by Karl Johanson
36 years ago today, a major release of radioactive material took place in Washington State. The explosive event which lead to the release, killed 61 people and was covered extensively by the news media. However, the release of radioactive material was never mentioned in this coverage. The amount of radioactive material released can only be roughly approximated, but the following is a fair estimate.
- Actinium-227 13 grams
- Thorium-228 18 grams
- Radium-228 60 grams
- Lead-210 300 grams
- Protactinium-231 20 kilograms
- Radium-226 22 kilograms
- Thorium-230 1,000 kilograms
- Uranium-234 32,000 kilograms
- Uranium-235 420,000 kilograms
- Uranium-238 60,000,000 kilograms
- Thorium-232 170,000,000 kilograms
- Potassium-40 300,000,000 kilograms
- Rubidium-87 337,000,000 kilograms
In addition to the above, the following radioactive isotopes were released in trace amounts:
- Astatine 215, 216, 218 & 219
- Bismuth 210, 211, 212, 214 & 215
- Francium 223
- Lead 211, 212 & 214
- Plutonium 239 & 244
- Polonium 210, 211, 212, 214, 215, 216 & 218
- Radon 219, 220, & 222
- Thallium 206, 2207, 208 & 210
- Thorium 227
Many of the listed isotopes are the daughter isotopes of Uranium 238, Uranium 235 and Thorium 232.
This amount of radioactive material is (very roughly) what one would expect to find in any 4 cubic kilometres of the Earth's crust. The event which expelled this material, involved a release of energy roughly 500 times that of the nuclear bomb used on Nagasaki. 500 hectares of land was devastated and shockwaves shook houses more than 30 kilometres away. Around 25% of the material was emitted as dust, which remained in the atmosphere for some time. The remainder precipitated out fairly rapidly over the nearby countryside.
To add some interesting perspectives on this amount of material, consider the following.
- 420,000 kilograms of Uranium 235 is enough to make more than 100,000 nuclear weapons.
- The US government is studying Yucca Mountain in Nevada with intent to store around 70,000 tonnes of spent nuclear fuel there.
- Some claimed that roughly 40,000 kilograms of depleted uranium (almost pure Uranium 238) was used in the Gulf war and that it represented 500,000 "potential deaths". (I make no commentary here on the ethics of weapon use in general, nor of the ethics of the use of this specific weapon.) I'm curious what those people would estimate the number of "potential deaths" would be from the emission of around 1,000 times as much Uranium 238.
- If you've heard and believed the mistaken claim that releasing 1 pound of plutonium would kill every human on Earth, consider the following. The 22 kilograms of Radium 226 (just one isotope from the above list) would have a specific level of alpha radiation equivalent to just over 350 kilograms (770 pounds) of Plutonium 239. Radium is also far more likely to form readily aspiratable particles and is more readily absorbed by the human body when ingested. Somehow, that powdered radium left more than 7 billion humans alive.
If you're at all curious, the event which released somewhere around the above estimated amount of material, happened on May 18, 1980 and was, of course, the eruption of Mount Saint Helens. Eleven years later, on June 13, 1991, Mt. Pinatubo released roughly one and a quarter times as much material (radioactive and otherwise) as Mount Saint Helens.
I would never suggest that a natural event emitting any given material should be used as ‘justification’ of humans releasing large amounts of similar materials. Nor does Saint Helens’ and Pinatubo’s emission of Lead and Uranium ‘justify’ the use of such things as Lead or Uranium bullets in any given situation. I do suggest however, that the Saint Helens and the Pinatubo examples (and dozens of other recent eruptions) are useful data points on the road to understanding the complex issue of the possible effects of releases of radioactive material.