• •
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I Acute Exposure
• •
• •
• •
• •
Exposure to a large, single dose of radiation, or a
series of moderate doses received during a short
period of time. Large acute doses can result from
accidental or emergency exposures, or from specific
medical procedures (radiation therapy).
• •
• •
• •
•	Alpha Particle •
•	•
• •
• •
A positively charged particle made up of two
neutrons and two protons emitted by certain
radioactive nuclei. Alpha particles cannot penetrate
most matter. A piece of paper or the dead outer
layers of skin is sufficient to stop alpha particles.
Radioactive material that emits alpha particles (alpha
emitters) can be very harmful when inhaled,
swallowed, or absorbed into the blood stream.
• •
• •
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•	Americium •
•	•
• •
• •
• •
A man-made element; a silvery metal. Trace
quantities of americium are widely used in smoke
detectors and as neutron sources in neutron moisture
gauges
• •
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•	Atom •
•	•
• •
• •
• •
Extremely small particles of which we, and everything
around us, are made. Atoms consist of a nucleus,
containing protons and neutrons, surrounded by
electrons.
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•	Beta Particle •
•	•
• •
• •
• •
An electron or positron emitted by certain radioactive
nuclei. Beta particles can be stopped by a layer or two
of clothing or by a few millimeters of a substance
such as aluminum. They are capable of penetrating
the skin and causing radiation damage, such as skin
burns. As with alpha emitters, beta emitters are most
hazardous when they are inhaled or ingested.
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Environmental Protection
^^Lal	Agency

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I Chain Reaction !
• •
• •
• •
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A reaction that initiates its own repetition. In a fission
chain reaction, a fissionable nucleus absorbs a neutron
and fissions (splits) spontaneously, releasing additional
neutrons. These, in turn, can be absorbed by other
fissionable nuclei, releasing still more neutrons. A fission
chain reaction is self-sustaining when the number of
neutrons released in a given time equals or exceeds the
number of neutrons lost by absorption in non-fissionable
material or by escape from the system.
• •
• •
• •
•	Chronic Exposure •
•	•
• •
• •
Continuous or intermittent exposure to low doses of
radiation over a long period of time. There is a delay
between the exposure and the observed health
effect.
• •
• •
• •
•	Cosmic Radiation •
•	•
• •
• •
• •
Radiation from space, like a steady drizzle of rain. This
shower of cosmic radiation is created by charged
"sub-atomic particles" (parts of atoms) that originate
in our galaxy and the sun. The particles interact with
Earth's atmosphere and magnetic field to create
cosmic radiation.
• •
: dna :
• •
•	(deoxyribonucleic acid) •
•	•
• •
• •
The "blueprints" that carry our genetic information.
DNA ensures that a perfect copy of the original cell is
created when our body repairs or replaces cells.
•	Decay Chain •
•	•
• •
• •
JL United States 	
The series of decays or steps that certain unstable
(radioactive) atoms go through before reaching a
stable form. For example, the decay chain that begins
with uranium- 238 culminates in lead-206, after
forming uranium-234, thorium-230, radium-226 and
radon- 222.
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Environmental Protection
^^Lal	Agency

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• •
• •
• •
• •
I Direct Exposure !
• •
• •
• •
• •
Exposure to radioactive material from a source
outside of your body
• •
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•	Dose •
•	•
• •
• •
• •
The quantity of energy absorbed by a person exposed
to radiation.
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• •
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•	Dosimeter •
•	•
• •
• •
• •
A small portable instrument (e.g., a film badge,
thermoluminescent dosimeter or pocket dosimeter)
used for measuring and recording the total
accumulated personal dose of ionizing radiation.
• •
• •
• •
I Dosimetry !
• •
• •
• •
• •
The monitoring of individuals to accurately determine
their radiation dose equivalent.
• •
• •
; Electromagnetic :
• •
; Spectrum ;
• •
• •
Energy that travels in the form of waves or high-
speed particles. The electromagnetic spectrum
extends from low to high frequencies of energy
including radio waves, microwaves, infrared light,
visible light, ultraviolet light, x-rays and gamma rays.
The electromagnetic spectrum is divided into two
major categories: ionizing radiation and non-ionizing
radiation
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Environmental Protection
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I Electron !
• •
• •
• •
• •
Particles that orbit the nucleus as a cloud. They are
negatively charged and balance the positive electrical
charge of the protons in the nucleus. Interactions
with electrons in the outer orbits affect an atom's
chemical properties.
• •
• •
• •
•	Exposure Pathways •
•	•
• •
• •
The way in which people are exposed to radiation or
other contaminants. The three basic pathways are
inhalation (contaminants are taken into the lungs),
ingestion (contaminants are swallowed) and direct
(external) exposure (contaminants cause damage
from outside the body).
• •
• •
• •
Fission
• •
• •
• •
• •
The splitting of a nucleus into at least two other
nuclei and the release of a relatively large amount of
energy. Two or three neutrons are usually released
during this type of transformation.
• •
• •
• •
•	Fusion •
•	•
• •
• •
• •
The union of atomic nuclei to form heavier nuclei
resulting in the release of enormous quantities of
energy when certain light elements unite.
• •
• •
• •
•	Gamma Rays
•	•
• •
• •
High-energy electromagnetic radiation emitted by certain
radioactive elements when their nuclei transition from a
higher to a lower energy state. These rays have high
energy and a short wavelength. Gamma rays are very
penetrating. Several feet of concrete or a few inches of
lead may be required to stop gamma rays. While gamma
rays can easily pass completely through the human body, a
fraction of the energy will always be absorbed by tissue.
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Environmental Protection
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• •
• •
• •
• •
I Geiger Counter !
• •
• •
• •
• •
A radiation detection and measuring instrument. It
consists of a gas-filled tube containing electrodes,
between which there is an electrical voltage, but no
current flowing. When ionizing radiation passes through
the tube, a short, intense pulse of current passes from the
negative electrode to the positive electrode and is
measured or counted. The number of pulses per second
measures the intensity of the radiation field. It is the most
commonly used portable radiation detection instrument.
•
•
•
•
•
•
•
•
•
•
•
•
•
Half-life :
•
•
•
•
The amount of time it takes for half of the radioactive
atoms in a sample to decay into a more stable form.
Every radioactive atom has a different half-life. Half-
lives vary from billionths of a billionth of a second to
billions of years.
• •
• •
• •
•	Health Physics •
•	•
• •
• •
A scientific field that focuses on radiation protection
of humans and the environment. Health physics uses
physics, biology, chemistry, statistics and electronic
instrumentation to help protect individuals from any
damaging effects of radiation.
• •
• •
• •
! Ingestion !
• •
• •
• •
• •
Eating or drinking. When used with these materials it
refers to eating or drinking radioactive material.
•
•
•
•
• ¦ ¦
•	inno
•
•
•
•
JL United States

•
•
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•
lion *
•
•
•
•
Breathing in. When used with these materials it refers
to breathing in radioactive material.
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Environmental Protection
^^Lal	Agency

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•
•
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: i
•
•
•
•
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•
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Ion !
•
•
•
•
An atom that has too many or too few electrons,
causing it to have an electrical charge, and therefore,
be chemically active.
• •
• •
• •
•	Ionizing Radiation •
•	•
• •
• •
Energy given off as either particles or rays from the
unstable nucleus of an atom. The most energetic
form of radiation; capable of removing electrons from
atoms and damaging living cells and the DNA of those
cells. Ionizing radiation includes x-rays, gamma rays
and alpha and beta particles.
• •
• •
• •
•	Isotope ;
•	•
• •
• •
A form of an element that has the same atomic
number (same number of protons), but a different
atomic mass due to the presence of a different
number of neutrons.
• •
• •
; Man-made I
I Radiation ;
• •
• •
Radiation that is produced for medical,
manufacturing and consumer purposes.
• •
• •
• •
•	Meson •
•	•
• •
• •
• •
A subatomic particle that holds nucleons together in
the atomic nucleus.
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Environmental Protection
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• •
I Monitoring !
• •
• •
• •
• •
The use of sampling and detection equipment to
determine the levels of radiation or other toxic
materials in land, air or water.
•	Natural •
•	•
•	(Background) •
I Radiation I
•	•
The radiation present in the natural environment;
includes cosmic, terrestrial and internal radiation .
• •
• •
• •
•	Neutron •
•	•
• •
• •
• •
A small particle, with no electrical charge, typically
found within an atom's nucleus. A neutron has about
the same mass as a proton.
• •
• •
I Non-ionizing 1
I Radiation ;
• •
• •
Radiation that has lower energy levels and longer
wavelengths than ionizing radiation. It has enough
energy to move atoms, but not enough to alter them
chemically. It can be strong enough to heat tissue and
cause harmful biological effects. Examples include
radio waves, microwaves, visible light and infrared
from a heat lamp.
• •
• •
• •
Nucleus
• •
• •
• •
• •
The heat energy produced by the process of nuclear
reaction (fission or fusion) within a nuclear reactor or
by radioactive decay.
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Environmental Protection
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• •
•	Nuclear Fallout •
•	•
• •
• •
• •
The slow descent of minute particles of radioactive
debris in the atmosphere following a nuclear
explosion.
• •
• •
• •
Nucleus
• •
• •
• •
• •
The central part of an atom that contains protons and
neutrons. The nucleus is the heaviest part of the
atom.
• •
• •
! Photon !
• •
• •
• •
• •
A "packet" of electromagnetic energy. Photons have
no mass and travel at the speed of light. Gamma and
X-rays are photons.
• •
• •
• •
•	Proton •
•	•
• •
• •
• •
A small particle, typically found within an atom's
nucleus, that possesses a positive electrical charge.
The number of protons is unique for each chemical
element.
• •
• •
• •
•	Radiation •
•	•
• •
• •
• •
Radiation is energy that travels in the form of waves
and makes up the electromagnetic spectrum. The
electromagnetic spectrum is divided into two major
categories: ionizing radiation and non-ionizing
radiation.
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Environmental Protection
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• •
• •
• •
•	Radiation Exposure •
•	•
• •
• •
Exposure occurs when a person is near a radiation
source. Receiving an x-ray is an example of exposure.
Though the radiation penetrates the body, it does not
remain on the skin or in the body.
• •
• •
; Radiation Exposure :
; Pathways ;
• •
• •
The way in which people are exposed to radiation or
other contaminants. The three basic pathways are
inhalation (contaminants are taken into the lungs),
ingestion (contaminants are swallowed) and direct
(external) exposure (contaminants cause damage
from outside the body).
• •
J Radiation ;
• •
; Protection ;
• •
• •
Radiation is energy that travels in the form of waves
and makes up the electromagnetic spectrum. The
electromagnetic spectrum is divided into two major
categories: ionizing radiation and non-ionizing
radiation.
• •
• •
• •
•	Radioactive Atom •
•	•
• •
• •
• •
An atom with an unstable nucleus that emits ionizing
radiation (alpha particles, beta particles or gamma
rays) as it decays and attempts to become stable.
• •
: Radioactive ;
• •
; Contamination ;
• •
• •
A deposit of radioactive material on the surfaces of
structures, areas, objects or people. It may also be
airborne, external or internal (inside components or
people).
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Environmental Protection
^^Lal	Agency

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• •
• •
• •
• •
•	Radioactive Decay •
•	•
• •
• •
Exposure occurs when a person is near a radiation
source. Receiving an x-ray is an example of exposure.
Though the radiation penetrates the body, it does not
remain on the skin or in the body.
• •
: Radioactive ;
: Materials ;
• •
• •
The way in which people are exposed to radiation or
other contaminants. The three basic pathways are
inhalation (contaminants are taken into the lungs),
ingestion (contaminants are swallowed) and direct
(external) exposure (contaminants cause damage
from outside the body).
• •
• •
• •
•	Radioactivity j
•	•
• •
• •
Radiation is energy that travels in the form of waves
and makes up the electromagnetic spectrum. The
electromagnetic spectrum is divided into two major
categories: ionizing radiation and non-ionizing
radiation.
• •
• •
• •
•	Radium •
•	•
• •
• •
• •
An atom with an unstable nucleus that emits ionizing
radiation (alpha particles, beta particles or gamma
rays) as it decays and attempts to become stable.
• •
• •
• •
•	Radon •
•	•
• •
• •
• •
A deposit of radioactive material on the surfaces of
structures, areas, objects or people. It may also be
airborne, external or internal (inside components or
people).
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Environmental Protection
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•
•
•
•
•
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•
Rem •
•
•
•
•
Doses are most commonly reported in millirem (mrem). A
millirem is one thousandth of a rem (1000 mrem = 1 rem).
Countries that use the metric system measure radiation
dose in units of sieverts (Sv). A millisievert is one
thousandth of a sievert (1000 mSv = 1 Sv). Converting
sieverts to rems is easy. One sievert equals 100 rem (1 Sv =
100 rem). One millisievert equals one hundred millirems (1
mSv = 100 millirems).
• •
• •
; Strong Nuclear :
• •
; Force ;
• •
• •
A powerful force between nucleons: proton-to-
proton, neutron-neutron, and proton-neutron. It
extends only a very short distance, about the
diameter of a proton or neutron.
• •
• •
• •
! Shelter-in-place 1
• •
• •
• •
Selecting a small, interior room, with no or few
windows, and taking refuge there.
• •
• •
; Terrestrial
I Radiation ;
• •
• •
Radiation that is emitted by naturally occurring
radioactive materials in the earth.
•
•
•
•
• ¦_
•	X'
•
•
•
•
•
•
•
• ¦ • 	 •
ritium *
•
•
•
•
Tritium (chemical symbol H-3) is a radioactive isotope
of the element hydrogen (chemical symbol H).
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Environmental Protection
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• •
•	Unstable Nucleus •
•	•
• •
• •
• •
An atom is unstable (radioactive) if the forces among
the particles that make up the nucleus are
unbalanced (has an excess of internal energy).
• •
• •
• •
•	Uranium •
•	•
• •
• •
• •
A radioactive (unstable) element generally found in
the environment. As uranium (U; atomic number 92)
decays, it releases radiation and forms other
elements (like radium and radon) until it becomes a
stable element (lead).
• •
• •
j X-rays j
• •
• •
• •
X-rays and gamma rays differ in origin, but have
essentially the same properties. All x-rays are less
energetic than the most energetic gamma rays. Most
diagnostic medical x-rays are stopped by a few
millimeters of lead.
Directions:
•	Print these cards, single sided, for each student.
•	Allow students to familiarize themselves with the terms and definitions. Go over any questions to-
gether as a class.
•	Have students cut along the solid black lines, and review each word with its definition visible. Once
students have reviewed the vocabulary a couple of times, fold along the middle dotted line to cre-
ate a flashcard.
•	Students can use double sided flashcards to test their knowledge of Radiation Vocabulary.
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Environmental Protection
Agency

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