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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.
I think it is important to move away from the current reliance on fossil fuels as quickly as possible and move towards nuclear power generation as the only realistic sustainable alternative power generation scheme.
Many of the world's problems exist because of the small patch of oil-soaked land out in the Middle East and the lack of trustworthy stewards of those fields. With Gulf War II over and those oil fields finally in the hands of Western democracies we may see some improvement in global stability vis a vis the opening of OPEC to its main customers. However, because we continue to rely on oil as our primary power source we will likely continue to have problems as the oil fields run drier and drier.
It is good to see Africa (of all nations!) take the lead in this new system of nuclear power generation. Older systems like the ones in Canada and France are fine, however it would be a stretch to say that they are perfect. There is plenty of room for improvement in those power plants. This usage of uranium pebbles is one such improvement, but there are more.
It is a problem that people would be willing to block the development of Africa because they object to the usage of these newer power systems. Especially so because for the most part the same protesters unwittingly reap the benefits of their own country's nuclear power generation systems.
The perennial question is one of waste disposal. It's all very well having a realtively clean source of energy right now, but if you have to guard against people getting hurt for X years, where X is a very large number...
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They claim the graphite and silicon carbide around the pebbles will keep it sealed for ~ 1 million years, which is impressive. It'll be interesting to see if humanity is around in ~1 million years
It also produces about 19 tons of radioactive waste (in the form of these coated pebbles) every year. That's going to be some landfill site, if the technology takes off...
Simon.
Physicists get Hadrons!
Reading some of the comments in this article, I have to wonder when 'Geek' and 'Nerd' transformed into 'Reactionary Luddite'.
"Africa's state-run utility giant"... WTF?
Africa is not a state or a single country for that matter, it's a continent made up of many states. Please be specific, ppl are very ignorant about this, just like many think that all africans speak the same langauge (there are over 200 langauges in Nigeria alone for example).
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).
For you geographically challenged people. Africa is a whole continent. Like North America, South America and Australia.
South Africa is a country. It's at the tip of Africa. You'll never guess where it is in Africa.
It was a British Colony, but gained independence about 55 or so years ago, and promptly began to institutionalise pernicious racially-based discrimination. It was called Apartheid. After a long struggle (40 years) the white people agreed to share power and democratic elections took place. Nelson Mandela (you may have heard of him) was elected president.
The economy of South Africa is split - there's a strong first world component, and a large third world component. The first world component rivals the economies of Europe and the USA in sophistication - though it's much smaller. The third world component - i.e. subsistence farming, and subsistence trading - involves many more people. Unemployment rate is high - a few years ago it was 40%. Not sure what it is now. HIV/Aids rate is probably the highest in the world - hitting around 10% of population. Some places have rates as high as 40%. The current government until recently has ignored the problem.
Eskom is a world-class power utility. They have existing nuclear reactors, which were learning grounds for the Apartheid state in their quest for nuclear weapons. (Ten or so years ago South Africa admitted that they had nukes, and then destroyed them. Thank you Nelson Mandela and South Africa for making the world a safer place.)
It's questionable whether South Africa needs more nuclear power plants but Eskom has traditionally had a strong technocratic streak. (I was an employee a long time ago.) SA is rich in coal and natural gas.
I personally think that the money could be better spent given South Africa's problems - the only justification would be to export the technology. And maybe greater access to nuclear expertise is not what the world needs.
Jeff Veit
This technology has been around for at least 30 years. The Germans even built an example pebble bed reactor at Hamm-Uentrop which has led to the technology being heavily criticized by enviromentalists. Normally I would be hesitant to swallow raw what enviromentalists feed onto the internet, especially the religiously fanatical German anti nuclear lobby, but in this case their claims are reenforced by the fact that their opinions of pebble bed reactors are shared by the German state who shut the Hamm-Uentrop plant down in 1989 after the management covered up serious problems with the reactor. The whole affair has led the People of Hamm-Uentrop to start a citizens group which among other things aims to start an Information exchange with the people of South so that the Africans can take into account the German experiences before one of these things gets built in their back yard. Feel free to call this a troll but with so many people singing the "See!! I told you nuclear is safe" psalm here I figured the other side of the coin deserved a mention.
Only to idiots, are orders laws.
-- Henning von Tresckow
Such reactors are not new, e.g. there was/is one in Hamm-Uentrop, Germany called "THTR 300".
Building started 1970, reaction started 1983, shut down 1988, disassembling started 1991.
Its output was 308MWe, so I assume it was not just a toy.
AFAIK they had problems with the moderation and breaking of the balls.
Nothin' new, actually.
Seriously. I hate buying gas. Would be nice not to have to buy gas again - ever.
Oh sure, what happens if I get into an accident? Well, that's why you build the reactor compartment the same way as an airplane's black box, if that can survive a plane crash, a car crash should be a walk in the park.
There's a problem with terroists getting uranium and making dirty bombs you say? Not a problem either! Just outlaw radiation suits so anyone that opens the reactor is instantly nuked like a frozen chicken pot pie. Of course, that means no more tinkering with your car, but would you really miss it if you never had to buy gas again?
I want my nuclear car, damnit.
---
DRM is like antifreeze, to the MPAA/RIAA it's sweet, to the consumers it's poison.
It's been done before. In Germany. It was called "schneller Brueter". It never went operational.
The rationale was that it would be vatsly more efficient. In practice, those "balls" were harder to control than the normal rods. In testruns they would jam as they were processed in the facility.
So it's neither the first time this is being built, nor is it the answer to all energy-questions in the world.
Yeah, disposal is a problem.. but it's not like it wasn't just lying around to begin with.
Oh please.. that old, tired argument again. YES, uranium occurs in most rocks in concentrations of 2 to 4 parts per million and is as common in the earth's crust as tin, tungsten and molybdenum. HOWEVER, uranium in the natural state is a mix of two isotopes; 99.3% U-238 and 0.7% U-235. And guess what? 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.
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.
Fact: There is little or no pollution from an operative reacor.
Fact: Spent fuelrods from reactors are a major enviromental problem.
You might find this and this webpage interesting.
Everything in the world is controlled by a small, evil group to which, unfortunately, no one you know belongs.
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
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...
True, if you only consider what is legally released into the environment while the nuclear plant is operating. If you consider the fission byproducts and their "disposal" (e.g. long term storage) then this isn't true. Yucca Mountain nonwithstanding, the problems associated with nuclear waste may not be worth the benefit (and I'm a nuclear-trained engineer).
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
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.
Direct quotes from the PBMR web page:
"This turbine forms part of the High-pressure Turbo...Next, the helium flows through the Low-pressure Turbine, which is part of the Low-pressure Turbo Unit...The helium is then cooled in the inter-cooler. "
In other words: they're going to build a twin-turbo nuclear reactor with an intercooler.
I didn't see any mention of chrome exhaust tips, cupholders, cruise control or racing stripes, but how far behind can these things possibly be? That's gonna be one decked out nuclear reactor...I wonder what kind of stereo system they'll put into it?
Perhaps for the opening ceremony I'll fly to Africa and plant a "Type R" decal on the side of the reactor building.
I think a lot of us fall into a 'middle-ground.' I'm fearfull of the long term effects that plant melt-downs have. . . but at the same time I realize that there potentially are safe(r) designs. If someone can truly come up with a 'disaster proof' reactor design that doesn't produce highly dangerous waste (it sounds like the design you mentioned is a likely candidate) then I'm willing to at least consider them.
Safe designs for nuclear reactors actually kind of excite me, because we clearly need to get away from fossil fuel energy.
Although, ultimately, I'm most excited about bio-mass energy (if it can ever be made to be practical at a large scale), because while burning bio-mass derivative fuels produces CO2 - at least the next generation of fuel will re-fixate that CO2 as it grows. . . it's a stable system where we are at least not increasing the amount of CO2.