknown in details the chemistry and physico-chemical processes taking place in and between the coatings of the uranium dioxide kernel. Our aim is to provide fundamental understanding leading to optimised structural properties and chemical composition of material used in the production of fuel pebbles. Research in materials electrochemistry is focused mainly on carbon nanotubes and metal nanoparticles for the development of fuel cells and supercapacitors. Charge transport phenomena of electro-active materials are studied
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