Nuclear Fuel Replacement Schedule Impact on System Operation Costs

In the management of the nuclear combustible life-cycle, periodic shutdowns are necessary to replace and rearrange fuel elements in the core. During the weeks of maintenance other sources are used to supply the energy gap, typically at higher costs. However, in systems with large integration of renewable energy sources, where the energy availability and costs are seasonal, the shutdown schedule may play an important role in the system costs. Thus, this paper evaluates the impact of a nuclear power plant fuel replacement in the system operation, mainly in the supply of electricity and its costs. A part of the Brazilian southeast hydroelectric system was used to illustrate the impact of the shutdown scheduling and how the system planning can minimize its operation costs. The system operation costs were lower with the shutdown scheduled during the season with large availability of energy resources. However, in Brazilian hydro-dominated power system, this cost variation can be partially compensated by the modification the hydroelectric operation.