There's only one problem. Spent fuel that's more than a year old doesn't melt down. Melting down requires a sustained nuclear reaction, which you can't get either without water as a neutron moderator, or using spent fuel, due to the over-abundance of isotopes that poison a chain reaction. There's some unpleasantness that you *can* get, like Hydrogen explosions and steam burns, but not a meltdown.
What most people don't understand is the "half life" concept. I know that you're familiar from drugs, but you might not have extended it to this. We hear a lot about the virtually infinite time that spent fuel is radioactive. But it gets those long half lives by *not being particularly radioactive*. Now, spent fuel straight out of the reactor is HELLA radioactive. It's been in a chain reaction environment for a year or 2. BUT, because it's so radioactive, it's decomposing pretty fast. that means that the radioactivity is dropping dramatically over time. For the first week after you pull it out of the reactor, it'll boil water. After 5 years, it's warm to the touch (I don't advise touching it).
So, let's look at what specific isotopes tend to be harmful to humans. The big one is iodine 131. It's dangerous, not because it's particularly radioactive, but because it collects in the thyroid gland. It has an 8 day half life. That means that in 3 months of the cessation of fission (10 half lives), it's basically gone. Then there's strontium 90, which is stored in bone. It's not an acute problem, more of one of those "if you live off the land for your entire life, you *may* build up enough to be harmful. 28 year half-life, so it's around for a good while, but again, not particularly radioactive. Try to avoid eating it, which means, if you live on the bikini atoll, try to vary your diet, at least a little. Less dangerous, but still an issue is Caesium-137. It doesn't build up in the body, and has a 30 year half life. But because it's got a metabolic half life of 70 days, it's only generally dangerous if you *keep* eating it at pretty high levels.
All of these isotopes, I should mention have not been found in the surroundings of Fukushima in anything more than 1% of a dose that a reasonable person would call "dangerous".
Freaking out about contingencies that violate the laws of physics is not productive.
I find that those most knowledgeable about the science are almost always the most sanguine about the scenarios.
In general, I agree that WHO is lukewarm, they've been caught in some outright lies. Mostly the one that jumps to mind is suppressing data about HIV transmission rates through heterosexual sex because "it sends the wrong message". That said, they generally err on the side of more alarmism, not less. For the rest of it, I'll await evidence of even 1 sick person.
![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png)
timeasmymeasure
no subject
Date: 2013-09-30 06:03 am (UTC)What most people don't understand is the "half life" concept. I know that you're familiar from drugs, but you might not have extended it to this. We hear a lot about the virtually infinite time that spent fuel is radioactive. But it gets those long half lives by *not being particularly radioactive*. Now, spent fuel straight out of the reactor is HELLA radioactive. It's been in a chain reaction environment for a year or 2. BUT, because it's so radioactive, it's decomposing pretty fast. that means that the radioactivity is dropping dramatically over time. For the first week after you pull it out of the reactor, it'll boil water. After 5 years, it's warm to the touch (I don't advise touching it).
So, let's look at what specific isotopes tend to be harmful to humans. The big one is iodine 131. It's dangerous, not because it's particularly radioactive, but because it collects in the thyroid gland. It has an 8 day half life. That means that in 3 months of the cessation of fission (10 half lives), it's basically gone. Then there's strontium 90, which is stored in bone. It's not an acute problem, more of one of those "if you live off the land for your entire life, you *may* build up enough to be harmful. 28 year half-life, so it's around for a good while, but again, not particularly radioactive. Try to avoid eating it, which means, if you live on the bikini atoll, try to vary your diet, at least a little. Less dangerous, but still an issue is Caesium-137. It doesn't build up in the body, and has a 30 year half life. But because it's got a metabolic half life of 70 days, it's only generally dangerous if you *keep* eating it at pretty high levels.
All of these isotopes, I should mention have not been found in the surroundings of Fukushima in anything more than 1% of a dose that a reasonable person would call "dangerous".
Freaking out about contingencies that violate the laws of physics is not productive.
I find that those most knowledgeable about the science are almost always the most sanguine about the scenarios.
In general, I agree that WHO is lukewarm, they've been caught in some outright lies. Mostly the one that jumps to mind is suppressing data about HIV transmission rates through heterosexual sex because "it sends the wrong message". That said, they generally err on the side of more alarmism, not less. For the rest of it, I'll await evidence of even 1 sick person.