Department of Physics, Engineering Physics & Astronomy

Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

Computer Simulations For Candu Fuel Rods During Severe Accidents

Dr. Barbara Szpunar, P.Eng
Atomic Energy of Canada Ltd., Chalk River Laboratories*

Friday, November 15, 2002
12:30 PM @ Stirling B


The safety of the operation of nuclear power plants is of a major concern and the extensive computer simulations of severe accidents are part of safety analysis. A model has been developed to describe the fuel oxidation behavior in operating defective nuclear fuel rods. Based on a general Stefan-Maxwell equations it is considered how incoming steam diffuse into a breached rod against a counter-current flow of non-condensable fission gases and out-flowing hydrogen that is produced from the internal reaction of steam with the Zircaloy cladding or urania. The simulations are able to predict the melt radius in a defected rod that had operated at an average mid-plane linear heat rating of 52 kW/m. With the assumption of fuel sheath cracking, the model is able to reproduce the fission product release kinetics and the final fuel stoichiometry. The ability of the oxidized clad to act as a physical barrier to either hydrogen or oxygen diffusion is further investigated with a molecular-dynamics approach, with the interactions between atoms represented by a Modified Embedded Atom Method. This presentation demonstrates that microstructural features control the properties and performance of engineering components to the large extent and predictive modeling techniques are necessary for tailoring microstructures. We conclude that improved modeling and simulation capability may be the most important future direction for Materials Science & Engineering.

*This analysis was done at RMC and was supported by NSERC, DND and OPG.

Dr. Barbara Szpunar is a candidate for the ATOP-funded position in the Department.

Refreshments will be served in the lounge after the talk.