18 HM-- RADIATION SOURCES -NATURAL AND MAN MADE

Natural and Man-Made
Radiation Sources
Dr. HARSH MOHAN
DEPARTMENT OF PHYSICS
M. L. N. COLLEGE
YAMUNA NAGAR
HARYANA

Radiation and need for its measurement,
Physical features of radiation, Conventional
sources of radiation,
Exposure to natural radiation: external to the
body, Radiation from cosmic rays and solar
radiation,
Internal exposure to the body,
Radioactivity arising from technological
development:
Possible health hazards from nuclear and laser
radiations

Natural Background Radiation
• Cosmic Radiation
• Terrestrial Radiation
• Internal Radiation

Radiation has always been present and is all around us in many forms
(see Figure ). Life has evolved in a world with significant levels of
ionizing radiation, and our bodies have adapted to it.
Many radioisotopes are naturally occurring, and originated
during the formation of the solar system and through the
interaction of cosmic rays with molecules in the
atmosphere. Tritium is an example of a radioisotope
formed by cosmic rays’ interaction with atmospheric
molecules. Some radioisotopes (such as uranium and
thorium) that were formed when our solar system was
created have half-lives of billions of years, and are still
present in our environment. Background radiation is the
ionizing radiation constantly present in the natural
environment
Introduction

We divide all these radiation sources into different groups:
1. Cosmic radiation. 2. External radiation from natural radioactive sources
(Terrestrial radiation). 3.Internal radioactive sources (radioactivity in the
body). 4. Radon.
Cosmic Radiation
Victor F. Hess discovered the cosmic rays in 1912. In a series of balloon experiments with
ionization chambers he found a noticeably increase from 1,000 m onwards, and at 5 km height
the ionization level was several times that observed at sea level. He concluded that this
ionization was due to radiation from the atmosphere. This radiation is called; Cosmic
radiation.
The cosmic rays were discovered in 1912 by Victor F. Hess. He received
the Nobel prize in physics in 1936 for this discovery.
Victor F. Hess
(1883 – 1964)
The earth’s outer atmosphere is continually bombarded by cosmic
radiation. Usually, cosmic radiation consists of fast moving particles that
exist in space and originate from a variety of sources, including the sun
and other celestial events in the universe. Cosmic rays are mostly
protons but can be other particles or wave energy. Some ionizing
radiation will penetrate the earth’s atmosphere and become absorbed by
humans which results in natural radiation exposure

Cosmic rays may be termed "primary" or "secondary". Those, which have not
yet interacted with matter in the earth's atmosphere, lithosphere, or hydrosphere, are
termed primary. These consist principally of protons (≈85%) and alpha particles
(≈14%), with much smaller fluxes (<1%) of heavier nuclei. Secondary cosmic rays,
which are produced by interactions of the primary rays and atmosphere, consist
largely of subatomic particles such as pions, muons, and electrons. At sea level,
nearly all the observed cosmic radiation consists of secondary cosmic rays, with
some 68% of the flux accounted for by muons and 30% by electrons. Less than 1%
of the flux at sea level consists of protons
Cosmic Radiation
Primary cosmic rays usually possess tremendous kinetic energy. These rays are
positively charged and gain energy by acceleration within the magnetic fields. In the
vacuum of outer space, charged particles may exist for long periods of time and
travel millions of light years. During this flight, they gain high kinetic energies, on
the order of 2 to 30 GeV (1 GeV = 109 eV). Occasional particles having energies up
to 1010 GeV have been observed
The origin of the high energy particles is from outer space. It is assumed that
particles with an energy up to about 1015 eV are coming from our own galaxy,
whereas those with the highest energies probably have an extragalactic origin

The high energies of primary cosmic rays enable them to literally
blast apart atoms in the earth's atmosphere upon collision. Such high-
energy reactions are termed "fragmentation", depending upon the size
of the fragments and of the residual nucleus. Notice that the
cataclysmic reaction, as well as neutrons, protons and subatomic
particles may form lighter elements, such as hydrogen, helium, and
beryllium. Muons are always charged and also decay rapidly to
electrons or positrons.
Cosmic Radiation
A considerable number of radionuclides are continuously produced in
the atmosphere by cosmic ray interactions with matter (Table 1). Most
of these radionuclides are produced as fragments, but some are
formed by activation of stable atoms with neutrons or muons. The
natural production of radionuclides in the atmosphere shows
elevational and latitudinal patterns similar to those of cosmic ray
intensities. About 70% of the fragmentation-produced nuclides arise
in the stratosphere, while about 30% are formed in the troposphere

With the possible exceptions of H-3
and C-14, the radionuclides are
normally found in very minute
concentrations. Tritium is diluted and
mixed with the earth's water and H-2
gas reservoirs, while C-14 combines
with oxygen to form CO2, which
mixes with the atmospheric CO2 pool.
Carbon-14 enters plants through the
process of photosynthesis.
Solar wind contribution
A small component of the cosmic rays is generated near the surface of the sun by
magnetic disturbances. These solar particle events (solar flares) are comprised
mostly of protons of energies below 100 MeV and only rarely above 10 GeV .
These particles can produce significant dose rates at high altitudes, but only the
most energetic ones affect the dose rates at ground level
Cosmic Radiation

Path of incoming solar radiation

Albedo: a measure of how well a surface reflects in isolation

Cosmic Radiation
The high-energy particles hitting the atmosphere interact with atoms and molecules
in the air. This results in a complex set of secondary charged as well as uncharged
particles, including protons, neutrons, pions and some other particles. These
secondary nucleons in turn generate more particles, and we get a cascade in the
atmosphere. Neutrons, which have a long free pathway, dominate the particle
component at lower altitudes. The neutron energy distribution peaks between 50
and 500 MeV and with a lower energy peak, around 1MeV
The pions generated in the nuclear interactions are an important component of the
cosmic radiation field in the atmosphere. The neutral pions decay into high-energy
photons, which produce high-energy electrons, which in turn produce photons etc.,
thus producing the electromagnetic, or photon/electron, cascade. Electrons and
positrons dominate the charged particle fluency rate at middle altitudes. The
charged pions decay into muons, whose long mean free path in the atmosphere
makes them thedominant component of the charged-particle flux at ground level.
They are also accompanied by a small flux of collision electrons generated along
their path.

we have a complex picture of radiation from ground level and up to the top of the
atmosphere. In recent years the radiation intensity in the atmosphere has been
measured – and we can give some details about doses at ground level – and also
present information about doses at aircraft altitudes.
Cosmic Radiation

Altitude Dependence of Cosmic Ray Dose
(dose equivalent; does not include the neutron component).
Altitude, m
(ft)
Dose Rate,
mrem/y
Example
Sea level 31 Los Angeles
1,525 (5,000) 55 Denver
3,050 (10,000) 137 Leadville,
Colo.
9,140 (30,000) 1900 Normal jetliner
15,240
(50,000)
8750 Concorde
24,340
(80,000)
12,200 Spy plane

Cosmic Radiation
Cosmic rays are extremely energetic particles,
primarily protons, which originate in the sun,
other stars and from violent cataclysms in the
far reaches of space. Cosmic ray particles
interact with the upper atmosphere of the earth
and produce showers of lower energy
particles. Many of these lower energy particles
are absorbed by the earth's atmosphere. At sea
level, cosmic radiation is composed mainly of
muons, with some gamma-rays, neutrons and
electrons.
Because the earth's atmosphere acts as a shield the average amount of exposure to
cosmic radiation that a person gets in the Unites States roughly doubles for every
6,000 foot increase in elevation.

Cosmic Radiation
• The earth, and all living things on it, are
constantly being bombarded by radiation
from outer space (~ 80% protons and 10%
alpha particles).
• Charged particles from the sun and stars
interact with the earth’s atmosphere and
magnetic field to produce a shower of
radiation.
• The amount of cosmic radiation varies in
different parts of the world due to differences
in elevation and to the effects of the earth’s
magnetic field.

Natural Sources of Radiation
Source Annual Dose
(Sv)
Radon and thoron gas from rocks and
soil
800
Gamma rays from ground 400
Carbon and potassium in your body 370
Cosmic rays at ground level 300
Total = 1870

2. External radiation from natural sources
The composition of the earth’s crust is a major source of natural radiation. The main
contributors are natural deposits of uranium, potassium and thorium which, in the
process of natural decay, will release small amounts of ionizing radiation. Uranium
and thorium are found essentially everywhere. Traces of these minerals are also
found in building materials so exposure to natural radiation can occur from indoors
as well as outdoors.
Terrestrial radiation Radio nuclides, which appeared on the Earth at the time of
formation of the Earth, are termed "primordial".
Of the many radio nuclides that must have been formed with the Earth, only a few
have half-lives sufficiently long to explain their current existence. If the Earth was
formed about 6⋅109 years ago, a primordial radionuclide would need a half-life of at
least 108 years to still be present in measurable quantities. Of the primordial radio
nuclides that are still detectable, three are of overwhelming significance. These are
K-40, U-238 and Th-232. Uranium and thorium each initiate a chain of radioactive
progeny, which are nearly always found in the presence of the parent nuclides .
Other primordial long-lived radio nuclides which occur in nature are Rb-87, La-138,
Ce-142, Sm-147, Lu-176 etc. Those radio nuclides are generally have very low
concentrations.

Even though the primordial radionuclides are everywhere, their concentrations
vary substantially with location. The main reservoir of natural radioactivity is the
lithosphere. However, considerable variation in radioactivity exists within the
lithosphere. Some variations appear associated with specific types of formations
and certain minerals, while other variations appear to be strictly regional, with
little correlation to types of rocks and minerals.
Figure1.Majorpathwas
of primordial radio
nuclides and important
offspring in terrestrial
ecosystem. Symbols:
K- potassium isotopes,
U - uranium isotopes,
Th - thorium isotopes,
Ra - radium isotopes,
Rn - radon isotopes

Weathering of bedrock, the main reservoir of the primordial radionuclides, releases
U, Th, and K to the soil.From soil, K, Ra, small amounts of U and extremely small
quantities of Th are taken up by plants. The plants utilize potassium-40 in the same
manner as it uses the essential element, stable K. Radium, an important longer-lived
progeny of U-238, is utilized by the plant, not because it is an isotope of an essential
element, but because it is chemically similar to calcium, which is essential. The
uptake of U and Th by plants is usually small or negligible since these radionuclides
normally are relatively insoluble.
Radon The most important of all sources of natural radiation is tasteless, odorless,
invisible gas about eight times heavier than air, called radon.
It has two main isotopes – Radon-222, one of the radionuclides in the sequence
formed by the decay of U-238, and Radon-220, produced during the decay series of
Th-232. Bedrock, soil, plants, animals, and decomposer compartments all release
radon to the atmosphere. Radon is the decay product of radium and is produced in
any material containing radium. Since radon is one of the inert gases, it can escape
from surfaces, which are in contact with the atmosphere . Radon and its first 4 decay
products, with rather short half-lives, are called the "radon family". We find one
radon family in the uranium-radium series and one family in the thorium-series (also
called the "thoron family").

Radon is a noble gas and does not combine chemically with other atoms or
molecules. The radon gas may be released from the place where it is formed and
come into the atmosphere, both outside and into houses.
Radon
The half-lives for the two radon isotopes are 3.82 days and 55.6 seconds
respectively. Both radon isotopes disintegrates into negative metal ions (called
"radon daughters"). These ions become attached to water molecules and other
molecules in the air and get a diameter of about 5 nm. In this form the radon
daughters are considered to be free. The majority of the radon daughters become
attached to larger aerosol particles in the air (from 50 – 500 nm in diameter). Both
the free and the bound daughters will deposit on the walls, roof and floor inside and
to the ground, trees, houses, etc. outside. Consequently, it will never be equilibrium
between radon and radon daughters in the air we are breathing. The radiation from
radon and its decay products is a mixture of α-particles and β-particles as well as γ-
radiation. As long as these isotopes are outside the body, only the γ-radiation will
be able to give a dose. However, when the isotopes come inside the body, all types
of radiation contribute. Since the α-particles have the largest energy (in the range
from 5 to 8 MeV) they are the most important for the dose (more than 80 % of the
absorbed energy is due to the α-particles).

The amount of isotopes ingested with the food is negligible, and all concern is
about the breathing and the deposition of radon daughters in the bronchi and in the
lungs. For a long time we have been aware of the health risks associated with high
radon exposures in underground mines, but relatively little attention was paid to
environmental radon exposures until the 1970s, when some scientists began to
realize that indoor radon exposures could be quite high, because the local
concentration of uranium and/or thorium is high. At the same time the radiation
weight factor of 20 was introduced for the α particles in the radon family.
Radon

Radon It is important to note that radon is a noble gas, whereas all the other
isotopes in the two families are metals.
The gas may be trapped in the soil until it decays, but it is the only isotope that also
has a chance to be released to the air. When radon disintegrates, the metallic
daughters are ions that will be attached to other molecules like water and to aerosol
particles in the air. The radon concentrations in the soil within a few meters of the
surface are important for the entry into the atmosphere. The main mechanism for
this is molecular diffusion. The concentrations of Rn-222 in soil vary over many
orders of magnitude from place to place and show significant time variations at any
given site. Because of the short half-life of thoron (Rn-220) in the soil, a large
fraction of the atoms will disintegrate before they reach the surface.
Radon into the houses Several possibilities exist for the release of radon into houses
The main sources are the rock or soil on which the house is built, as well as the
water supply. The rock formations under a house always contain some radium and
the radon gas can penetrate into the house through cracks in the floor and walls of
the basement. Furthermore, the building materials is also a source for radon.
Another source for radon is the water supply. Water from wells, in particular in
regions with radium rich granite, may contain high radon concentrations. When
water is the carrier, the radon gas is readily released.

The indoor radon concentrations usually show
an annual variation with the largest values
during the winter. This is quite usual in places
with frost on the ground. The frost makes it
difficult for the gas to diffuse out of the
surrounding ground and to be released directly
into the air. Consequently,
the radon gas is more likely to seep into the
house. It is the radon concentration averaged
over a long-time that is important with regard
to health risk and, consequently, remediation.
Decisions on what action to take are generally
based on an average annual level.
Radon (world average)
UNSCEAR 2000
Outdoor: 10 Bq m–3
Indoor: 46 Bq m–3

Terrestrial Radiation
(Uranium, Actinium, Thorium decay series)
• Radioactive material is found throughout
nature in soil, water, and vegetation.
• Important radioactive elements include
uranium and thorium and their radioactive
decay products which have been present
since the earth was formed billions of years
ago.
• Some radioactive material is ingested with
food and water. Radon gas, a radioactive
decay product of uranium is inhaled.
• The amount of terrestrial radiation varies in
different parts of the world due to different
concentrations of uranium and thorium in soil.

Radioactivity in the Earth
When the earth was formed it
contained many radioactive
isotopes. The shorter lived
isotopes have decayed leaving only
those isotopes with very long half
lives along with the isotopes
formed from the decay of the long
lived isotopes. These naturally-
occurring isotopes include U, Th
and their decay products, such as
Rn.

3. Internal Radioactivity (sources inside the body)
The food we eat and the air we breathe contains radioactive isotopes. Dust particles
in the air contain isotopes of both the U-238 and the Th-232 series. We have
therefore small amounts of radioactivity in our bodies. The most important isotope
with regard to dose is K-40. The daily consumption of potassium is approximately
2.5 gram. From this we calculate that each day eat about 75 Bq of K-40. Potassium
is present in all cells making up soft tissue. The potassium content per kilogram
body weight will vary according to sex and age. The dose due to K-40 will of
course also vary in a similar way.
K-40
The other naturally occurring radioactive
isotopes which come into our bodies are C-
14 and a number of isotopes from the
Uranium family (U-238, Th-230, Ra-226,
Pb-210 and Po-210). From the thorium
family (Th-232, Ra-228, Th-220 and U-235)

C-14
This isotope is formed in the atmosphere when neutrons react with nitrogen. C-14 is
taken up by plants in the form of carbon dioxide, CO2. The amount of C-14 in the
body is about 35 Bq/kg. C-14 emits a β-particle with maximum energy 156 keV – an
average energy of 52 keV per disintegration. This would yield a body dose of
approximately 10 mGy per year = 0.01 mGy/year or 0.01 mSv/year.
Uranium and thorium series radio nuclides
UNSCEAR have, based on a large number of investigations, presented values
about the annual intake by humans of the different isotopes. We can mention the
following; Ra-226 (22 Bq/year), Pb-210 (30 Bq/year), Po-210 (58 Bq/year) and
Ra-228 (15 Bq/year). The other isotopes have smaller intake. Based on the
concentrations of radioisotopes in foods and the consumption rates for infants,
children, and adults the concentrations in the body have been calculated.
Furthermore, the distribution throughout the body has been calculated based on
models. U-isotopes, Ra-isotopes, Pb-210 and Po-210 are concentrated mainly to
the bone (about 70 %). Based on all the data from the different countries the
UNSCEAR 2000 report arrive at an annual effective dose of 0.12 mSv. The main
contributor to this dose is Po-210 (α-emitter).The amount of polonium in food
varies. It is particularly high in reindeer and caribou meat because it concentrates
in lichen, an important food source for these animals. The tobacco plant also takes
up Po-210; thus, smokers get an extra radiation dose to their lungs.

K-40
If we sum up this, we can conclude that the world average effective dose due to
the natural isotopes is; 301 μ Sv per year – or 0.3 m Sv/year

Internal Radiation
• People are exposed to radiation from radioactive
material inside their bodies. Besides radon, the most
important internal radioactive element is naturally
occurring K-40, but uranium and thorium are also
present as well as H-3 and C-14.
• The amount of radiation from potassium-40 does not
vary much from one person to another. However,
exposure from radon varies significantly from place to
place depending on the amount of uranium in the soil.
• On average, in the United States radon contributes
55% or all radiation exposure from natural and man-
made sources. Another 11% comes from the other
radioactive materials inside the body.

Natural Radioactivity in the Body
Small traces of many naturally
occurring radioactive materials
are present in the human body.
These come mainly from
naturally radioactive isotopes
present in the food we eat and
in the air we breathe.
These isotopes include tritium
(H-3), carbon-14 (C-14), and
potassium-40 (K-40).

Enhanced Natural Sources
• Air travel (cosmic rad. is increased)
• Accumulation of rad. material
(uranium)
• Consumer products (radium dials,
smoke detectors)

Man-Made Radiation/Artificial sources of ionizing radiation/
Radioactivity arising from technological development
Over the last few decades man has "artificially" produced several hundred radio
nuclides. And he has learned to use the power of the atom for a wide variety of
purposes, from medicine to weapons, from the production of energy to the
detection of fires, from illuminating watches to prospect for minerals.
The following are the most common sources :
• Medical sources:
• Industrial sources:
• Nuclear Explosions/bomb :
• Nuclear Power
Nuclear and Radiation accidents

Radioactive material is used in:
• Medicine - diagnostic (X-ray, CAT)
• Medicine - therapeutic (Co-60, Linac)
• Medical research (radio-pharmaceuticals, accel.)
• Industry - (X-ray density gauges, well logging)
Man-Made Radiation

Man-Made Radiation Sources
• Exposure of selected groups of the
public:
– diagnostic radiology (X-rays)
– nuclear medicine
(radiopharmaceuticals)
– radiotherapy (Co-60, Linacs)

Man-Made Radiation Sources
• Medical sources:
The use of radioisotopes in medicine is widespread and may potentially have
significant radiological impact. These applications can be classified as (1)
diagnostic uses, (2) therapy, (3) analytical procedures and (4) pacemakers and
similar portable sources. Both sealed sources and a wide variety of radioactive
tracers are used in diagnostic applications; medical institutions usually distinguish
carefully between these two applications as Radiology and Nuclear Medicine,
respectively. X-ray fluoroscopy is a well-known diagnostic radiographic procedure,
typically employing an X-ray tube as source. However, there is variety of isotopic
source applications for medical radiography, employing gamma sources, beta
sources and, experimentally, neutron sources for image formation under conditions
where X-ray units would be inconvenient, inappropriate, or might cause
operational hazards. Environmentally, radiographic sources are negligible as source
terms as long as they remain accountable and are disposed of properly. In that
respect, the history of radium sources, radon needles, and radium-containing
luminescent compounds has not been encouraging.

• Medical sources: Occupational exposures from work on radium-containing watch dials
and tritiated luminous signs have been substantial and radium-
contaminated rooms and buildings, many of them dating to the early
decades of this century, are being found from time to time all over the
world.
The emergence of 252Cf as a portable neutron source has made neutron radiography
more widely available, although generally the method is still heavily dependent on
nuclear reactors as sources. There are also a number of routine applications for 90Sr or
147Pm-based bremsstrahlung sources. The major potential environmental impact
arises from the use of radioactive tracers in nuclear medicine, a field that has grown
enormously in recent years. Nuclear medicine exposures can be classified as (1)
exposure of the patient, (2) exposure of hospital personnel, (3) exposure during
transport of radioactive pharmaceuticals, (4) exposure during manufacture and (5)
exposure from radioactive waste .
Most often radionuclides used in medicine are:
99mTc – bone marrow scan, brain scan, cerebral blood scan, heart scan, liver scan, lung scan,
thyroid scan, placental localization;
131I – blood volume, liver scan, placental localization, thyroid scan, and thyroid therapy;
51Cr – red blood cell survival or sequestration, blood volume;
57Co – schilling test;
32P – bone metastases;

• Industrial sources:
Radioisotopes are much more widely used in industry
than is generally recognized and represent a significant
component in the man-made radiation environment
The principal applications include industrial radiography,
radiation gauging, smoke detectors and self-luminous
materials. Because most of these applications entail the
utilization of encapsulated sources, radiation exposures
would be expected to occur mainly externally during
shipment, transfer, maintenance, and disposal.

Table ---lists the principal radio nuclides involved and typical applications

• Nuclear Power
The production of nuclear power is much the most controversial of all the man-
made sources of radiation. yet it makes a very small contribution to human
exposure. In normal operation, most nuclear facilities emit very little radiation to
the environment. This starts with the mining and milling of uranium ore and
proceeds to the making of nuclear fuel. After use in power stations the irradiated
fuel is sometimes "reprocessed" to recover uranium and plutonium. Eventually the
cycle will end with the disposal of nuclear wastes. At each stage in this cycle
radioactive materials can be released . About half of the world's uranium ore comes
from open cast mines and half from underground ones. It is then taken to mills,
usually nearby, for reprocessing. Mills produce large amount of waste or "tailings"
– totally hundreds of millions tones. The wastes remain radioactive millions of
years after mills cease operation albeit resulting in radiation exposure that are very
small fraction of natural background . After leaving the mills, uranium is turned
into fuel by further processing and purification and, usually, by passing through an
enrichment plant. These processes give rise to both airborne and liquid discharges,
but effects are very much smaller than from other parts of fuel cycle

Figure - showing the kinds of materials that can be released to the environment.
The quantities of different types
of radioactive materials released
from these reactors vary widely,
not only from type to types, but
even between different designs
within these types,

Nuclear and Radiation accidents Some severe nuclear and radiation accidents are
created radioactive contamination in the
environment. we have had four major reactor accidents with release of radioactive
isotopes. briefly mention the following accidents in chronological order:
1.Kyshtym – September 29, 1957 (and in 1967). 2. Wind scale – October 10,
1957.3. Three Mile Island – March 28, 1979. 4. Chernobyl – April 26, 1986.
5. Fukushima – March 11. 2011 .The Chernobyl accident is the most serious
one.
Kyshtym It was in the Chelyabinsk province, about 15 kilometers east of the city of
Kyshtym on the east side of the southern Urals
that Igor Kurchatov built the first plutonium production reactor for the bomb program. The
first reactor was built in 18 months and several more reactors were built – mainly for the
production of plutonium. The area is now polluted by radioactivity, due to accidents and bad
handling of radioactive waste.
In September 1957, the cooling system of a radioactive waste containment unit
malfunctioned and exploded – and released a large amount of isotopes. The radioactive
cloud moved towards the northeast, reaching 300–350 kilometers from the accident. The
fallout of the cloud resulted in a long-term contamination of an area of more than 800
square kilometers with Cs-137, Sr-90 (α β-emitter with half-life 29.2 years), Zr-95 (65
days), Ce-144 (284 days) and others. Cs-137 and Sr-90 are of importance with regard to
extra doses to the people in the region. A region of 23 000 km2 was contaminated to a
level of more than 1 Ci/km2 (equal to 37 000 Bq/m2).

Kyshtym
Here is a map of the area for the atomic accident in Kyshtym. The fallout area is shown and
marked by red color. It is stretched out more than 100 km. Some values for the total fallout is
given on the map. All these values, as well as the doses to the people involved are mainly
estimates. Extra annual doses via the food of 0.1 mGy have been mentioned
The last event in this region happened in 1967. A small lake (Lake Karachy) that was used for
waste disposals and during the long hot summer of 1967 the lake dried up and wind re
suspended the sediments. About 22 • 109 Bq of Cs-137, Sr-90 and Ce-144 was released to
the nearby region.

Wind scale The Windscale reactors in Cumberland, England were built in order to
produce plutonium for a fission bomb.
The work started in 1947 and the first bomb was tested in Australia in October
1952. The two reactors in Windscale (today Sellafield) used graphite as moderator.
they used to release the energy by annealing – and it was during such an annealing
process the fire started on October 10, 1957. It was just a fight in order to stop the
fire. The core was burning for about one day and they managed to stop it by water.
The fire resulted in the release of radioactive isotopes such as I-131, Cs-137, Ru-
106, Xe-133 and even Po-210. Altogether about 700 TBq was released. I-131 was
considered to be the main problem – and it was found in the milk the day after. As a
result the milk from a region of 500 km2 was dumped into the Irish Sea for a month.
The highest activity of 50,000 Bq/l was found in milk from a farm about 15 km
from the reactor. Furthermore, as a result of this accident it was decided that milk
with an activity of more than 0.1 mCi per liter (3700 Bq per liter) could not be sold.
It was calculated that the thyroid dose to the people in the area was 5 – 20 mGy for
adults and 10 – 60 mGy for children.

Three Mile Island A well-publicized accident happened on Three Mile Island near
Harrisburg, Pennsylvania, March 28, 1979. It was the most
serious in U.S. commercial nuclear power plant operating history, even though it led
to no deaths or injuries to plant workers or members of the nearby community. But
it brought about sweeping changes involving emergency response planning, reactor
operator training, human factors engineering, radiation protection, and many other
areas of nuclear power plant operations. It also caused the U.S. Nuclear Regulatory
Commission to tighten and heighten its regulatory oversight. Resultant changes in
the nuclear power industry and at the NRC had the effect of enhancing safety.
The cooling on a pressurized water reactor (PWR) was lost, and parts of the reactor
core melted down in the course of 6 to 7 hours before the reactor was covered with
water. The reactor had a safety container and only minor amounts of radioactivity
were released. In fact, the activity released was smaller than that normally released
every year from the natural radioactive sources in Badgastein, Austria,
Because of some misunderstanding between the Nuclear Regulatory Commission
and the authorities, it was recommended that children and pregnant women, living
within 8 km from the reactor be evacuated. This recommendation, which was quite
unnecessary, had the unfortunate consequence of raising anxiety and fear among
the public.

There was also a huge nuclear accident at the Chernobyl
Nuclear Power station in the former USSR in 1986.
Workers there were carrying out experiments on the
reactor rods which caused fires to start. A number of
firemen were exposed to very large amounts of radiation
and 31 people died as a result.
The damage to the power station was extensive and the
radiation effects over a wide area were considerable.
Chernobyl Nuclear Power Station

 135 000 people were removed from an area within a
radius of 30 km.
 The smoke and radioactive debris reached a height of
1200 m and travelled across Russia, Poland and
Scandinavia.
 A cloud of material from the accident reached the UK
and, with heavy rain, there was material deposited on parts
of north Wales, Cumbria and Scotland. This caused certain
farm animals (e.g. lambs) to be banned from sale as they
had absorbed radiation from the grass.
Chernobyl Nuclear Power Station

Chernobyl
A picture from 1986, just after the accident

A new picture which shows that the reactor is buried in
Chernobyl

On 26 April 1986, the most serious accident in the history of the
nuclear industry occurred at Unit 4 of the Chernobyl nuclear power
Chernobyl
plant in the former Ukrainian Republic of the Union of Soviet Socialist
Republics, near the common borders of Belarus, the Russian Federation and
Ukraine.
The safety systems had been switched off, and improper, unstable operation of the
reactor allowed an uncontrollable power surge to occur, resulting in successive steam
explosions that severely damaged the reactor building and completely destroyed the
reactor The steam explosion, might have lifted the reactor core and all water left the
reactor core. This resulted in an extremely rapid increase in reactivity, which led to
vaporization of part of the fuel at the centre of some fuel assemblies and which was
terminated by a large explosion attributable to rapid expansion of the fuel vapor
disassembling the core. The explosion blew the core apart and destroyed most of the
building. The dramatic accident which happened at 1.24 on April 26 was known to
the world a couple of days later when the released radioactivity reached Poland and
Sweden. Major releases of radionuclides from the Chernobyl reactor continued for
ten days . The total release of radioactive material was about 14 EBq (1EBq = 1018
Bq), including 1.8 EBq of 131I, 0.085 EBq of 137Cs, 0.01 EBq of 90Sr and 0.003 EBq
of plutonium isotopes. Radioactive noble gases contributed about 50% of the total
activity released.

Chernobyl During the first days after the accident, the wind direction was to the
northwest (towards Scandinavia).Considerable amounts of fission
products were transported to the middle regions of Sweden and Norway.
Unfortunately, it was raining in some of these areas and the fallout was consequently
large. Thus, in parts of Sweden (the area around Gävle, north of Stockholm) and in
Norway the fallout of Cs-137 reached up to 100 kBq/m2 (about 3 Ci/km2). The
average value, however, was much smaller and on the order of 5 to 10 kBq/m2.

plutonium the colored area indicate
levels above 3700 Bq/m2
Sr-90 the darkest colored area
indicates a deposition above 111
kBq/m2. The dashed circle indicate
30 km from the reactor
Chernobyl

In the table below we give some of the most important data for the
release of isotopes
Chernobyl

On March 11, 2011 an earthquake, of the order 9.0 on the Richter scale,
occurred off the northeast coast of Japan and the tsunami that followed
killed about 19 000. The height of the tsunami varied considerably and
maximum has been calculated to 127 feet.

Radioactivity was released (mainly I-131 and the cesium isotopes
(Cs-137 and Cs-134) to the environment .In August 2011, the
Nuclear Safety Commission (NSC) of Japan published the following
results. for the total amount of radioactive materials released into the
Fukushima
the air during the accident at Fukushima. The
total amounts released between March 11 and
April 5 were 130 • 1015 Bq (130 pBq) I-131 and
11 • 1015 Bq Cs-137. This is approximately 10
% of the Chernobyl release. The nuclear
accident was eventually classified at Level 7,
the highest on the International Nuclear and
Radiological Event Scale (INES). No radiation-
related deaths or acute effects have been
observed among nearly 25,000 workers
involved. The thyroid doses from iodine-131
ranged up to several tens of milli gray and were
received within a few weeks after the accident.
The whole-body (or effective) doses mainly
from caesium-134 and caesium-137 ranged up
to ten or so milli gray

• Nuclear bomb /Explosions: Nuclear Bombs
In an atomic bomb, a mass of fissile material, greater than the critical mass, must
be assembled instantaneously and held together for about a millionth of a second
to permit the chain reaction to propagate before the bomb explodes. During the
war the "Manhatten project" included the most competent physicists in the world
with the purpose to construct a fission bomb. A laboratory was built in Los
Alamos, New Mexico, in late 1944. On the lava flows of an extinct volcano 35
miles north of Santa Fe. Robert Oppenheimer, a brilliant physicist from the
University of California, led the development of the first nuclear fission
weapons.The fissionable materials, solid uranium tetrafluoride from Oak Ridge
and plutonium nitrate paste from Hanford, began to arrive at a Los Alamos, and
chemists purified the two metals and metallurgists shaped them into forms
suitable for the weapons. Two possible mechanisms were worked out in order to
bring the fissile material together and reach critical mass or above. In the "gun
method" two subcritical masses were brought together and in the "implosion
method" the fissile material formed in a hollow sphere were forced together.

During the Second World War, two atomic bombs
were dropped on Hiroshima and Nagasaki in Japan.
Those people who survived the blast were exposed
to a large dose of radiation. Such doses caused
severe damage to cells all over the body, especially
in the skin, blood, bone tissue and gut.
Many of these people died within a few weeks.
Those people who were exposed to a smaller dose
recovered from such immediate effects.
WW2 – Hiroshima and Nagasaki

The Bombs
Over Hiroshima
~Named “Little Boy”
Size=8,900 pounds
Over Nagasaki
~Named “Fat Man”
Size=10,800 pounds

Mushroom Cloud of Hiroshima
Smoke had billowed 20,000 feet in the air and had spread 10,000 feet on the
target.

Mushroom Cloud over Nagasaki
The cloud was at a height of 60,000 feet.

The Bombing:
Nagasaki
Before After

The Mushroom Cloud
8:15 AM, “The
Little Boy” was
dropped over the
center of Hiroshima
It exploded about
2,000 ft. above
the city and had a
blast the equivalent
to 13 kilotons of
TNT.
Due to radiation,
approximately
152,437 additional
people have died.

• Primary source of information:
• 86,500 individuals of:
• both sexes and
• all ages
• dosimetric data over a range of doses
• Average dose – 0.27 Sv
• ~ 6,000 individuals exposed in dose >
0.1 Sv
• ~ 700 individuals exposed in dose > 1
Sv
Hiroshima and Nagasaki

Purpura, Vomiting, …
Purpura, or bleeding under the skin, is one of the symptoms of acute
radiation sickness. The heavily exposed survivors experienced fever,
nausea, vomiting, lack of appetite, bloody diarrhea, epilation, purpura,
sores in their throat or mouth (nasopharyngeal ulcers), and decay and
ulceration of the gums about the teeth (necrotic gingivitis). The time of
onset of these symptoms depends on the exposure level.

• Nuclear Explosions/ test bomb : For the last 50 years, everyone has been
exposed due to radiation from fall-out from
nuclear weapons. Almost all is the result of atmospheric nuclear explosions carried
out to test nuclear weapon. This testing reached two peaks: first between 1954 and
1958 and second, greater, in 1961 and 1962 . Several nuclear tests were performed in
the lower atmosphere. When a blast takes place on the ground or in the atmosphere
near the ground, large amounts of activation products are formed from surface
materials. The fallout is particularly significant in the neighborhood of the test site.
The first fission test was the one in New Mexico on July 16. 1945 – and
the first fusion test took place at the Eniwetok atoll in the Marshall Islands
on November 1. in 1952 (the Mike test). The largest nuclear weapon ever
tested was the "Tsar Bomba" of the Soviet Union at Novaya Zemlya on
October 30, 1961, with an estimated yield of around 57 megatons. The
fallout from this explosion as well as the other atmospheric tests at Novaya
Zemlya was considerable for Scandinavia.

Nuclear weapon tests sites
The first nuclear bomb test took place near Almagordo in New Mexico
(marked 9 in the map) in July of 1945. Since then, the United States, the
Soviet Union, England, France, China, India, Pakistan and Korea have
tested the weapons in the air, on the ground and under ground. The map
below shows most of the places used for these nuclear tests.

The following test sites are marked in the map: 1. Alaska (US) -- 3 Tests, 2.
Johnston Island (US) -- 12 tests, 3. Christmas Island (UK & US) -- 30 tests, 4.
Malden Island (UK) -- 3 tests, 5. Fangataufa Atoll (France) -- 12 tests, 6.
Mururoa Atoll (France) -- 175 tests, 7. Nevada (US) -- 935 tests, 8. Colorado
(US) -- 2 tests, 9. New Mexico (US) -- 2 tests, 10. Mississippi (US) -- 2 tests, 11.
South Atlantic Ocean (US) -- 12 tests, 12. Algeria (France) -- 17 tests, 13. Russia
(USSR) -- 214 tests (many at Novaya Zemlya), 14. Ukraine (USSR) -- 2 tests,
15. Kazakhstan (USSR) -- 496 tests, 16. Uzbekistan (USSR) -- 2 tests, 17.
Turkmenistan (USSR) -- 1 test, 18. Pakistan (Pakistan) -- 2 tests, 19. India
(India) -- 4 tests, 20. Lop Nur (China) -- 41 tests, 21. Marshall Islands (US) -- 66
tests, 22. Australia (UK) -- 12 tests
The "fallout" of radioactive isotopes from the bomb tests, depends on the type of
bomb and, most of all, whether the bomb is detonated in the air, on the ground or
underground. The fallout of radioactive isotopes is due to the atmospheric tests.
Furthermore, if the explosions take place at altitudes where the so called "fire ball"
reach the ground a large amount of radioactive isotopes may be formed. For the
atmospheric nuclear tests a considerable amount of radioactivity reach the
stratosphere. Due to the low exchange between the troposphere and stratosphere
these isotopes may stay for a long time in the stratosphere.

In general
Because of the extreme temperature of a nuclear explosion, the radioactive material
becomes finely distributed in the atmosphere. A certain fraction is kept in the
troposphere (the lower 10 km) and is carried by the wind systems almost at the
same latitude as the explosion. This part of the radioactive release will gradually
fall out, the average time in the atmosphere being about one month. The main
fraction of the radioactive debris from an atmospheric test goes up into the
stratosphere (10 to 50 km). This fraction can remain in the stratosphere for years
since there is a very slow exchange between the troposphere and the stratosphere.
The fallout consists of several hundred radioactive isotopes; however, only a few
give significant doses. The most important are the following:
• Zirconium-95 (Zr-95) has a half-life of 64 days and iodine-131 (I-131) has a
half-life of 8 days. Both of these isotopes, in particular I-131, are of concern for a
short period (a few weeks) after being released to the atmosphere.
• Cesium-137 (Cs-137) has a half-life of 30 years. The decay scheme for this
isotope shows that both β-particles and γ-rays are emitted. The β-emission has an
impact on health when the isotope is in the body or on the skin. The γ-radiation has
an impact both as an internal and external radiation source.

• Strontium-90 (Sr-90) has a half-life of 29.12 years. This isotope emits
only a β-particle and is difficult to observe (maximum energy of 0.54
MeV). This isotope is a bone seeker and is important when the isotope enters
the body. It should be noted that Sr-90 has a radioactive decay product, Y-90,
which has a half-life of 64 hours and emits β-particles with a maximum
energy of 2.27 MeV. With this short half-life, it is likely that this amount of
β−energy will be deposited in the same location as that from Sr-90.
• Carbon-14 (C-14), while not a direct product of fission, is formed in the
atmosphere as an indirect product. The fission process releases neutrons
that interact with nitrogen in the atmosphere and, under the right conditions,
C-14 is formed as an activation product. The individual doses from this
isotope are extremely small. However, due to the long half-life of 5730 years,
it will persist for many years. When C-14 is used in archeological dating, it is
necessary to correct for the contribution from the nuclear tests.

Average Annual Effective Dose
Natural Background mSv
Radon 2.0
other 1.0
Occupational 0.009
Medical
diagnostic X-rays 0.39
nuclear medicine 0.14
__________________________________
Total (rounded) 3.6 mSv / year
From: Mettler et al., Ionizing Radiation

Man-Made Sources of Radiation
Source Annual Dose
(Sv)
Medical uses – x-rays, etc. 250
Chernobyl (first year) 50
Fall-out from weapons testing 10
Job (average) 5
Nuclear industry (e.g. waste) 2
Others (TV, aeroplane trips, etc.) 11
Total = 328

Death Risk - Cause
Death Risk - Cause Death Risk – 40 Year Old
All causes 1 per 500
Smoker – 10 per day 1 per 2000
Road accidents 1 per 5000
Home accidents 1 per 10 000
Work accidents 1 per 20 000
All radiations 1 per 27 500
Medical Radiations 1 per 240 000

8
8
11
4
3
1
55
11
Radon
Terrestrial
Cosmic
InternalMedical
X-rays
Nuclear
Medicine
Consumer
Products
All other:
Fallout
Occupational
Nuclear Power
Sources of Radiation Exposure

Significance
of inner-
shell
ionization
parameters
in L X - ray
production
mechanism
from proton-
atom
collisions
Cross
section for
induced L
X - ray
emission
by protons
of energy
< 400 keV
Seattle,
Washington
U.S.A.
June 23 – 28, 2013

 Effect of vacancy de-excitation parameters on L X-rays of Pb using H+ beam
 L X – ray production from Au with proton beam in low energy region

1. Theoretical calculation of total cross sections
for e+ - NH3 molecule at low energies.
2. Low energy elastic scattering of positrons by
argon atoms.
29 July – 1 August, 2009, Toronto, Canada

XXVI ICPEAC - Kalamazoo,
Michigan, U.S.A.
22 - 28 July, 2009
 Role of measured vacancy de-excitation parameters for H+ - Pb.
 Investigation of L X - ray production from Au with protons in low
energy.

20th International Conference on the Application
of Accelerators in Research and Industry
University of North Texas U.S.A
L X - ray intensity ratios in Pb
with protons.
Role of measured vacancy de-
excitation parameters in the
proton induced X - ray
emission.

INVESTIGATION OF DIFFERENTIAL CROSS SECTION FOR ELECTRON
SCATTERING WITH ENVIRONMENTALLY RELEVANT MOLECULES
Characteristic
X - ray
production by
H+ projectiles
in Bismuth
target between
260 & 400 keV

Study of L
X - ray
intensity
ratios in Bi
with low
energy
proton.
Investigati
on of cross
sections
for
electron
scattering
with GeH4
molecules.

Dec. 12 – 14, 2012
Elastic
scattering of
electrons
from
phosphine
molecules

Tata Institute of Fundamental Research
Mumbai 400 005
March 28 – 31, 2012
Effect of Fluorescence and
Coster-Kronig yield on L X
- ray intensity ratios of Bi
by H+ ion impact.

Importance of
atomic
parameters in X -
ray intensity
ratios of Bismuth.

Study of
Proton-
induced L X -
ray intensity
ratios in Au.
Measured
vacancy de-
excitation
parameters in
Au for the
proton
induced L X –
rays.

18 HM-- RADIATION SOURCES -NATURAL AND MAN MADE

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to 18 HM-- RADIATION SOURCES -NATURAL AND MAN MADE

Similar to 18 HM-- RADIATION SOURCES -NATURAL AND MAN MADE (20)

More from Harsh Mohan

More from Harsh Mohan (10)

Recently uploaded

Recently uploaded (20)

18 HM-- RADIATION SOURCES -NATURAL AND MAN MADE