Nuclear fuel cycles and reactor technologies

The course aims at providing a full overview of the life-cycle of nuclear fuel, from its fabrication to its disposal, with two main focuses: the fuel-cycle approaches concerning resource utilisation and waste production and management - including the aspects of waste disposal -; and the behaviour of oxide fuel during irradiation with a particular attention on the physical phenomena involved.

Concerning the latter part, the physical phenomena that will be discussed concern oxide nuclear fuel either in the form of uranium oxide or mixed oxides. Some of these phenomena will be more or less evident depending on the type of reactor in which the fuel is irradiated; the link between these phenomena and the design choices for specific reactor technologies will be also considered.

The course can be schematically divided, trying to follow the historical moments in the fuel lifetime, as:

1.  Introduction (fuel-cycle concepts; cycles based on uranium, and uranium-plutonium; the problems with radioactive waste)
2. Uranium fuel cycle (resources; extraction and treatment; enrichment processes; oxide fuels and fuel fabrication process)
3.  Irradiation in a nuclear reactor:
   1.  Macroscopic considerations (depletion and in-reactor management; residual heat and source term; thermal properties of Oxide Fuels and fuel thermal performance)
   2.  Microscopic Considerations – Evolution of the fuel Matrix (oxygen potential and stoichiometry; fuel restructuring; behaviour of solid and gaseous fission products; swelling; and fission gas release)
   3. Evolution of the fuel-cladding gap (thermal considerations; mechanical considerations; corrosion considerations)
   4. Evolution of fuel-cladding materials (typical materials; irradiation effects on the materials; Evolution of mechanical properties and state due to irradiation)
4. Post-irradiation stage (Possible spent fuel management strategies: Fuel Cycle Back End; Reprocessing approaches)
5.  Management of radioactive waste, with a focus on spent nuclear fuel (Inventory and classification of nuclear waste; treatment and conditioning; Management options and disposal concepts; Overview of repository designs; Assessment of the safety of geological disposal)
6. Strategies for waste reduction (Considerations on plutonium recycling and thorium-uranium fuel cycle; Partition & Transmuting)

• Understanding of the life-cycle of nuclear fuel and the processes involved

• Understanding of the problematics concerning radioactive waste and possible solutions

• Acquire the fundamentals and physical insights concerning the behaviour of nuclear fuel under irradiation and its performance