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RADIOACTIVE WASTE

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... waste consists of microcurie, millicurie and at times curie activity waste. ... Sewer Disposed (Regulations allow curie levels of some isotopes to be sewer ... – PowerPoint PPT presentation

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Title: RADIOACTIVE WASTE


1
GEORGIA STATE UNIVERSITY
Peter Farina 404-651-4866
Radioactivity Waste
2
Structure of the Atom
3
Radioactivity
Definition Any spontaneous change in the state of
the nucleus accompanied by the release of energy.
Major Types
alpha (?) particle emission (decay) beta (?)
particle emission (?-), positron emission (?)
and orbital electron capture (ec) gamma (?)
decay including internal conversion
4
Ionizing Radiation
Definition - Any type of radiation possessing
enough energy to eject an electron from an atom,
thus producing an ion.
Major Types of Ionizing Radiation Alpha, Beta,
Gamma
Alpha Particle
Large Mass (nuclei) Helium Atom with a 2 charge
Beta Particle
Small Mass - Electron (subatomic particle)
No Mass (Electromagnetic Radiation)
Gamma Photon and X-Rays
5
? Decay
? has a discrete energy that can be measured and
related to the parent. The neutron to proton
ratio is to low !
4He Nucleus Ejected from Nucleus
2
Most of the energy associated with
? (monoenergetic)
This is radioactive!!
6
? Decay
Either too many neutrons or too many protons
Change a neutron into a proton take away - charge
neutrino
Electron (negatron)
anti-neutrino
Change a proton into a neutron take away charge
(positron)
7
Electron Capture
8
? Decay
  • Emission of a photon from the nucleus
  • Most often occurs after ? or ? emission when
    nucleus is left in an excited state
  • Given off with discrete energies
  • Can measure photon energy and possibly identify
    parent

or
2
9
Radiation Dosimetry Units Exposure, X
amount of charge produced anywhere in air by the
complete stoppage of all electrons liberated by
photons in an incremental volume of air per unit
mass of air in that volume.
Standard International (SI) unit
Coulomb/kilogram (C/kg) Traditional unit
roentgen ( R ) 1 R 2.58x10-4 C/kg
Exposure definition applies only to photons of
energy less than or equal to 3 MeV interacting in
air.
10
Radiation Dosimetry Units Absorbed dose
RAD
is the energy deposited by any type of ionizing
radiation in a volume element of mass.
SI unit gray (Gy)
Traditional unit rad 1Gy 100 rad
Absorbed dose definition applies to all forms of
ionizing radiation in any material.
11
Relative Biological Effectiveness and Quality
Factor
Relative Biological Effectiveness (RBE)
Quality factor (Q) radiation Q photon,
? 1 proton, neutron 10 alpha 20
12
Relative Biological Effectiveness
Ln (S)
Shoulder of curve indicates cell repair at low
doses
No shoulder - no cell repair
Neutrons
Effect
Gamma Photons
Dn
Dg
Same Biological Effect Different Dose from 2
types of radiation
Dose
13
Radiation Dosimetry Units Dose Equivalent
Dose equivalent allows the description of the
biological effect of an absorbed dose of a
particular type of radiation or mixed radiations
for the Human Body.
Dose Equivalent (DE) in Rem Dose in Rads x Q
SI unit sievert (Sv) traditional unit rem
1 Sv 100 rem millirem
For photons 1 R ? 1 rad 1 rem
14
PRECAUTIONS FOR AVOIDING UNNECESSARY RADIATION
EXPOSURE
15

External Radiation Exposure
Definition Exposure of the body from radiation
originating outside of the body
Level of Hazard and Control Depend Upon
1. Type of Radiation (Alpha, Beta Gamma)
2. Energy of the Radiation (Low or high energy)
3. Dose Rate (Low or high dose rate)
16
Reducing External Radiation Exposure
  • Time
  • reduce time spent in radiation area
  • Distance
  • stay as far away from the radiation source as
    possible
  • Shielding
  • interpose appropriate materials between the
    source and the body

17
Radioactive Waste
  • We will discuss -
  • Low Level Radioactive Waste
  • High Level Radioactive Waste
  • Mining Tailings

18
Radioactive Waste
  • Low Level Radioactive waste consists of
    microcurie, millicurie and at times curie
    activity waste.
  • (A Curie is a unit of nuclear transformations. 1
    Curie is 3.7 x1010 transformations per second)

19
Radioactive Waste
  • Low level radioactive waste consists of
  • Contaminated solids
  • liquids
  • animal carcasses
  • small sealed sources

20
Radioactive Waste
  • Low level radioactive liquids are either
  • Incinerated
  • Deep well injected (not as frequent anymore)
  • Solidified
  • Sewer Disposed (Regulations allow curie levels of
    some isotopes to be sewer disposed of if dilution
    is large enough)

21
Radioactive Waste
  • Radioactive animal carcasses are either
    incinerated or buried onsite.

22
Radioactive Waste
  • Small sealed sources are Stabilized in concrete
    and buried. Stabilized concrete is concrete
    that is certified to resist wear for a certain
    time period.

23
Radioactive Waste
  • Low level contaminated solid wastes are buried.
    GSU has its solid waste Supercompacted at
    30,000 psi to reduce the volume to be buried

24
Radioactive Waste
  • Most low level wastes come from Government
    and Utilities. These consist of contaminated
    solids from nuclear reactor usage and weapon
    construction.

25
Radioactive Waste
  • Colleges, research and medical applications
    account for less than 25 of the low level
    Radioactive wastes created

26
Radioactive Waste
  • Class A low-level radioactive waste is the least
    hazardous, containing mostly short-lived
    radionuclides that will be reduced in
    radioactivity (decay) in a relatively short time.
    It contains only small amounts of radionuclides
    that take a relatively short time to decay. Class
    A waste will be disposed of in concrete canisters
    that will maintain their shape and strength for
    hundreds of years.

27
Radioactive Waste
  • Class B low-level radioactive waste is more
    hazardous than Class A waste. Most of it comes
    from nuclear reactors. It must be in a stable
    form for disposal and will also be disposed of in
    concrete canisters. Stabilization can be
    accomplished by solidifying liquid waste,
    compacting solid waste, or placing the low-level
    radioactive waste in a container that will be
    stable for many years. Class B low-level
    radioactive waste makes up only a small percent
    of the waste volume generated but along with
    Class C waste, it contains the largest portion of
    the total radioactivity.

28
Radioactive Waste
  • Class C low-level radioactive waste is the most
    hazardous and must be handled accordingly. It
    also must be disposed of in a stable form.

29
Radioactive Waste
30
Radioactive Waste
  • There are 3 LLRW Burial sites
  • Hanford
  • Envirocare
  • Barnwell

31
Radioactive Waste
32
Radioactive Waste
33
Radioactive Waste
  • Politics of LLRW
  • Compacts
  • On-site burial
  • NIMBY

34
Radioactive Waste
  • The compact system was set up by NRC to have all
    states share in the responsibility of disposal of
    radioactive waste and to limit waste transport
    distance. Georgia is in the Southeast compact.
  • Until 1992, all states within the SE compact
    (excluding Florida) would host a LLRW landfill on
    a 20-25 year revolving timetable.

35
Radioactive Waste
  • Kentucky was the first (Maxie Flats), then South
    Carolina (Barnwell). In 1995, North Carolina was
    to open a site but the citizens protested and
    sued. The State legislature refused.
  • North Carolina was then kicked out of the S.E.
    compact and left with no place to dispose of
    waste. Other States followed N.C.s lead and
    refused
  • This lead to the collapse of the traditional
    compact system and the

36
Radioactive Waste
37
Radioactive Waste
  • In the past, many Universities and companies
    were allowed to bury their radioactive wastes
    onsite. Some were allowed to deep well inject
    liquid radioactive waste.

38
Radioactive Waste
  • N.I.M.B.Y.
  • Not
  • In
  • My
  • Back
  • Yard
  • The true politics of Hazardous Waste

39
Radioactive Waste
  • Did North Carolina, by not opening up a waste
    site, better protect its citizens?

40
Radioactive Waste
  • High-Level Radioactive Waste is the irradiated
    fuel from the cores of nuclear reactors, the
    liquid and sludge wastes that are left over after
    irradiated fuel has been reprocessed (a procedure
    used to extract uranium and plutonium), the solid
    that would result from efforts to solidify that
    liquid and sludge from reprocessing.

41
Radioactive Waste
  • Because there is currently no high level
    radioactive waste disposal facility, HLRW is held
    On-Site in water pools

42
Radioactive Waste
  • Once these Pools are full, Waste is transferred
    to casks which are also held on-site

43
Radioactive Waste
44
Radioactive Waste
  • A HLRW repository is being constructed at Yucca
    Mountain in Nevada to hold all this waste. NIMBY
    again is playing a role in the opening

45
Radioactive Waste
  • YOUR THOUGHTS AND DISCUSSION
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