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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.'"
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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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?
They spend a lot of money on nuclear physics. It's the same reason why the United States has such great computing research compared to its population.
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).
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.
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.
The real risk is some of the (radioactive) material getting stuck on the containers. I'm sure that's far more manageable than all of the original waste.
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Once it is past the Earth's escape velocity, it's gone, regardless of the planet's orbital velocity. If the rocket is launched on a sunward trajectory, the sun's gravity will pull it in (unless some other body interferes).
No, because it's still carrying the Earth's velocity in orbit around the Sun with it. All launching it as greater than escape velocity means is that it won't go into orbit around the Earth; instead it will settle into another orbit around the Sun. If we launch it sunward, this orbit will tend to be somewhat tighter than Earth's -- but not a whole lot, and it will also be somewhat eccentric, which means there's a good chance of it intersecting Earth's orbit at some point in the future. Congratulations! You've solved the nuclear waste burial problem, and replaced it with the nuclear waste meteorite problem.
The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.
- 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.
OK, so we slingshot it around a few times. Orbital mechanics may not be well understood by me, but the folks at NASA seem to have it down pretty good.
I have every confidence that the NASA guys could get a payload to the sun. It actually only takes high school physics (well, it also takes state-of-the-art engineering).
The problem is cost. You have to generate a delta-V of approximately the Earth's orbital velocity - that is 30 km/s. The parent post suggested that the Sun would do most of the work. This is incorrect - the sun will only do work once the craft has no solar orbital velocity - then it will just fall straight down into the sun. The real work is getting rid of 30 km/s of orbital velocity - if you don't do that the waste will just orbit the sun very close to the earth, and sooner or later it will come back (even if it had escape velocity - that just gets it out of earth's orbit - if it swings around the sun a few times and comes back at us it will still re-enter earth orbit).
The problem is trivial to surmount - you just need a really big rocket. But then again, keeping the waste on earth just needs a really big hole in the ground. The only real decision is which engineering project is more expensive or risky - and most likely it will turn out to be the hole in the ground.
Slingshotting it around a few times is not really a great solution - you still need a ton of energy to get to anything to slingshot off in the first place. The other problem is launch windows - if you want to do multiple slingshots then you have to be really patient for a window. The craft will also need a lot of course corrections - if you're going to launch thousands of waste containers that is a lot of manpower to keep them all on course (unless you just want to drop them on Venus - but even that needs accuracy if you don't want to risk slingshotting it back into solar orbit near the earth). So, maybe with some fancy slingshotting you might only need 15-20 km/s of delta-V - that is still a lot of impulse. The Saturn-V was good for about 7.5GNs - so that is good for about 300 metric tons of payload if you only need 15 km/s (plus escape velocity). Well, that is actually a major overestimate - it doesn't factor in the weight of the rocket itself (which is an exercise in calculus which I'm not bored enough to do). It certainly can be done, but you're talking about a lot of HUGE rockets.
All in all, the hole in the ground is probably the best bet.
Well, the USA isn't (yet) using this technology, but the Chinese are. Even Toshiba has one of these super-safe "pre-fab" tiny reactors, that are intended for distributed use. By distributing power generation, you eliminate many of the grid effects (like blacking out a significant portion of the country when there's a problem). Oh, and as a byproduct, you also get a plentiful supply of hydrogen. It's a crime that instead we are burning coal - releasing more "natural" radioactivity than any reactor ever has, as well as poisoning our seafood with mercury.
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