Halving Half Lives 406
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.'"
Doubling halve life (Score:3, Informative)
And also, first we need to build a fusion reactor to have energy to cool that shit.
Re:why bury it all? (Score:5, Informative)
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.
There's way too much waste (Score:5, Informative)
Re:This requires not storing in insulators? (Score:5, Informative)
Re:Kerning (Score:4, Informative)
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.
Re:Um (Score:5, Informative)
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).
Re:dumber than an arkansas hound dog, these guys (Score:2, Informative)
Why is this modded informative? Has the poster or the moderator actually done this experiment? Have they even Read the Fine Article?
Counterintuitive, maybe. But then so is most of Quantum ElectroDynamics.
I thought this was about fast reactors (Score:5, Informative)
Re:Kerning (Score:2, Informative)
On the other side: Beer might help...
I'm not sure about the working models that feepness mentioned either. Nuclear radiation is only allowed to gain energy and for medical reasons, no warfare whatsoever, so I guess there are lots of countries with more possibilities to explore nuclear energy.
And a couple of years ago our government even decided to shut down all nuclear plants in about 10 years time.
I think the only reason was (and because of gobalisation no longer is), that in the days if Bohr and Planck and Einstein and so on it was common that scientists discussed matters in quite close circles. I'm sure all these people are connected, somebody beeing a student of someone else or working at the same university for some time and such.
Its the same with artists, they create "schools" and so most artists for, say, qubism come from a quite close circle.
Today with internet and planes and stuff its more common that someone from, say, Japan has a new theory, some US-scientists work further on it, some french guy has the first breakthrough and so on.
Not the trench, though (Score:5, Informative)
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 [newscientist.com] about this.
Re:why bury it all? (Score:3, Informative)
The sun's gravity is counteracted by the orbital velocity of the earth, from which said rocket is launched. It can't be counted on for a single erg.
Re:Um (Score:4, Informative)
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.
Re:Um (Score:3, Informative)
Gamma would do next to nothing.
Alpha not to much.
beta I am not sure about.
neutron is the problem but then you would tend to get deuterium and maybe some tritium.
deuterium is harmless as acts as a moderator and tritium is very useful and has a very short half-life of around 11 years.
Re:Um (Score:3, Informative)
It depends on the kind of radiation, if it receive gamma radiation, it will become hot or even ionize. It may gather electrical charge (and beccome hot) from betta radiation. Alpha radiation may convert tiny amounts of it into lithium 5 or magnesium 20 that would almost instantameous (I'm not sure the latter one would even happen) decay by betta or neutron emissions, but since the material would probably encapsulated, the alpha radiation would never reach the water. Or it can change into hidrogen 2 (quite stable) or oxigen 17 (i don't know what happens with oxigen 17) if it receives neutrons.
But I am one more person that doubts that it will work.
Re:why bury it all? (Score:4, Informative)
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.
Re:This requires not storing in insulators? (Score:3, Informative)
not plausible (Score:5, Informative)
- 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.Re:wait for the real fallout (Score:1, Informative)
Most people don't seem to understand that carbon dating is rarely useful for specimens much older than a few tens of thousands of years. For older specimens other dating methods are used.
Re:why bury it all? (Score:4, Informative)
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.
Re:What a waste (Score:5, Informative)
Well, the USA isn't (yet) using this technology, but the Chinese are [wired.com]. Even Toshiba [nukku.net] 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 [ornl.gov].
Re:Um (Score:2, Informative)
In France, Japan, and the UK, they do exactly this. Spent fuel rods are reprocessed. It's dangerous, and fission products remain a waste management problem. The problem ends up that separating various materials requires more energy to accomplish, than is obtained, at least in economic terms. The other problem, of course, is that the plants needed to do this kind of processing, is a weapons proliferation concern in the eyes of some people whose opinions seem to carry some weight in the current climate of global politics.
Re:Um (Score:3, Informative)
You forgot neutrons.
Neutron activation [wikipedia.org].
breeder reactors (Score:3, Informative)
Even if we could dispose of the current high-level radioactive waste using this technique, it would still be irresponsible. Non-breeder reactors use only a tiny fraction of the energy stored in the nuclear fuel and throw away the rest, and that's an unacceptable waste.
Re:why bury it all? (Score:1, Informative)
Re:Alpha radiation (Score:2, Informative)
I don't understand your response... (Score:3, Informative)
Your post talks about prefab reactors, like the French have been using for years and are improved further (it seems) with pebble-bed designs. These are not breeder reactors.
Also, the US has used breeder reactors. Fermi 1 even operated for a short time as a commercial breeder reactor.
Why do you turn one thing into another?
Toshiba's design uses liquid sodium as a coolant. These designs have been problematic in the past, for example Fermi 1 or Soviet nuclear subs.
I do agree with you that nuclear power is very misunderstood.
Re:What a waste (Score:3, Informative)
Coal contains about 3ppm of uranium. Ordinary soil contains about 1.8ppm of uranium [speclab.com]. Coal may be an enviornmental disaster due to its chemical and kinematic properties, but a radioactive pollutant it is not.
Two words: "Breeder Reactor" (Score:3, Informative)
"Use of a breeder reactor assumes nuclear reprocessing of the breeder blanket at least, without which the concept is meaningless. In practice, all proposed breeder reactor programs involve reprocessing of the fuel elements as well. This is important due to nuclear weapons proliferation concerns, as any nation conducting reprocessing using the traditional aqueous-based PUREX family of reprocessing techniques could potentially divert plutonium towards weapons building. In practice, commercial plutonium from reactors with significant burnup would require sophisticated weapon designs, but the possibility must be considered. To address this concern, modified aqueous reprocessing systems are proposed which add extra reagents which force minor actinide "impurities" such as curium and neptunium to commingle with the plutonium. Such impurities matter little in a fast spectrum reactor, but make weaponizing the plutonium extraordinarily difficult, such that even very sophisticated weapon designs are likely to fail to fire properly. Such systems as the TRUEX and SANEX are meant to address this. [8]"
Re:What a waste (Score:3, Informative)
That's great when the coal is unburned. Once you burn away the organics, the remaining ash (10% coal weight, typically) is around 30ppm. Even if you aren't concerned about the fact that at least a small percentage of particulates make it past the scrubbers resulting in higher ambient radiation directly downwind of coal plants than downwind of nuclear plants, you should be concerned about the roughly 120 million tons of coal ash, containing a total of 3,600 tons of uranium (30ppm over 120 million tons of ash)
Note that 12,000 tons of nuclear waste are created annually and it is only 3% high level waste, containing the equivalent of about 360 tons of uranium. So if we mixed all the nuclear waste into the coal ash, we'd only increase the radioactivity of the coal ash by 10%. If 3ppm isn't a problem, 3.3ppm shouldn't be much more of a problem.
Coal ash is often used in scenarios I don't find dangerous (concrete, metallurgy, etc) but I am somewhat concerned about it being used in home construction (wallboard, roofing materials, insulation), as a material for snow melting, but most particularly soil fill.
With 30ppm uranium, coal ash fill is a great potential source of radon gas. You know, that lung-cancer causing radioactive gas created in soils with a higher than average uranium density. Like, I dunno, having 15x the uranium density of common soil.