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.
See an animated schematic of the
Much of the early work on fusion was undertaken by universities,
before being centered at Harwell and Aldermaston. 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
co-operation began and is an absolute prerequisite in the development
of fusion research given the long time- scales and high costs involved.
The consequent declassification led directly to the setting
up of a custom-built laboratory at Culham.
Most of the world participates in fusion research to a greater or
lesser extent, 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.
Prophetically, one of the great Russians pioneers of fusion
physics said: "We will not harness the potential of fusion until
it becomes a necessity". Europe will still have sufficient fossil-fuel
reserves to maintain its energy requirement at its present level well
into the 21st century. But what then?
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%.
There are a number of other factors which must be taken into consideration.
In 1990 some 75% of the world's population (those in the developing
countries) were responsible for only 33% of the world's energy consumption;
by the year 2020 that 75% is likely to have risen to 85% and the energy
consumption to around 55% (see chart). Thus
there will be greater competition for the fuel resources available.
Another important factor is likely to be a further tightening of international
agreement regarding CO2 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
The UK contributes to fusion research in two ways: through the
UK's own programme and through our contribution to the Joint European
Torus (JET) project which is Euratom's flagship experiment. JET is situated
at Culham next to our own laboratory.
Key features of the UK fusion research programme are:
MAST - Mega
Amp Spherical Tokamak, operating since 1999, and successor to START
(Small Tight-Aspect Ratio Tokamak) which was operational at Culham from
1991 until 1998, the first high temperature spherical tokamak in the
- UKAEA operates the JET facilities on behalf of Europe. The experimental
programme is co-ordinated by a European Unit at Culham, and involves
scientists from all over Europe including UKAEA.
Also at Culham, but no longer operational: COMPASS-D,
a highly adaptable medium-sized tokamak with the same magnetic geometry
as JET and ITER.
See also: The Spherical
Tokamak - an extended feature, with interactive Power Plant
International co-operation is strong with the focus on the
International Thermonuclear Experimental Reactor (ITER), which
will have the same magnetic geometry as JET. Similar but much bigger
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
periods (over 500 second pulses) and will help to demonstrate the
scientific and technological feasibility of fusion power. Most importantly,
will be the first fusion device designed to achieve sustained burn
- at which point the reactor becomes self-heating and productive.
ITER is to be built at Cadarache, france, and is an international collaboration
between the European Union, USA, Japan, the Russian Federation, China,
South Korea, and India.
See: A giant leap
for fusion - Can fusion offer the world a secure energy supply?
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 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 1995 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
rapidly, and they present no accumulating or long-term burden on future
generations. They would not need guaranteed isolation from the environment
for very long timespans. In addition to these favourable results, fusion
produces no climate-changing or atmosphere-polluting emissions.
See also Fusion Power and Sustainable