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Title: Now for the Feature Presentation

Silence is Golden
  • Now for the Feature Presentation

NuclearR D TION
Melissa Chan
Since Antoine Henri Becquerels accidental
stumble onto the phosphorescent ability of
uranium and Marie and Pierre Curies discovery
and coining of the term radio-active, nuclear
radiation has traveled a long way in its history
of construction and destruction. It played an
important role in World War II and the Cold War.
Now, nuclear radiation pervades modern society,
making its appearance in medicine, in nuclear
electric plants, and in never-ending research.
This is a journey to uncover its fundamental
Vy Dang
The Discovery of Radioactivity
A. H. Becquerel 1896
  • Natural radioactivity was first observed in 1896
    by A. H. Becquerel, who discovered that when
    salts of uranium are in an unexposed photographic
    plate carefully protected from light, the plate
    becomes exposed.
  • the salts exhibit phosphorescence and are able
    to produce fluorescence. Since these effects are
    produced both by salts and by pure uranium,
    radioactivity must be a property

Cindy T.
Marie and Pierre Curie 1898
  • Won the Nobel Prize in 1903 for their research on
    the phenomena Marie named radioactivity.
  • Marie and Pierre Curie extended the work on
    radioactivity, demonstrating the radioactive
    properties of thorium.
  • Their work also led to the discovery of two new
    elements--polonium and radium in 1898.

Cindy T.
Others who contributed...
Frédéric and Irène Joliot-Curie discovered the
first example of artificial radioactivity in 1934
by bombarding nonradioactive elements with alpha
In 1899 E. Rutherford discovered and named alpha
and beta radiation, and in 1900 P. Villard
identified gamma radiation.
Frédéric and Irène Joliot-Curie
Harriet Brooks
Harriet Brooks' first real discovery came from
working with radium, After studying and observing
the emanation from radium, Brooks decided that it
had to be a gas.
Cindy T.
E. Rutherford
Radioactivity refers to the phenomenon in which
particles are emitted from the nucleus of an atom
due to nuclear instability
The products of radioactivityalpha, beta, and
gammawere distinguished when scientists found
that they could be separated by either a magnetic
or electric field
Vy Dang
Radioactive Elements
Melissa Chan
Not all nuclei are stable however, they will
decay into a more stable atom. This radioactive
decay is completely spontaneous.
There are three ways that a nucleus can decay.
It may give out
  • an alpha particle (symbol a)
  • a beta particle (symbol b)
  • a gamma ray (symbol g)

Melissa Chan
Radioactive Decay Equations
Mass Number
Atomic Number
Element Symbol
The one way to apply half-life is the explain the
process of radioactive decay and its relationship
to the concept of half-life. The primary intent
is to demonstrate how the half-life of a
radionuclide can be used in practical ways to
"fingerprint" radioactive materials, to "date"
organic materials, to estimate the age of the
earth, and to optimize the medical benefits of
radionuclide usage.
Melissa Chan
Half-Life Calculations
Definition The length of time for half of a
given number of atoms of a radioactive nuclide to
decay Equations n Number of half life cycles
Time passed Half life of
isotope Original amount(g) x 0.5n Final
remaining amount(g) Final amount (g) x 2n
Original amount (g)
Vy Dang
Radiation Units
  • Gray (Gy) One joule of energy per kilogram of
    tissue absorbed dose
  • Rad Absorbed dose
  • Becquerel (Bq) Measure of actual radioactivity
    in material S.I. unit
  • Curie (Ci) Activity of radioactive source
  • Sievert (Sv) Takes into account biological
    effects of different types of radiation
  • REM Converted dose-equivalent from rads or
    grays biologically effective dose
  • Roentgens Intensity of radiation source
  • Dose Equivalent (DE) may be regarded as an
    expression of dose in terms of its biological
  • Conversions
  • 1 Bq 1 disintegration per second (dps)1 Ci
    3.7 x 1010 dps1 Ci 3.7 x 1010 Bq
  • 1 gray 100 rads1 sievert 100 rem1
    becquerel 27 picocuries or 2.7 x 10-11 curies

Vy Dang
Sources of Radiation
Vy Dang
  • Two types of radiation nonionizing and ionizing
  • Grays (Gy) measure the energy of radiation
    absorbed by the target in joules per kilogram.
  • Rems (Sv) measure dose quantity in joules per
  • The Rems and Grays both measure the effect of
    radiation on the target, but the rem takes into
    account the effects of different types of
    radiation on human tissue.

Some forms of Exposure
  • Amount of exposure differs.
  • Suns ultraviolet rays
  • Water
  • Atmosphere
  • Electromagnetic fields
  • Nuclear bombs and reactors
  • Occupation

Nonionizing Radiation
  • The kind we are exposed to day-to-day (i.e.
    low-frequency electromagnetic fields)
  • Generally harmless
  • Electric appliances, power lines, radio/TV
    broadcasting, thunderstorms, radar,
    telecommunicates, light, etc.
  • Can pass through human bodies without apparent
  • Microwaves high intensities can cause heating of
    tissue and burn injuries to skin
  • Ultraviolet cause skin cancer
  • Cell phones expose sensitive parts of the human
    body to radiation try not to use often

Ionizing Radiation
  • The more dangerous type
  • Where radioactive particles remove the valence
    electrons of the elements in living materials and
    changes the chemical reactivity of the affected
  • Damages biological molecules (proteins/nucleic
    acids) and ruptures cell membranes.

Biological Effects
Dosage (Gy) Damage
gt100 Central nervous system loss of coordination and death within 1-2 days
9-100 Gastrointestinal tract nausea, vomiting, and diarrhea. Dehydration results in death in several weeks
3-9 (Therapy) Bone marrow damage, loss of appetite and hair, hemorrhaging, inflammation, and secondary infections
lt3 Non lethal, but can cause loss of appetite and hair, hemorrhaging and diarrhea.
Average exposure for a U.S. resident is around 0.36 Rem per year Average exposure for a U.S. resident is around 0.36 Rem per year
2 mSv/year Typical background radiation experienced by everyone (av 1.5 mSv in Australia, 3 mSv in North America).
1.5 to 2.0 mSv/year Average dose to Australian uranium miners, above background and medical.
2.4 mSv/year Average dose to US nuclear industry employees.
up to 5 mSv/year Typical incremental dose for aircrew in middle latitudes.
9 mSv/year Exposure by airline crew flying the New York - Tokyo polar route.
10 mSv/year Maximum actual dose to Australian uranium miners.
20 mSv/year Current limit (averaged) for nuclear industry employees and uranium miners.
50 mSv/year Former routine limit for nuclear industry employees. It is also the dose rate which arises from natural background levels in several places in Iran, India and Europe.
100 mSv/year Lowest level at which any increase in cancer is clearly evident. Above this, the probability of cancer occurrence (rather than the severity) increases with dose.
350 mSv/lifetime Criterion for relocating people after Chernobyl accident.
1000 mSv/cumulative Would probably cause a fatal cancer many years later in 5 of every 100 persons exposed to it (ie. if the normal incidence of fatal cancer were 25, this dose would increase it to 30).
1000 mSv/single dose Causes (temporary) radiation sickness such as nausea and decreased white blood cell count, but not death. Above this, severity of illness increases with dose.
5000 mSv/single dose Would kill about half those receiving it within a month. (The 28 people who died within four months of the Chernobyl disaster appear to have received more than 5000 mSv in a few days, while those who sufered acute radiation sickness averaged doses of 3400 mSv.)
10,000 mSv/single dose Fatal within a few weeks.
Vy Dang
Geiger Counter
  • Invented from a German Physicist Hans Geiger.

Cindy Garza
  • Works by measuring the amount of ionization
  • Radiation particles enter the tube and turn into
  • Ions are electrically charged.

Cindy Garza
  • The Geiger Counter Are
  • Nuclear Chemist
  • nuclear power plants
  • Teachers
  • emergency services
  • Homeland security
  • EMTs
  • Golf ball companies.

Cindy Garza
  • The detector uses americium- 241.
  • It sends out a beam of neutrons in a straight
  • When smoke enter the detector the smoke breaks
    the line, and thats when it rings.

Cindy Garza
  • Conclusion
  • The present advancement in the understanding of
    nuclear radiation has been brought about by
    numerous people through years of research and
    experimentation. Its complexity is shown in the
    many units involved. This exploration has guided
    you through the fundamentals of nuclear
    radiation. It is now your turn to dive deeper
    into the areas specific to your interests.
    Perhaps one day your name will be written in the
    book of radioactive history

Vy Dang
The End
Works Cited
  • Achey, Phillip M. ""Radiation Biology""
    McGRAW-HILL ENCYCLOPEDIA OF Science Technology.
    9th ed. 15 vols. Chicago, IL McGraw-Hill, 2002.
  • Farndon, John . "The Curies." MAS Ultra - School
    Edition. 11/08/07 lthttp//
  • Harvey, Blatt. America's Environmental Report
    Card. Cambridge, MA MIT P, 2005.
  • Hicks, Jennifer. "Harriet Brooks Working with
    Radioactivity ." Ebsco. 11/08/07
  • "Images SI INC." Images SI INC. 2007 . Images SI,
    Inc. 12 Nov 2007 lthttp//
  • Lerner, K. Lee, and Lerner W. Brenda, eds.
    "Radioactive Fallout." The GALE ENCYCLOPEDIA of
    SCIENCE. 3rd ed. 5 vols. Detroit, MI Thomson
    Gale, 2004.
  • Lerner, K. Lee, and Lerner W. Brenda, eds.
    "Radioactive pollution." The GALE ENCYCLOPEDIA of
    SCIENCE. 3rd ed. 5 vols. Detroit, MI Thomson
    Gale, 2004.
  • Mitcham, Carl. "Radiation." Encyclopedia of
    Science Technology and Ethics. 3 vols. Detroit,
    MI Thomson Gale, 2005.
  • "Radioactive Smoke Alarms." Radioactive Smoke
    Alarms. December 1999. 12 Nov 2007
  • Radioactivity ." Columbia Encyclopedia. 11/08/07
  • Settle, Frank. "The Biological Effects of Nuclear
    Radiation." Chemcases. 2005. National Science
    Foundation. 9 Nov. 2007 lthttp//

Vy Dang