Davage wrote:I look at references like:
http://en.wikipedia.org/wiki/Nuclear_reprocessing and have no idea which reprocessing technologies are the best to use and in what combination. I don't know just how low a half-life, radioactivity, and volume we can get the waste down to, I don't know how much usable fuel, material, etc. we can get out of it, and what might be the best reactor types to pursue to make use of that fuel that normal US reactors can't use.
From what I've heard, the U.S, France, and Russia have the most experience using Liquid Metal Cooled Fast Breeder Reactors (LCMFBRS). For more information:
http://www.nucleartourist.com/type/metal.htmI know it seems a bit unaesthetic. We have a whole bunch of radioactive materials in an unmoderated reaction reacting in a pool full of molten sodium. The good news, however, is that the reactor isn't under pressure. That means that if there's a leak, unlike with a PWR or BWR (the two designs we use in the U.S; both of them fall under a broader category known as "Light Water Reactors", or LWRs), we won't have coolant quickly leaving the reactor. Additionally, the design would still retain a 4-ft thick concrete containment structure.
Liquid Metal Fast Breeder Reactors split Pu-239 in order to generate neutrons to turn U-238 into more Pu-239 than it uses up.
In normal nuclear reactors, we split U-235, or potentially, Pu-239, in order to generate heat to make electricity. In order to split U-235, we either need slow neutrons, or a lot of fast neutrons (that's how nuclear weapons work). Because it's a lot of work to turn regular uranium into having huge concentrations of U-235 in it, we opt to have 3% of our uranium be U-235, and work with using slow neutrons to split U-235, instead of having a lot of U-235 and using fast neutrons to split it. So, in order to slow down fast-moving neutrons from splitting U-235 and keep the chain reaction going, we use a moderator. Without a moderator to slow neutrons down so they can split other U-235 atoms, the reaction would stop. In U.S. reactors, both our moderator and our coolant is water. This way, if the reactor ever loses coolant, the reaction shuts down.
However, in order to turn U-238 into Pu-239, we need fast, high-energy neutrons. Thus, we can't have a moderated reaction. Instead, we need lots of Pu-239- like around 20%. It's easy to separate U-238 from Pu-239, since they're two different types of atoms with different chemical properties. So we have a big core of 80% U-238 and 20%- Pu-239. And around it, we put lots of U-238. When we factor in the U-238 that's surrounding the Pu-239 core, the reactor turns much more U-238 into Pu-239 than it burns up Pu-239. U-238 is about 140 times as abundant as U-235, which is the only thing we currently use to run nuclear reactions.
The Pu-239 can then be diluted to 3% by Uranium-238, non-fissile Plutonium (I think Pu-240 and 242 are non-fissile), or some other actinide, I think, and sent off to be used in a regular nuclear reactor.
The only big safety concern that I have about Fast-Breeder Reactors is that the only thing that can stop the reaction is the control rods, or losing critical mass. In a 3% U-235, 97% U-238 reaction, the fuel needs to be in the presence of a moderator to react. So in an LWR, we imagine that if the fuel makes it out of the reactor vessel, it's probably not going to be producing heat at 3 GWH, and if it is, there'll be water to cool it down. In an FBR, that still might be possible, somehow.
I'm also wondering if 20% Pu-239, 80% U-238 can react violently, but I'm not a nuclear engineer, and they'd probably be the only ones who can tell us that.
So I'd like to discuss the options with you guys here, get your opinions, work out a plan together, and have something to present Nevada lawmakers with by the end of the year. And in that, I don't want to just use you guys for this information (like those annoying people that don't like to do their own research), I want to work up the plan and presentation with you guys and then schedule a time to present it with you guys (and with credit going to everyone who worked on it).
I think one great way to do this might be to set up a website and get your friends from Nevada involved. Right now, I'm working on setting up a website for lobbying moderate midwestern senators and congressmen to lower the speed limit to 55, and getting my friends from Illinois involved. It'll be important for us to avoid getting any help, money, or support from the nuclear industry so Greenpeace will look crazy if they accuse us of being co-opted, but at the same time, we need to find a nuclear engineer to get on board to help, for example, reassure people that an FBR- if we choose to go that route- won't "explode like a bomb".
I'll be happy to provide space and, if I'm not too busy as a Junior in an engineering/CS degree seeking a summer internship, I might even be able to help do some design work for the website.
As we develop the plan, I want to keep contacting those representatives, I want to get them interested. There will of course be politics involved, and I imagine leaving such things as money for accepting the waste up to them (personally, I hate that idea! I don't want waste in my state, I recognize the need to do it, and taking money for the DOEs plans leaves a foul taste in my mouth).
Well, you're the Nevadan. I just want to make sure that whatever happens, that we can make things more fair for your state without completely blocking nuclear energy as an option to help prevent another energy crisis. And, if you get your senators on board, the rest of us can work on ours to allow FBRs and fund them.
So, still interested? If so, it seems that we need to start with the seed, the best combination of reprocessing processes to acheive those goals of minimal waste and maximum fuel/material return, and hopefully a way a private entity could get a profit out of it. What does everyone think the best process/combination-of-processes is/are?
FBRs are the most proven technology we have. At the very least, they'll be the easiest ones get people to accept. One of the things that I've learned from these forums is that it's important to choose simple arguments that have already been proven. Most people know that the U.S. nuclear industry has been meeting a lot of our energy needs for years without too much help from the federal government, and we haven't had a single major release of radioactive materials during that time.
France's commercial FBRs have already proven that FBRs in the U.S. can operate relatively safely. And putting the two FBRs in the Nevada Test Range would ensure that, should something happen, it couldn't possibly have any more impact on the rest of the country than a weapons test done in the '50s or 60's. We can probably dig up the numbers on the costs of France's FBRs, and demonstrate that it wouldn't be much more expensive to recycle the waste than to bury it.