NUCLEAR+FUSION+-+Thomas


 * Nuclear Fusion**

Nuclear fusion is the process in which two or more atomic nuceli join together to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy. Large scale thermonuclear fusion processes, involving many nuclei fusing at once, must occur in matter at very high densities and temperatures. Nuclear fusion occurs naturally in all active stars. Synthetic fusion as a result of human actions has also been achieved, although this has not yet been completely controlled as a source of nuclear power In the laboratory, successful nuclear physics experiments have been carried out that involve the fusion of many different varieties of nuclei, but the energy output has been negligible in these studies. In fact, the amount of energy put into the process has always exceeded the energy output. __**Accidents**__ The likelihood of small industrial accidents including the local release of radioactivity and injury to staff cannot be estimated yet. Nevertheless there is no possibility of a catastrophic accident in a fusion reactor resulting in major release of radioactivity to the environment or injury to non-staff, unlike modern fission reactors. The primary reason is that nuclear fusion requires precisely controlled temperature, pressure, and magnetic field parameters to generate net energy. If the reactor were damaged, these parameters would be disrupted and the heat generation in the reactor would rapidly cease. In contrast, the fission products in a fission reactor continue to generate heat through beta-decay for several hours or even days after reactor shut-down, meaning that melting of fuel rods is possible even after the reactor has been stopped due to continued accumulation of heat.

__ **Magnetic confinement fusion** __ Magnetic confinement fusion is an approach to generating fusion energy that uses magnetic fields to confine the hot fusion fuel in the form of a plasma. Magnetic confinement is one of two major branches of fusion energy research, the other being inertial confinement fusion. The magnetic approach is more highly developed and is usually considered more promising for energy production. A 500-MW heat generating fusion plant using tokamak magnetic confinement geometry is currently being built in France.

__ **Inertial confinement fusion** __

**Inertial confinement fusion** (**ICF**) is a process where [|n] uclear fusion reactions are initiated by heating and compressing a fuel target, typically in the form of a pellet that most often contains a mixture of deuterium and tritium. To compress and heat the fuel, energy is delivered to the outer layer of the target using high-energy beams of laser light, electrons or ions, although for a variety of reasons, almost all ICF devices to date have used lasers. The heated outer layer explodes outward, producing a reaction force against the remainder of the target, accelerating it inwards, and sending shock waves into the center. A sufficiently powerful set of shock waves can compress and heat the fuel at the center so much that fusion reactions occur. The energy released by these reactions will then heat the surrounding fuel, which may also begin to undergo fusion. The aim of ICF is to produce a condition known as "ignition", where this heating process causes a chain reaction that burns a significant portion of the fuel. Typical fuel pellets are about the size of a pinhead and contain around 10 Milligram of fuel: in practice, only a small proportion of this fuel will undergo fusion, but if all this fuel were consumed it would release the energy equivalent to burning a barrel of oil.

__**Reference**__ __**www.wikipedia.org**__