JEE Main & Advanced Physics Nuclear Physics And Radioactivity Nuclear Reactor

A nuclear reactor is a device in which nuclear fission can be carried out through a sustained and a controlled chain reaction. It is also called an atomic pile. It is thus a source of controlled energy which is utilised for many useful purposes.

(1) Fissionable material (Fuel) : The fissionable material used in the reactor is called the fuel of the reactor. Uranium isotope \[({{U}^{235}})\] Thorium isotope \[(T{{h}^{232}})\] and Plutonium isotopes \[(P{{u}^{239}},\,\,P{{u}^{240}}\,\,\text{and}\,\,P{{u}^{241}})\] are the most commonly used fuels in the reactor.

(2) Moderator : Moderator is used to slow down the fast moving neutrons. Most commonly used moderators are graphite and heavy water \[({{D}_{2}}O)\].

(3) Control Material : Control material is used to control the chain reaction and to maintain a stable rate of reaction. This material controls the number of neutrons available for the fission. For example, cadmium rods are inserted into the core of the reactor because they can absorb the neutrons. The neutrons available for fission are controlled by moving the cadmium rods in or out of the core of the reactor.

(4) Coolant : Coolant is a cooling material which removes the heat generated due to fission in the reactor. Commonly used coolants are water, \[C{{O}_{2}}\] nitrogen etc.

(5) Protective shield : A protective shield in the form a concrete thick wall surrounds the core of the reactor to save the persons working around the reactor from the hazardous radiations.

(6) Uses of nuclear reactor

(i) In electric power generation.

(ii) To produce radioactive isotopes for their use in medical science, agriculture and industry.

(iii) In manufacturing of \[P{{u}^{239}}\] which is used in atom bomb.

(iv) They are used to produce neutron beam of high intensity which is used in the treatment of cancer and nuclear research.