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Halving Half Lives
An anonymous reader writes "PhysicsWeb is reporting that German scientists may have found a way to significantly reduce the radioactive decay time of nuclear waste. This could render the waste harmless in just tens of years and make disposal much less difficult as opposed to current standards. From the article: 'Their proposed technique - which involves slashing the half-life of an alpha emitter by embedding it in a metal and cooling the metal to a few degrees kelvin - could therefore avoid the need to bury nuclear waste in deep repositories, a hugely expensive and politically difficult process. But other researchers are skeptical and believe that the technique contradicts well-established theory as well as experiment.'"
One word: Challenger.
On the bright side, it would seriously reduce the lobbying strength of the AARP.
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How do these Germans know so much about the atomic nucleus? Did Neils Bohr leave them a working model or something? The German contribution to nuclear physics seems really disproprtionate to their actual population. Is there something unusually German about the model they committed us all to when they kicked off the science in the 1800s?
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Actually yes it is wise.
It is easy to shield high level waste. Water will work just fine. If you only have to store it for a few years then it really becomes a simple problem.
The sad thing is I doubt that this could work they way the say it will. It really needs to be tested.
I could understand if they used a good neutron emitter like beryllium. When an Alpha particle hits that you get neutrons. The neutrons could then cause an increase in decay type reactions, if it was captured by a nuclei of the the substance that you wanted to degrade. Even that is a big maybe since I am just thinking of ways it could work without doing any math.
Even then it seems like you wouldn't get anything like what this guy is claiming.
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I had the pleasure of witnessing a container test.
they took this container, put it into a rocket that was on it' side, and then launched it into a specially designed bunker.i.e a real think ass wall.
the container survived without a leak.
It is much easier to create a device that will survive a traunmatic event then it is to create one for people.
They could just send it down to the Mariennes trench. Naturally people with no knowledge of radiation, or the trench would complain about it.
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There are lots of different kinds of nuclear waste - the worst excesses are things like uranium mines and the US's Hanford Washington and Rocky Flats compounds, plus wherever the Russian and Chinese nuclear weapons development work was done, with huge volumes of fairly high-level waste and even huger volumes of low-level waste. Leave aside the risks of rocket failure, we simply don't have the payload capacity to haul significant quantities of it into Earth orbit, much less out of the gravity well to take it on a sundive.
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Insulators block electricity, not radiation. An insulator might help keep in beta-particles as they're just electrons, but not alpha. Remember, an alpha-particle is just a helium nucleus and (if memory serves) can be stopped by tissue paper. Gammas, of course, are the real nasty ones and need lead or something similar.
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I know this is snark...but...aside from the challenger issue, it would be highly cost-prohibitive. The world produces about 12,000 pounds of nuclear waste a year. At current rates this would cost about $250 billion just to get into orbit. The US has It would be much more expensive to actually escape the earth and get it to the sun, even considering the sun's gravity could do a lot of the work.
d isposal, although I am skeptical, at current rates to get the 600,000 metric tonnes of waste that the DoE has into orbit would cost about $10 trillion.
Wikipedia disagrees: http://en.wikipedia.org/wiki/Nuclear_waste#Space_
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Actually, if the GP is correct and they are increasing the radiation output in proportion to the reduction in the half life, what's to stop us from harnessing that output as power? The major reason we can't use many forms of nuclear waste as a power source is the difficulty in converting low levels of radiation into usable power; fast fissioning material on the other hand is perfectly usable as a fuel source.
Of course, the temperature of the storage device poses a major problem (if we have to supercool it, then harnessing the radiation as a heat source is right out). Assuming we can't do this at a higher temperature, and I don't understand the article well enough to make a guess here, then we'd have to find a way to convert the energy output of the waste into usable power without heating the storage vessel to the point where the accelerated half life drops back to normal.
I wonder if there is some way to allow the radiation to escape the waste storage vessel and transfer it's energy into something useful...
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The Marianas Trench? Are you insane, man? Don't you remember what happened last time we dumped nukes in the Pacific?
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In order to get the radiation down to safe levels, you have to out-radiate everything up to that level. Same radiation, doesn't matter if it takes the normal amount of time or less.
Actually it matters quite a bit. There are plenty of places where all that radiation would be hardly noticed, and if the timescale is lessened to something managable by today's governments, we will be able to avoid the monumental task of warning future generations.
I'd say that's quite a big win, if this pans out.
It is pretty easy to shield using water, since that's how spent fuel is stored after discharge from commercial plants until it's cool enough to move to dry storage (temperature cool, not radiation). Dry storage works just fine once the thermal loadings are low enough. Casks such as this are present at nearly every nuclear facility that hasn't moved fuel offsite.
My question about doing this on a large scale, is how are you going to keep this much material cool enough to reduce the half life assuming that this works in the first place? Alpha emission of transuranics has around 6.5 MeV of energy per particle, which translates into a large amount of heat for not so large amounts of material. The coolant material to waste ratio would be enormous! Also, the refrigerant energy to do this would probably render the entire process even more inefficient than the current idea of reprocessing (remember that reprocessing has lots of particularly nasty chemicals associated in large quantities). Since alpha emitting isotopes are neutron rich, meaning they are either fissile or fissionable, they can be used as fuel. Why destroy fuel when you can burn it? At worst, continue MOX reprocessing as is currently done. At best, fuel some RTG's for space exploration. In my mind, this type of research is "neat" at best, but if the purpose is trying to force schrodinger's cat back into the bag, they can forget it now that global warming is becoming a hot issue with nuclear power the sole possibility for continuing the current growth rate of electricity demand (way too many puns there, I apologize).
The world produces about 12,000 pounds of nuclear waste a year. At current rates this would cost about $250 billion just to get into orbit.
Your numbers are a bit off. A single Delta IV Heavy rocket can carry about 28,000 pounds to GTO, or about 20,000 to escape orbit, at a cost of around $250 million.
We can achieve the same goal by allowing the reprocessing of nuclear "waste". PBS had a good interview on the subject, which mentions that power generating reactors are only permitted to extract less than 1 percent of the energy. This is what leaves the "waste" highly radioactive.
I keep putting the word waste in quotes, because it's more like a nuclear fuel reserve than an unusable energy source. Use all the energy, and the half-life of what's left is a few decades.
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I just read an article in from a few months ago in Scientific American about fast reactors that can use the "spent" fuel from thermal reactors. Their waste is 95% smaller than thermal reactors and dangerous for only 10s of years, not 10s of thousands of years. _That_ technology has proven in prototype reactors.
Prove this process and in less than a year the anti-evolutionists will be using it to discredit carbon dating.
> you slow down an atom to near absolute zero, you would be lengthening the half-life, say from 200,000 years to 400,000 or whatever, because the binding energy would stay the same, just the ability of the particles to break free would be reduced because of the slowed movements between the particles. you might even generate a spike in atomic activity when it warms up.
FYI, radioactive decay isn't caused by thermal energy. Notice the lack of a term for temperature in the relevant equations.
> how does some of what passes for scientific papers get accepted, anyway? box tops? there's a lot of stuff that the mass media picks up on and publicizes that just can't stand the smell test.
One might ask a similar question about Slashdot moderation.
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Well, it's currently illegal to dump waste at sea due to the London Convention, so don't expect this solution any time soon.
Also, subduction zones aren't particularly stable and predictable, so the waste would likely spew about rather than being neatly sucked away. There was an article on New Scientist about this.
That's actually the idea - to make radioactive substances even more radioactive under controlled conditions so as to decay them into safer forms over a much shorter period of time, decreasing the amount of dangerously radioactive waste that has to be disposed of. Sure, it becomes more radioactive, but only under specific conditions and within a small timespan.
I just think it's a shame the Integral Fast Reactor project got canned back in Clinton's day. If it hadn't been shut down, maybe nuclear waste wouldn't be nearly as huge a problem now...
- fission
- alpha emission
- electron emission
- positron emission
- electron capture
(I don't include gamma emission, because, although it does occur frequently in the aftermath of one of the types of decay above, it generally has a very short half-life, so it typically doesn't affect the time it takes for an entire decay chain to go.) Processes 1-4 are all purely nuclear, and don't depend in any way on the surrounding electrons. Process 5 does depend on the surrounding electrons, and, e.g., can't occur in an atom that's been completely ionized down to the bare nucleus. However, when it does occur, the electron that gets captured, with extremely high probability, is one of the ones in the innermost electron shells (known as the K shell in nuclear physics). That's because the K-shell electrons are the ones whose wavefunctions overlap the nucleus the most strongly. If you embed the atom in metal, or cool the substance it's embedded in, it has very, very little effect on the K-shell electrons. The electrons in the surrounding substance aren't going to get into the act, either, basically because of the Pauli exclusion principle.Find free books.
It's all pretty much a waste of time. Nuclear waste is really just 99% active and usuable nuclear fuel. IFR, or 4th generation nuclear power generation would easily use most of that stuff up. This is one of the reasons why launching it into the sun or burying it in a subduction zone is so stupid. It's still very valuable. Sure the stuff is safe where we put it, but using it up as fuel in a very safe, impossible to meltdown, non-proliferating, safe nuclear reactor.
Even the old crap we built 30 years ago is still pretty safe and pretty good. And the tech has only gotten better... while at the same time the coal stuff (though a better) is still poisoning the planet. Nuclear power = Green power.
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Well, first off, the reason I drew the ocean comparison is the idea of contamination. Urine isn't just gross, it's also toxic, at least to animals like us. However, while nobody would want to get it in their drinking water (fetishists nonwithstanding), nobody would seriously think that pissing in the ocean is going to hurt anybody. It's not that urea is harmless; it's that in a large enough body of water, it becomes irrelevant.
Now as to the effect of dropping waste into the sun, consider both it's size and age. Radioactives are not that uncommon in space, and the sun is an awfully large target. Over 4 billion years, how much uranium do you suppose it's swept up? Hell, during the earlier days of the solar system, it's likely that entire planetary masses fell into the star. These things happen when a system forms. If a "stupid sci-fi apocolypse" scenario was going to happen, it would have done so already.
It's similar to the arguement that particle colliders could create black holes. Given that the same type of reactions occur naturally in the upper atmosphere as they do in a collider, we'd expect miniature black holes to form repeatedly over billions of years. The fact that none have destroyed the planet yet is strong evidence that it won't happen - and our current theories surrounding Hawking radiation says it can't happen anyways.
Remember that all the damage mankind has done to our home throughout history (pre and post industrial) has been climatic or ecological. These systems are delicate and respond strongly to even fairly minor human input, such as importing species into an evironment that they aren't native to. It's also worth remembering that climate change and mass extinctions have happened before; these kinds of destruction did not begin with human civilization, we've merely done more damage in a shorter time frame. In other words, we're effecienty destructive, but the type of damage we've caused isn't novel.
Stuff like igniting the atmosphere and other doomsday scenarios capture our imagination, but are massively implausable. Nuclear weapons are merely the most powerful weapon made to date; far more powerful explosions have occured in the past due to asteroidal collisions. The fear was unfounded then, but was taken seriously nonetheless.
We've seen the amount of damage we can do to the biosphere, and thereby overestimate just how much harm we can do to other pre-existing systems.
If a doomsday scenario can happen naturally, then I will worry about it happening accidentally due to human error (a good example would be anti-biotic resistant bacteria, or global warming). If it can happen due to human malice, then I will likewise worry (nuclear war comes to mind). If it can't happen accidentally, or should already have happened without our help, then I wouldn't worry about it.
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