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8/6/2019 General Introduction to Properties of Nuclear Sysytems And Radiation
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INTRODUCTION TO PROPERTIES OF
NUCLEAR SYSYTEMS AND RADIATIONS
PRESENTED BY:
SHIREEN QURESHI
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RADIATIONS
Radiations is really nothing more than the emission of
energy waves through the space, as well as through
physical objects.
Usually these energy waves are classified into:
Ionizing waves
Non ionizing waves
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NON IONIZING WAVES Electromagnetic radiations
Visible light
Infra red radiations
Micro waves Radio waves
Very low frequency
Extremely low frequency
Thermal radiations Black body radiations
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VISIBLE LIGHT: Light or visible light is a very narrowrange of all possible electromagnetic radiations ofwavelength about 400-700 nm.
INFRARED: It has wavelength between 0.7 to 300micrometer. They are longer than visible light butshorter than microwaves.
MICROWAVES: It has wavelenght ranging from aslong as 1m to as short as 1mm with frequencybetween 300MHz to 300GHz.
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RADIO WAVES: They have wavelength longer than
infrared light.
VLF: VLF refers to radio frequencies in the range of 3
to 30KHz.
ELF: ELF refers to radio frequencies from 3 to 30Hz
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THERMAL RADIATIONS: A common synonym of
infrared radiations , the process by which the surface
of an object radiates its thermal energy in the form
EMW. They are generated when heat from movementof charged particle within atom is converted to
electromagnetic radiations.
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IONIZING RADIATIONS Alpha radiations
Beta radiations
Gamma radiations
X-rays
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ISOTOPE: An isotope of an element is comprised ofatoms containing the same number of protons as allother isotopes of that element, but each isotope has a
different number of neutrons eg carbon-12 carbon-13. ISOTONE: Two nuclides are isotones if they have
equal number of neutron but different number ofproton.
RADIOACTIVITY: Its a natural and spontaneousprocess by which the unstable atoms of an isotope ofan element transform or decay to a different state andemit or radiate excess energy in the form of particle orwave.
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ALPHA RADIATION Alpha radiation is the emission of alpha particles from
atoms nucleus. An alpha particle contains 2 protonsand 2 neutrons and is similar to He nucleus i.e 2He
4 .
They are commonly emitted during decay of largenuclei.
An example of alpha transmutation takes place whenuranium decays into the element (Th) by emitting analpha particle
92u238 2He4 + 90Th234
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BETA RADIATIONS Beta radiation is the transmutation of a neutron into a
proton and an electron. when an atom emits a beta
particle the atoms mass will not change, however the
atomic number will increase by 1.
6C14 -1e
0 + 7N14
Beta radiations are of two types:
Beta(-)Beta(+)
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GAMMA RADIATIONS Gamma radiation is composed of photons (1019 Hz)
and photons have neither mass nor electric charge.
They penetrate much further through matter than
alpha and beta.
X-rays emitted during the beta decay of cobolt-60 are
a common example of gamma radiation.
Wavelength smaller than 10nm.
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NUCLEAR REACTIONS While many elements undergo radioactive decay
naturally, nuclear reactions can also be stimulated
artificially.
There are two such types of reactions
NUCLEAR FISSION: reactions in which atoms
nucleus splits into smaller parts, releasing a large
amount of energy in the process. Most commonly thisis done by firing a neutron at the nucleus of an atom.
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FISSION REACTION OF URANIUM-235
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NUCLEAR FUSION: reactions in which two or more
elements fuse together to form one large element,
releasing energy in the process.
In this tremendous amount of energy is released andis known as thermonuclear reactions.
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NUCLEAR FUSION OF TWO HYDROGEN
ISOTOPES
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RADIATIONS TYPEOF
RADIAT
ION
MASS CHARGE SHIELDINGMATERIAL
ALPHA particles 4 +2 Paper, skin,clothes
BETA particles 1/1836 +1 Plastic, glass,light metals
GAMMA Electromagneticwave
0 0 Dense metal,concrete, Earth
NEUTRONS particles1 0
Water, concrete,polythene, oil
PROPERTIES OF RADIATIONS
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PROPERTIES Alpha particles are heavy and doubly charged which
cause them to loose their energy very quickly in
matter.
They are considered hazardous to a persons health ifan alpha emitting material is ingested or inhaled.
Beta particles are much smaller and have one charge.
They are effectively shielded by thin layers of metal orplastic and are again only considered hazardous if a
beta emitter is ingested or inhaled.
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Gamma radiations are highly energetic photons.
They penetrate deeply into the matter
They are difficult to stop.
X-rays are EMW with wavelength smaller than 10nm
X-rays and gamma rays are best shielded by thick
layers of lead and are hazardous to people when are
external to body..
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Neutrons are categorized according to their speeds
High speed neutrons have ability to ionize atoms
Neutrons are best shielded with concrete
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BENEFICIAL EFFECTS OF NUCLEAR
RADIATION Medicinal such as radiotherapy for cancer and X-rays
Level indicators and thickness gauges
In smoke detectors
In tracing locations of gas and liquid leaks In tracing location of malfunctioning in the body such
as blocked kidney.
in communications like variation in intensity ofradiation represents changes in information beingtransmitted.
Researchers use radioactive atoms to determine ageof radioactive materials that were once part of livingorganism.
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NUCLEAR RADIATION DAMAGES CELLS Radiation can damage cells and DNA inside them
through its ionizing effect .If enough ionization occurs
DNA ,cell & tissue damage results.
A common example is sunburn caused by ultravioletlight.
Mutation can result melanoma & other cancers.
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Thank you!!!