RADIATION LAB TIME DISTANCE SHIELDING Health Physics Society

RADIATION LAB TIME - DISTANCE - SHIELDING Health Physics Society Power Reactor Section Radiation Science Education

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

Shielding

Shielding • 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. • + = #2 • = #3 • = #2 - #3 • background #4

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.

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

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.

Time • Place the lantern mantle in your pocket and take a open window measurement. • _____ c/m • If you leave it there for 4 hours, how many counts does your leg see? • c/m * 4 hours * 60 • If you leave it there for 24 hours, how many counts does your leg see? min/hr = _____ counts • c/m * 24 hours * 60 min/hr = _____ counts

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 won’t.