5 ms·

Now that I look at the chart again, I'm a little confused. It says ~3.5 micro sievert 'extra dose from one day in average town near the Fukushima plant as of Ma

by jschuur 16y ago

Now that I look at the chart again, I'm a little confused. It says ~3.5 micro sievert 'extra dose from one day in average town near the Fukushima plant as of March 17th, varies quite a bit' in the blue squares, but also 'one day dose (~3.6 milli sievert) at two sites 50 km NW of Fukushima on 3/16, seen again on 3/17' in the green ones. Even factoring in the variation they mention, that's a 1000x difference. I know the dosage drops off exponentially, but first example must be a lot further away than 50km, which is no longer 'near' in my book. Perhaps the latter measurements were extreme cases caused by wind patterns.

Tichy 16y ago
Lies, damn lies and statistics... :-) In the green area, it says that doses where as high in some places, but much lower in other places. So presumably on average they were low, which doesn't help much if you accidentally live in one of the places where radiation is/was high.
- tptacek 16y ago
  Can we be more careful with the words "high" and "radiation"? Firefighters at the plant were exposed to high levels of radiation. Their exposure to damaging radiation is measured cumulatively in many hundreds or even thousands of millisieverts. We can legitimately talk about their health being endangered by high radiation. People living 50km from the plant have not been exposed to high radiation. They have, in the very worst possible interpretation of the numbers we have now, been exposed to multiple cross-country flights worth of radiation. If you want to call that "high radiation", I think in all fairness you must also advocate for flight attendants to be issued lead-lined suits.
  - Tichy 16y ago
    That is not what the XKCD chart seems to imply. It implies that in some spots the daily radiation was a twentieth of a level linked to increased cancer risk. So presumably after 20 days you would have reached a level that increased your cancer risk - if you live there, it seems likely that you'll be there 20 days. Yes, maybe the higher levels did not persist in one spot for for twenty days (we don't know). I don't find that very comforting, it still seems like a russian roulette style of living (there may be 20 days of higher exposure or not - you can not know unless you start carrying a radiation meter at all times). Btw according to the chart, a cross country flight is only a 150th fraction of the radiation at those spots 50km from Fukushima. Few people fly that often.
    - tptacek 16y ago
      A single cross-country flight is a 40usv exposure; flight attendants make the equivalent of 20 of those flights on average every month. An hour maximally exposed to the highest recorded level of outdoor radiation 50km away from the plant is roughly equivalent to two round trips between LA and New York. If you want to call this "Russian Roulette", that's fine, as long as you're also never going to get into a car, never going to eat red meat, and never going to ride a bike down a city street. All three of those things are demonstrably more dangerous than standing at the gates of the Fukushima plant. I want to point out that we are talking about you misunderstanding risks at two different points: (1) You appear to perceive a spot outdoor measurement of 170usv as a significant amount of radiological exposure, when it is in fact a very minor exposure, equivalent to an amount of air travel common in western culture --- and this, despite a concomitant spent fuel pond fire at a nuclear reactor. (2) You appear to perceive a cumulative 100msv (note unit) exposure as a significant carcinogenic risk, when it is in fact the lowest level of exposure you can endure at which there is any measurable impact on cancer; the behaviors (such as eating red meat) that I am hammering you with produce what appear to be much higher levels of carcinogenesis.
      - Tichy 16y ago
        "A single cross-country flight is a 40usv exposure; ... An hour maximally exposed to the highest recorded level of outdoor radiation 50km away from the plant is roughly equivalent to two round trips between LA and New York." Well that is not what the XKCD chart says. I was merely counting blocks (not converting units). According to XKCD, one flight is two green blocks. So two round trips LA/NY would be 8 green blocks. According to XKCD the 50km radiation was 180 green blocks, or 22 times the round trip (in a shorter amount of time). Blame XKCD if his chart is wrong, not me. Also XKCD says "CLEARLY linked to increased risk in cancer". Again maybe blame XKCD if his chart is misleading. If Fukushima is so harmless, why did they evacuate a 50km radius? Because of the media?
        tptacek 16y ago
        Because all else being equal if you can avoid an exposure of 10's of msv, you do, just like if you are getting over a bad cold you avoid driving if you can because you might get lightheaded and run off the road, but you almost certainly won't. And because in the very epicenter of a crisis, you can't predict exactly what's going to happen next and so you act conservatively. The funny thing about your logic is, it's how the people in charge of Chernobyl thought too. They couldn't simply work out the likely exposures and take action accordingly --- at least, not at first. So they spent zillions of dollars on cleanup and mitigation but didn't tell farmers not to pass unchecked milk on to children, who subsequently contracted thyroid cancer because of the uptake of radioactive iodine. You are illustrating the point. "If they evacuate", you think, "there must be some gigantic risk they aren't telling us about".
Wientje 16y ago
Radiation is not a static. If a particle happens to decay at your detector when it is detecting, you'll get a massive spike. As the radiation changes between hours, places and the specific isotopes decaying, it's near impossible to get fast and accurate results for average dose recieved.
- eliasmacpherson 16y ago
  The way they monitored people during the human plutonium injection trials[1] for the WW2 nuclear program was monitoring the radioactive content of the human excrement and urine, not sure how practical that is. They injected people that had terminal illnesses and short life expectancies with ~5 micrograms of plutonium(and other elements) to ascertain the effects, so the dangers to nuclear scientists working on the program would be known. The study didn't find much in the way of damage (i.e not fatal or cancerous) to those studied, but the isotope injected seems to be of high importance as some isotopes are more radioactive than others. [1]http://inpp.ohiou.edu/~massey/pdf/10_human_Pu.pdf http://inpp.ohiou.edu/~massey/pdf/10_human_Pu.pdf
- neutronicus 16y ago
  If a particle happens to decay at your detector when it is detecting, you'll get a massive spike. This is not true. The energy deposited by a single quantum of radiation is negligible, and at this point most of the activity is from long-lived isotopes and so shouldn't change from day to day. I would guess that wind patterns are responsible for the variability in measurements, not nuclear physics.
- Tichy 16y ago
  I would think one decaying event is one blip, and higher readings indicate more decaying events. A single particle can not decay very often and hence can not result in a spike.
jedbrown 16y ago
The prevailing winds are to the NW. Presumably the smaller doses are for towns in other directions, but that would be a rather biased average.
lukeschlather 16y ago
Living downwind from certain coal plants is worse. It's as the article said: we're looking at increase of a few percentage points risks and shitting ourselves without regard to the wide variety of things like cigarette smoke that cause four-fold increases in cancer rates.
- Tichy 16y ago
  The article did not say that at all. It says that fear harms people, it did not say that radiation does not harm people. The cigarette comparison is extremely silly, as most people actually choose to not smoke cigarettes out of concern for their health.
  - lukeschlather 16y ago
    >it did not say that radiation does not harm people. Neither did I.
    - Tichy 16y ago
      The article did not even mention radiation levels at Fukushima, yet you quoted it as radiation being not worse than cigarettes.
      - tptacek 16y ago
        The radiation levels at the plant gate at Fukushima are quite probably much less carcinogenic than a cigarette habit.
        Tichy 16y ago
        So why don't they evacuate 50km radius around everybody who lights up a cigarette? Don't get me wrong, I want to believe you, and I am actually hopeful that no lasting damage has been done at Fukushima. But somehow all the optimism does not seem to add up 100%.

by jschuur 16y ago

Tichy 16y ago

Lies, damn lies and statistics... :-) In the green area, it says that doses where as high in some places, but much lower in other places. So presumably on average they were low, which doesn't help much if you accidentally live in one of the places where radiation is/was high.

tptacek 16y ago
Can we be more careful with the words "high" and "radiation"? Firefighters at the plant were exposed to high levels of radiation. Their exposure to damaging radiation is measured cumulatively in many hundreds or even thousands of millisieverts. We can legitimately talk about their health being endangered by high radiation. People living 50km from the plant have not been exposed to high radiation. They have, in the very worst possible interpretation of the numbers we have now, been exposed to multiple cross-country flights worth of radiation. If you want to call that "high radiation", I think in all fairness you must also advocate for flight attendants to be issued lead-lined suits.
- Tichy 16y ago
  That is not what the XKCD chart seems to imply. It implies that in some spots the daily radiation was a twentieth of a level linked to increased cancer risk. So presumably after 20 days you would have reached a level that increased your cancer risk - if you live there, it seems likely that you'll be there 20 days. Yes, maybe the higher levels did not persist in one spot for for twenty days (we don't know). I don't find that very comforting, it still seems like a russian roulette style of living (there may be 20 days of higher exposure or not - you can not know unless you start carrying a radiation meter at all times). Btw according to the chart, a cross country flight is only a 150th fraction of the radiation at those spots 50km from Fukushima. Few people fly that often.
  - tptacek 16y ago
    A single cross-country flight is a 40usv exposure; flight attendants make the equivalent of 20 of those flights on average every month. An hour maximally exposed to the highest recorded level of outdoor radiation 50km away from the plant is roughly equivalent to two round trips between LA and New York. If you want to call this "Russian Roulette", that's fine, as long as you're also never going to get into a car, never going to eat red meat, and never going to ride a bike down a city street. All three of those things are demonstrably more dangerous than standing at the gates of the Fukushima plant. I want to point out that we are talking about you misunderstanding risks at two different points: (1) You appear to perceive a spot outdoor measurement of 170usv as a significant amount of radiological exposure, when it is in fact a very minor exposure, equivalent to an amount of air travel common in western culture --- and this, despite a concomitant spent fuel pond fire at a nuclear reactor. (2) You appear to perceive a cumulative 100msv (note unit) exposure as a significant carcinogenic risk, when it is in fact the lowest level of exposure you can endure at which there is any measurable impact on cancer; the behaviors (such as eating red meat) that I am hammering you with produce what appear to be much higher levels of carcinogenesis.
    - Tichy 16y ago
      "A single cross-country flight is a 40usv exposure; ... An hour maximally exposed to the highest recorded level of outdoor radiation 50km away from the plant is roughly equivalent to two round trips between LA and New York." Well that is not what the XKCD chart says. I was merely counting blocks (not converting units). According to XKCD, one flight is two green blocks. So two round trips LA/NY would be 8 green blocks. According to XKCD the 50km radiation was 180 green blocks, or 22 times the round trip (in a shorter amount of time). Blame XKCD if his chart is wrong, not me. Also XKCD says "CLEARLY linked to increased risk in cancer". Again maybe blame XKCD if his chart is misleading. If Fukushima is so harmless, why did they evacuate a 50km radius? Because of the media?
      - tptacek 16y ago
        Because all else being equal if you can avoid an exposure of 10's of msv, you do, just like if you are getting over a bad cold you avoid driving if you can because you might get lightheaded and run off the road, but you almost certainly won't. And because in the very epicenter of a crisis, you can't predict exactly what's going to happen next and so you act conservatively. The funny thing about your logic is, it's how the people in charge of Chernobyl thought too. They couldn't simply work out the likely exposures and take action accordingly --- at least, not at first. So they spent zillions of dollars on cleanup and mitigation but didn't tell farmers not to pass unchecked milk on to children, who subsequently contracted thyroid cancer because of the uptake of radioactive iodine. You are illustrating the point. "If they evacuate", you think, "there must be some gigantic risk they aren't telling us about".

Wientje 16y ago

Radiation is not a static. If a particle happens to decay at your detector when it is detecting, you'll get a massive spike. As the radiation changes between hours, places and the specific isotopes decaying, it's near impossible to get fast and accurate results for average dose recieved.

eliasmacpherson 16y ago
The way they monitored people during the human plutonium injection trials[1] for the WW2 nuclear program was monitoring the radioactive content of the human excrement and urine, not sure how practical that is. They injected people that had terminal illnesses and short life expectancies with ~5 micrograms of plutonium(and other elements) to ascertain the effects, so the dangers to nuclear scientists working on the program would be known. The study didn't find much in the way of damage (i.e not fatal or cancerous) to those studied, but the isotope injected seems to be of high importance as some isotopes are more radioactive than others. [1]http://inpp.ohiou.edu/~massey/pdf/10_human_Pu.pdf http://inpp.ohiou.edu/~massey/pdf/10_human_Pu.pdf
neutronicus 16y ago
If a particle happens to decay at your detector when it is detecting, you'll get a massive spike. This is not true. The energy deposited by a single quantum of radiation is negligible, and at this point most of the activity is from long-lived isotopes and so shouldn't change from day to day. I would guess that wind patterns are responsible for the variability in measurements, not nuclear physics.
Tichy 16y ago
I would think one decaying event is one blip, and higher readings indicate more decaying events. A single particle can not decay very often and hence can not result in a spike.

jedbrown 16y ago

The prevailing winds are to the NW. Presumably the smaller doses are for towns in other directions, but that would be a rather biased average.

lukeschlather 16y ago

Living downwind from certain coal plants is worse. It's as the article said: we're looking at increase of a few percentage points risks and shitting ourselves without regard to the wide variety of things like cigarette smoke that cause four-fold increases in cancer rates.

Tichy 16y ago
The article did not say that at all. It says that fear harms people, it did not say that radiation does not harm people. The cigarette comparison is extremely silly, as most people actually choose to not smoke cigarettes out of concern for their health.
- lukeschlather 16y ago
  >it did not say that radiation does not harm people. Neither did I.
  - Tichy 16y ago
    The article did not even mention radiation levels at Fukushima, yet you quoted it as radiation being not worse than cigarettes.
    - tptacek 16y ago
      The radiation levels at the plant gate at Fukushima are quite probably much less carcinogenic than a cigarette habit.
      - Tichy 16y ago
        So why don't they evacuate 50km radius around everybody who lights up a cigarette? Don't get me wrong, I want to believe you, and I am actually hopeful that no lasting damage has been done at Fukushima. But somehow all the optimism does not seem to add up 100%.