Radiation dosages in perspective
Posted by Richard on March 29, 2011
Grim reports about the Fukushima nuclear plant continue every day. The media are now reporting that radiation from the plant has been detected in "miniscule" amounts across the US. They don't define miniscule, apparently merely quoting some government source. But every so often, they trot out some "expert" who warns us that there is no safe dose of ionizing radiation, that any additional quantity leads to additional deaths from cancer.
To put all this ominous news into perspective, I suggest that you take a look at xkcd's radiation dose chart (click the image to see it full-size). It elegantly illustrates the relationships across a broad range of radiation exposures, from sleeping next to someone or holding a banana to standing beside the molten core of a reactor. I think Edward Tufte would approve.
After spending some time studying the chart, I wondered if the "no safe dose" advocates always sleep alone, never eat (or even stand near) bananas, never go into buildings containing granite or marble, never fly on airplanes, and live only at sea level. Somehow, I doubt it. But how sad for them if they do.
I'm going to remain in Colorado, where I get lots of extra ionizing radiation due to the altitude. But somehow, people still manage to live longer.
Rick Shultz said
Richard, speaking from 6 years of experience in the nuclear power industry, I compliment you on your chart. It is excellent for your limited experience with radiation, and the time you had to put it together. There are a couple minor things I would like to mention if it’s ok though. For one thing Sieverts are not units you will see very much and are not as informative to the layperson as the more common radiation-absorbed-dose (rad). And not quite as clear as to cummulative effect. And your figures for Chernobyl are probably underestimated as none of the dosimiter units were very useful at Chernobyl due to all of them being pegged out in only seconds from the levels. It has been mathimatically determined for example that the level inside the reactor buidling at the time the core excursion occurred were 30,000 roentgen’s per hour which will kill a human after a VERY few minutes of exposure. All in all though, I felt it was very good for a fast effort and a good looking chart.
Rick Shultz said
And just as a BTW. I’m not a believer in the “no safe dosage” theory because cells in your body are being replaced by it all the time INCLUDING radiation damaged cells. So the accumulated dosage theory has IMHO at least one big hole in it right there. Accumulated over short time, yes. But long term accumulation, no because it’s at least partly negated by your body’s natural processes.
rgcombs said
Thanks for the kind words, Rick, but it’s not my chart — I just linked to it. As it states at the bottom, the chart is by Randall Munroe. He’s also the creator of the fine comic strip, xkcd, which I encourage you to visit regularly. 🙂
Rick Shultz said
Sorry Richard. I somehow got the impression from the note at the beginning of the chart that you had worked on it with someone else. Should have taken your frequent advice and read the whole thing :=(
David Bryant said
Rick Shultz wrote: ”But long term accumulation, no because it’s at least partly negated by your body’s natural processes.”
Maybe yes and maybe no, Rick. It’s not clear what the effect of a gamma ray is going to be if it rips through a molecule of your DNA. It might just bust it in half, and that cell might die. Or it might garble things up a little bit, but not enough to confuse the error-correcting code (DNA apparently has some built-in redundancy features, but we’re not sure exactly how they work). Or it might scramble up some portion of the code enough to create a rogue cell that eventually grows into a tumor. That last possibility isn’t very likely, but it can’t be ruled out entirely.
One thing the news media are not very clear about is the difference between actual radiation (EM waves, and say Alpha particles) and radioactive nuclei that may be released into the water, earth, and air. I’ve seen a few reports about radioactive cesium that may have leaked from the Fukushima Daiichi plant, but nothing reliable so far. Apparently some gamma rays characteristic of CS-137 decay have been detected in samples of seawater collected near the plant, but I haven’t seen any well-written reports about it. Have you?