RADIATION LAB TIME - DISTANCE - SHIELDING

1
RADIATION LABTIME - DISTANCE - SHIELDING

• Health Physics Society -
• Power Reactor Section
• Radiation Science Education

2
Radiation Measurements

• ______ c/m
• ______ c/m
• ______ c/m
• ______ c/m

• 1 - Take a background measurement. Use the
  lower scale - counts per minute (c/m).
• 2 - Measure the radiation level on contact with
  the plate or mantle using the open window
  detector.
• 3 - Place a medium thick piece of material
  (wood) over the object and repeat the
  measurement.
• 4 - Place a very thick piece of material over
  the object and repeat the measurement.

3
Shielding
4
Shielding

• ? ? 2
• ? 3
• ? 2 - 3
• background ? 4

• The first measurement included beta and gamma
  radiation from the plate/ mantle plus background
  radiation (alpha radiation was too weak to pass
  through the detector wall).
• All the beta radiation was shielded by the medium
  thick material so 3 measured gamma only.
• Nearly all of the gamma radiation was shielded by
  the very thick piece of material.

5
Shielding

• If you increase the shielding around a radiation
  source, it will decrease your exposure.
• If you stand out in the rain without an umbrella,
  you will get wet.
• But, if you use an umbrella to shield you from
  the rain, you will remain dry and protected.

6
Distance

• ______ c/m
• ______ c/m
• ______ c/m
• ______ c/m

• Measure the radiation level at the surface of the
  plate or mantle.
• Move 2 inches away and repeat the measurement.
• Move 12 inches away, repeat the measurement.
• Move 3 feet far away, repeat the measurement.

7
Distance

• The farther away you are from a radiation source,
  the less exposure you will receive.
• Compare this to sitting in front of a fireplace.
  You can sit directly in front or across the room.
• If you are far from the source, your exposure
  would be much lower.

8
Time

• _________ c/m
• c/m 4 hours 60 min/hr _____ counts
• c/m 24 hours 60 min/hr _____ counts

• Place the lantern mantle in your pocket and take
  a open window measurement.
• If you leave it there for 4 hours, how many
  counts does your leg see?
• If you leave it there for 24 hours, how many
  counts does your leg see?

9
Time

• Decrease the amount of time you spend near the
  source of radiation, and decrease the amount of
  radiation exposure you receive.
• If you spend a lot of time on the beach,
  ultimately you get a sunburn. But, if you spend
  less time in the sun, you wont.