Zr Alloy Manufacturing and Effects on In-reactor, DBA and Interim Dry Storage Performance
To ensure safe operation of nuclear fuel, certain performance criteria must be met both during normal operation, anticipated operational occurrences and during postulated accidents. Zr Alloy material properties impact some of the most important performance criteria such as:
- Pellet Cladding Interaction (PCI) Pellet Cladding Mechanical Interaction (PCMI) corrosion and hydriding properties which in turn, are dependent upon:
» Chemical composition.
» Crystallographic texture and cladding microstructure.
» Cladding strength/ductility/fracture toughness.
- Re-opening of the pellet-cladding gap, lift-off, which is partly related to the fuel cladding creep properties.
- Excessive dimensional changes (resulting in e.g. excessive Fuel Assembly (FA)bowing) of fuel components that are a function of creep (including oxide induced and residual stress relaxation creep), irradiation growth, and hydrogen pickup in the components.
- Loss of Coolant Accident (LOCA) performance that is related to hydrogen pickup both during the base irradiation, before the LOCA event, as well as during the high temperature LOCA oxidation.
- Maintaining fuel integrity and fuel retrievability under normal dry storage and transportation conditions.
- Maintaining sub-criticality and shielding requirements under transportation accidents