Nuclear Clarifications Related to Fukushima

[NEOWatcher]

I started this so I don't interfere with the Scare over nuclear power stations in Fukushima thread which seems to be a good discussion on ongoing issues.

I've been hearing some statements in the news, and I come up with questions about certain statements, and I'm sure there are others with similar questions, or others that run across something that might be misleading.

They are suggesting that residents stay indoors. I've heard that being indoors is usually "sicker". I can understand in the beginning of an airborne disaster that indoors would be safer, but wouldn't that situation reverse over time? Wouldn't the radiation effects build up inside?

I heard on the radio this morning something about the safety around a plant near here. I can't remember the context of the statement, but they said "there's less radiation than you get walking through a Best Buy" (electronics store chain).
Wouldn't there be a big difference in the types of radiation causing different effects?

[Antice]

depends on what part of best buy you go trough. the shelf with smoke detectors sure does contain a bit of radioactive elements. other electronic components may or may not contain any depending on type/class of device.

if the best buy is a basement store then you are likely to be breathing fair amounts of radon too. probably get a bigger dose from that than anything else in that store tbh.

Those stone columns in government buildings. them's got some activity going too. enough to set off a personal dosimeter alarm.

[kamaz]

wouldn't that situation reverse over time? Wouldn't the radiation effects build up inside?

If radioactive dust gets in, then it can be removed just like normal dust. Of course washing it off or using a wet cloth is preferable, because you don't want this stuff to become airborne again.

Wouldn't there be a big difference in the types of radiation causing different effects?

Yes. But if the dose in given in REM or Sievert, then it is already corrected for this: http://en.wikipedia.org/wiki/Equivalent_dose

[NEOWatcher]

If radioactive dust gets in, then it can be removed just like normal dust. Of course washing it off or using a wet cloth is preferable, because you don't want this stuff to become airborne again.

That's one of the things I was thinking of. As the air clears, the wind blows the dust away, etc. Your house still has the radioactive dust.

But; on further reflection, I'm also thinking about the radiation itself (not radioactive materials), and the possible protection of having some walls around you.

Yes. But if the dose in given in REM or Sievert, then it is already corrected for this: http://en.wikipedia.org/wiki/Equivalent_dose

Yeah; I read that earlier, but since I posted this thread. It does make sense, but it's the factors that correct for each type which I was questioning.
Now I'm wondering if what I heard was based on the sievert computation or not.

[Ara Pacis]

If the released radionuclides are gamma emitters, then you can receive radiation poisoning from staying indoors. If it's just a beta and/or alpha emitter, you have to ingest it somehow to get significant damage from it. So, if you shelter in place and block air from flowing in, you might be okay. Of course, it also depends on whether the radionuclides are in a gas or as aerosols/particulates.

[korjik]

Dust dosent penetrate a closed house very quickly. As long as there is no traffic in or out of the building, there wont be much outside dust inside. That allows the buildings to block all the alpha and beta emitters, and staying inside means you wont breathe them.

The other part is that the dust will still be around till the first good rain. Till then you will just be kicking dust around if it gets windy, but you do have the advantage of the radioactivity decreasing over time.

Barring being in a direct wind flow, the gasous components should diffuse away pretty quickly. Shouldnt be a big problem.

[danscope]

Those house were shook within an inch of their structural lives. I doubt that they are that tight. You are going to need
first class carbon filter respirators 24/7 for a very long time. And replacement filters in quantity. Once you ingest these isotopes, they continue to bombard your bloodstream, and you really don't want that.
The pity is that so many homes do not exist , nor the quality respirators . Those paper masks aren't great for even sawdust.
The whole scene is so devastating.

Dan

[korjik]

Those house were shook within an inch of their structural lives. I doubt that they are that tight. You are going to need
first class carbon filter respirators 24/7 for a very long time. And replacement filters in quantity. Once you ingest these isotopes, they continue to bombard your bloodstream, and you really don't want that.
The pity is that so many homes do not exist , nor the quality respirators . Those paper masks aren't great for even sawdust.
The whole scene is so devastating.

Dan

Not unless one of the reactors does a Chernobyl. There isnt that much released to worry about. Even then, most of the radioactivity is gaseous not dust.

Besides, even if there is alot of dust, it will only be around till the next strong rain. Dust tends to get washed away at that point.

[Van Rijn]

They are suggesting that residents stay indoors. I've heard that being indoors is usually "sicker". I can understand in the beginning of an airborne disaster that indoors would be safer, but wouldn't that situation reverse over time? Wouldn't the radiation effects build up inside?

As a general rule, the most dangerous radionuclides are the ones that decay the fastest, and so emit the most radiation. So, danger drops off quickly. That's the idea with fallout shelters, where with fallout with extreme radioactivity, you would stay inside for a few weeks.

Staying inside means dust is less likely to get inside your body and that's makes a big difference in the risk of exposure to some radionuclides. And, distance is important with gamma emitters. In the old N-war recommendations, as one option they would suggest an interior hallway, and blocking the ends of the hallway.

[Ara Pacis]

Are any of the fission products at the plant gamma-emitters? I know that the MOX fuel at Unit 3 could have Americium-241, but any others? If the radioactive material is only beta and alpha emitters, then you should be safe with a tinfoil hat... and suit.

[Van Rijn]

Cesium 137 is an important one. Gamma as well as beta in the decay process.

[Van Rijn]

A clarification on iodine. A number of times in the news I've seen the claim that "iodine tablets protect against radiation."

Iodine tablets (or other iodine sources) do not provide general radiation protection. They reduce uptake of radioactive iodine if you're exposed to it. Radioactive iodine 131 is produced in nuclear reactors.

But, regarding the panic buying in the U.S., iodine 131 has a half-life of about 8 days. That means that even if a significant amount got out of the plant, much of it would decay before it could get to the U.S.

And, taking too much iodine can cause serious health problems. Unless there are reliable reports or recommendations for your location, the pills (or other large doses) aren't a good idea.

[Ara Pacis]

FYI, There is a new drug being trialed that can protect against radiation. I wrote about it here.

[kamaz]

Iodine tablets (or other iodine sources) do not provide general radiation protection. They reduce uptake of radioactive iodine if you're exposed to it. Radioactive iodine 131 is produced in nuclear reactors.

Specifically, the thing is that your thyroid takes iodine from the air. If you have radioactive iodine flying around, your thyroid will absorb this too, and you get thyroid cancer. So the idea is to give you body enough iodine that it stops absorbing radioactive one from the air.

[HenrikOlsen]

FYI, There is a new drug being trialed that can protect against radiation. I wrote about it here.

The thing to notice is that this is a drug to alleviate acute radiation syndrome, not to help with increased cancer risk from low level contamination.

I saw a picture yesterday purporting to be a counter showing that radiation had reached Tokyo. It was showing 0.6 µSv/h
In terms of increased cancer risk, that's equivalent to smoking one cigarette every 16 hours.

[Joe Durnavich]

I saw a picture yesterday purporting to be a counter showing that radiation had reached Tokyo. It was showing 0.6 µSv/h

In terms of increased cancer risk, that's equivalent to smoking one cigarette every 16 hours.

Just for fun, we should state these in barium enema equivalents too.

[HenrikOlsen]

Ok, it's equivalent to having a barium enema every 666 days.
It's actually a good unit as it's pretty close to being equivalent (in terms of increased cancer risk) to smoking 1000 cigarettes.

[geonuc]

Are any of the fission products at the plant gamma-emitters?

I think most of them are. Gammas are the most common form of radiation in the various isotopic decay chains.

[Ara Pacis]

I think most of them are. Gammas are the most common form of radiation in the various isotopic decay chains.

Yeah, but how much, is what I was wondering. For example, looking up ¹³¹I, I read that 90% of the radiation is beta and only 10% is gamma.

[Ara Pacis]

Also, I can't find where I saw it originally, but either here or elsewhere on the web I read that there is some scientific/medical evidence that low levels of radiation can actually be good for you. Radiation Hormesis.

OK, I remember now, it was an Ann Coulter piece that someone linked to.

[slang]

Also, I can't find where I saw it originally, but either here or elsewhere on the web I read that there is some scientific/medical evidence that low levels of radiation can actually be good for you. Radiation Hormesis.

OK, I remember now, it was an Ann Coulter piece that someone linked to.

And here's PZ Myers commenting on that.

[Joe Durnavich]

I take the point of the Coulter piece (besides her brand of comedy) is that reporters have over sensationalized the effects of radiation, and that the increased exposure in Japan is not necessarily going to equate to increased cancer rates.

I can't tell what Myers is recommending. Does it follow from his article that we should get rid our smoke detectors and ban nuclear medicine? After all, if there is no threshold below which radiation is not harmful, why allow any ionizing radiation?

[HenrikOlsen]

Increased exposure to radiation does lead to increased cancer rates, that's universally accepted in health physics.
The thing is that the increase can easily be small enough to be indistinguishable from random sampling noise and/or overwhelmed by other cancer inducing risks.
As I mentioned when someone posted a picture stating that a city in Japan had measured 1 µSv/h, that's an increase in cancer risk equivalent to smoking a cigarette every 10 hours. Since a lot of people smoke a lot more than that, if any of them get cancer it will be impossible to tell what they got it from.

[Joe Durnavich]

Increased exposure to radiation does lead to increased cancer rates, that's universally accepted in health physics.

What about the Linear No-Threshold Debate? I thought this was a point of contention.

[HenrikOlsen]

One of the reasons why it's contentious is that the hypothetical point below which radiation damage will get repaired without any effect in terms of increased cancer risk, is so low that it's really impossible to tell if it's happening or not, because it's essentially impossible to have a large enough and controlled enough sample size to get the effect measurable to any significance.

Plus I think it's going to be a lot easier to be believed by starting with accepting that there is an increased risk, then showing how small it is, rather than by denying that there is an increased risk to begin with.
The latter will just make people think you're a disinfo agent.

[Van Rijn]

And here's PZ Myers commenting on that.

I think the takeaway message from that is:

Then, of course, the major reason recommendations are made on the simple linear model is that it is the most conservative model. The data are weaker at the low end; there is more variability from individual to individual; the safest bet is always to recommend lower exposures than are known to be harmful.

(emphasis added) A bit of background - back in the Three Mile Island scare, you'd see a scientist or medical professional that would tell people not to panic given the low radiation exposure, perhaps mentioning the well accepted LNT model and how that is used to measure cancer risk versus radiation. Then for "balance" the news people would often have someone that would claim that was all wrong, and the risk was hundreds, thousands, or even millions of times greater.

The LNT model is based on cancer risk at high radiation exposure levels (quite a lot of information there from WWII Japan, ironically) and extrapolated down to low levels where the risk of radiation is lost in the noise (there's a lot of cancer, and there are definitely a lot of causes other than radiation). There is some evidence that it OVER states the risk of cancer at low radiation exposure. It can't be much greater (if that were the case, you should see increases at locations with significantly higher natural background radiation).

So, again, don't panic about low radiation levels. By the way, I don't like Ann Coulter, but I don't think he is accurately representing her article, and I don't think someone that uses the title "Will radiation hormesis protect us from exploding nuclear reactors?" should talk about someone else being irresponsible.

[Ara Pacis]

So far as I can tell, the talking heads have mostly avoided talking about the uninhabitable nuclear wasteland scare that I see in some news blog comments. People who go on about how someplace might be radioactive for thousands and millions of years make me wanna explain why that's a good thing.

[cjameshuff]

One of the reasons why it's contentious is that the hypothetical point below which radiation damage will get repaired without any effect in terms of increased cancer risk, is so low that it's really impossible to tell if it's happening or not, because it's essentially impossible to have a large enough and controlled enough sample size to get the effect measurable to any significance.

That's how I understand the situation...it's less that homesis is in dispute, and more that we just have poor information on what the optimum level is in relation to normal background radiation...how low it has to get before it starts doing damage without activating the various repair and protection mechanisms. Made worse because there may be multiple local optima and wide individual variations. The radiation might increase human resistance to radiation, but it's also entirely possible that natural background radiation already has us past the peak. Effects of such low levels are just too hard to measure.

Similarly, though, you can't rely on the linear model to say that bananas and brazil nuts kill people...

[HenrikOlsen]

No, but you can use the linear model to put upper levels on the consumption of bananas and brazil nuts for that reason. It's gives an upper bound.

[Ara Pacis]

You can have my banana when you pry it from my hot, radioactive, dead fingers.