The actual constraints and consequences of the maneuvering operation of PWRs — An optimum seeking approach

Apart from the increasing share of uncontrollable renewables in the energy mix, and aside from the successive stopping of traditional, fossil-fueled power plants, the consumption–production balance of the grid must be permanently assured. This necessitates the controllability also of many nuclear power plants. Traditional load control solutions focus only on the controlled variable; as an upgrade, a more comprehensive optimum seeking approach is proposed by the current study. If a nuclear power plant is in the maneuvering regime, the actual constraints and consequences of the nonstationary transitions have to be recognized, formulated, and considered. The external expectations are stated from the grid operator’s side – generally as time-dependent constraints on the electrical load output. The internal aspects are the versatile side-effects of the transients, mostly caused by thermal stresses. For finding the optimal balance between fast electrical load change and low damage on the reactor-side, a cost function is needed, which considers and weights the consequences, while adhering to the constraints. The resulting actuator trajectories indicate that a simple slowing down of the reactor’s load change is far from the optimal load-following strategy.