O&M costs of nuclear power plants are the non-fuel cycle costs for plant operation and related services and are generally divided into fixed (inde­pendent of electricity generation) and variable cost components. Essential O&M cost components are salaries for plant staffing and costs for materials, liability insurance, decommissioning, security, outsourced support services, administration and maintenance.

The O&M costs are further determined by the size and type of plant and the mode of operation (load-following or base-load operation). The number of similar units at a particular site has a strong influence on the O&M cost components.