Slashdot Mirror
Uranium Pebbles May Light the Way
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'."
I applaud this kind of work.
Nuclear Power, despite the cries of environmentalists, is possibly the cleanest mass power source. On a scale of power generated per ton of input material it is incredibly efficient (bested only by those power sources which require no nonrenewable input, like wind/tidal/etc.), generates no effluent or air pollution, and needs only a competent staff (and, unfortunately, security), to stay running properly.
Nuclear plants may be prohibitively expensive to build these days, but if "pebble bed" reactors cost significantly less, then they may lead the way back towards what I view as our ideal energy source.
It's time to give nuclear a second chance.
It's how to handle the waste. That represents a real engineering challenge - some of that stuff is going to remain toxic for tens of thousands of years. Not only does it have to be stored safely and securely, but you have to work out some way of marking it so that should anyone stumble across it in a couple of thousand years, they understand not to touch it. The amount languages and cultures change, you can't just write on it, and even things like skull pictures could be interpreted as meaning "burial chamber - archaelogists, get digging!".
That said, I'm not against nuclear power (from fusion) per se. Of the options we have, it's one of the best at the moment. "Alternative" power sources need a lot more work, and fusion, whilst extrememly promising, just isn't practicable yet (unless I've missed a major breakthrough in the last couple of years). I'm just pointing out that there are still other problems that need to be addressed.
It's official. Most of you are morons.
Reading some of the comments in this article, I have to wonder when 'Geek' and 'Nerd' transformed into 'Reactionary Luddite'.
19 tons of heavy metal radioisotope doesn't take up much space. These elements are quite dense.
I remember seeing a demo of this stuff in school.. It's so safe to use in a reactor it's crazy; they referred to it as "walk-away" safe. Lose _all_ cooling in the core, leave it over the weekend, fix it on Monday. It was going to bring about a revolution in safety WRT nuclear power generation. It's nice to see this finally coming to fruition.
Africa's state-run utility giant Eskom /rant
I'm going to pop a vein! Afirca is not a country, it's a continent . South Africa, the country where Eskom resides, is a country in Africa (easily confused with South America by Americans. South America is a continent south of North America, the continent with three different countries on it, including the USA). There are 54 independent, different countries in Africa, each with their own government. Africa is not simply a big ol' jungle where everyone speaks Swahili (only 50 million of the more than 700 million people in Africa speak Swahili).
OK, now that I got that off my chest: Eskom has been talking about this for a while now, and they are facing some resistance to the idea. The problem being the general conception that "nuclear is evil".
We (USA in the 90s) promised two of these (or very simiar to these) to North Korea so that they a) could have plenty of power and thus might spend money on economic growth/feeding their people and b) couldn't develop nuclear weapons from the material. but oops, congress wouldn't approve it. Now look where we are with them. big mistake
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).
Guess what? The enriched uranium they use in reactors contains in the region of 3% to 4% U-235 - making it litterary too hot to handle. Even 'spendt' reacorfuel contains more U-235 than ordinary oranium-ore, as well as more than a bit of Pu-239 and Pu-240 (the longer the fuel stays in the reacor, the more Pu-240). And Pu-239 and Pu-240 is two isotopes of an element better known as plutonium... granted, it's not weapongrade plutonium, but it's still something I wouldn't have scattered about.
Sure, we "enrich" the uranium-- largely by sorting isotopes. There's no reason why you couldn't choose to de-enrich/deplete the uranium back down for storage, if you thought this was beneficial. This is why it's entombed in glass in many storage proposals, and why it's often reprocessed-- so you can sort the "useful fuel to reuse" and "spent fuel/waste".
There are intermediate-term (80-500 year) storage problems involved with the high level wastes produced in fission reactors. The thing is, these wastes inherently have short half lives and decay to more harmless stuff very quickly.
Nuclear power is a subject that is near and dear to my heart having spent a part of my life working in the industry for Uncle Sam. There are three real issues with Nuclear power that keep it a hot button issue:
* Proliferation of WMD. Widespread use of nuclear power creates huge opportunites for people to get their hands on fissile material or highly radioactive material. A "dirty bomb" consisting of a few hundred pounds of waste and a few hundred pounds of explosives could do incalcuable damage. Nuclear power and nuclear weapons are NOT high tech. It's technology from the era of propeller airplanes, black and white movies, radio and vaccum tube electronics.
* Economics: widespread use of nuclear power would render a large sector of the global economy useless. There is a substantial interest in keeping the world dependent on our dwindling supplies of fossil fuel -- remember suply and demand? What happens when the supply decreases and demand increases? Many nations, corporations, and ultimately individuals stand to get very, very rich by monopolizing the resource (OPEC is a benign example compared to what we'll see in the future)
* Finally, there is a more practical issue: much of today's power challenges are demand side issues. Most people are blissfully unaware of what it takes to supply a couple of killowatt hours to their homes and especially businesses.
-- $G
The basis for this technology has been around for at least 30 years, as you would know if you read the background on the site. The PBMR is not the same technology as the AVR or THTR at Hamm-Uentrop.
The THTR reactor was not closed due to technical problems. The problems it experienced were related to the loading of fuel, an issue addressed by the PBMR. Even Greenpeace admits regarding the THTR "In 1989 the reactor was permanently closed due to both economic and political reasons."
Whenever the issue of pebble-bed reactors has been discussed there has been allusion to "problems" in all reactors produced so far (in Germany, Japan and the US) -- without indicating that none of these reactors have been closed down for safety reasons! The biggest problem with these reactors so far has been getting them to reliably and economically perform their purpose.
As for information exchange so that South Africans know whats getting build "in their back yard" - we have a strong anti-nuclear lobby already. Unfortunately we also live in a country where 16% of the populate are illiterate and only 25% have completed secondary education -- so just how do you think it is possible for the public to make an educated decision on how long our coal reserves are going to last, whether a particular incarnation of nuclear technology is better or worse than pumping out greenhouse gasses, and what our electricity requirements are going to be in 2010?
i-name =twylite [http://public.xdi.org/=twylite], see idcommons.net
Chernobyl had a lot of things that were just wrong.
The reactor increased in efficiency as temperature increased. This is a nice little feedback loop. Most reactors lose efficiency as temperature increases, meaning that it is difficult to try and overload the reactor, even on purpose.
The reactor was designed to be cheap, and it did not have a dome. Domes contain radioactive material very well. Tests have shown that an aircraft hitting a dome would hardly scratch it.
As another cost-cutting measure, the reactor didn't have any good backup power. It may seem silly to have a power plant that needs power, but nuclear power plants do need power to start up and in case of emergencies. Western plants have batteries and generators.
As if these technological blunders weren't enough, some bonehead transfered control of the power plants from the ministry that designed and built them, where all the trained personnel are employed, to the ministry of energy. There are reports of operators sitting on the control board and people showing up to work drunk.
Basically, in 1986, the Chernobyl reactor demonstrated a bunch of "don'ts" to a world that should have already known.
There will always be technology out there that can be misused. The amount of that technology will only increase. Do we ban knives because people get stabbed? Do we ban nuclear power because a couple of Russians cut costs?
The 'ball' nuclear reactors are basically foolproof. You put a bunch of balls next to each other and you get heat. This is not weapons grade Uranium.
I only see one problem with nuclear -- the small amount of waste that is generated needs to be handled properly. It can be done, but it just has to be done right.
I would like to see the Department of Naval Reactors, in conjuction with the Department of Energy and the U.S. Navy be contracted to design, build, man and run nuclear power plants for commercial power consumption. Then turn around and sell that power to the utilities companies.
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.
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.
Human genome = 3 billion base pairs = 6 GBit. Windows + Office = 20 Gbit. Which is more impressive?
Fact: There is little or no pollution from an operative reacor.
Fact: Spent fuelrods from reactors are a major enviromental problem.
Fact: The byproducts of all other currently viable forms of energy production are major environmental problems.
I can't think of anyone who would say that nuclear waste is not bad. But I for one, and many others who have researched the topic, believe it is less bad than the alternatives.
I would rather have a small amount of really bad stuff being controled, than a huge amount of pretty bad stuff being spewed into the air I breath every day.
"I'll have a Guinness, no wait, make that a Coors Light" -Grad student I work with, who shall remain anonymous...
U-238 is barely radioactive, with a halflife of about 4500 million years. U-235 on the other hand is way more radioactive, and thus the part they are interested in using for reactorcores.
Not true. The half-life of U-235 is 710 million years -- enriched uranium is NOT too hot to handle.
Pu-239 (half-life 24400 years) and Pu-240 (half-life 6580 years) are hotter and are the reason spent fuel needs to be sequestered for so long. But the really nasty, ultra-hot radioisotopes are all the neutron-rich fission byproducts from splitting U-235 or Pu-239. Byproducts like barium-140, cesium-134, cesium-137, and iodine-131 have half-lives in the days to only a few years that make them intensely radioactive (thousands of times more radioactive than Plutonium and millions of times more radioative than U-235). Worse, these byproduct elements will chemically react with ordinary matter, form water-soluable compounds, and lodge in living tissue if injested.
Fact: Spent fuelrods from reactors are a major enviromental problem.
Extremely true, but not because of U-235.
Two wrongs don't make a right, but three lefts do.
Yep, some people will die from an increased incidence of cancer...
I don't know if that is the case... Coal, the major alternative to nuclear, has numerous carcinogens among it's combustion byproducts. These carcinogens are not tightly controled like the nuclear ones are, they are simply dumped into the environment surrounding the plant. I would much rather have a nuke in my back yard, than a coal burner...
"I'll have a Guinness, no wait, make that a Coors Light" -Grad student I work with, who shall remain anonymous...
The latest cost estimates for building a 'demo model' is about R10 billion, and will be completed in 2008. That's about 5 years over schedule, if my memory serves me. The PBMR company ltd., not Eskom directly, is building this thing. That company's shareholders are currently Eskom and BNFL. Since BNFL is currently being restructured, as the cleanup costs for Sellafield have forced it into bankruptcy, Eskom is the only real player. (US company Exelon was involved, but now they've pulled out)
R10 billion is way more than Eskom can afford. Therefore they are looking for external partners to invest in the project, and that depends on selling PBMRs being commercially viable. Now, nuclear electricity is very expensive - one of the reasons that the world nuclear industry is in the doldrums. There was a paper in the South African Journal of Science about this some time back, which examined the economic models Eskom was using for PBMR, and found them to be wildly optimistic.
So if the economics are so screwy, why is Eskom pursuing this project? No one really knows, but I'm sure the fact that the chairperson of Eskom, Reuel Khoza, effectively controls one of the main contractors (IST), through a holding company has got something to do with it. Even if the PBMR project fails, Khoza and buddies will end up much richer. IST got handed a R260 million (?) contract, which is about as much as its previous annual turnover. Their shareprice went through the roof, making Khoza and co's share options worth a lot more.
Besides the Reuel Khoza link, there is an argument to be made that difficult-to-manage technologies like PBMR will be an incentive for the government to keep a much more centralised and powerful Eskom around for much longer. Eskom is currently facing deregulation and restructuring, and this Apartheid-legacy parastatal needs to justify why it still needs to exist. Experience in other companies has shown that deregulating nuclear power is very hard, so PBMR might be a bargaining chip in the complicated game around Eskom's future.
Funnily enough, the Wired article and the Slashdot responses have all the hallmarks of engineers - in love with 'sexy technology' while pretty much ignoring the bigger political/economic picture.
Peter
Whatever happened to vitrification? Mix the stuff into glass, cast into handy-sized lumps, bury in moist earth, post a guard to keep the bad guys from digging it up. As deep as they want to bury it, any post-catastrophe society capable of reaching the stuff should be developed enough to figure out that it is dangerous, particularly since, unlike natural ores (which are also dangerous), the stuff will be *marked*.
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 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.
Fire and Meat. Yummy.
Most of the re-use part of nuclear fuel is, as I understand it, prohibited by government regulation, something having to do with plutonium generation. My understanding of a possible use involving breeder reactors, though, involves using the plutonium's natural decay to enrich uranium fuel, allowing the plutonium to break down into less harmful byproducts while the uranium is enriched for fuel in the near future. This seems a more complete use of the fuel to me, and could result in less hazardous waste.
... For the complete nuclear fuel cycle, from mining to reactor operation to waste disposal, the radiation dose is cited as 136 person-rem/year; the equivalent dose for coal use, from mining to power plant operation to waste disposal, is not listed in this report and is probably unknown."
However, use of plutonium is rather taboo for some reason -- witness the furor over Cassini's radioisotope generator, which some environmentalists claimed could kill thousands in the event of an accident on launch in 1997 or during the flyby of Earth in 1999, with one site suggesting a 10-micron particle could result in the exposure of a person inhaling it to thousands of REMs. Their argument was that the release of the 72 pounds of plutonium would be catastrophic over centuries.
An article in a 1993 Oak Ridge National Laboratories Review states, "according to NCRP Reports No. 92 and No. 95, population exposure from operation of 1000-MWe nuclear and coal-fired power plants amounts to 490 person-rem/year for coal plants and 4.8 person-rem/year for nuclear plants.
Even factoring in mining -- where radioactive dust presumably goes into the air -- and disposal -- where various bits of radioactive dust and water are released -- nuclear plants produced only about a quarter of the average radiation dosage that coal plants do over their lives. I've seen the strip mines that are used to get at uranium, and while it's not pretty, it's not nearly as bad as the destruction of entire mountains in the Appalachians. There is also research going into extracting uranium from seawater for about $120 per pound, which, although about 10 times the current rate, could be more environmentally safe and could provide thousands of years of power, presuming we operated on nuclear power for that length of time.
I'm all for nuclear energy. While I am also a proponent of renewable sources, I don't like the environmental damage caused by hydroelectric. Solar has issues of night-time electricity use, and it is reportedly a messy thing to make, with some pretty dangerous chemicals involved, not including any batteries that would be needed for cloudy days and night use. Wind has issues of reliability, and tidal generators have a range issue, not to mention that I wonder how it would affect the beaches to have thousands of them operating.
I recognize the dangers of nuclear energy. I know that it's hard to clean up, and that there are significant security risks; I'd much rather be in a room with an exposed piece of coal than an exposed piece of reactor-grade uranium. But that piece of uranium will be useful long after the ash from the coal has been carted off and buried. It will have given off no CO2 or nitrogen or sulfur oxides during its use (save whatever transportation is used for it), and less radioactivity.
In balance, I believe that nuclear reactors are a far better source of energy than anything else we have at the moment.
You can never go home again... but I guess you can shop there.
I don't think I'd want to carry it around as a good luck charm, though.
Well, reprocessing "spent" fuel to get the unconsumed U back was what I meant by "recycling". It's a good idea and, if we can do it right, we ought to do it.
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.