Tuesday, 5 April 2011

Counting X-Rays

My comment on J.Michael Cole's otherwise commendable article criticizing Taipower's typically Taiwanese, 差不多 attidude toward maintenance and cleaning of its' nuclear power plants:

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Good work - I entirely agree that Taipower ought to be exposed to this sort of criticism, and it is the proper function of journalists to do exactly this sort of work.

Yet I think there may be a numerical error in your report:

"Contact dose rates on the suppression chamber liner at the conclusion of the cleaning work showed a significant decrease in radiation levels, from 10 millisieverts per hour to more than 80 millisieverts per hour (or the equivalent of 800 chest X-rays) before work to 0.15 millisieverts per hour to 2 millisieverts per hour after its conclusion."

I fact-checked this using wikipedia (in this case there is little reason to doubt the veracity of the article) and actually, a typical chest X-ray does not involve an exposure to 0.1 mSv, but to only 0.06 mSv. A value of 80 mSv therefore would be equivalent to 1,333 chest X rays, not 800 chest X rays. Bad though that level is, it ought to be borne in mind that symptoms of light radiation sickness don't generally occur at doses below 1000 mSv per hour, or 16,662 chest X-rays.

Yes let's have Taipower brought to heel by all means, but let's not add any fuel to the fire of public panic and ignorance over the dangers of radiation. There's more than enough of that already.

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Update: The Blogger Glitch ate my comment a couple of times. Anyway, a bit more scooting around reveals that J.M's value of 0.1 mSv per chest X-ray is an average value (students doing the X-rays and mucking them up half the time - hence a range), though properly done, the exposure should be less and I suspect the wikipedia figure of 0.06 mSv is probably the one that the professionals would stipulate to. Anybody know?


  1. I read that article in the newspaper and thought, "Normal for Taiwan". I had a coworker that had worked at Taipower. He actually quit a very nice job in his chosen profession with them to teach kindergarten.

    Normal in any centralized govt command-control economy for state-owned corporations to fudge spending on maintenance and safety equipment for other more glamorous things like solar energy farms in Luzhu or windmills.

    I have a bone to pick with you about bio-fuels btw. I prefer riddles though. Before the US went about turning 1/6 of their corn crop into everclear to burn in cars thereby causing spiking food prices, revolutions and riots worldwide, what was the huge biofuel craze before that?

  2. Can't remember - was it algae?

  3. Whale oil, which was replaced by kerosene

  4. Hmm - not sure what you're getting at with your mention of whale oil and why it's a "bone to pick with me" (do tell...), but I think your point on the consequences of the ethanol craze (or rather the prior provision of State subsidies which encouraged it) is a good one and deserves more attention.

  5. "Whale oil, which was replaced by kerosene."

    Idiot! Of course - biofuel replaced by gas. Sorry Okami it's late and my brain has probably absorbed too many neutrons to continue fissioning sentences apart.


  6. Mike: “I think the better contextual referent would have been the >1000 mSv per hour rate at which light radiation sickness begins; let’s not add to the panic.”

    The main point I was making in my article isn’t whether the radiation level inside the suppression pool is high enough to cause sickness (after all, no one but divers goes in there), but that the levels were much higher than they should, so much so that this prevented thorough maintenance by diving crew. The 60 or so bags of foreign materials removed weren’t radioactive when they fell into the pool, which means that radiation came from somewhere else (that is, the core reactor) and was attracted to the silt and debris. The more energy (that is, radiation) there is inside the pool, the less effective the stopgap mechanism would be in the case of an emergency.

  7. "...this prevented thorough maintenance by diving crew."

    I re-read your report and yes, I'll concede that. My apologies.

    The AEC is going to have to order inspection of those plants by outside firms more often.


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