By James Donahue
In the rush to find an
environmentally clean solution to the growing world demand for energy, scientists from several nations of the world, including
the United States, have agreed to work together to build an International Thermonuclear Experimental Reactor (ITER) in southern
France to test theories of using nuclear fusion.
Fusion involves the fusing
together of atomic nuclei rather than the splitting of the nuclei as is done when we use nuclear fission for atomic power.
While the words look
similar, they describe radically different concepts. In fact, nuclear fusion has only been a theory and so far has never been
used because of the complex problems linked to using it under controlled conditions.
Physicists know that
nuclear fusion is at work in the core of the sun. There, working at temperatures ranging from 10 to 15 million Kelvin, hydrogen
is converted to helium by fusion, and this is being turned into the energy that keeps the sun burning. That is natural fusion,
and it is working on a giant scale. What the scientists want to attempt in the French project is find a way to harness fusion
energy on a much smaller scale.
If successful, they believe
the process could offer a viable alternative energy supply within the next 30 years, that will burn environmentally clean,
leave no nuclear waste to be disposed of, and supply enough energy to meet world needs for the next thousand years.
In the world of physics,
the proposed process going on at the ITER is introducing a lot of new words that most people are unfamiliar with. To create
fusion, the reactor will have to create extreme temperatures comparable with that of the sun. This is required before the
atoms turn into something called plasma, a hot, electrically charged gas, where the atoms separate and the electrons are stripped
from the atomic nuclei. These radical electrons are called ions. The trick is to get the ions to fuse and physicists say this
will occur if the temperature is hot enough.
To harness fusion energy,
scientists and engineers are learning how to generate and control these high temperature plasmas, and then sustain this energy
so that a fusion reaction can occur. The massive machine they believe will do this job has been designed. It is called a tokamak.
The plan is to use the
tokamac, a large doughnut-shaped chamber with powerful magnetic coils, to form the plasma. But there has been a technical
problem because during the process, sudden fluxes or eddies occur on the outer edge of the plasma that erode the inner wall
of the tokamak. But a team of U.S. physicists now think they have this problem solved, and
so the French project has perhaps moved one step closer to a successful conclusion.
While the heat chamber
does not sound like it, scientists insist that the concept of nuclear fusion is extremely safe and environmentally clean.
Such a power station would be working with small amounts of deuterium and tritium. While the plant is a nuclear process and
portions of the plant will become radioactive, this activation decays within years and there is no radioactive waste by-product
created from the reaction. The fusion byproduct is Helium, an inert and harmless gas.
Participating in the
French project are the European Union, the United States, Russia, Japan, South
Korea and China.