Reactors

The nuclear fission process can be carried out in a controlled manner, in order to prevent destruction, with the help of a very effective device called nuclear reactor. The nuclear reactor has been very skillfully built in order to make sure that the energy released is not let out of control. It consists of control rods, moderators, a shielding device, the fuel which undergoes fission and generators which produce electricity. The control rods, made of steel are used to absorb the excess of neutrons and are hence used to control the reaction, in case. It goes out of hand. It was found that slow moving neutrons are more efficient than fast moving neutrons, so moderators were included to slow down the fast moving neutrons. Graphite or heavy water (an oxide of deuterium) is generally used as a moderator.

The most commonly used fuels are a few oxides of uranium or plutonium. When the mass of the fuel used is greater than the critical mass, the product neutrons collide with the remaining fuel and chain reaction occurs. In order to avoid this, the excess neutrons are absorbed by control rods. Shielding is something which prevents the heat radiation from escaping the reactor. The fuel is surrounded by a thick steel pressure vessel which in turn is surrounded by concrete and another larger steel vessel. Thus by bringing together all these parts the nuclear reactor has been built. The world’s first nuclear reactor is a natural reactor at Oklo.