The History of Fusion

PARTI

• Read the text given below and say whether it is about nuclear power or not.

Fusion power offers the potential of an almost limitless source of energy for future generations but it also presents some formidable sci­entific and engineering challenges. It is called 'fusion' because it is based on fusing light nuclei such as hydrogen isotopes to release ener­gy. The process is similar to that which powers the sun and other stars. Effective energy-producing fusions require that gas from a combina­tion of isotopes of hydrogen — deuterium and tritium — is heated to very high temperatures (100 million degrees Centigrade) and confined for at least one second. One way to achieve these conditions is to use magnetic confinement. The most promising configuration at present is the tokamak, a Russian word for a torus-shaped magnetic chamber.

The original large-scale experimental fusion device on which British physicists worked during the 1940s and 50s was housed in a hangar at Harwell. The device called ZETA - Zero Energy Toroidal Assembly was at first, shrouded in secrecy but with the temporary thaw in the Cold War created in the late 1950s by the visit of Kruschev and Bulganin. The Russians by bringing their leading fusion expert Academician I.V. Kurchatov to give a lecture "The Possibility of Producing Thermo­nuclear Reactions in a Gas Discharge" revealed their own work in the field and we shared our experience with ZETA. International coop­eration began and is an absolute prerequisite in the development of fu­sion research with the principal countries involved in large-scale fusion research being the European Union, USA, Russia and Japan, support­ed by vigorous programmes in China, Brazil, Canada, and Korea.

104 Section I. Power Engineering

The Place of Fusion in Europe's Power Source Mix

Prophetically, one of the great Russian pioneers of fusion physics said: "We will not harness the potential of fusion until it becomes a necessi­ty" According to a study undertaken by the World Energy Council, by 2020, Western European oil and gas reserves will have declined to a point at which only Norway is expected to have significant reserves of natural gas and Western Europe may well enter a phase of declining oil produc­tion and rising oil import dependency. In 25 years time, Europe's de­pendence on the external supply of conventional fuels is likely to have increased from the current level of around 50% to around 70%.

Another important factor is likely to be a further tightening of inter­national agreement regarding C0₂ emissions to decelerate the effects of global warming and consequent climatic changes. All this amounts to the need for intensified scientific research to achieve greater effi­ciency and conservation of our energy resources.

Given that, in the short term, some contribution will be made by various renewable energy systems — primarily biomass, hydro, solar, wind and geothermal systems — which is thought unlikely to exceed 20% of the total by 2020, the currently available non-fossil alternative to provide the major proportion of the outstanding 80% is nuclear fis­sion but it is also clear that fusion could have an important role to play in the energy balance.

International cooperation is strong with the focus on the Interna­tional Thermonuclear Experimental Reactor (ITER), which will have the same magnetic geometry as JET [ http://www.iter.org ]. Similar but much bigger than JET and with the addition of a number of key tech­nologies essential for a future power station, ITER will be able to op­erate for very much longer periods (over 1000 second pulses) and will help to demonstrate the scientific and technological feasibility of fu­sion power. Most importantly, it will be the first fusion device designed to achieve ignition and sustained burn — at which point the reactor becomes self-heating and productive.

Fusion Power: Safe and Clean

The imperative to demonstrate that fusion has the potential to be a safe and clean method of generating base load electricity led to the setting up

Unit 14. Fusion 105

of the European Safety and Environmental Assessment of Fusion Power (SEAFP) team in 1992. The main participants in SEAFP were the NET (Next Experimental Torus) team, the UKAEA, other European fusion laboratories, and a grouping of major European industrial companies.

The work embraced the conceptual design of fusion power stations and the safety and environmental assessments of those designs. Detailed work was done on the identification and modelling of conceivable acci­dent sequences, the potential hazards of normal operation, waste man­agement, the long term availability of materials and other issues.

The major conclusions reached by the SEAFP team in were that fusion has very good inherent safety qualities; there are no chain reactions and no production of'actinides'. The worst possible accident originating in a fusion power station could not breach the confinement; any releases could not approach levels at which evacuation would be considered.

The radiotoxicity of a fusion power station's waste materials decays very rapidly; after less than 100 years it is equal to the radiotoxicity of the waste from a coal-fired power station. Thus, fusion wastes present no accumulating or long-term burden on future generations. They would not need guaranteed isolation from the environment for very long time spans. In addition to these favourable results, fusion pro­duces no climate-changing or atmosphere-polluting emissions.

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