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.'"

Comments

Re:why bury it all?

[geekoid]

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.

There's way too much waste

[billstewart]

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.

Re:This requires not storing in insulators?

[techno-vampire]

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.

Re:Um

[zerus]

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 thought this was about fast reactors

[Chris.Nelson]

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.

Not the trench, though

[PIPBoy3000]

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.

not plausible

[bcrowell]

This whole thing isn't very plausible. Here are the common types of nuclear decay:

1. fission
2. alpha emission
3. electron emission
4. positron emission
5. 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:What a waste

[macemoneta]

"This is crazy. I had never heard of this fact before. After reading the PBS thing and a bunch more on the web, I can't believe that fuel reprocessing/breeder reactors haven't been put more widely into use."

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.