radiation: sources, effects and uses
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Radiation: Sources, Effects and Uses. Mark Pierson Associate Professor Virginia Tech. The Foundation for Nuclear Studies Longworth 1539 November 4, 2011 10:00 AM. Fear of Radiation - Radiophobia. Why is there so much fear by the public about radiation? - PowerPoint PPT PresentationTRANSCRIPT
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Radiation: Sources, Effects and Uses
The Foundation for Nuclear StudiesLongworth 1539November 4, 2011 10:00 AM
Mark PiersonAssociate Professor
Virginia Tech
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Why is there so much fear by the public about radiation?Cannot see it, feel it, or sense itDid not learn about it in school Mysterious and unknown (like the bogey
man)Can cause serious health effects in LARGE amounts
Other ideas from the audience?
Fear of Radiation - Radiophobia
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Alpha Particle(Helium Nucleus)
Parent Nucleus 226Ra
Daughter Nucleus 222Rn
Alpha particle decay αHigh charge (+2), high mass (4 amu)
particleDeposits all of its energy in a very short
distance
Types of Radiation
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Parent NucleusCobalt -60Z= 27
Daughter NucleusNickel -60Z= 28
Beta Particle (electron)
Antineutrino
Beta particle decay βAn electron emitted from nucleus,
negatively or positively charged (-1 or +1)
Types of Radiation
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Gamma Rays
Parent NucleusCobalt-60
(Beta decay)
Daughter NucleusNickel-60
Gamma Ray emission A high energy photon
Types of Radiation
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X-Ray emission A low energy photon
Types of Radiation
X-Ray X-rays
Bremsstrahlung
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Electromagnetic spectrumTypes of Radiation
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Ionizing radiation
+ Ion
- Ion
Electron ejected from
orbit
Ionizing RadiationTypes of Radiation
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alpha
alpha
beta
gamma
neutron
High charge, dense ionization, short path
Less mass/charge than alpha, longer path
No charge or mass, much less interaction
No charge, interacts through nuclear events
Penetrating RadiationTypes of Radiation
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Alpha
Beta
Gamma and X-rays
Neutron
Paper Plastic Lead Concrete
n
Shielding radiationTypes of Radiation
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Units of radiation dose equivalentU.S. unit is the rem or millirem (1 mrem
= 0.001 rem)International unit is the Sievert (Sv),
milliSievert (mSv), or microSievert (μSv) 1 mSv = 0.001 Sv1 μSv = 0.001 mSv = 0.000001 Sv
Multiply Sieverts by 100 to obtain remDivide mSv by 10 to obtain rem
1 mSv = 100 mrem = 0.1 rem
Radiation Dose
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Radiation DoseExternal Dose
X-Ray Machine Image
(film)Subject is not radioactive but has been exposed to a radiation dose (single chest xray = 5-10 mrem).
After
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Radiation Everywhere
Radon
X-Rays
ConsumerProducts
NuclearPower
RadioactiveWaste
Nuclear Medicine
Solar Radiation Cosmic Rays
TerrestrialRadiation
Food &Drink
Each Other
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Average Dose in U.S. is 620 mrem/year
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200 mrem/yr from Radon in your home
4 mrem from round trip airline flight from NYC to LA
200 to 400 mrem/yr for flight crews
10 mrem typical chest x-ray1000 mrem = 1 rem from torso
CT scan30 mrem from food and water
consumed throughout the year100 mrem from a mammogram
Radiation Perspective
We are showered in radiation daily
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Annual Radiation Limits due to Occupational Exposure
U.S. Units International Units
Member of Population
100 mrem 1 mSv
Occupational Worker
5 rem 50 mSv
In Emergency Only
25 rem 250 mSv
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How much radiation is produced?Activity: decays per unit time (Curies,
Becquerel)How much energy is absorbed by
tissue?Dose
How much biological damage does the radiation do per energy absorbed in the tissue?Dose Equivalent
Measuring Radiation Effects
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Pathways into the Body
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Do not buy potassium iodide pillsDo NOT take potassium iodide in
the U.S. due to radioactivity released by the Japanese nuclear plantsKI is a drug and may have side effectsThere is no benefit
Potassium Iodide (KI)
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Radiation Damage to Cells
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Radiation Induced Water Decomposition
H2O
H2O+
e-H+
H2O2
OHo
HO2
OH-
Ho
H2
WATERIncoming Radiation
Production of free radicals within the cell can result in indirect effects
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Radiation can have a direct effect on the DNA molecule in a cell by ionization or excitation of the molecule and subsequent dissociation of the molecule
Many other entities cause breaks in DNA Temperature, chemicals, etc.
Human DNA suffer millions of DNA breaks dailyMost are repaired
Damage to DNA
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All radiation interactions do not result in cancer
Within a person’s body, 10 million cells are struck by ionizing radiation per minute from naturally-occurring radioactive isotopes (e.g., K-40, C-14) and background radiation
Cells have a high capability for repair through the action of the cell itself or replacement of badly injured cells by mitosis of healthy cells
Outcomes of Radiation Interaction with Cells
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Cell Repair After Chronic Dose Damage
Time
Rad
iatio
n D
ose
Accumulated Irreparable
Reparable
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Genetic Defects in HumansNO direct evidence
of radiation-induced genetic effects in humans, even at high doses.
Analyses indicate rate of genetic disorders produced in humans would be extremely low, on the order of a few disorders per million live born per rem of parental exposure
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Cancer LatencyLatency period
is the time from exposure until the effect is exhibited
Radiation exposure does not produce cancer in every exposed person
Cancer latency can be 10 to 20 years later for high radiation doses
Time (years)
Risk
Time radiation dose received
Latent periodPeriod at risk
Risk curve
0 4 30
Leukemia latency and time at risk periods
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Linear No Threshold (LNT) Model
• S = Supralinear – higher than expected damage at low dose levels• L = Linear – damage is proportional to the dose, always some damage• T = Threshold – below a certain dose level there is no biological damage• H = Hormesis – low level doses can actually be beneficial to your health
Known damage due to dose of about 10,000 to 100,000 mrem
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Radioactivity limit for I-131 is 1 pCi/ml in water
A typical banana has 540 pCi, eating one-a-day could yield about 3 mrem/yr
Traces of I-131 detected in rain water and milk in U.S. from Fukushima have been well below limits
Impact to the U.S. population from the radioactivity released in Japan is essentially nonexistent
No known effects from radioactivity released during Three Mile Island accident to those within 50 mi
Radioactivity from Fukushima
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Who has suffered from food poisoning?
How much more would you pay for food if you could reduce significantly the probability of getting sick?
According to the Center for Disease Control, in 1999, food-borne disease was responsible for:76 million illnesses, 325,000
hospitalizations, 5000 deaths,$6-30 billion impact
UN Food Administration Organization~25% of worldwide food production is
lost after harvesting due to insects, bacteria and spoilage
Food Safety
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New commercial technology to eliminate disease-causing germs
Comparable to pasteurization… but cold
Food is exposed to carefully controlled amounts of ionizing radiation (gammas, high-energy electrons)
Radiation damages DNA of microbes and parasitesReduces disease-causing germsKills bacteria that cause spoilingSlows or stops sprouting in vegetables
Food Irradiation
uw-food-irradiation.engr.wisc.edu
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When used in conjunction with proper food handling procedures:food-borne diseases are reduced or
eliminatedshelf-life is increasedthe nutritional value of the food is
preservedthe food does not become radioactivedangerous substances do not appear in
the foods
Results of Food Irradiation
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What Foods Can Be Irradiated?Approval Year Food Purpose
1963 Wheat Flour Control of mold
1964 White Potatoes Inhibit sprouting
1986 Pork Kill Trichina parasite
1986 Fruit and Vegetables• Insect Control• Increase Shelf Life
1986 Herbs and Spices Sterilization
Bacterial pathogen reduction
1990(FDA)1992(USDA) Poultry
1997(FDA)1999(USDA) Meat
2000 Eggs Kill Salmonella
2003 School Lunch Program E-coli & Salmonella
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Food Irradiation Facility
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Radiation Level Gauge
Source Gamma Detector
Shielding
To fill control
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Radiation Thickness GaugeIntegrator Beta
Detector
Radioactive Source
Amp
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Cereal BoxesFilled using radiation level gauge
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Soda CansRadiation used in making and
filling the cans
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Blue TopazColor created by neutron
irradiation in a reactor
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CosmeticsIrradiated to remove harmful
bacterial impurities
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Environmental Protection
Electron beam cleans flue gas from fossil fuel plantsElectron beam
ionizes SO2 & NOx
SO2 & NOx react with injected Ammonia ==> Solid fertilizer
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Comparision of Radiation Technology to…Fortune 500 Companies
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Comparision of Radiation Technology to…Major industries in U.S.
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Humans are made of radioactive material and we eat radioactive foods
We are exposed to radiation everywhere in our daily lives
Low levels of radiation are not harmful
Large amounts of radiation can cause cancer many years later, but no genetic effects
We use radiation technology for everyday uses that improve our lives
There is no reason to be afraid of radiation
You now know more than the rest of the general public --- so be empowered to use your knowledge
Radiation Conclusions
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Questions
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What happens after Fukushima Daiichi natural disaster?
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U.S. public opinion of nuclear energy fell after Fukushima but is now reversing
Luntz Global survey on behalf of Nuclear Energy Institute
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Survey results six months after Fukushima by Bisconti Research with GfK Roper are promising
62% favored used of nuclear energy for electricity generation. Those strongly favoring nuclear energy outnumbered those strongly opposed by two-to-one.
67% rate U.S. nuclear power plant safety as high 59% agree that we should definitely build more
nuclear power plants in the U.S. in the future 85% agree that we should renew the licenses of
those nuclear power plants that continue to meet federal safety standards
67% agree that it would be acceptable to build another nuclear reactor at the closest nuclear power plant to them