Japan’s Nuclear Reactors

I have a surprising number of friends and colleagues living in or visiting Japan right now. The biggest concern is the safety of the nuclear reactors that have been affected by the earthquakes. I intend to point people here as a resource for information, such as I have it.

The best advice I’ve heard is to seek out potassium-iodide pills. The Japanese government is talking about distributing them; if so, people in the area should take them. My understanding of the mechanism is as follows:

  • Radioactive iodine is released into the air and water in a damaged nuclear facility
  • When ingested by a human, the iodine is taken in by the thyroid
  • Radioactive iodine has been linked to incidence of thyroid cancer

By taking potassium-iodide pills with a rather large dose of iodine, the “safe” iodine gets taken up in the thyroid. If radioactive iodine is ingested later, it is not taken up by the ‘full’ thyroid, but is instead safely excreted by the body. In the real world, during the Chernobyl disaster, areas where the population received potassium-iodide pills went for years without incidence of thyroid cancer. Population in affected areas which did not receive the pills were subject to epidemic levels of thyroid cancer.

Table salt in some areas is fortified with iodine, particularly for populations that don’t eat sufficient quantities of fish. However, the amounts of iodine in this salt is extremely low and insufficient for prophylactic use in a nuclear emergency.


  1. The best data I’ve found on Japan’s nuclear sites is here, the World Nuclear News website. A brief look around the site and its supporters makes me think that it is an industry mouthpiece. However, it does have up-to-date news and it does give technical details in non-jargon English. YMMV. They also have a Twitter update here.
  2. UPDATE 3/14: This is the single best general overview of the situation from a scientist/engineer, here.
  3. Details on the potassium-iodide uptake in a nuclear emergency are here.
  4. 3/12/11 1pm PST update. A blog post by Michio Kaku, a physicist, on the situation here.
  5. Best up-to-date news service is Al Jazeera English, here.

I’ll update this site with other data as I have it.


  • I am not a doctor. Don’t take medical advice from amateurs like me.
  • I am not a physicist. I do have an undergraduate degree in physics, but never worked in the field. See here.
  • I originally did the research on potassium-iodide uptake when I moved my family to within 20 miles of a seaside Southern California nuclear plant in 2004. We lived there for six months.
  • I am neither a nuclear power proponent, nor do I oppose nuclear power. I’m neutral on the subject.

2 Responses to “Japan’s Nuclear Reactors”

  1. […] written some notes on the relevant nuclear issues with links and placed them on my personal website. It’s […]

  2. Iodine sounds like a good idea. Probably best to leave the area if possible or stay inside. Still a concern with leukemia. (Ed’s edit: My sister Helen *is* a doctor.)

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