As is well known, the inexhaustible energy of the sun is produced
by nuclear fusion reactions occurring in its hot interior. The
objective of fusion research at JAERI is to develop the technology
of a nuclear fusion reactor which will harness fusion reactions
here on earth to generate useful electric power. In other words
we aim to develop a man-made sun. Owing to its potential advantages
of abundant and evenly-distributed resources (seawater is a basic
fuel), benign influence on the environment and some other favorable
features, nuclear fusion is expected to be a new energy source
for the world from the 21st century on.
The most readily attainable fusion reaction on earth is a reaction
of the nuclei of the isotopes of hydrogen, deuterium and tritium
(the DT reaction). For fusion reactions to occur, it is necessary
to heat the fuel, a rarefied mixture of gases of deuterium and
tritium, to a very high temperature exceeding 100 million degrees
centigrade, and to confine the hot gases called a plasma in a
reactor vessel by applying a strong magnetic field. A tokamak-type
fusion device is shown in Fig. 2-1. An electric current flowing
through the plasma (a plasma current) is required for plasma confinement
in a tokamak. Figure 2-2 illustrates how a fusion reactor would
produce electricity.
Fusion research and development has made remarkable progress world-wide
in various scientific and technological areas. In particular,
in the research of fusion plasma using large tokamak devices,
we have now reached the frontier, where the "self-sustained (ignition)"
condition is "within our grasp". Work to reach the ignition condition
is now in progress by means of an international cooperation among
four parties, the European Union (EU), Japan, the Russian Federation
(RF) and the USA. This takes the form of the International Thermonuclear
Experimental Reactor (ITER) project.
JAERI is a leading fusion research and development (R&D) center
with its comprehensive fusion R&D program as shown in Table 2-1.
Proceeding step by step on the path toward a nuclear fusion reactor
as shown in Fig. 2-3, our efforts are now concentrated on the
next - step fusion experimental reactor, ITER. Also we are attempting
to pioneer the innovative physics and technology required for
a future tokamak fusion power reactor, such as the development
of a reliable method for the "steady-state" operation of the tokamak,
the development of blanket technology and the creation of new
reactor materials, since they all need a very long lead time to
establish. |
