Monday, January 25, 2016

Specific Activities

When interested in relatively low-level radioactive material, the picocurie, or pCi (one-trillionth of a curie, remember?), is used. In Table 6, the activity is in pCi per liter and in Bq per liter. [You will also run across Bq per cubic meter (Bq/m3) in some radon studies. Multiply Bq/l by 1,000.]

Table 6 – Specific Activities of Common Substances
Material
Picocuries/liter
Becquerels/liter
Normal air
2
0.074
Typical radon level in homes
3
0.111
EPA limit: Ra-226 in drinking water
5
0.185
Nuclear power plant leak
15
0.555
“Contaminated” milk at TMI*
22
0.814
Rainwater **
360
13.3
Whiskey
1,200
44.4
Salad oil
4,900
181.5
Spa waters of Bad Gastein
16,200
599
Drinking water in Maine***
53,700
1,987
*The increase in radioactive iodine in Harrisburg after the Three Mile Island “disaster” was 1/20 that caused by Chinese A-bomb tests in 1976. You remember how Jane Fonda and Ralph Nader protested those, don’t you?
**Measured at Santa Fe, 5/11/1986. (Probably atmospheric carbon 14 and wind-blown potassium 40 salts.)
***Based on an average of 226 samples. Radiation Controversy, Ralph Lapp, Reddy Communications, 1979.

Since most Americans have no idea what danger might lurk in a glass of water having 200 picocuries per liter, we are at the mercy of those who might use this lack of knowledge to their political advantage. Professor Petr Beckmann pointed out that activity in a well-publicized reactor leak at Indian Point power plant outside New York City was equivalent to that in a pint bottle of salad oil. Without this knowledge, an interested citizen would be led to believe (a) nuclear power was unreliable, and (b) such technology was a danger to life and limb - exactly what anti-techologists Nader, Commoner, Ehrlich and their fellow primitivists would have us believe. Exactly the opposite of the truth.

You might want to bookmark this page, for easy reference to Table 6 as you read on.

In answer to the question posed in the chapter title, 100 picocuries is the approximate activity in a handful of average soil produced by the disintegration of potassium 40. (I always knew there was something dangerous about working out in the yard.)

Next we'll take a look at how the effect of ionizing radiation on the human body is measured.