Regarding radiation, and when they say "x is less than y" ...

[Duer 157099]

Such as in this excerpt:

"Ministry spokesman Takayuki Matsuda said Sunday that radioactive iodine three times the normal level was detected in Iitate, a village of about 6,000 people 30 kilometers (19 miles) northwest of the Fukushima Dai-ichi nuclear plant. That's still one twenty-sixth of the level of a chest X-ray and poses no danger to humans, he said."

Does it take into account that a chest x-ray usually last mere seconds? Does that mean that if you stay in such an area for 26x the amount of time that you're exposed to a chest x-ray, then you have been exposed to the equivalent of 1 chest x-ray? What if you stay there for 260x? 2600x?

Chest x-ray = 10 seconds (probably much, much less than that actually)

260 seconds (about 4 minutes) in area with that radiation level = 1 chest x-ray.

???

http://www.sfgate.com/cgi-bin/article.cgi?f=/n/a/2011/03/20/international/i025005D28.DTL

[slackmaster]

1. Comparing ionizing radiation to non-ionizing radiation is what bothers me about that

:nuke:

[drm604]

3. I think they're both ionizing radiation.

What are referring to as "non-ionizing radiation"?

[slackmaster]

5. Are X-rays regarded as ioninizing? I thought they were not. I'll have to check now.

The core of what I meant was comparing electromagnetic radiation to particles. I don't see how you can draw much similarity between the effects of a high dose of gamma rays compared to inhaling plutonium dust or radon.

[drm604]

8. Absolutely they are.

As someone who worked as an X-ray technician years ago I can say for a fact the X-rays are ionizing. Wikipedia agrees with me.
http://en.wikipedia.org/wiki/X-rays

[drm604]

9. They're not comparing gamma rays to plutonium or radon.

They're comparing X-rays to iodine 131. From googling it appears that I131 gives off gamma (electromagnetic, like X-rays) and beta (electrons and positrons) radiations when it decays.

I think when they compare X-rays to beta and gamma they're comparing the amount of energy deposited. How valid a comparison that is I can't say.

[northoftheborder]

2. me confused

[drm604]

4. I assume it means

that if you consume the amount of water people typically consume your exposure is only 1/26 of what you would get from a chest X-ray. My question then is, how many days worth of consumption gives you that dose? If you're getting 1/26 each day then that's like a chest X-ray every 26 days - not good. Of course iodine 131 has a half life of 8 days so you wouldn't be getting that high a dose every day.

Perhaps it means that if you consume the normal amount of water every day, by the time it decays to background levels you will have received 1/26 of a chest X-ray dose, but there's not way to tell if that's what it means from the poor explanations we're getting from the media.

[nc4bo]

6. Very good questions drm604 and it's something I'd also like to know.

These people will be subjected to this for days, weeks, months perhaps years not just seconds or minutes.

[davepdx]

10. Your question is exactly what the reporter should have asked

There information needed to determine exactly what he was meaning is incomplete. This is probably due to to a reporter that didn't know what followup questions to ask. There must have been some assumption as to how many days someone would be drinking water to come up with that answer. We don't know the assumptions used in the quoted assessment.

Diagnostic xrays (machine produced) and gamma rays from radioative decay are both ionizing radiation.

Edited for spelling and again for grammar.

[suffragette]

12. Wouldn't the multiple ways they are being exposed also be factors?

I've been wondering about that.
They've brought up amounts in water, in food and I saw in an article that they will be reporting levels in dust and rain soon.
People there are likely exposed to all of the above, not just one element.

[Azathoth]

7. self-delete

[TheMadMonk]

11. Unless otherwise specified generally assume a year's dosing at that level vs...

...the x-ray.

Three times normal levels is naf all. Assuming no additions, the excess will be halved in 2 months amd And within a year nearly 99% of the excess will be gone. The background level remains, because that's the rate at which the world generates radio-iodine through natural radioactive breakdowns. This of course is assuming you are reporting this correctly, and it was three times background levels of radio-iodine that was detected and not sufficient radio-iodine to raise total background radiation to three times normal. This would be a little more serious, but still low enough to be negligible. A diet heavy on seafood (with its high idodine) would give you a bigger dose from natural sources if you kept it up for any extended period of time.

(The decay rate remains the same BTW.)

Simple fact is, no member of the public has recieved (or will likely receive) a dose as large as a person would get on a mountain holiday. And only one worker has received a dose outside permissable operational limits and his exposure remained inside emergency limits.

Something that we should find reasssuring about the condition of the reactors is that the emergency workers ARE NOT in there soaking up their maximum permissable emergency dose. Obviously whatever is catching fire and still occasionally exploding is not particularly critical kit.