Environmental radiation


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This Lecture is focussed on Environment Hazards of Nuclear Radiation and its Danger for the future of mankind; with special reference to Indo-Pak relations.

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Environmental radiation

  1. 1. ENVIRONMENTAL RADIATION:BOON or BANE H.S. VIRK #360 Sector 71, SAS Nagar Ex-Professor GNDU, Amritsar
  2. 2. References To Literature
  3. 3. INTRODUCTION • The term radiation generally refers to emission and propagation of energy through space in the form of electromagnetic waves. The spectrum of EM waves extends from X-rays to Radio & Micro Waves. For our purpose, Radiation refers to radioactivity and X-rays which were discovered during the last decade of 19th century by Marie Curie & Roentgen. Public interest and concern about environmental radiation has increased during recent times after the Chernobyl reactor accident on 26 April 1986.
  4. 4. Sources of Environmental Radiation • The sources of environmental radiation are both natural and artificial; the bulk of average annual effective dose (2.4 mSv) being contributed by the natural sources of radiation including radon (52.5%) and cosmic rays (16.2%). • Artificial sources include Radioisotopes, Accelerators, Nuclear Reactors and Atomic Bomb Explosions.
  5. 5. Natural Radioactive Decay Series
  6. 6. Artificial Sources of Radiation
  7. 7. Nuclear Radiation Hazards • The first demonstration of environmental contamination due to artificial radioactivity was the Atomic bomb explosions of Hiroshima and Nagasaki. Radiation accidents have been almost nil at accelerators but the most dramatic episode concerning reactor was the Chernobyl accident on 26 April, 1986. Reactor accidents and nuclear explosions have created a mediahype and a ‘nuclear neurosis’ among the general public to veto setting up of any nuclear facility in the neighbourhood or even in remote areas.
  8. 8. Manhattan Project • Beginning with the Manhattan Project, during the World War II, USA created a vast arsenal of nuclear weapons based on plutonium. The inputs came from a number of nuclear complexes spread across the country and they included a number of nuclear reactors to produce plutonium, reprocessing plants to extract plutonium and weapon-research laboratories and production plants. As an example, at Hanford (Washington State), a typical nuclear weapons’ complex, there were 9 nuclear reactors producing plutonium, 5 reprocessing plants and 200 tanks storing nearly 200,000 m3 of high – level radioactive waste.
  9. 9. Nuclear Arsenal in USA • Nearly a thousand weapons were detonated by USA for testing and the arsenal comprised of tens of thousands of weapons. The leftovers from this cold war legacy are believed to contain several large highly-contaminated reprocessing plants, thousands of tons of irradiated fuel in basins that act as ‘radioactive dustbins’, hundreds of underground tanks each containing hundreds of thousands of cubic metres of high-level radioactive waste in hazardous state, dozens of tons of unsecured plutonium and so on.
  10. 10. Nuclear Scenario in Russia • Reports from the European press state that the erstwhile Soviet Union secretly dumped nuclear reactors and radioactive waste into the bordering seas, indicating more damaging nuclear legacy of the Cold War than previously known. It is said that nuclear reactors from at least 18 nuclear submarines and icebreakers were dumped in the Barents Sea. The Russians are reported to have dumped unprocessed nuclear waste into The Sea of Japan. The latest in this scenario is that on 12 August 2000, the giant Russian nuclear submarine Kursk, carrying a crew of 118, sank in the icy waters of the Barents Sea after what Russian officials described as a ‘catastrophe that developed at lightning speed’.
  11. 11. Problem of Radioactive Waste • It may not be wrong to guess that any other weapon-producing complex in any other country also operates in a similar manner. Only the scale of operation may be large or small depending on the resources that are pumped in. The secrecy, callousness in handling the radioactive waste and the problems that each nation faces would be qualitatively no different; quantitatively they increase as weaponization takes deeper roots.
  12. 12. Indo-Pak Nuclear Scenario • Zia Mian et al.(Currernt Science,2001) have reported the estimated risk and health hazard effects of nuclear warheads deployment in South Asia, with particular reference to India and Pakistan. Considering the political situation in the sub-continent, the authors assume that the dangerous situation may change for the worst in the not-too-distant future on the deployment of nuclear weapons.
  13. 13. • Both India and Pakistan have developed a variety of ballistic missiles for carrying nuclear weapons. These missiles are propelled by highly volatile hypergolic liquid propellants and hence the risk of deployment is always there even when there is no nuclear warfare. Using the famous ‘wedge model’ for estimating the effects of a nuclear weapon accident, the authors calculate the number of deaths due to cancer caused by dispersal of plutonium from the nuclear weapons. Any serious accident caused by detonation of propellant/fuel can convert the fissile material of nuclear warhead into aerosol particles which will disperse into the environment.
  14. 14. Probability of Cancer Deaths • There is also a possibility that detonation of a highly explosive propellant/fuel in the pit may trigger in turn the detonation of the nuclear weapon. Such an explosion might be mistaken for a nuclear attack and lead to a nuclear response. Thus there is always a danger that an accidental nuclear explosion may even trigger a nuclear warfare. The dispersal of plutonium aerosols, even without nuclear warfare, may cause 5000 cancer deaths in a metropolitan like Delhi. One can imagine the situation in Punjab!
  15. 15. What is the Solution? • Considering all the facts and figures in this study, the scientists and political leaders of both India and Pakistan must enter into a dialogue for safe deployment of nuclear weapons. The best solution will be to store them far away from missiles carrying potentially explosive fuel. To reduce the risk of a nuclear weapon being launched through error, panic or miscalculation, it is advisable to keep the nuclear weapons disassembled.
  16. 16. Nuclear Radiation Disasters • Nuclear fission was discovered by Otto Hahn, Strassman and Lise Mietner in 1938 in Germany, when they bombarded uranium with neutrons. Enrico Fermi demonstrated the chain reaction in a nuclear pile (reactor) on 2nd December 1942 in Chicago (USA) which led to the making of first Nuclear Bomb (Atomic Bomb) under the Manhattan Project at Los Alamos in the desert of New Mexico (USA). Two thousand million dollars was the budget estimate for Manhattan Project. The test explosion of Atomic Bomb on 16th July 1945 was a complete success.
  17. 17. Demonstration of Nuclear Disaster • The test explosion of Atomic Bomb on 16th July 1945 was a complete success. The First Atomic Bomb was thrown / dropped on Hiroshima on 6th August 1945 and the second on Nagasaki on 9th August 1945. The bomb had the power of 20,000 tons of TNT. Hiroshima nuclear explosion killed 92,133 Japanese and more than 100,000 were permanently injured and disfigured. The disaster was worst in the recorded history of mankind.
  18. 18. Nuclear Bomb Explosion
  19. 19. Japanese Radiation Victim
  20. 20. Public Reaction in the Press • The following lines appeared in an American newspaper after the demonstration of Nuclear Hazard: The Atom Bomb is here to stay, Most scientists agree. Oh, the bomb is here to stay, The question is, are we?
  21. 21. Causes of Nuclear Disaster • • • • Shock Wave: destroys all buildings within a radius of 15 kms. from Ground Zero. Heat Wave: burns all in its path. Nuclear Radiations: in the form of gamma rays and neutrons destroy all living beings. Radioactivity of fission products remains for many years after the nuclear explosion.
  22. 22. Types of Radiation Effects • • • Somatic effects affect the person exposed to radiation and a dose of 600 Roentgen (r) can prove fatal. Genetic effects appear in the successive generations of exposed person. Radiation dose limits are defined for general public and occupational workers by ICRP (International Commission on Radiation Protection) set up under UN. Health Physics is study of protection of man and his environment from unwarranted radiation exposure.
  23. 23. Global Average Whole Body Radiation Dose • The annual average world-wide whole body radiation dose estimated by UNSCEAR (2000) from natural and manmade sources is as follows: • • • • • Natural Background Radiation = 2.4 mSv, Diagnostic Medical Examination = 0.4 mSv, Atmospheric Nuclear Testing = 0.005 mSv Chernobyl Reactor Accident = 0.002 mSv Nuclear Power Production = 0.0002 mSv
  24. 24. • It is evident that nuclear tests, reactor accidents and nuclear power plants contribute negligible amount of radiation dose at global level. More than 80% annual dose is due to natural background radiation, out of which more than 50% is contributed by radon/thoron decay products. Radon –222 and decay products can build up to vary high values in enclosed spaces with poor ventilation, which include mines, cellars, basement areas and air-conditioned energy conservative homes such as in USA and Europe. Radon poses a great health hazard in mines where it emanates from the uranium bearing rocks into the tunnels. Hence the tunnel air will contain very high levels of randon-222, if adequate ventilation is not provided.
  25. 25. Nuclear Radiation as a Boon • Recent studies have established that environmental radiation has been a boon for mankind. The creation of universe with a BigBang was responsible for environmental cosmic radiation about 20 billion years ago. Evolution of life leading to human species had been possible due to radiation exposure. Beneficial health effects of low-level radiation are well-established by some workers (S. Kondo in Japan, 1993 Wei et al. in China, 1990).
  26. 26. Radiation as a Tonic • Health-stimulating effects of natural radon were known to Europeans and the radon spas were used for treatment of patients in Romania, Austria, Hungary, Germany and Russia, more than a century ago. Radium-rich water was used as a tonic. Most of the thermal springs are rich source of radon and have been pilgrimage centres in India, for example, the Manikaran spring is also believed to have miraculous healing powers.
  27. 27. • The radon spas were used for treatment of patients in Austria, Romania, Hungary, Russia and Japan. Treatments at the radon sauna and spas have been reported to be effective for rheumatoid arthritis, spondylosis, neuritis and complications of endocrine and sex harmone systems. Radon spas of Badgastein in Austria, Misasa in Japan, Boulder in USA, Matradrescke in Hungary and Manikaran in India have been used in curing rheumatoid arthritis and other related diseases. Radon spa near Moscow was used for the health recovery of Russian army generals and Politburo members. Radium-rich water was used as a tonic in Europe.
  28. 28. Radiation Hormesis • It has been reported that radiation appears to enhance immunological responses and to modify the balance of hormones in the body. The radiation may be able to stimulate the repair of prior radiation damage, thus strengthening the body’s natural defence mechanism (ICRP, 1991). This response to low dose exposure is referred to as ‘Radiation Hormesis’ or ‘adoptive response’. We may thus conclude that radiation exposure can be both beneficial and harmful depending upon the radiation dose levels in the environment.
  29. 29. Comparison of Risk Factors • • • • • • • For sake of comparison, we compare the risk factors of life, involving a risk of one death in a million: 650 kms of air travel, 100 kms of car travel, smoking ¾ th of a cigarette , drinking half a bottle of wine, using oral contraceptive pills for 2 ½ weeks , exposure to 0.10 mSv of ionising radiation, or living three years in the vicinity of a nuclear power station.