The most significant challenges for a tokamak fusion power plant are:

  • Plasma confinement
  • Engineering feasibility and reactor availability
  • Tritium fuel cycle
  • Cost
  • Radioactive waste
  • Safety

These multifaceted issues are examined in pages on this website as indicated below.


Plasma confinement

Plasma confinement has been the main goal of numerous experimental devices built since the 1950s.  Problems with plasma stability remain, and the main task of the upcoming ITER project is to solve them. Nevertheless, "disruptions" ,where the plasma is lost in an uncontrolled way, must be reduced to a very low level for operations of a commercial reactor. This is discussed on the page Tokamak Fusion Reactors.


Engineering feasibility and reactor availability

A nuclear fusion reactor is an immensely complicated machine with multiple new and unique systems. The neutron flux emitted by the fusion reactions will be enormous, on a level never previously dealt with, and new materials are required to withstand the effects of the radiation. The neutrons have two different effects on materials, Radiation Damage and Neutron Activation, and any new material must both retain mechanical stability and avoid becoming radioactive. Although progress has been made in developing suitable materials with decades of R&D, extensive testing in a realistic environment is still required to completely qualify them. No fully suitable facility exists at present, as discussed on the page: Test Facilities needed for Materials and Breeder Systems. Certain components which are critical for the tokamak operation, have particular design difficulties, and some examples, Superconducting MagnetsBreeder BlanketDivertor and Limiter, are explained. These particular pages go into some depth of engineering detail, in order to fully grasp the complexity of the tokamak systems. A paramount requirement of any design, is the feasibility of manufacture and construction on a desirable site. The page, Pharaonic Size and Byzantine Complexity, argues that this is not realistic for a commercial fusion power plant competitive with an equivalent fission reactor. Utterly essential in the engineering design, is the need to have high reactor reliability and availability. This is a critical issue and is described in the page, Maintenance, Breakdowns and Availability. Towards an understanding of the inevitable contributions to downtime of a fusion reactor, this page covers the remote maintenance system which is required to regularly replace the components submitted to large radiation damage. 


Tritium fuel cycle

Mainstream plans for fusion reactor use tritium as fuel but tritium is very rare and the supply is possibly a "show-stopper". Only about 30 kg of tritium exists in the oceans of the world with about another 25 kg in world stocks from production in fission reactors. A GW fusion reactor would consume about 50 kg per year of tritium. This issue is explained in the page: Impossibility of Tritium Fuel Supply.


Costs

Ultimately, the cost of electricity generated by fusion, relative to other possible clean generation technologies, will decide if fusion enters into commercial exploitation. At present, the cost of fusion is not well evaluated but a discussion of this essential issue, giving some estimates and guesses is given in the page: Reactor Costs, Fusion compared to Fission


Radioactive waste

Radioactive waste is a common objection to nuclear fission power and fusion propaganda suggests that fusion has little waste and so should replace fission. In reality, the waste from fusion is short lived, but large volumes while fission waste is long lived, but small volumes. This is covered in the page: Neutron Activation and Radioactive Waste.


Safety

Another feature of fusion propaganda, are statements along the lines: Fusion is intrinsically safe and fission is intrinsically unsafe. The reality is not simple and a measure of the real safety risks for fusion reactors can be judged from the need to construct three metre thick containment structures around them. A rather extensive discussion on the relative safety risks for fusion and fission, together with some specific examples of risks for fusion power plants, is giving in the page, Safety