The design of a fusion power plant faces several major challenges that must be overcome before reliable electricity production becomes possible.

Tritium Breeding

One of the most crucial challenges is tritium self-sufficiency. A deuterium–tritium fusion power plant will have to breed enough tritium to replace the fuel it consumes. This requires an efficient breeding blanket containing lithium, together with systems for extracting, processing and recycling the tritium. The blanket must also provide heat removal and neutron shielding while allowing maintenance and eventual replacement of components damaged by neutron irradiation.

Tritium must be extracted continuously from the breeding material and returned to the fuel cycle with very high efficiency. At the same time, neutron irradiation gradually activates and damages the blanket structure, limiting its lifetime. Developing materials, remote-maintenance procedures and recycling or disposal routes for replaced blanket components is therefore an important part of fusion power plant design.

Augmented-reality and digital-twin technologies could support the assembly, inspection and remote maintenance of future fusion power plants.

Divertor

Another major challenge is the divertor, which must remove intense heat and particle fluxes from the plasma edge. Although divertors have been used in tokamaks and stellarators for decades, a fusion power plant will expose plasma-facing components to far higher sustained heat loads and neutron irradiation. Future divertors will therefore require advanced materials, efficient cooling and plasma-exhaust techniques capable of keeping local heat loads within acceptable limits.

Magnetic Coils

Magnetic confinement reactors require powerful superconducting coils capable of producing strong magnetic fields while withstanding very large electromagnetic forces. Future power plants must combine high magnetic performance with mechanically robust support structures, effective quench protection and sufficient shielding from neutron radiation. The optimal magnet size and field strength will depend on the reactor concept.

ITER uses Nb₃Sn superconductors for its strongest magnets, and the experience gained from their manufacture and operation will be valuable for future reactors. However, high-temperature superconductors such as REBCO are increasingly being investigated because they can operate at higher magnetic fields and potentially simplify some aspects of magnet design. Both approaches still require further development for reliable long-term power-plant operation.

Neutron-resistant Materials

Materials inside a fusion reactor will be exposed to intense 14.1 MeV neutron irradiation, high temperatures and repeated thermal and mechanical loads. Neutrons can cause embrittlement, swelling and changes in material properties while also activating structural components. Reduced-activation steels such as EUROFER, together with tungsten and copper alloys for high-heat-flux components, are therefore being developed and qualified for future fusion power plants.

Remote Maintenance

Neutron activation will make direct human access to many reactor components impossible during maintenance. Large blanket and divertor modules will therefore have to be inspected, repaired and replaced remotely using robotic systems. These operations must also be completed quickly enough to maintain a high plant availability, making reliable remote handling one of the key engineering challenges of commercial fusion power.

Steady-state Regime

Continuous steady-state operation would be advantageous for a fusion power plant, but it is not essential. Some tokamak power-plant concepts may operate in long pulses separated by short dwell periods. Such pulsed operation creates additional challenges for plasma control, reactor components and the power-conversion system because thermal and mechanical loads vary repeatedly between pulse and dwell.

One possible solution is intermediate thermal-energy storage that smooths the heat supply to the turbine during the dwell period; molten-salt storage has been investigated for European DEMO concepts. Another route is to increase the non-inductive fraction of the plasma current and extend pulse duration or ultimately achieve steady-state operation. The optimum solution remains an open design question.