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| Suggestion:
Use during 2 team prep days. Ionizing radiation can be harmful, especially if the body receives too much of it. For this reason, nuclear scientists, engineers, and technicians are constantly refining a set of rules, or “best practices,” which should be followed to help anyone who works in an area exposed to dangerous radiation, protected as much as possible. The set of rules, or practices are called, ALARA. ALARA stands for “as low as reasonably achievable.” The Brookhaven National Laboratory maintains these rules and records of all discussions about them. Some of the ALARA rules come from common sense. But, because radiation is invisible and we cannot feel it, common sense has to be turned into rules. Here’s an example of how, by using common sense, you would avoid unnecessary exposure to radiation at a friend’s party. You are invited to an outside pool party at your friend’s house. The weather is chilly, and your friend builds a large fire in the grill near the pool to help keep everyone warm. Do you sit on top of the flames? No. Do you move closer to the fire until you feel its warmth begin to take away the chill? Probably. You feel your skin getting warm, maybe even hot. What do you do? You might walk around until you cool down. You might jump in the pool. The water is warmer than the chill night air. When you begin to grow chilly, however, you get out and move close to the flames. If you happen to meet someone that you enjoy talking to, you might decide to stand where the fire is neither too warm nor too cold. In this way you won’t have to keep moving. As the night progresses, your eyes become tired from staring into the bright glow of the flames. What do you do? You might put on your sunglasses to shield your eyes, cover them with you hand, or turn and look away from the flames. At the party your body tells you where to stand and where to move to regulate its exposure to the heat of the fire. Ionizing radiation requires the same behaviors; the only problem is that we don’t know when we are standing in the flames. The ALARA Rules ALARA rules are followed by radiation workers to protect them from too much radiation exposure. Astronauts are considered radiation workers. The three ALARA rules involve time, distance, and shielding. Time: Spend the least amount of time around or exposed to radiation. Your body “measured” the heat of the fire and you adjusted your position accordingly. It told you when to move. Instruments on the space station measure the levels of radiation the astronauts are exposed to and tell the astronauts when to move. Distance: Keep your distance from a radioactive source. You could feel the heat from the fire lessen as you moved farther away. Under most conditions, distance from radiation helps limit exposure. The astronauts are not this lucky. The space station’s orbit and the lack of atmosphere between them and the sun exposes them to dangerous levels of radiation. Shielding: Lead, water, and polyethylene are three examples of effective shielding from radiation. They either stop or slow down the ionizing photons and radioactive particles. The astronauts have shielded sleeping and work areas. They can move into these areas during dangerous periods of radiation in the same way you put on your sunglasses, or turned away, to shield your eyes from the brightness of the flames. If you were monitoring the astronaut’s exposure to radiation, you would want to keep in mind the three ALARA factors of time, distance, and shielding. |
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| • The Campfire • Acute Effects of Radiation • TEPC |