Mahatma gandhi

8 August 2016

Radioactivity is a phenomenon of spontaneous emission of proton (a-particles), electrons (? -particles) and ? -rays (short wave electromagnetic waves) due to disintegration of atomic nuclei of some elements. These cause radioactive pollution. Radiations are of two types ionising and non-ionising. Non-ionising radiations affect only those components which absorb them and have low penetrability. Ionising radiations have high penetration power and cause breakage of macro molecules.

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Man-made sources of radiation pollution are mining and refining of plutonium and thorium, production and explosion and nuclear weapons, nuclear power plants and fuels and preparation of radioactive isotopes. There are commonly three types of radiation, namely: Alpha particles, can be blocked by a piece of paper and human skin. Beta particles can penetrate through skin, while can be blocked by some pieces of glass and metal. Gamma rays can penetrate easily to human skin and damage cells on its way through, reaching far, and can only be blocked by a very thick, strong, massive piece of concrete.

Sources and Methods We can classify major sources that lead to radioactive pollution to the following categories: Nuclear power plants Nuclear weapon Transportation Disposal of nuclear waste Uranium mining Biological effects of radioactive pollution The amount of injury caused by a radioactive isotope depends on its physical half-life, and on how quickly it is absorbed and then excreted by an organism. Most studies of the harmful effects of radiation have been performed on single-celled organisms.

Obviously, the situation is more complex in humans and other multicellular organisms, because a single cell damaged by radiation may indirectly affect other cells in the individual. The most sensitive regions of the human body appear to be those which have many actively dividing cells, such as the skin, gonads, intestine, and tissues that grow blood cells (spleen, bone marrow, lymph organs). Radioactivity is toxic because it forms ions when it reacts with biological molecules. These ions can form free radicals, which damage proteins, membranes, and nucleic acids.

Radioactivity can damage DNA (deoxyribonucleic acid) by destroying individual bases (particularly thymine), by breaking single strands, by breaking double strands, by cross-linking different DNA strands, and by cross-linking DNA and proteins. Damage to DNA can lead to cancers, birth defects, and even death. However, cells have biochemical repair systems which can reverse some of the damaging biological effects of low-level exposures to radioactivity. This allows the body to better tolerate radiation that is delivered at a low dose rate, such as over a longer period of time.

In fact, all humans are exposed to radiation in extremely small doses throughout their life. The biological effects of such small doses over such a long time are almost impossible to measure, and are essentially unknown at present. There is, however, a theoretical possibility that the small amount of radioactivity released into the environment by normally operating nuclear power plants, and by previous atmospheric testing of nuclear weapons, has slightly increased the incidence of certain cancers in human populations. However, scientists have not been able to conclusively show that such an effect has actually occurred.

Currently, there is disagreement among scientists about whether there is a threshold dose for radiation damage to organisms. In other words, is there a dose of radiation below which there are no harmful biological effects? Some scientists maintain that there is no such threshold, and that radiation at any dose carries a finite risk of causing some biological damage. Furthermore, the damage caused by very low doses of radiation may be cumulative, or additive to the damage caused by other harmful agents to which humans are exposed.

Other scientists maintain that there is a threshold dose for radiation damage. They believe that biological repair systems, which are presumably present in all cells, can fix the biological damage caused by extremely low doses of radiation. Thus, these scientists claim that the extremely low doses of radiation to which humans are commonly exposed are not harmful. One of the most informative studies of the harmful effects of radiation is a long-term investigation of the survivors of the 1945 atomic blasts at Hiroshima and Nagasaki by James Neel and his colleagues.

The survivors of these explosions had abnormally high rates of cancer, leukemia, and other diseases. However, there seemed to be no detectable effect on the occurrence of genetic defects in children of the survivors. The radiation dose needed to cause heritable defects in humans is higher than biologists originally expected. Radioactive pollution is an important environmental problem. It could become much worse if extreme vigilance is not utilized in the handling and use of radioactive materials, and in the design and operation of nuclear power plants.

Types and Effects of Radioactive Pollution 1. UV Rays. Short waves having wavelength 100-300 nm and having high energy UV rays of 260nm wavelength are most effective against DNA. It damages the cells of cornea leading to permanent blindness. It injures cells of germinative layer of skin and produces blisters and reddening of skin (skin cancer). Normally our skin possess pigmentation to protect against UV rays but some lack this pigmentation and are more probable cases. This state is called xeroderma pigmentosum. UV rays increase incidences of cancer and mutations in man. 2.

Cosmic rays. They have radiations less than 0. 001A having high energy sufficient to disintegrate every organic compound on which they fall. But fortunately they are trapped in stratosphere and only a little amount reaches the earth. Other radiations are X-rays, background radiations from nuclear fall out which have reached to such an extent they have slowed evolution of various organisms on earth. Effects were noted in 1909 when uranium miners were found to suffer from sun burns and caner. High altitude plants have developed polyploidy as a protective mechanism against radiations.

During a nuclear fall out immediate effect is through isotopic I-131 and Sr-90. Radioactive I-131 get concentrated in thyroid gland like ordinary iodine (I-127). It causes damage to WBCs, bone marrow, spleen, lymph nodes etc. It impairs eyesight and produces sterility, skin cancer and lung tumours. Radioactive Sr-90 is mistaken for calcium and enters bones to cause bone cancer e. g. Historic examples of heinous nuclear fall out are atomic bomb dropping at Nagasaki and Hiroshima (Japan, 1945) How to control radioactive pollution? The radioactive pollution can be controlled by number of ways.

It includes the stoppage of leakage from the radioactive materials including the nuclear reactors, industries and laboratories. The disposal of radioactive material must be safe and secure. They must be stored in the safe places and must be changed into harmless form. The wastes with a very low radiation must be put into the sewage. The nuclear power plants must follow all the safe instructions. The protective garments must be worn by the workers who work in the nuclear plants. The natural radiation must be at the permissible limits and they must not cross it. [edit] Nuclear power plants.

Currently, twenty nuclear power reactors produce 4,780. 00 MW (2. 9% of total installed base). [53][54] Power station Operator State Type Units Total capacity (MW) Kaiga NPCIL Karnataka PHWR 220 x 4 880 Kakrapar NPCIL Gujarat PHWR 220 x 2 440 Kalpakkam NPCIL Tamil Nadu PHWR 220 x 2 440 Narora NPCIL Uttar Pradesh PHWR 220 x 2 440 Rawatbhata NPCIL Rajasthan PHWR 100 x 1 200 x 1 220 x 4 1180 Tarapur NPCIL Maharashtra BWR (PHWR) 160 x 2 540 x 2 1400 Total 20 4780 The projects under construction are:[55] Power station Operator State Type Units Total capacity (MW) Kudankulam NPCIL Tamil Nadu VVER-10001000 x 2 2000 Kalpakkam BHAVINI Tamil Nadu PFBR 500 x 1 500 Kakrapar NPCIL Gujarat PHWR 700 x 2 1400 Rawatbhata NPCIL Rajasthan PHWR 700 x 2 1400 Total What is Radioactive Pollution?

Radioactive pollution can be defined as the emission of high energy particles or radioactive substance into air, water or land due to human activities in the form of radioactive waste. Radioactive waste is usually the product of a nuclear process such as nuclear fission, which is extensively used in nuclear reactors, nuclear weapons and other nuclear fuel-cycles. The radioactivity of nuclear waste diminishes with time.

That means the waste needs to be isolated from the reach of living beings until it no longer pose a threat to living beings. This time period may take from days to months and to years depending upon the radioactive nature of the waste. Radioactive pollution that is spread through the earth’s atmosphere is called “Fallout”. The atmospheric nuclear pollution become prominent during the world war 2 period when United States, Britain and Soviet Union started conducting nuclear tests in the atmosphere. The best example of fallout is the nuclear bomb attack on Hiroshima and Nagasaki, Japan in 1945 by United States of America during world war 2.

As a result of nuclear bomb attack, nearly 2,25,000 people had died as a result of long-term exposure to radiation from the bomb blast within 5 years of attack due to radiation effect and cancer. In land and water, the major source of radioactive pollution remains with the nuclear fuel cycle. The nuclear fuel cycle is used in nuclear power plants, extraction and refinement of materials from nuclear substance to be used in nuclear reactors and nuclear weapons, where the contaminants are left behind after the useful material (Nuclear Isotope) is extracted.

Effects of Radioactive Pollution on human beings: The effects of radioactive pollution or exposure to nuclear radiations were first reported in early 20th century when people working in uranium mines suffered from skin burn and cancer. The effects vary from organism to organism and from level of radioactivity of nuclear isotopes. The radiations destroy the cells in human body and causes cancer. Radioactive particles forms ions when it reacts with biological molecules. These ions then form free radicals which slowly and steadily start destroying proteins, membranes, and nucleic acids.

A longer exposure to radioactive radiations can damage the DNA cells that results in cancer, genetic defects for the generations to come and even death. Sources of radioactive contaminants: Following are the major sources where most of the radioactive waste is generated and is responsible for causing radioactive pollution: Production of nuclear fuel Nuclear power reactors Use of Radionuclides in industries for various applications Nuclear tests carried out by Defense Personnel Disposal of nuclear waste Uranium Mining

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