Radioactive
Contamination
•
Radioactive
Contamination
•
Half
Life & Biological Half Life
•
Sources
Radioactive
Contamination Definition
Radioactive contamination is radioactive material that is uncontained and in an unwanted place.
Radioactive contamination is radioactive material that is uncontained and in an unwanted place.
Radioactive
Half Life
Radioactive
half-life is the time it takes for one half of the radioactive atoms present to
decay.
•
U-238:
4.5 billion years
•
Pu-239:
24 thousand years
•
H-3:
12 years
Some
Important Elements and Their Half Lives
Element
|
Symbol
|
Half
Life
|
Carbon
|
C14
|
5760 years
|
Cobalt
|
Co60
|
5.27days
|
Zinc
|
Z65
|
245 days
|
Sulpher
|
S35
|
87days
|
Strontium
|
Sr89
|
55days
|
Phosphorus
|
P32
|
14.2days
|
Iodine
|
I131
|
8 days
|
Sodium
|
Na24
|
15 hrs
|
Phosphorus
|
P30
|
11 min
|
Thorim
|
Th220
|
54 sec
|
Thorium
|
Th216
|
0.14 sec
|
Biological
Half-life
Biological
half-life is the time it takes for one half of the radioactive atoms present in
the body to be biologically removed.
•
Pu
- in liver: 40 years
•
Pu
- in bone: 100 years
•
H-3:
10 days
Why is
Radiation Harmful?
Radiation
deposits small amounts of energy, or "heat" in matter
As a Result of it:
- Alters
atoms (ionization/excitation)
- Damage to
cells & DNA causes mutations and cancer Stochastic Effects
- Cell
death may cause radiation injury Deterministic Effects
- Much of
the resulting damage is from the
production of ions
Radioactive
Contaminants
Radioactivity
releases to the environment:
•
Natural
sources
•
Artificial
sources
–
Nuclear
installations
–
Nuclear
accidents
–
Nuclear
weapons testing
–
Nuclear
explosions
–
Radionuclides
uses
Chernobyl
Nuclear Reactor Accident
•
The
Chernobyl accident was the worst disaster in the history of peaceful
application of nuclear energy.
•
On
26th April 1986, one of the four graphite reactors at Chernobyl near
Kiev in Ukraine was destroyed by an explosion caused by a prompt critical power
excursion
•
Resulted
in the increase of radioactive contamination at a global level
IRALF
•
Interim
International Radionuclide Action Levels for Food (IRALF) were introduced in an
expert consultation organized at FAO Headquarters, Rome in December 1985.
•
To
avoid undesirable exposure to public, Pakistan like other countries imposed
radioactive contamination levels on food items, The gazette of Pakistan, PNSRP
Regulations, 1990.
•
Every
effort should be made to reduce undue exposure of radiation and even the low
level radioactivities should not be neglected.
Fukushima Daiichi
nuclear disaster
was a nuclear disaster at the Fukushima I Nuclear Power
Plant that began on 11 March 2011, resulting in a meltdown of three of the
plant's six nuclear reactors
No deaths followed short term radiation exposure, while
15,884 died (as of 10 February 2014due to the earthquake and tsunami.
In June 2011, TEPCO stated the amount of contaminated water
in the complex had increased due to substantial rainfall.[227] On 13 February
2014, TEPCO reported 37,000 becquerels (1.0 microcurie) of cesium-134 and
93,000 becquerels (2.5 microcuries) of cesium-137 were detected per liter of
groundwater sampled from a monitoring well
Monitoring
of Radionuclides in Foods
Various
techniques used to determine the radioactivity in different food items for
comparing with the recommended limits are:
•
A
low level environmental laboratory with modern counting systems and research
facility set up at PINSTECH, was used for the measurement of various
radionuclides present in trace quantities in food samples.
•
Alpha
and Beta counting systems
•
Gamma
spectrometry
–
the
most simple technique for the measurement of radioactivity
–
widely
applicable large variety of sample matrices
–
enables
us to easily measure in low level radioactivity in food stuffs
Certificate is provided by PNRA
for Export/Import samples.
Organizations
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Custom
House, Karachi
- Habib
General Ltd., Karachi
-
Central Lab., Chaklala
-
Trading Corporation of Pakistan Ltd.,
- WAPDA
Power Station, Tarbela
- M/s.
Sulemanji & Sons (Pvt) Karachi
- Rice
Export Corporation of Pakistan Ltd.
-
Karachi Nuclear Power Plant (KANUPP)
Samples Analyzed
•
Samples
analyzed on routine basis (water, soil, meals, vegetables,
etc.) around nuclear installations
•
Nationwide
network for air monitoring samples to
check radioactivity across the
border (Nuclear tests of neighbor countries
and nuclear accidents)
•
Samples
analyzed after Chernobyl accident
•
Pre-operational
samples analysis of nuclear installations
•
Samples
analyzed during Ph. D Studies
o
Sellafield effluents in Irish Sea (Tc-99, ICP-MS)
o
Chernobyl samples (Tc-99, ICP-MS)
o Air
samples from Graphite Research Reactor (C-14, LSC
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