Valuing shorter maintenance cycles and operational flexibility for fusion plants*

We present two studies relating the value of fusion plants to their operational abilities.

Fusion plants may require maintenance periods longer than those of typical plants, to replace internal components. It is generally assumed that lost operational time is proportional to lost revenue. However, decarbonized power systems may have strongly seasonal electricity prices, such that appropriately timed maintenance can reduce lost revenues. We study plants requiring $m$ months of maintenance every $n$ years in a decarbonized United States power grid. For example, plants needing 3 months of maintenance each year might lose 12%, not 25%, of their value.

Second, proposals for fusion plants often claim the potential for flexible operation: the ability to ramp output power at will. However, this ability may be limited by the phenomenon of thermal fatigue. We study the value of plants that can operate flexibly compared with those limited to a certain number of thermal cycles per year. For example, plants with variable costs of $12/MWh may lose only 5% of their value if their output must be constant.

These studies can inform designers of power plants of the value of potentially more costly designs that would support flexible operation, quicker maintenance, or longer-lasting components.