Lee Hsun Lecture Series
Topic: A MODEL FOR THE CORROSION OF SPENT NUCLEAR FUEL, AND THE RELEASE OF RADIONUCLIDES, INSIDE A FAILED WASTE CONTAINER.
Speaker: David Shoesmith
Surface Science Western and the Department of Chemistry
Western University, London, Ontario, N6A 5B7，Canada
Time: 10:00-11:30, (Tue.) Mar.14th, 2017
Venue: Room 468, Lee Hsun Building, IMR CAS
The internationally accepted approach for the disposal of spent nuclear fuel is to seal it in a corrosion-resistant metal container and bury it in a stable deep geologic repository. While the prospects for containment are good, it is judicious to investigate the consequences of container failure, when the fuel waste form could be exposed to groundwater. Under these conditions, radiolytic corrosion of the fuel (uranium dioxide (UO2) containing a range of fission and activation products) could lead to the release of radionuclides to the groundwater, the critical first step in their transport into the environment.
Two corrosion fronts will exist within the failed container; one on the fuel surface driven by radiolytic oxidants, and a second on the carbon steel vessel sustained by water reduction. The coupling of these two corrosion fronts via diffusive transport in the groundwater would then lead to an evolution in redox conditions with time which will control the fuel corrosion rate. Based on an extensive series of electrochemical, corrosion and chemical dissolution studies, a finite-element based model has been developed to determine this evolution in redox conditions and its influence on fuel corrosion/radionuclide release. The key properties of the spent fuel which influence its reactivity will be described and their effect on the fuel corrosion process calculated. An attempt will be made to validate the model based on a wide range of international studies on spent fuels and simulated fuels.