Behaviour of fuel cladding under accident conditions

The behaviour of the fuel cladding during accidental transients is a key phenomenon which determines whether an actual or a design basis accident will or will not lead to activity release to the coolant or to the environment; it determines also the extent of core damage which can possibly penalize further power plant operation. In off-normal and accidental situations, a strong chemical interaction may arise between Zircaloy and coolant. This results essentially from the chemical affinity of Zircaloy for oxygen, together with the thermodynamic conditions of the interaction. It is the objective of the present chapter to review this type of interaction, on the basis of some recent publications