Slashdot Mirror
Better Nuclear Waste Storage Plans than Yucca Mountain
NuclearRampage writes "Technology Review has an in-depth article about A New Vision for Nuclear Waste based on the premise that 'storing nuclear waste underground at Yucca Mountain for 100,000 years is a terrible idea.' The article looks at the current DOE plans for Yucca, its shortcomings and what temporary solutions we have to use while a better permanent plan is formulated."
We already have the technology. We shove them into a breeder reactor to get nuclear material that we can use. The problem is that Carter put a ban on breeder reactors in the US.
Fly me to the moon Let me sing among those stars Let me see what spring is like On jupiter and mars
France also has a great reprocessing system, which would be a great idea for this nuclear waste problem.
Why not just press for reprocessing of spent fuel? All the 250,000 year stuff is from material that can be recovered back into the fuel cycle. If you remove the junk lower down on the periodic table (the real nuclear waste) it only will be dangerous for a few hundred years.
On a side note, has anyone heard of the natural reactor in Oklo? A naturally occurring nuclear reaction there produced all the same waste of a modern reactor and it all stayed in place in de-facto geologic storage.
yucca is ready to accept waste, vitrification is mature. I really don't see why Yucca is still a controversy other than NIMBY and ignorance.
Blaze a trail to the New World
If the waster is radioactive, it is inherently releasing energy. I have never understood why no one has tried to take advantage of this with some kind of "dirty" reactor.
The problem is that the fuel has been "poisoned" by decay products from previous reactions. Enough of these absorb neutrons that you can't sustain a critical fission reaction, and so you're left with sub-critical decay. This gives off energy, but far, far more slowly than a nuclear plant's active fuel bundles do. So you can't put them in a conventional reactor, and you can't get useful amounts of heat off them outside of one.
There are some types of reactor - actinide-burning fast-breeders - that have less trouble with these decay products than conventional slow-neutron reactors. These are widely viewed as one method of disposing of or at least reducing the amount of spent fuel waste. You can also chemically reprocess the fuel to remove the decay products (which are then disposed of as waste, but the majority of your "spent" fuel is reused). Neither of these solutions is allowed in the US, due to proliferation risks and handling concerns.
The real problem with Yucca Mountain is the water table issue and the fact that most of these waste materials are extremely toxic. Nuclear reactors do not produce large amounts of isotopes "hundreds of thousands of times more radioactive" than "natural" uranium. And if they did, the half-life for them would be extremely short. The reason it takes millions of years for these waste materials to become functionally inert is because they are alpha emitters with very long half-lives. In other words, they do not produce large amounts of dangerous radiation. As they decay they will hit stages of greater radiation, but remember, alpha particles cannot even penetrate the layer of dead skin cells covering our bodies. A sheet of paper is strong enough shielding. Beta emmiters are somewhat more dangerous, but not significantly so. Additionally, while alpha particle radiation can still cause mutagenic aberrations if it can get passed your clothes and skin; the real danger is application to an open wound, inhalation, or ingestion of the radioactive materials. Not only does this allow the alpha particles to damage sensitive internal organ tissue, but the materials themselves are highly toxic. This is one of the reasons that radon (the end product of the uranium in the earth naturally decaying) in our basements is such a concern. Radon being gaseous enters our lungs where the alpha particles can actually do damage.
Chernobyl's problem was not the release of radiation into the atmosphere. That is disapated very rapidly by prevailing winds and does not affect the surrounding area significantly (not from a single event such as that). The problem with Chernobyl was that when the top blew chunks of radioactive debris like pieces of the graphite cooling system rained down over the surrounding countryside and got into the ground and the water supply.
Most of the deaths in Nagasaki and Hiroshima were caused by the shockwave and the subsequent fires, not the radiation. This is not to say that there weren't many people killed by radiation, there were. But those individuals dying of cancer caused by those blasts are the individuals that were present at the time of the attacks. Both areas are still thickly settled and do not have higher than normal cancer rates outside of the population of the bomb drop survivors.
Additionally, far larger amounts of the same materials used and produced in nuclear power production (including uranium 235, uranium 238, and thorium among others) are pumped into our atmosphere every day by coal burning plants. In fact, if we took all the radioactive materials we send into the air every year and put them in nuclear reactors, we'd be able to make more energy that the coal plants that put them into the atmosphere did during the same timeframe.
On top of that, if breeder and pellet based plutonium reactors were actual in service we could use the waste from standard light water reactors to feed breeder reactors whose waste would feed the pellet based reactors. Drastically reducing the amount and lethality of the nuclear waste that we'd ultimately have to store.
Uranium-238 Decay Series
Nuclide Half-Life Radiation
U-238 4.468 109 years alpha
Th-234 24.1 days beta
Pa-234m 1.17 minutes beta
U-234 244,500 years alpha
Th-230 77,000 years alpha
Ra-226 1,600 years alpha
Rn-222 3.8235 days alpha
Po-218 3.05 minutes alpha
Pb-214 26.8 minutes beta
Bi-214 19.9 minutes beta
Po-214 63.7 microseconds alpha
Pb-210 22.26 years beta
Bi-210 5.013 days beta
Po-210 138.378 days alpha
Pb-206 stable
Once more unto the breach dear friends...
Disclaimer: I am a nuclear engineering graduate student.
The main reason we're having such problems with nuclear waste repositories such as Yucca mountain is because of the rather long timescales of decay of a small class of fission byproducts. This class of elements (the 'transuranics' ; Z > 92) comprises a very small fraction of the total waste volume and has (in general) the majority of ill-effects, such as long half-lives, toxicity, excessive heat generation, etc. (Different isotopes contribute to each of these effects in some small fashion.)
A key insight to the problem is that we do not have to store the waste as it comes out of the reactor (or otherwise packaged for long-term storage). It is possible to process the spent fuel in a way to transmute the problem isotopes into others that decay away quickly (days to tens/hundreds of years vs 1x10^6 + years). Neutron bombardment is one method of 'bumping' these decay chains onto different tracks. Doing this effectively, efficiently, and economically is the challenge; many people (including some of my professors) have been working on it at Los Alamos. A good introduction to the process and its rationale are located here.
Of couse, these transmutation schemes require their own energy to run them, and we can't beat the second law of thermodynamics -- it has to come from somewhere. These days it's mostly coal, the same source we're trying to replace with nuclear power! (Don't get me wrong -- nuclear power plants are by far the best we've currently got in terms of environmental impact, reliability, and production capacity. It's not the best, but it's the least of the other evils at the moment.) A better solution would be to provide this energy from an environmentally clean source, such as fusion energy. (It's nice to see two nuclear physics articles in a day!)
Of course, providing funding for disposal solutions such as Yucca and transmutation technologies is expensive and a political hot potato. (It also requires members of Congress to be a bit more forward-sighted, instead of just looking ahead to the next election cycle. Just think: ITER is on the order of $10B [a drop in the bucket to Congress], and has been scrounging for funds from all across the world for more than 20 years -- when it has the potential to unlock safe, envirionmentally clean energy that's powered from constituents of seawater.)