Brooke’s High School Presentation Notes (90 minutes)
Minimum Equipment Needed
Alpha Meter (alternately you can use a alpha only source with the pancake)
Pancake GM meter
Fiestaware Plate
Box with radiation signs containing Bananas
Preparation: (1) Ask teacher student’s current understanding of the atom, (2) set up
overhead, (3) set up safe place for hotplate, (4) put bananas or No-Salt in the Ammo box,
explain to the teacher about the Anti-C surprise
I
What Is Radiation, and what are the biological effects.
1) Introduce yourself. Describe what is a Health Physicist.
2) Ask class: “When I say radiation, what thought come to mind?”
Write down the categories on the board, these usually include;
Death, Mutations, Glowing things, Nuclear power, Atomic Bombs,
& Cancer (if cancer is mentioned, ask what about cancer (i.e.,
identify both cure and cause).
Hold up Comic books and ask if they think radiation does this
3) Ask class: “So is Radiation good or bad?” It works best to have
them raise their hands to “vote.” Regardless of how the vote goes, tell
them that you will ask the question again at the end of the class
period, and you want them to see if they change their answer any.
4) Ask class: “What is radiation?” you will get a variety of answers,
ask them if the following are forms of radiation:
a. Light
e. X-rays
b. Heat
f. Gamma Rays
Non-Ionizing Radiation
Does not have enough energy to remove
electrons from surrounding atoms
c. Radio waves
d. Microwaves
5
5) Explain: These are all forms of EM radiation.
What you as a Health Physicist primarily care
about is Ionizing Radiation. The viewgraph
shows the entire electromagnetic radiation
spectrums. Show how the high energy side of
the spectrum is considered Ionizing
Radiation.
There Are Lots Of Types Of Radiation
3
6) Ask: What does “Ionizing” mean? (Note this section needs to be
tailored for the knowledge of the class).
(Simplified Answer: It causes chemical changes, much like a
sunburn causes chemical changes that turn your skin red.)
For the advanced Students (who have had some chemistry/nuclear
physics background).
a. Use the “Pizza” slide.
Pizza -> Ingredients -> Chemicals -> molecules > Atoms -> Protons, neutrons, and electrons.
b. Ask: What is an “Ion?” Review
the ionization process.
Atomic Structure
All matter is made up of atoms
Protons
Neutrons
Electrons
c. Explain: The effects of Ions in
living tissue.
Not all atoms are stable
Unstable atoms are known as radioactive
atoms
7) So now we know how Ionizing Radiation
can hurt you. Is one ion going to hurt
you?
4
a. Explain: that our bodies have the truly wonderful ability to
repair themselves. Radiation isn’t the only thing that
damages our cells. Natural
Our Bodies Are Resilient
“chemicals” in the food we eat
and the Air we breath also cause
damage. Heck, even when your
brother or sister pinches your
arm, thousands of cells are
damaged or die.
_
DNA damage is most important and
can lead to cell malfunction or death.
_
Our body has ~ 60 trillion cells
» Each cell takes “a hit” about every 10
seconds, resulting in tens of millions of
DNA breaks per cell each year.
» BACKGROUND RADIATION causes only a
very small fraction of these breaks
(~ 5 DNA breaks per cell each year).
_
Our bodies have a highly efficient
DNA repair mechanisms
5
b. Every cell in our body takes a “hit” about every 10 seconds. In
the course of this lecture everyone’s body will have taken 10s
of trillions (a million million) of hits1.
c. Ask: “Should we worry?”, Explain: Too much of anything
can be bad for you, but our bodies can easily handle the
usual assaults from our environment, our food, and even
our brother (for the most part ☺).
8) Ask: “Other than creating ions, what is another property of X-ray
radiation?” Answer: “They can see through things!”
9) Show: X-ray..
Ask: “What are X-rays good for”
X-ray machines are often used by doctors
to see what is wrong with people’s insides,
without having to cut them open!
10)
11)
Ask: “So, is X-ray radiation good
or bad?”
II The Difference between Radiation and
Radioactive Material
12)
Ask: “How many of you have had an X-ray?” Select one of
the students who raised their hand, and (looking wary) ask if they are
now radioactive?
The Projector trick: Turn the overhead projector around so the light
shines toward the audience. Place your hand over the lens.
Discuss:
• How some of the light actually gets through your hand (like an Xray)
• Ask: “where is the rest of the light going?” Why, into my hand
of course! Now since this is non ionizing radiation, it is
1
Trefil, J, “How the Body Defends itself from the Risky Business of Living,”
Smithsonian, V26, number 9 (Dec ’95).
depositing the energy in the form of heat. In fact your hand should
be getting pretty warm!
• Turn the projector off, then remove your hand. Hold you hand
up, Ask: “Is my hand glowing?” Use this analogy to explain
why being exposed to radiation doesn’t make you radioactive.
13)
Ask: “So where does radiation come from?”
Some radiation comes from machines, like X-ray machines. This kind
of radiation can be turned on and off like a light bulb.
Some radiation comes from radioactive material, like Co-60, Sr-90,
Uranium and Plutonium. The nucleus of these atoms are unstable and
they will transform into other, more stable atoms, and give off a little
energy in the process. The energy that they give off is in the form of
radiation!.
14)
III
Half-life: Describe the concept of half life.
The types of Radiation (α, β, & γ)
Ionizing Radiation -
can deposit energy in neighboring atoms
resulting in the removal of electrons.
15)
Describe the different types of
radiation. Be sure to note that Alpha &
Beta are charged particles.
The FiestaWare Plate Demonstration. Give
the plate to a student, ask them if it feels
warm, appears to be glowing, or is making any
noise. Take the plate back and describe how it’s lovely Orange color
comes from Uranium in the glaze. Since uranium is radioactive (it has a
half life of 4.5 billion yrs and has been around since the Earth was
formed)
{Note: Item 16 & 17 below requires an alpha only meter or a
pancake meter with an alpha only source}
16)
The Alpha Demo:
Inform the students the Alpha Radiation is the most energetic kind,
then ask them to guess how far the alpha radiation will travel in
air. Describe the function of the Alpha Meter, then have a
volunteer slowly lower the probe to the plate.
6
17)
Alpha Shielding Demo: After explaining why the Alphas only
travel a few inches in air, Ask the Students How much paper do
they think is required to block alphas? Demonstrate, then discuss
how alphas are even blocked by our dead layer of skin!
18)
Introduction to background Radiation: hold up and describe
the Pancake GM Meter. Turn the meter on. Act surprised when
it begins clicking with background. Ask the students what is going
on? Explain about background (cosmic and terrestrial) radiation.
19)
The Beta Demo: Remind the students about Beta radiation.
Ask the students how far they think the beta radiation will travel in
air. Get a volunteer to hold the plate and another to hold the meter,
have them walk toward each other until the class hears counts above
background. Inform the class that Beta’s can travel around 12 feet
in air.
20)
The Beta Shielding Demo: Ask the students what they
think it will take to block the Beta Radiation? Start with a single
piece of paper and move onto overheads and thicker plastic. Explain
that the clicks above background that they still hear with the plastic
shield in place are actually from gamma rays, which are far more
penetrating.
IV Background Radiation and Commercial Uses of
Radiation:
21)
Ask: “So where does radiation come from and how is it
used?”
a. Reaffirm background radiation,
discuss the different sources,
including ingestion (uranium,
potassium, etc..)
b. Medical uses of radiation (diagnostic
& treatment)
Background and Manufactured Radiation
In the U.S. Contributes
360 mrem per Year
radon - 200
cosmic - 28
diet - 40
terrestrial - 28
13
c. Commercial Uses: Smoke Detectors,
Radioluminescent, etc.
d. Industrial Uses (Radiography,
Nuclear power, sterilization)
Uses of Radiation
Nuclear Power
Food sterilization
Industrial and
Medical Uses
Consumer products
15
e. Nuclear weapons.
22)
Ask: “So is radiation Good or Bad?” Hopefully the students
answers should reflect what has been discussed. Emphasize that
radiation isn’t good or bad, but how it is used can help us, or hurt
us.
V
Contamination:
23)
Ask: “If alpha radiation can’t even get past the dead layer
of skin how can it hurt us?” Discuss: There is no protection inside
your body, and all of that energy is deposited into living tissue.
24)
Hold Up Some Anti-Contamination clothing (anti-Cs), Ask:
“What are these, will they protect you from radiation?”
Place the Anti-Cs over the plate, demonstrate how the radiation
goes right through them.
Ask: “what good are they?”
Discuss: The concept of contamination, and why it is important that
we keep it outside of the body. Not only for alpha radiation, but for
all forms of radioactive material. Discuss how radioactive material
inside your body continues to expose you and you can’t just walk
away.
25)
Ask for 2 volunteers to dress out in anti-Cs. (if there is a 2nd
HP, have them dress the students out, stash a radium dial watch or
lantern mantel in the pant cuff).
26)
Bring out “the source” Box, Discuss how you knew there
would be some properly prepared people to help you open the box, so
as long as they were dressed out…. Demonstrate how hard it is to
understand what people are saying while wearing a respirator.
Make everybody move back and have the students open the ammo
box.
27)
Ask: “Are Bananas (or No Salt) radioactive?”
Answer: YES! They contains potassium which is naturally
radioactive. Hold up the meter to the banana, demonstrate that there
is not much radiation there.
28)
Ask: “So should you stop eating bananas?”
Answer: heck no! In addition to natural radiation from space and
the ground, there is little bit of natural radioactive material in all
the food we eat and the water we drink…. Your body can handle
a little radiation, but I doubt you would be around for long if you
stopped eating and drinking!
29)
Ask: “So what do you say if somebody says to you: WATCH
OUT DUDE! THAT STUFF IS RADIOACTIVE!”
Answer: Everything is radioactive, You should ask if it is
radioactive like a banana or like a nuclear reactor.
30)
Now that the “operation banana” is complete, demonstrate
how we would survey the students before they remove the anti-Cs.
(discover the watch/lantern mantel).
V
TLD Demo (optional):
Discuss TLDs and remind them about the HOT plate.
Remember, Have Fun! Please e-mail me if you have
any comments or suggestions!
- Brooke Buddemeier
- brooke2@llnl.gov