Uranium Pebbles May Light the Way 629
kristy_christie writes "According to Wired News, South Africa's state-run utility giant Eskom and its international partners want to build the world's first commercial 'pebble bed' reactor, which, instead of using fuel rods, 'is packed with tennis ball-size graphite "pebbles," each containing thousands of tiny uranium dioxide particles'. To developers, the Pebble Bed Modular Reactor promises a rebirth of nuclear energy. Proponents insist that the reactor's design features make it 'meltdown-proof' and 'walk-away safe'."
Clean nuclear power (Score:1, Interesting)
Environment/North Korea (Score:5, Interesting)
though many popular activists site environmental reasons as opposition to nuclear energy, disposing of nuclear waste really isn't that difficult. Most scientists (at least those in the field) object to nuclear power because of the potential of the spread and proliferation of weapons. while environmental issues ARE a concern (there's always some governmental dweeb that screws things up), it is something that can fairly easily be isolated given the proper precautions. Part of the reason that these reactors get so much attention is that these same experts have much fewer qualms with them precisely because they are so much more difficult to make weapons-grade uranium/plutonium from. (i cite Howard Margolis, Dealing with Risk as a decent summary of this topic).
Re:Meltdown isn't the (whole) problem (Score:2, Interesting)
Re:Meltdown isn't the (whole) problem (Score:4, Interesting)
burying it deep in some stable part of the earth is the best way currently though(at least much better than the sometimes used method of just stacking it in a shack). and besides, ancient egyptians got their cursed tombs, WHY CAN'T WE HAVE THEM??!?!?-)
however, we have much bigger waste problems than just nuclear waste.
Re:Meltdown isn't the (whole) problem (Score:5, Interesting)
Maybe it's time to reconsider those bans, as it is becoming quite apparent that there is no near term solution to the energy problem apart from nuclear energy and there is no other good way to handle nuclear waste.
Re:Meltdown isn't the (whole) problem (Score:3, Interesting)
I would be very surprised if this is true, care to provide some links? I have had dealings with BNFL - British Nuclear Fuels Limited. They carry out this reprocessing of spent Uraniaum on facilities less than 50 miles from where my parents lived all their lives.
Re:Meltdown isn't the (whole) problem (Score:3, Interesting)
a) it's quite messy, dangerous and difficult to do safely. Not impossible, but neither easy nor cheap.
b) You turn a lot of moderately radioactive waste into a smaller amount of highly radioactive waste (purified fission products) and some reusable fuel (some of which is plutonium, which raises certain accounting and security issues) and in the process create a whole lot of medium level waste (irradiated machinery and such).
Neither is insuperable, but recycling is not a panacea
I'm a fan of fusion. If you look at the whole solar system, there are really only two large pools of energy -- light elements that could be fused and gravitational and kinetic energy in the planets orbital motion. Using the latter on a really large scale runs into a few problems with conservation of angular momentum, and also involves dropping Jupiter into the Sun, which is a but destructive, so it seems that fusion must be the way. Whether it is better to have one big central fusion reactor (as at present) and broadcast the energy (surely rather wasteful) or to distribute the generation more widely, I'm not sure. Breaking up the Sun into local sunlets might also be seen as a bit radical.
Re:Sweet (Score:3, Interesting)
There is a 30-turbine site proposed on the Isle of Skye. Each turbine will produce 10MW of electricity, and they are *huge*. Furthermore, the bases for each pylon will require 400 cubic metres of concrete - 2800 tonnes. Making this concrete will release 2800 tonnes of CO2 into the atmosphere - and that's for *one* turbine base, never mind the concrete pylon it will sit on.
Re:Meltdown isn't the (whole) problem (Score:2, Interesting)
Burying it in subduction zones should do the trick. wouldn't it take the wastes even further down in the mantle where they won't bother anyone?
I know the process is slow, but even so it _is_ faster than waiting for the most dangerous wastes to be harmless.
Re:Waste disposal (Score:2, Interesting)
Trouble is, the earths biosphere is a very large and very, very complex thing. How can we know that accientially causing somethign to change in the deep sea won't affect the life in the higher layers of the sea, thus creating the possibility that we loose a major foodsource for humanity?
One suggestion I've heard that _could_ work is to deposit nucular waste at one of those places where one contineltal plate is sliding under another. A few hundred years,and the waste will be carried deep into the core of the earth.
Another workable idea would be to finally get of our asses and build a space-elevator (which would benefit us anyway) and use that to lift the wast first into orbit and then fling it into the sun.
Re:Meltdown isn't the (whole) problem (Score:2, Interesting)
Sorry, doesn't work like that. The fuel rods have to be removed from the reactor not when the U235 is exhausted, but when the fission products start to build up. These fission products are orders of magnitude more radioactive than the original fuel was, and when present in any quantity will poison the nuclear reactions. This will happen after only a small proportion of the U235 has fissioned. "Reprocessing" simply consists of seperating out the unused fuel from the fission products so you get a second chance to use the remaining fuel.
Fast breeder reactors are a solution to an entirely different problem, i.e. converting unusable U238 into fissionable Pu239. There is currently no way to deal with fission products except waiting a few thousand years for the worst of the radioactivity to die away. It's also difficult to handle because with the extreme levels of radioactivity it generates there is also a lot of heat, if you encased it in concrete and buried it, it would just burn it's way out and end up in the groundwater.
Nuclear waste is a problem that already has a solution, and a solution that is ecologically sound and very much in line with recycling and reuse.
You don't have a clue what you're talking about.
Re:Sweet (Score:2, Interesting)
Renewables have matured considerably since nuclear power was first envisaged - to the point where they are very competitive. Some of the new offshore wind farms are contracted to supply power to the UK grid for $0.03/kw/hr - and that figure could drop with scale. See the British Wind Enrgy Association page [bwea.com]. Other forms like tidal, solar, etc are promising, yet unexploited..
There is no good reason to take the risk with nuclear, we have better alternatives these days..
meltdown proof??? possibly, but NOT fireproof... (Score:3, Interesting)
Sorry, but I have no faith in any process which combines a combustible material run at high temperatures and relying on keeping air out...
Let the Navy do it... (Score:5, Interesting)
They already buy power from one another on a regular basis and the more importantly the track record of the U.S. Navy in Nuclear Power useage is impeccable. The training program, security, design protocols, safety record and tradition of excellence make them the only people in the world I would trust 100% to run a nuclear power plant.
Re:Environment/North Korea (Score:4, Interesting)
Re:Rational thinking. (Score:2, Interesting)
How about the Sun? Didja know it's a variable star?
Fires? (Score:5, Interesting)
Another problem with pebble-beds is that they use natural or low-enriched uranium in a cycle where the fuel passes through the reactor relatively quickly and continuously (no big refueling outages). This makes them ideal Plutonium factories, which is obviously a matter of concern. Most of the graphite-moderated reactors ever built were designed primarily to produce Plutonium, including the Soviet RBMK's and the piles at Sellafield.
Don't get me wrong - I'm all for nuclear power for many reasons, but I'm not sure the pebble bed is that much of a breakthrough, and I don't think graphite is the best choice of material. And any operator of a plant in trouble that went home for the weekend should be shot. "Walk-away safe" my ass.
Re:Chernobyl was stupid (Score:3, Interesting)
The press is essential to things like safety. In the UK, someone blew the whistle on results being falsified at Sellafield. BNFL immediately sacked 5 staff.
Let's say hypothetically BNFL hadn't, and just decided to cover it up, and then the press had found out about it - the uproar against the power industry would have been massive. Then, if government did nothing that would have damaged them.
The totalitarian equivalent is - nuclear agency fakes results, but because the public don't have a free press, no-one can tell them. And even if they do find out, they can't kick out the government.
IIRC the worst nuclear accident was Three Mile Island. AFAIK, no-one was directly killed in this, although there is some debate over indirect effects.
And comparing possible nuclear power deaths in say UK and US with car deaths each year, it looks pretty small.
BTW Anyone know why France has a huge nuclear industry and the UK doesn't?
Re:Decomissioning and waste management? (Score:2, Interesting)
Nuclear types like to measure radioactivity in what is known as activity:
A=(lambda)*N,
(lambda)= (ln 2)/ t1/2,
where is the decay constant, N is the concentration, and t1/2 is the half-life.
What this means is that activity is inversely proportional to half-life. So in order to have a highly radioactive sample with a long half-life you must have a high concentration of it. It doesn't work this way with U-235. It has a 713,000,000 year half-life. Doing a quick calculation you will find that even a pure large sample of U-235 (subcritical of course) would have very low activity.
Re:Sweet (Score:2, Interesting)
"Unsafe" was a poor choice of words, although not completely tangential. Clean-up is the big issue. Follow the Yucca Mountain issue much? Nobody wants nuclear waste. Until you can change that, there's no point in proposing ways to make more of it. And saying, "Well, people shouldn't be so frickin' uptight about it" is not a solution.
While the deaths from Chernobyl pale next to coal-mining and other "uninteresting" power-production deaths, 115,000 people were evacuated and the town of Pripyat was and still is abandoned, and nuclear material was spread all over Western Europe. (The initial discovery of the problem in the West was when Swedish nuclear techs started registering for radioactive dust, and a check of their plant didn't discover a leak there.)
Then there's the terrorism issue. Every time the alert level rises, the National Guard gets sent out to guard powerplants. That doesn't fill me with love for the things.
And what of Iran, North Korea, et al? Every time they start talking nuclear power, we get very nervous, and with good reason. One bomb in the hands of the wrong people would make 9/11 look like a fender-bender. Maybe these new tech reactors would provide power without needing the wrong type of nuclear expertise and fuel, but as-is, nuclear power plants have made the world less safe by giving totalitarian gov'ts a rationalization for working with nuclear fuels.
Re:Sweet (Score:3, Interesting)
The biggest argument is cost - these plants are proving very expensive to decommission, and the waste expensive to dispose of adequately. In the UK, its the poor taxpayer who is being left with this bill from the first generation of plants..
The biggest arguments against Nuclear are capitalist (cost) - not anti-capitalist. Although there are also Environmental issues..
Re:Sadly, you got your facts all wrong... (Score:2, Interesting)
As others have said modern anti-tank rounds are basically very fast, very dense crossbow bolts and achieve their killing effect via kinetic energy. By contrast APHE get to the same end-point (breaching a tank's hull) by creating an explosion on the outer surface of the tank - there are various different wrinkles regarding how this explosion translates into a hole through the armour, but the basic operating principal of APHE is fundamentally different to that governing kinetic rounds.
As others have also said DU is not nuclear waste, the 'depleted' part of DU refers to the fact that the more radioactive isotope (U238) has been removed leaving the less radioactive isotope (U235) behind. DU is the natural consequence of the enrichment process - you start with natural uranium (NU) and after running it through an enrichment process you are left with a small quantity of enriched uranium (EU) and a larger quantity of depleted uranium (DU).
Now EU is used as feedstock for nuclear reactors or to make the warheads for certain types of nuclear weapons, so DU is certainly a byproduct of the nuclear industry but it is not 'nuclear waste' as the term is generally used. It should also be pretty obvious that DU is actually less radioactive than either EU or NU - its still a bit radioactive (because U235 is an alpha emitter) and its still chemically toxic (as all heavy metals are). These attributes make the post-battle effects of DU munitions problematic, but the same can be said of pretty much any kind of war materiel. People still get hurt in northern France by munitions dating from the 1914-18 war for example.
Regards
Luke
Go nukes! (Score:3, Interesting)
I *would* like to suggest that, in a setting with such grave consequences for error, engineers tell themselves daily that "meltdown-proof" really means "all failure modes are unknown." I think that would lead to a healthier attitued toward the whole thing.
Re:Sweet (Score:4, Interesting)
And generate all sorts of weapons-gradd material in the process. It's a major proliferation risk; that's why the U.S. has not chosen that option.
Nuclear waste simply is not a significant reason not to use nuclear power. The only problem is what to do with old, worn-out reactors.
There's another little reason: the risk of terrorist attacks on the plants. People argue all day about the technical safety and waste disposal issues. However, the security issues of proliferation and terrorist risks are by themselves enough to make avoiding nuclear power a no-brainer.
Our president has been running around hysterically shouting about WMDs for several years now. What's one of the most significant sources of material WMDs? It's when 2-bit countries convince people to let them have their own nuclear reactors. Again and again, we find out that they start producing weapons materials as soon as they crank up their plants. Part of the "war on terrorism" should be developing energy sources that allow us to totally eliminate nuclear power with its fuel cycle that has allowed several countries to hide their nuclear arms programs. Not to mention the problem that nuclear plants in your own country allow someone to turn a truck bomb or an airplane into a WMD (and don't bother bringing about the 3-foot thick shield around the reactor; I'm talking about attacking the unshielded spent fuel storage ponds).
Re:Partly true... (Score:5, Interesting)
Also, we've done well with Reduce and Recycle, but how are we doing with Re-use? It seems to me that much rad"waste" is just a resource for which nobody has tried hard enough to find a use. Medicine, nondestructive testing, long-term preservation of organic matter, etc. all have uses for long-lasting sources of radiation. (I tell my kids to remember where the landfills are, because their grandchildren will want to mine them.)
The Lessons of Chernobyl (Score:5, Interesting)
the problem that most people have with nuclear power is tchernobyl(or similar catastrophy that would release radioactivity to a wide area).
I'm glad you mentioned Chernobyl...
'is packed with tennis ball-size graphite "pebbles," each containing thousands of tiny uranium dioxide particles'... Proponents insist that the reactor's design features make it 'meltdown-proof' and 'walk-away safe'."... because apparently these people haven't learned anything from it.
The most important lesson of Chernobyl is that graphite burns. So if you lose control of this thing, it will catch fire. And the fire will spread radioactive decay daughters all over the place.
I am a big proponent of nuclear power, but only of one design: CANDU (CANadian Deuterium-Uranium). It's inherently impossible for it to melt down. It uses U-238 (natural uranium, in the form of "ceramic" pellets of uranium dioxide) which is NOT capable of a chain reaction without a heavy water moderator. (Heavy water is just water where the hydrogens have neutrons. Non-radioactive, naturally occurring, and just slightly heavier than normal water.)
As a result, if you lose control of a CANDU reactor, the reactor will overheat. Pressure will build up in the heavy water system until something breaks. The moderator will escape as steam, and since the fuel is essentially non-water soluble, with only extraordinarily small trace amounts of radioactive materials. With no moderator, the chain reaction stops, and the reactor cools down. This process occurs as a result of the laws of physics; in other words, Chernobyl cannot happen at Pickering or Darlington even if all the control systems fail or someone goes to extraordinary lengths to circumvent them.
The other great lesson is not to let boobs run the reactor. All nuclear power programs have had problems with this in the past; a "walk away" approach simply encourages this.
Re:Waste disposal (Score:3, Interesting)
The key error in this thinking is the assumption that the site has to be stable.
I propose a deep sea trench, like the Marianas.
1) The depth of the trench will provide more security than can ever be achieved on land, given the pressures of miles of ocean water.
2) The waste will have to be packaged in non-water-soluable form. These ceramic pebbles seem to be just the thing.
3) Any waste release in the trench will have to penetrate miles of ocean water to harm anyone, surface sea life included.
4) The waste will slowly be covered in silt, and even more slowly will flow with the ocean bed into the subduction zone under the opposing continental plate, ending up many, many miles beneath the surface in the mantle itself.
5) After millions of years, subduction heat will melt the waste and mix it with magma, and some will eventually appear in volcanoes beyond the trench zone, right above the subduction melt point.
Well, after millions of years, the waste will probably be no more significantly radioactive than magma normally is.
Re:Chernobyl was stupid (Score:1, Interesting)
Re:Decomissioning and waste management? (Score:2, Interesting)
Re:Partly true... (Score:5, Interesting)
I don't think I'd want to carry it around as a good luck charm, though.
Re:Partly true... (Score:5, Interesting)
By "reuse" I meant take the stuff that's no good for large-scale power reactor fuel and use it for something else. Like sterilization or probing metal castings for flaws. And if all else fails, someone else pointed out that the gunk still produces quite a bit of heat -- not enough for a commercial electric plant, but maybe enough for something that has to sit in an inaccessible place for decades without resupply.
Hydro...yeah, come to Indianapolis and ask the old-timers where Dandy Trail is. (It's at the bottom of a reservoir now, not such a fun place to go anymore.)
Stuff like solar, wind, tides, etc. can be stored as compressed air, used to extract hydrogen from water, pushed into high-performance flywheels, etc. so batteries are not necessarily needed.
Tidal generation might actually be a good thing for e.g. the barrier island systems of the North American east coast. Hmmm.
Oh, and coal mines are hard to clean up too. Ask about all the acid runoff. Ditto the mines that produce whatever materials go into your favorite alternative energy source.
We could boil all this down pretty compactly: energy production is messy and dangerous. So's millions dying of cold or fighting the wolves off with sharp sticks, though.
Re:Partly true... (Score:3, Interesting)
A nuke plant produces about 6.5 ounces of waste per minute, or about 20 tons per year for a typical thousand megawatt plant. A single coal plant produces about 10 tons of waste per minute, or about 300,000 tons of waste per year. Since the radioactives don't burn, they get concentrated in the ash. That thousand-megawatt coal plant releases about 20 tons of uranium and thorium (alone) from the 4 million tons of coal it burns.
All waste is an "emission", whether it literally goes up in smoke, is stored on site, or gets bundled into bricks and hauled away by truck. The only question is in what form, and where and how you transport it and store it.
Where do you think all that coal ash goes? They retain most of it at the power plant and bury it -- just like nuclear waste. Some of it gets made into building materials. The FAS estimates there are 2000 additional cancer deaths per year from radioactivity from the 5% of coal ash incorporated into building materials; it would be 40,000 if all the ash were used.
You can imagine the panicked public reaction if nuke plant waste were spread out by diluting it with a lot of neutral material and built into people's houses.
And, of course, the non-radioactive toxins from coal, like lead, cadmium, mercury, and C02, remain toxic forever, with a nearly infinite half-life.
There's no funny accounting going on here, with the coal emissions being counted while all the nuke emissions are ignored because they're stored at the plant, as you suggest. The radioactive emissions from a coal plant are indeed about the same as the total waste produced from a nuke plant. But then you have to pile on all the other waste from those fossil plants. Nuclear plants are cleaner, in total, and surprisingly not even any messier when it comes to radioactive waste alone.
Re:Partly true... (Score:2, Interesting)