Capacity management is the academic concept and methodological approach focused on planning, optimizing, and controlling the operational capacity of complex energy generation systems. It investigates strategies for aligning the potential output (such as thermal or electrical power from nuclear fission or fusion processes) with predicted demand, while rigorously considering physical limitations, resource constraints, safety parameters, and long-term operational requirements inherent in these systems. Its significance lies in ensuring reliable energy supply, efficient resource utilization, and safe, sustainable operation of critical infrastructure.