spirilis
Senior Membrane
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How effective and are current methods of decontamination and recycling, and how do they impact the environment? Dealing with waste/residue of nuclear reactions has always been a challenge of nuclear energy.
I'll confess I've not studied this subject to much degree but I know of a few things.
1. Nuclear waste is pretty small in quantity. I've seen it mentioned that, if 100% of your lifestyle were powered by nuclear fission (that includes the feedstock energy used to produce everything you've ever owned, bought, the concrete and asphalt underlying the highways you drive, etc), at some nominal value of an "American" lifestyle, one human being's entire contribution to nuclear waste from birth to age ~70 should be a ~20lb sphere. Multiply that times billions of people and of course you're talking about a problem that needs long-term solutions, but we're a long ways away to powering our entire planet with nuclear.
2. The first step in handling waste is reprocessing to extract the reusable stuff and possibly isotopes of other importance. Problem is, much of this reprocessing work has been made illegal for political reasons (that I don't agree with; the theory of preventing proliferation of plutonium that may end up in the hands of rogue actors creating nuclear bombs is shot down a bit by the fact that much of the plutonium arising from civilian reactors is 240Pu, which is an undesirable isotope for weaponry that is difficult to isolate from the "good" weapons-grade 239Pu.)
3. The remainder of the waste is handled by essentially immobilizing it into glass and storing it somewhere underground. WIPP is the major repository we use today for military waste and it's pretty effective (basically a salt mine). Folks have probably heard of the Hanford site as a debacle of decontamination, there's also a site in Ohio and Georgia that has driven some controversy. As I've heard with Hanford, part of the problem here may be political - finding an expedient solution for the problems is technically feasible but "cleaning up" the site will result in finishing the job, netting a loss of economic activity. This was discussed a bit in a podcast: Atomic Show #201 - Better Way to Clean Up Hanford Tanks - Atomic Insights
4. In the absence of reprocessing, you basically store the used fuel as is, first in a deep water pool for ~5 years while the really "hot" isotopes decay and then entomb in dry-cask storage in a parking lot above ground with a multilayer combination of steel/helium-filled layer/steel/concrete or something like that which can withstand a substantial amount of abuse (including small missile blasts). Most of what we call "spent nuclear fuel" in fact has a wealth of valuable fuel materials, most of the 238U from the original fuel (which can be converted into fuel in a fast-neutron breeder reactor), etc. but we just entomb it for now. This can be harvested for fuel feedstock in future designs.
A purpose-built facility for recycling spent reactor cores should be quite feasible. I would advocate putting it somewhere like INL, Idaho National Laboratories, the nation's nuclear tinker site, which was chosen (some ~890 square miles of desert) in no small part because the sandy soil easily locks up radionuclides from seeping into groundwater. Many nuclear reactors have been intentionally driven to the point of meltdown or supercriticality and blown to pieces all over the Arco desert with no noticeable problems. Still, storing radioactive waste as water is mostly something we did in the early days of the atomic age, now we know better how to immobilize and manage it.
A major opportunity I see with reprocessing spent nuclear materials is the potential to isolate valuable rare elements, e.g. Technetium-99 which makes a catalyst in the same vein as palladium & platinum.
edit: Another one of those Atomic Show podcasts featured a bit on technetium and related catalysts, as potentially valuable materials for e.g. Hydrogen fuel cells or possibly the production of such "green" fuels as hydrogen, ammonia, methanol, etc. Food for thought. (also can't remember exactly which one, as I've listened to over 200 of them... think it was a NNadir interview)