The document discusses sources of environmental radiation including natural sources like radon and cosmic rays, which contribute most of average annual radiation exposure, as well as artificial sources from radioisotopes, accelerators, nuclear reactors, and atomic bomb explosions. It also examines nuclear weapons programs in countries like the US and Russia and their resulting radioactive waste legacies. Several nuclear radiation disasters are described like atomic bombings in Japan and the Chernobyl accident. Both benefits and risks of low-level radiation are discussed.
6. 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.
7. 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.
15. 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.
16. 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.
17. 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.
18. 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’.
19. 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.
20. 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.
21. • 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.
22. 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!
23. 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.
24. 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.
25. 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.
29. 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?
30. 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.
31. 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.
32. 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
33. • 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.
34.
35. 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).
36. 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.
37. • 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.
38. 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.
39.
40. 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.