Essay on Radioactive Pollution!
Radioactive substances are among the most toxic materials known. The magnitude of their injurious effects is in a range that might be said figuratively to represent a ‘quantum jump’.
H.P. Jammet, Chief of Atomic Hygiene and Radio Pathology, French Atomic Energy Commission, defines radioactive pollution of the environment “as the increase in natural background radiation, emerging from the activities of man involving the use of naturally occurring or artificially produced radioactive materials. The atmosphere screens out much of the sun’s radiation, including most of that which would be lethal to life”.
Naturally occurring, radioactive elements are present in the rocks, water and air, and in all living organisms. The composite of all forms of natural radiation that we are exposed to, is called background radiation. For millions of years, background radiation remained at a relatively constant level.
Recently, however, the radiation that we are normally exposed to has increased and is expected to increase further. Man-made radiation includes that from X-ray machines, radioactive fallout, nuclear reactors, research laboratories, industrial and medical uses of radioactive materials and radioactive wastes from the production of radioactive materials.
Environmental radiation may be divided into two types:
(i) Natural and
Naturally occurring radiations are:
(i) Cosmic radiations from the outer space reaching the earth’s surface, and
(ii) Terrestrial radiation from natural radio-isotopes present in the earth’s crust. Cosmic ray bombardment of the atmosphere continuously produces a few radioactive materials of short half-life.
The half-life of a radionuclide refers to its period of radioactivity and has a bearing on the length of time that a radioactive substance might remain active as an environmental pollutant.
The following table indicates the half-life and radiation of the important radioactive elements:
Man-made radiations originate from the activities of man involving the use of radioactive materials. They are used for the production of nuclear weapons, nuclear fuel and electric power.
One of the most harmful uses of radioactive material is in nuclear weapons, especially in atom bombs. The world has already seen the nature of destruction as well as impact of radioactivity on man and environment during the Second World War when atom bombs were dropped over Hiroshima and Nagasaki—the two Japanese towns.
During the last forty years, there have been a number of nuclear weapon testing’s either in sea or underground, resulting in the increase in the level of radiation of the environment. A study revealed that the radioactive materials which cause such explosions are fission products as Strontium-90, Caesium-137, Iodine-131 and unused explosives. These elements either settle down in the soil or water or remain suspended in the atmosphere, thus becoming a major cause of radioactive pollution.
Nuclear fuels used in the operation of reactors also contribute to radioactive pollution. The heat liberated during fission and activation process is converted into electricity.
During this process, two types of wastes are formed:
(i) The fission products remaining in both the primary and secondary fuels and (ii) extraneous activation products in the coolant.
The disposal of radioactive or nuclear wastes is a great problem and a cause of environmental pollution. It includes remaining metal products at the site of mines, fission products and activation products. These are of three categories, viz., low level, intermediate level and high level. Among these, high level products remain in the environment for several hundred years.
Similarly, leakage in nuclear reactors often becomes the cause not only of environmental pollution but also of the death of hundreds of people as happened in case of leakage at Chernobyl Atomic Reactor in erstwhile USSR on 26 April 1986.