jrtom

Wired article: Let A Thousand Reactors Bloom

This is sufficiently cool in theory that I wish I knew enough engineering and physics to figure out what the catch is (I assume by policy that there almost always is one, even though it may be minor).

Anyone?

Current Mood: intrigued
Current Music: Gabriel, Peter - Secret World Live (Disc 2) - Secret World

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From:

amnesiadust.livejournal.com

Check out this long list of experimental reactors at Argonne National Laboratory (West). It appears that so-called "passive safety" has been a big concern for many years; indeed, there have apparently been reactors which were designed to be passively safe as early as the 1980s. So the Chinese emphasis on "passive safety" isn't new.

The basic fact claims made by the article are corroborated by Wikipedia, which also provides much additional interesting information (y'know, you're right, it rocks).

Of course the article didn't have enough detail for me to comment on whether the Chinese design in particular makes sense. Right now "Doppler broadening" has no meaning for me in this context; I'll have to learn more about fission reactions first. But I assume they mean that the cross section for uranium fission peaks under some set of conditions, and the reactor can be so constructed that any departure from the nominal operating conditions causes the cross section to go down... so that everything cools down and tapers off.

And yes, breeder reactors are good things, and plutonium can be used as fuel. Researchers at ANL-W are also apparently concerned with ways in which spent nuclear fuel can be re-processed so that the waste products have a much shorter half-life and can in turn have further energy extracted from them.

You're also right about the half-life issue with decay products. In fact there's an article by a UC Berkeley professor of physics which has been pinned to the INPA bulletin board at LBL for months now. His analysis claims that the expected levels of radioactivity at Yucca Mountain, even assuming some kind of leak, are still lower than the ambient radioactivity in ground water leached from uranium ore found in the bed of the Colorado River. That I find especially amusing.

It looks like most research into this got mothballed by Congress in 1994; I'm guessing it was just too much of a political hot potato. People are indeed afraid about reactor meltdowns, perhaps irrationally so. It's easy to be afraid of stuff you don't understand.

From: (Anonymous)

I remain skeptical.

I'm skeptical of the "fast decaying isotopes go away quickly and slow decaying isotopes aren't dangerous" argument. The background radiation we all get from natural radioactive isotopes in rocks, etc, is largely from stuff that has half lives in the hundreds of millions or billions of years. So unless you think a million years is "fast" even the slow decaying waste products can be expected to be at least a thousand times as radioactive as the natural sources, and if you don't think a thousand years is "fast", you can up that number to a million times. Sure, the slow decaying stuff isn't as dangerous in the "I touched a little of it and now all my hair is falling out and I'm gonna die of acute radiation sickness" sense. But increasing the background radiation by even a factor of two or three is still Not Good from a long term public health standpoint.

I'm skeptical of the "Expert John Doe said that nuclear power is perfectly safe because my calculations show that playing with kittens is actually more likely to cause cancer than eating a modern nuclear reactor" style of argument. I grew up within a few miles of the Department of Energy's Idaho National Engineering Laboratory, which does a lot of reactor engineering, and I spent much of my youth among people who made these arguments. My gut reaction to these people is now that they seem to believe things that they WANT to believe -- because their jobs, their life, and their work all go very badly if nuclear power isn't an interesting R&D subject. Since it's hard to convince yourself that weapons research is For the Good of Humanity, there's a lot of psychological pressure to believe that civilian nuclear power reactors are a Good Thing. So they do optimistic calculations. Incidentally, I frequently heard the "nuclear waste can be stored safely" line from the same people and with the same confidence as the "Co2 doesn't cause global warming" line and the old Reagan standby "Trees cause more pollution than they cure". So when I see the dueling factoids (those on the other side being things like "Just the ambient radiation from the trucks going to Yucca Mountain under normal conditions will measurably raise the cancer rates for everybody within the I5 freeway corridor") I basically am forced to conclude that this whole thing is a giant game of Russian Roulette and nobody can even agree about how many bullets got put in the chambers.

I'm less skeptical, but still very conflicted, about the various high tech reactor and waste processing technologies. On a purely technical level, breeder reactors seem to work fine, but I'm guessing there's a downside (aside from the "war on terror" classic that the output of a breeder reactor and a couple of college chemistry majors can be mixed together to make a nuclear weapon). Likewise, I can't tell whether In Situ Vitrification is a good way of stabilizing waste so it's less dangerous, or an exciting way to create big explosions which get rid of the waste by injecting it into the stratosphere.

None of this is to say that nuclear energy can't have a short term place in a sane energy policy. But any time I get a whiff of the notion that if we all just learn to love Plutonium then the whole energy vs. environment problem will just disappear, I gotta cringe and point out that this ain't no panacea, folks.

-JKL

From:

amnesiadust.livejournal.com

What, did I say "panacea"? It's certainly nothing of the sort. I don't mean to claim that there are, in fact, no problems to be solved regarding the safety of fission reactors. However, I am optimistic about the possibilities of finding technological solutions to those problems, if scientists are allowed to research them.
Your good point about the half-lives of stuff is noted. The relevant questions are:

how exactly does the amount of waste stored at a site translate into additional background radiation?

what kinds of background radiation pose health hazards?

how do you separate radiation-induced decline in health from other factors?

I don't really know the answers to any of these questions. It seems that (1) is probably the most easily answered, since the various decay products (electrons, neutrons, alpha particles, and gamma rays) can be worked out experimentally, although the decay chains are often problematic. The answer to (2) may in part be worked out by this. Perhaps some insight into (3) can be gained, e.g., by long-term studies of populations living around various sites where nuclear waste is stored. That could probably be looked up.

Regarding "Expert John Doe", here's Rich Muller's original essay to which I was referring. Mostly it's rhetorical, so you can ignore about 80% of it, but he does go through a few numbers. (mostly for

jrtom's benefit) Mainly he compares stuff to the level of radioactivity present in uranium ore -- although it has been pointed out that it isn't just the level of radioactivity (i.e., number of decays per unit time) but also the character of the radiation coming out.

In any case, I think the ideal situation is to store as little waste as possible, and reprocess as much as possible. If highly dangerous stuff can be broken down into other stuff which is less dangerous, and you can get energy out of the process, that would be fantastic (and would presumably be a coup for non-proliferation efforts). If no real feasible way to do this can be found, well, we're no worse off than we are already. It sounded as though some of the ANL-W reactors worked on this. (Is ANL-W the same as the DOE facility you mentioned?)

If I seemed unusually interested I think it's because I know little about nuclear power and had never heard of these new reactor designs. It was encouraging to see that other people besides the Chinese had been thinking about them. It would be nice to know what kind of progress is currently being made by American researchers on this subject.

Nevertheless, in the long term fission isn't going to be an acceptable solution either, regardless of whether we solve the safety problems or not; uranium is just another kind of stuff to dig out of the ground, really. If we're on track to go through all our natural reserves of coal and petroleum in something like 300 years, and we then turn to nuclear power, who's to say that our reserves of uranium will last much longer if people continue to consume at the present rate? It's certainly worthwhile to look into... but the point as I see it would be to buy the human race a little more time to investigate truly renewable sources of energy, and get our culture to the point where we're only using as much energy as these sources provide.