Conversion of Nuclear Energy

• Natural uranium consists of three isotopes of uranium as ₉₂U²³⁸, ₉₂U²³⁵, ₉₃U²³⁴. In natural uranium the availability of U²³⁸ is largest upto the extent of 99.28%, U²³⁵ is only 0.715% which is most unstable and the remainder 0.006% is U²³⁴.
• In ₉₂U²³⁸, number 92 represent 92 protons, number 238 represent its mass number and the difference (238-92) = 146 represent the number of neutrons in it.
• The isotope of an element which is not stable is called radio-active i.e. they convert spontaneously into isotopes of other element during which they emit alpha, beta and gamma radioactive waves.
• According to Albert Einstein the mass and energy are interchangeable and he suggested the following relationship between them :

E =  △m . C²

Where, △E =
energy prodced in Joules

               △m = mass in kg converted
into energy

                   C = speed of light = 3 x 10⁸
m/s

• The nuclear energy can be converted into thermal energy either by radioactive decay, fission or fusion. During the fission process the energy can be released by breaking up the heavy nuclei into the nuclei of intermediate atomic number. In case of fusion process the energy is released by combining the nuclei of light substances like H₂, and He.
• At present only the fission process is used producing large amounts of thermal energy carried out in a nuclear fission reactor.
• Fission of isotope of uranium ₉₂U²³⁵ can casily be carried out. If a neutron is bombarded at high or moderate speeds against the uranium nucleus, the probability is that nucleus will split and release the enormous amount of energy that binds the nucleus together. The chain reaction of U²³⁵is represented in Figure.
• Each fission nucleus releases two or three neutrons which can again hit the uranium nucleus and accelerate the splitting process even if some neutrons are fully absorbed.
• Such a continuous process is called chain reaction. It is observed that a gram of uranium can produce about 0.95 MW of energy per day.
• It is found that plutonium 239 (obtained from U238) and uranium 233 (obtained from uranium 232) both obtained by absorption of neutrons are also capable of being easily split by neutrons, thus producing the enormous amount of energy.
• Therefore, uranium 235, plutonium 239 and uranium 233 are used as nuclear fuels for power generation. These materials are called fissile materials.