Radiation “101”
Radiation Team
Air Toxics, Radiation &
Indoor Air Office
(ATRIA)
Mike Bandrowski
Ed Snyder
Shelly Rosenblum
Agenda
• Structure of the atom & radiation
• Type of radiation potentially
encountered in the field
• Rad units
• Health effects
• Rad protection
• Regulations & Limits
Working With Your
Community*
Trust & Credibility:
How To Build It
How To Keep It
*And living to talk about it!
Ionizing Radiation
• We’re talking about radiation which has
sufficient energy to remove electrons from
atoms.
• Non-ionizing radiation does not have that kind
of energy: radiowaves, visible light, low
frequency electromagnetic fields.
Ionizing Radiation
ee-
N
N P+ N
N P+ P+
P+
P+
N
N
P+
e-
eee-
Structure of the atom
The atom is mostly
“empty” space.
P+
N
The “empty” space is
filled with charge
fields.
Hang onto these points.
We’ll use them later when we
talk about interaction with
matter.
e-
The neutron
N
The neutron is a fusion of
an electron and a proton.
P+
N
e-
The nucleus
Like charges repel.
So strong forces must hold the nucleus together.
The ratio of protons to
N
N
P+
P+ P+
neutrons determines
P+ P+ P+ P+
stability.
N
N
N P+
P+
P+
P+ N
Nuclei with too few or too many neutrons are unstable
and will decay by giving off radiation, i.e. they’re
radioactive.
Radioactive decay
N
N
P+
P+ P+
P+ P+ P+ P+
N
N
N P+ P+
N P+
Energy: gamma ray: an
electromagnetic (EM)
wave
Fast moving
particles: neutrons,
protons, electrons
We refer to that altering of the nucleus as a
“disintegration” (even though it doesn’t completely
disintegrate).
Radiation / radioactivity
• “Radiation” refers to the energy given
off by an atom as it decays. The energy
may be in the form of a gamma ray or
fast moving particles.
• “Radioactivity” refers to the act of
decay (or disintegration) which results
in radiation being given off, i.e. it’s
active.
Contamination
• Refers to fine particles of a radioactive
material on a person or an object.
• May be removed by washing, grinding,
etc.
• Prevented by wearing protective
clothing. Dress properly and remove
properly.
Forms of radiation
• gamma: same as an x-ray but originates
in the nucleus & more energy. This is an
EM wave. (No charge)
• beta: an electron emitted from the
nucleus. (Charge of -1) (it’s small)
• alpha: two protons (Charge of +2) & two
neutrons (zero charge) (it’s the Orson
Welles of particles)
Neutron radiation
• Emission of neutrons from the nucleus.
• Does not generally result from normal
spontaneous decay.
• It results from fission.
• Since it has no charge it penetrates long
distances through matter.
• Not encountered in contaminated site work
(hopefully) or dirty bomb incidents.
The atom, the solar system & things
passing through.
• Without the effects of gravity, the
odds of an object passing through the
solar system hitting the sun or a planet
would be very small.
• Without the effects of charges, the
odds of a particle passing through an
atom “hitting” the nucleus or an electron
is small.
Penetration of radiation
• Atoms are mostly “empty” space.
• Odds of a particle contacting another particle
are small.
• Charge fields responsible for most of the
interaction between radiation and matter.
• The greater the charge and the greater
the mass, the greater the interaction with
matter (the shorter the penetration
distance).
Penetration of radiation
• The greater the interaction, the
greater the transfer of energy.
• The greater the transfer of energy, the
greater the biological damage.
Ionizing Radiation
ee-
N
N P+ N
N P+ P+
P+
P+
N
N
P+
e-
eee-
gamma
• Essentially a high energy x-ray. No mass or
“charge” but as an EM wave it interacts with
electrons.
• Penetrates many feet through matter.
• Requires dense material for shielding – lots of
lead.
• Those rad suits you see in the movies? They
prevent contamination not gamma penetration.
beta
• Negative charge of 1. Small particle
• Penetrates inches through matter.
• Can burn skin.
• Protective clothing will shield beta
particles.
alpha
• Positive charge of 2. Four large
particles.
• Won’t penetrate dead layer of skin.
• Danger is inhalation of fine particles of
alpha-containing material.
• Radon decay products emit alpha. (later
decay products can emit gamma)
Protection from radiation
• Time: preplanning to minimize time spent in
radiation field.
• Distance: all prep work should be located
away from source.
• Shielding: when possible. A car can
provide shielding. Position it to put as
much mass between you and the source.
Storage drums, walls, dirt mounds, your
partner…
• Dosimetry: so you can track what ya got!
Units of radioactivity
How many disintegrations per second
are going on in that material? i.e.
How radioactive is it?
Old Units
1 curie (Ci) = that amount of material in which 37 billion
disintegrations per second are occurring. (1 gram of radium)
New International Units
1 becquerel (Bq) = that amount of material in which 1 disintegration
per second is occurring.
Maria Skłodowska-Curie
Maria Skłodowska-Curie (born
Maria Skłodowska; known in
France and most other countries as
Marie Curie; November 7, 1867 –
July 4, 1934) was a Polish-French
physicist and chemist. She was a
pioneer in the field of radioactivity,
the first twice-honored Nobel
laureate (and still today the only
laureate in two different sciences),
and the first female professor at the
Sorbonne.
Antoine Henri Becquerel
In 1896, while investigating phosphorescence in
uranium salts, Becquerel accidentally discovered
radioactivity. Investigating the work of Wilhelm
Conrad Röntgen, Becquerel wrapped a
fluorescent mineral, potassium uranyl sulfate, in
photographic plates and black material in
preparation for an experiment requiring bright
sunlight. However, prior to actually performing the
experiment, Becquerel found that the
photographic plates were fully exposed. This
discovery led Becquerel to investigate the
spontaneous emission of nuclear radiation.
Radiation exposure
roentgen (R)
• It’s a measure of the ionizations of the
molecules in a mass of air.
• This can only be used to describe an amount of
gamma and X-rays, and only in air.
• One roentgen is equal to depositing in dry air
enough energy to cause a charge of 2.58E4
coulombs (a unit of electric charge) per kg of
air.
Wilhelm Conrad Röntgen
Wilhelm Conrad Röntgen (March 27,
1845 – February 10, 1923) was a
German physicist, of the University of
Würzburg, who, on November 8, 1895,
produced and detected electromagnetic
radiation in a wavelength range today
known as x-rays or Röntgen rays, an
achievement that earned him the first
Nobel Prize in Physics in 1901.
Radiation dose
Old Unit
RAD (radiation absorbed dose)
• Amount of energy deposited by any form of
radiation in some material.
• 1 rad = amount of radiation required to
deposit 100 ergs of energy into some
material.
New Unit
• Gray (Gy)
• One gray is equivalent to 100 rads.
Louis Harold Gray
Louis Harold Gray (10 November
1905 - 9 July 1965) was a British
physicist who worked mainly on the
effects of radiation on biological
systems, inventing the field of
radiobiology as he went.
Units related to health
Old Unit (equivalent dose)
rem (roentgen equivalent man)
Product of absorbed dose multiplied by a
quality factor which considers the radiation
and the organ or tissue sensitivity.
New Unit
Sievert (Sy)
1 sievert = 100 rem
Rolf Sievert, the man and the unit
One of the main initiators of both ICRP and ICRU,
1929. Chairman of ICRP 1956 - 1962. Chairman of
UNSCEAR 1958 - 1960. Professor at the
Department of Medical Radiation Physics in
Stockholm 1941 - 1965.
Adapted from: The Health Physics Society:
University of Michigan
http://www.umich.edu/%7Eradinfo/introduction/natural.htm
Source
Newer International Units | Old Units
Average annual effective dose equivalent
microsievert (uSv)
millirem (mrem)
Inhaled (radon & decay products)
2000
200
Other internally deposited radionuclides
390
39
Terrestrial radiation
280
28
Cosmic radiation
270
27
Cosmogenic radioactivity
10
1
Rounded total from natural sources
3000
300
Rounded total from artificial sources
600
60
3600
360
Total
How does radiation effect cells?
• By altering electron configuration of
cellular atoms, radiation affects cell
chemistry.
• Directly affects DNA and other
molecules.
• Indirectly by creating free radicals
from H20 which attack DNA or other
molecules.
High dose health effects
rem
Health Effect
5-10
50
55
70
75
90
100
400
1000
changes in blood chemistry.
nausea
fatigue
vomiting
hair loss
diarrhea
hemorrage
death
destruction of intestinal lining
internal bleeding
death
damage to central nervous system
loss of consciousness
death
2000
Time to Onset
hours
2-3 weeks
within 2 months
1-2 weeks
minutes
hours to days
Low dose cancer risk model
Linear
No Threshold
Model
Linear
Threshold
Model
Used by EPA and most
regulatory agencies.
Risk
of
Cancer
0
No risk
Dose
Low dose cancer risk model
Risk
of
Cancer
0
Dose
Regulations & Limits
• Nuclear Regulatory Commission (NRC)
– Worker: 18 year-old male: 5 rem/year
– Worker: pregnant woman: 500 millirem
(mrem) during pregnancy
• EPA
– NESHAP for public from DOE facilities:
10 millirem/year
– Administrative Levels for EPA Workers:
<50mrem/quarter; <500mrem/year;
>50mrem/quarter triggers some discussion.
So …
How much is
safe?
Questions?
Thanks
for your
attention!