Recycle Nuclear Waste? The current controversy over Yucca Mountain Nevada as the nations nuclear waste dump suggests to me that an alternative solution be explored. When nuclear power plants were first built, the idea was to use the U-235 enriched fuel rods once and then store the "waste" on site until a long term storage facility was built. The "waste" would be highly radioactive and dangerous for many thousands of years, so no one was eager to have it stored in their own back yard. In the decades since then the spent fuel rods have remained in pools near the reactors awaiting long term disposal even as the power companies are paying a charge for that disposal. Since then several things have happened that might alter the original plan. First nuclear opponents have gained strength, and combined with various terrorists could make moving the spent fuel to any storage location much more dangerous and expensive than was estimated at the time. But also separation technology and the ability to handle radioactive materials with robots has greatly improved. A "spent" fuel rod still has about 90% of its potential energy (and potential electric power production) remaining in it. In fact it is this "potential" (much in the form of plutonium isotopes) that make the spent rod hazardous for those thousands of years. The fuel rod is "spent" not because it has "run out of fuel" but because reaction products (like strontium and barium isotopes) are shutting down the chain reaction. While a fresh fuel rod has very little plutonium, one that is near the end of its (first -pass) life is getting about 1/3 of its energy output from the plutonium that has been created in it (from uranium isotopes) during its stay in the reactor core. There was much concern over "reprocessing" spent fuel rods to utilize their remaining fuel and to reduce the hazard of the remaining waste products. It was assumed that a few large reprocessing plants would be needed to do this, and that transporting spent rods to and new fuel from the plants would be too dangerous. And that maybe some of the plutonium removed from the rods would be diverted to unauthorized uses. My question: could small robot operated fuel rod reprocessing modules be made so that one at each nuclear reactor site could remove the "bad" waste products that block the chain reaction? Thus the "spent" fuel rods currently stored there could be converted into new (probably mixed oxide) fuel rods? Thus current power plants could continue to operate for hundreds of years without receiving any more fuel from outside, by consuming most of the hazardous material in their current supply of "spent" fuel waste. No need to ship tons of dangerous waste from all over the country to a single location. And at each power plant the "final" waste products (mostly Ba, Ce, I Sr isotopes) that cannot be used as fuel could be stored on location for the few hundred years it takes for them to decay to the level where transport to a final storage place would not be a problem. http://www.ldeo.columbia.edu/dees/ees/lithosphere/lab11/table_4.html ,,,,,,, _______________ooo___(_O O_)___ooo_______________ (_) jim blair (jeblair@facstaff.wisc.edu) Madison Wisconsin USA. This message was brought to you using biodegradable binary bits, and 100% recycled bandwidth. For a good time call: http://www.geocities.com/capitolhill/4834 REPLIES: > > >> current power plants could continue to operate for hundreds of >> years without receiving any more fuel from outside, by consuming >> most of the hazardous material in their current supply of "spent" >> fuel waste. Mike Darrett wrote: > > >They're called "breeder" reactors. The French have them. These >reactors are banned in the US because the politicians are afraid of >them. > >google: breeder reactor france >http://www.atomicinsights.com/oct95/Pu_oct95.html > >Breeders also tend to use liquid sodium as a coolant, and this becomes >radioactive too... > >Don't forget that in a nuclear reactor, you don't just have used fuel >rods as waste. Anything those neutrons hit has the potential to >become radioactive... which includes the concrete reactor walls, etc. glhansen@steel.ucs.indiana.edu (Gregory L. Hansen): Most of that would be short-lived, it should be pretty safe after a year, and greatly reduced within weeks. The long-lived radioactivity mainly comes from the actinides, which is basically another name for nuclear fuel. A problem is that neutron poisons also build up, and those need to be removed before the fuel can be used. Aside from that, I don't think there's much reason to try too hard to purify the metals of interest, except maybe for structural reasons. But the fuel pellets crack anyway, and the cladding keeps them in place. From me again: What I am suggesting is not a full blown breeder that runs on plutonium, but a sort of "partial breeder" that runs on mixed uranium and plutonium. And that avoids the large scale reprocessing plant. I picture trailer sized units that would be fabricated in one location and units shipped by truck to each power plant. Spent rods would go into one end, and out the other would come new mixed oxide fuel rods and glass balls containing the unusable waste. AND: Ray L wrote: > > http://www.ans.neep.wisc.edu/~ans/point_source/AEI/jun96/PHWR.html > > and it burns what others throw away and http://www.cns-snc.ca/events/CNS98/Abstracts/Log93/log93Abstract.pdf Hi, Good URL. This type of reactor would fit in with my on site reprocessing modules. Extending the fuel life is nice, but the waste recycling feature is even more of an advantage. Note that the Greens in Germany are forcing the adoption of coal as the main energy source by blocking shipments of spent nuclear fuel as a way to drive up the cost of nuclear. Even the governor of South Carolina want to block shipments of nuclear material from passing through the state. AND >"Paul F. Dietz" >... As you sieve out the uranium, >the > ocean will get more and more diluted and progressively more expensive >to > recover the uranium. "Karl Johanson" wrote: > > Rivers renew the oceans supply of uranium. "Paul F. Dietz" >> >> Not sufficiently quickly to matter for a global once-through >> fuel cycle, though. >> Paul Karl Johanson: > >As I recall, the rivers add enough for us to get 10 times our current total >power usage (not just electricity, but also transportation, heating, etc.) >if we use breeders. Without breaders that would be around 10% of all our >power without reducing the ocean's supply of uranium at all. Even if we did >use 100 times as much for once through, that would leave us tens of >thousands of years to develop breeders before we depleted the ocean's >uranium significantly. > >I've never seen estimates for thorium in the oceans. > >Karl Johanson > > Hi, I think this entire conversation is off the mark. You guys are using logic and applying economics. But the future of nuclear energy will be determined by politics and perceptions. I say the goal of research should be to eliminate the need to move the waste from the current reactors. That may well cost more than making additional uranium fuel rods. Sure "recycling" will make economic sense in that "long run" when natural uranium is depleted (be that decades or centuries) , but that is not my point. My point is that ANY long term storage location will become the focal point of opposition to nuclear (as Yucca Mountain is demonstrating) and that when shipments actually begin the "Greens" will go Postal. Look at Germany. Combine the various terrorists who WANT to use the spent fuel as a weapon with the "Greens" who want to disrupt shipments to demonstrate how dangerous nuclear waste "really is" add the use of press coverage and political theater, and you should be able to predict the result. On the power of perception over reality, did you see the recent USA TODAY article on natural gas? We are expanding its use (much of that by building new gas burning power plants) while production is dropping. We may soon need to expand the importing of liquid natural gas (LNG). The comment was that natural gas and LNG are "safer" than nuclear!!. No figures were give on the number of people killed each year by natural gas explosions. AND: While it's common for people to say that it takes 24,110 years for plutonium to lose half of it's level of radioactivity, this doesn't account for fact that most of the specific level of radiation from reactor grade plutonium is from other isotopes other than Pu 239. The shorter lived plutonium isotopes account for much of the biological danger of plutonium. (some rounding used) Spent fuel for typical light water reactors tends to have a plutonium isotope distribution of approximately: Pu 238 2% Pu 239 61% Pu 240 24% Pu 241 10% Pu 242 3% In terms of percentage of the specific level of radiation from the reactor plutonium we have approximately: Half life Pu 238 3.191% 87.7 years Pu 239 .354% 24,110 years Pu 240 .509% 6,564 years Pu 241 95.9% 14.35 years Pu 242 .0011% 379,00 years In 175 years (two half lives of Pu 238) the Pu 238, for example, will have decayed to 25% of what it was, etc. Pu 238 .8% Pu 239 .35% Pu 240 .5% Pu 241 .023% Pu 242 .0011% Total Approx 1.9% (of the specific level of radioactivity of the plutonium right out of the reactor) To put it another way, the specific level of radiation from light water reactor grade plutonium declines by more than 98% in less than 180 years. Karl Johanson And from Steve Harris: Plutonium from spent fuel rods can't be used in weapons-- that's a great urban myth, one which somebody milking DOE seems happy to perpetuate. By the time a rod has burned out in a reactor it has way too much Pu-240 in it to be usable in a bomb. It's been "denatured" just like alcohol, and a lot less reversibly (if you could separate Pu-239 from 240, you more easily can do U-235 from 238). If you want to make bombs, you must therefore deliberately remove fuel rods early, in order to get a bomb grade Pu239/240 ratio. AND: From: rabbitispoor@indmayingspray.com (Timothy Miller) A nuclear fuel cycle based on Argonne’s pyroprocessing technology offers substantial improvements in waste management, proliferation resistance and economic potential compared to conventional processing technologies used overseas. Fuel recycling: The key step is "electrorefining," which removes uranium, plutonium and the other actinides (highly radioactive elements with long half-lives) from the spent fuel, while keeping them mixed together so the plutonium cannot be used directly in weapons. Spent fuel from reactors that use metallic uranium fuel can go straight to the electrorefiner. Spent fuel from commercial reactors, which consists of uranium oxide, would first undergo an "oxide reduction" step to convert it to metallic form. Next, the uranium and other actinides are sent to the cathode processor to remove residual salts and cadmium from electrorefining. The actinides are cast into fresh fuel, while the salts and cadmium are recycled back into the electrorefiner. Nuclear waste: The waste consists of two forms. The stainless steel cladding that encased the spent fuel is combined with noble metal fission products in a metallic waste form. Salts and other fission products are combined with zeolites and converted into a ceramic waste. Both metal and ceramic waste forms are highly radioactive when they are created, but in less than 400 years, their radioactivity decays so they are less toxic than the natural ore the original fuel came from. Also try searching on IFR (integrated fast reactor). This is a program killed by Clinton in 94. The proposed reactors were to do all processing on-site, with no actinides ever leaving the plant. You will get a lot of hits on activist sites, since they hate any technology that might reduce waste production because they hope to shut down nuclear energy via the waste issue. Jeffrey Siegal wrote: When I first got involved in this business, in the mid-70s, there was some enthusiasm for "nuclear parks", clusters of maybe 10 reactors and a colocated reprocessing plant to handle their spent fuel. It never happened, largely because the economic disruptions of the 1970s dropped the rate of load growth to a level that couldn't justify building more generation (until just recently, as it has turned out), and because of Carter's decision to keep the US' hands clean by not reprocessing, to set an example for the other nuclear nations, most of which showed their admiration for the US lead by acquiring their own reprocessing capability, by building their own (Britain, France), working on developing their own (Germany, Japan) or participating in the British and French efforts. The closest thing I know of to such a "nuclear park" is the Fukushima facility in Japan, with 10 units on two adjacent sites. A big nuclear park like this would be a major electrical problem. Power transmission systems are easier to design and operate when generation is more distributed, rather than concentrated at one probably-remote location, and located close to the major load centers. I believe it also turns out that by the time you load and decontaminate a spent-fuel cask at a reactor site and unload it at a reprocessing site, you've paid for most of the costs of shipping it. The actual over-the-road (or railroad) haul dosn't add much to the costs, so there isn't much economic benefit to locating small reprocessing facilities close to reactors. And after reprocessing, you still have high-level waste shipments, admittedly a much smaller volume than spent fuel.