The (Semi-Irrational) Fear of Radiation

Fear is a crazy thing.  Often it’s born from the unknown.  This post isn’t about fear itself (although that’s a great topic…), but the fear of nuclear radiation.

With the ongoing nuclear situation (if Chernobyl, Hiroshima, and Nagasaki were nuclear crises, this isn’t) there are a TON of stories in the media that are really freaking people out, but what’s missing are useful comparisons.  All we hear are comparisons of current radiation limits to the legal allowable limits.

Take this NYT article from yesterday telling of water emitting 1,000 millisieverts per hour (of radiation), comparing that to the 250 millisievert per year limit for power plant workers.  Sounds pretty scary if you don’t know what a sievert is or why it’s bad.  As with everything in the nuclear industry, however, the factor of safety (this is basically the amount of cushion engineers give themselves when designing things, in the off-chance their calculations weren’t spot on) is pretty big.  If you swam in a pool of water that was uniformly emitting radiation at that rate, after an hour, you would increase your risk of cancer by 4%.  Now realize this was one reading, so it’s most likely not emitting at this rate, and no one is getting that close to it.  The real fear is that it may leak out into the ocean.

Four things are important to keep in mind here:

  1. The ocean is HUGE and would greatly dilute the radiation concentration.
  2. Radiation doesn’t last forever.  It’s from radioactive isotopes (radioactive atoms).  The biggest culprit, Iodine-131, has a half-life of 8 days, meaning half of the radioactive atoms will no longer be radioactive in 8 days.  Cesium-137 is another culprit, but has not been found in harmful quantities yet.
  3. Direct radiation exposure falls off by the cube of the distance from the radioactive material.
  4. Even if the iodine-131 or cesium-137 is ingested through spinach, milk, or maybe fish, you’d have to eat an astronomical amount to increase your cancer risk by even 4% with radiation at the current levels in those items.

All this to say, well, let’s not freak out.  There is definitely a danger, but there are much bigger dangers in Japan right now than from radiation.  Also, the rest of the world should not halt plans to grow nuclear power output because an old plant in Japan is leaking radiation after a gigantic earthquake.  Especially when the new systems are physically incapable of failing as the Japan systems did.

Here’s some more places to read about it from smarter people:

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