APR: your source for nuclear news and analysis since April 16, 2010

Tuesday, March 15, 2011

FACTS: Radioactive Half Life, Fallout

-Citizens outside the 20 km radius from Fukushima Daiichi nuclear station, but inside 30 km have been ordered to take shelter indoors and essentially perform decontamination of clothing when going indoors. Clothes on lines are not to be brought in, windows are to be shut and ventilation shut off to avoid bringing outside air -- and contamination -- indoors

-Radioactive Contamination is defined as the presence of radioactive materials in locations they're not normally found

-Radioactive Contamination cannot make people or things radioactive. If a can of food were left outside and got contaminated, it could be cleaned off with water and the food inside would be just fine... remove the contamination, remove the radiation

-Radiation, thus, can damage only living creatures.. and it does so by physically disrupting cells, and thus tissues

-The measures to reduce personal exposure to the effects of what essentially amounts to fallout are TIME - DISTANCE - SHIELDING

TIME: Radioactive material decays over time. "Half life" refers to the amount of time it takes for half the atoms of a substance to decay to stability. Here are some half lives of materials you may hear about in the coming days, from a booklet in the APRA collection issued as emergency response information for Maine Yankee Power Station, Maine Yankee Atomic Power Company:

Iodine 131, 8 days (a Beta and Gamma emitter)
Cesium 137, 30 years (a Beta and Gamma emitter)
Krypton 85, 10 years (a Beta and Gamma emitter)
Strontium 90, 28 years (a Beta emitter)
Uranium 235, 710,000,000 years (an alpha emitter)

Iodine tablets can be issued to ensure radioactive Iodine does not destroy a person's thyroid gland..

DISTANCE: Getting in your basement is the best; if fallout contaminates the roof of the house, and the walls, the best bet to obtain distance is the center of the basement

SHIELDING: Some materials like glass perform practically no shielding at all, and no attenuation of gamma radiation. Dense materials like concrete are best, so getting behind a lot of it helps most. Alpha particles penetrate little, Beta particles are harmful but stopped by most substances but gamma rays are very dangerous.

-Fallout can be rinsed off of foods that aren't porous and even a plastic bag if sealed is good enough to prevent contamination of food

The Japanese government has already issued the most basic of this type of instruction and information to its people near Fukushima Daiichi. Should the situation not improve, they will be given more of what you've read above.

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