ABSTRACT

The long-term reactivity of the core is not driven by the fuel temperature alone, and in general, it is driven by the burnup of the fuel. The instantaneous reactivity of a pressurized water reactor (PWR) core is usually controlled by dissolving boric acid in the coolant and by withdrawing some control rods to "fine-tune" the core power shape. In practice, the nuclear fuels manager is responsible for selecting a refueling strategy that makes the most sense for a utility and its shareholders. This must be accomplished in a way that guarantees the safest possible operation of the power plant, and this in turn requires the operator of the plant to ensure that: the fuel will not melt during normal plant operation, the cladding will not dry out during normal plant operation, the temperature coefficient of the reactivity will always be negative if the reactor temperature increases, and so on.