← Autodidact Archive · Original Dissent · Walter Yannis
Thread ID: 20525 | Posts: 16 | Started: 2005-10-05
2005-10-05 12:37 | User Profile
They're building 30 new nuclear power plants but their energy consumption is growing so fast (to fuel manufacturing) that nuclear power is projected to grow as a percent of total output only by a very small margin.
The projected size of the Chinese economy - an economy based on making real things as opposed to our own "services" economy - boggles the mind.
Also, I think that nuclear is the way to go for the foreseeable future. It's safe, relatively clean, and cheap compared to other sources of power. And nuclear energy is produced in country and is something we can control.
Wish we'd build another couple hundred.
Walter
OCTOBER 3, 2005 Business Week ASIAN BUSINESS
Reactors? We'll Take Thirty, Please
Westinghouse, GE, and their nuclear rivals are chasing $50 billion in Chinese power-plant deals
Power to the People's Republic! That could easily be the slogan of the nuclear power executives winging their way to Beijing these days to pitch next-generation reactor designs, downplay rivals' plans, and woo the Communist Party leadership. President Hu Jintao's government is committed to spending $50 billion to increase nuclear power generation capacity from 8.7 million kilowatts today to 40 million kilowatts by 2020. That's one of the largest buildouts in the industry's history. And by the time that $50 billion is spent, some 30 new reactors will be pumping power to China's most important cities, in addition to the nine operating today. Most are to be built along a rapidly industrializing coastal arc stretching from Shandong province in the northeast to Guangdong province in the south.
The sheer scale of the ramp-up has global energy players salivating, including such giants as France's Areva Group, the world's biggest nuclear engineering firm with $13.5 billion in sales, Westinghouse Electric, Mitsubishi Heavy Industries, and Russia's Atomstroyexport. General Electric Co.'s (GE ) nuclear division is in the chase as well, while Paris-based Alstom and Germany's Siemens hope to cash in on contracts for reactor turbines and control and instrumentation systems.
The first contract up for grabs, valued at roughly $8 billion, is for four reactors in southern China: two in Zhejiang province's Sanmen and another pair in Yangjiang in Guangdong province. Beijing is expected to make its decision in October, and right now it looks like a two-way race between Areva and a consortium led by Westinghouse, which is owned by British Nuclear Fuels. It has been years since an order for a reactor came from a U.S. utility, and even orders from nuke-friendly countries such as France have been skimpy. "It's pretty critical," says Westinghouse CEO Stephen R. Tritch. "If you are not selected early, you could be locked out of the market."
BROWNOUTS AND SMOG It is no secret that China needs a massive infusion of new energy to keep the juice flowing to its manufacturing sector. Electricity brownouts are a regular feature of life in Shanghai and Guangzhou. And nuclear power only kicked in about 2% of China's total power supply last year, vs. 30% in Japan. Even so, nuclear plants are just one part of a much larger Chinese push to expand and upgrade the country's power grid.
In fact, demand for power is growing so fast that even if China builds all the nuclear plants on the drawing board, industry officials say atomic energy will account for only about 4% of total electricity generation. That's because the country is also building dozens of conventional power plants. But China wants to move away from the high-sulfur coal-fired plants blamed for its world-class smog and acid rain woes, a goal that increases the value of nuclear power. "Nuclear is clean and environmentally sound," says Wu Zongxin, a professor at the Institute of Nuclear and New Energy Technology at Beijing-based Tsinghua University.
Areva and Westinghouse were thrilled when China opted for their type of pressurized water reactors in the current contract bidding. In doing so, the Chinese ruled out rival technology such as GE's boiling water reactors and the heavy water plants sold by Atomic Energy of Canada, two of which are already operating in China. GE and AEC say they hope to win over the Chinese in future plant orders. "We have been asking if we can bid, but unfortunately they want pressurized water reactors," says Andy White, president & CEO of GE Energy's Wilmington (N.C.)-based nuclear business. "China should move to a two-technology model, like other countries."
Yet Beijing is extracting a hefty concession from the bidders by insisting on massive transfers of nuclear knowhow to local partners. Both Areva and Westinghouse have committed to sharing their technology with the Chinese to clinch deals. China is following a well-worn path: Japan, South Korea, and even France used technology provided by GE and Westinghouse to build their own nuclear industries. "If they are interested in becoming totally self-sufficient, we will help them do so," says CEO Tritch. "We are always inventing better technology." The pressurized water reactor Westinghouse wants to sell to China is its new AP1000, which the company advertises as much safer than the 1970s-era reactors that dominate in China and elsewhere.
The French also have pulled out all the stops to snag contracts. Areva already has four Chinese reactors up and running, and it has won points for providing technical assistance for the construction of a pair of Chinese-designed reactors that came online in 2002 and 2004. The company's latest pressurized water reactor has 1,700 MW of capacity per unit, vs. 1,000 for the proposed Westinghouse reactor. "We have a product that is quite advanced,"says Arnaud de Bourayne, head of China operations for Areva.
Westinghouse's sales job has been complicated by a decision earlier this year by parent British Nuclear Fuels to exit the power plant business and sell Westinghouse. Rivals think this uncertainty could taint its bid. Another issue: U.S. congressional opposition to extending loans and loan guarantees from the U.S. Export-Import Bank. One reason is that Westinghouse, though based in Monroeville, Pa., is British-owned and will probably be sold to another foreign outfit, so critics say it doesn't deserve help from U.S. taxpayers.
THE POLITICS OF POWER An appropriations bill passed by the House of Representatives removed Ex-Im Bank financing authorization, but Westinghouse is hopeful the Senate will restore it in upcoming conference committee meetings. The company, which has the Administration's support, points out that Westinghouse still employs 5,000 workers in the U.S. To bolster their case, company officials indicate that the lack of such financing may be a dealbreaker. And fat orders for nuclear plants could help ease the U.S. trade imbalance with China.
The other big potential player is Japan's Mitsubishi Heavy Industries, which already supplies the Chinese with coal- and gas-fired plants. Mitsubishi is a longtime partner of Westinghouse and may even buy the company from the British. "Nuclear reactors are becoming a core business," says President Kazuo Tsukuda. "We need the Westinghouse brand to grow." Whoever wins this first round, count on foreign energy executives' mad dash to China to continue for many years to come.
2005-10-05 15:41 | User Profile
In a country not burdened with environmental legislation and lawyer sue-them mentaility, they are cheap. In the US, no one is going to invest in a technology that potentially may become a huge liability down the road. Provided, of course, the project gets off the ground (Nuclear power station? Not in my backyard!).
2005-10-05 15:52 | User Profile
[QUOTE=madrussian]In a country not burdened with environmental legislation and lawyer sue-them mentaility, they are cheap. In the US, no one is going to invest in a technology that potentially may become a huge liability down the road. Provided, of course, the project gets off the ground (Nuclear power station? Not in my backyard!).[/QUOTE]
The nuclear power industry has an enormous task before it to convince the general public that nuclear power is clean and safe. No doubt about that.
Just getting that nuclear waste site approved in NV cost enormous political capital.
But I'm thinking that the time is ripe to raise the issue. Nuclear power is very competitive, at least in those plants now in operations. They're real cash cows, as they've learned to make them run very efficiently. You're right about the start up costs, but like I say it's a public relations problem. That's where they really need to invest.
I think the hook is that cheap electricity from a few hundred new nuclear power plants would allow us to tap our enormous synfuels potential, begin to develop ultra-clean hydrogen technology, and wean us off imported oil before we find ourselves in the middle of a major conflagration.
The problem is folks don't really count the beans. The price of a barrel of oil on the Chicago commodities exchange doesn't reflect the cost of keeping the military in the middle east, or the billions we pay Israel and Egypt each year. Not to mention unquantifiable security issues. If you really do the accounting right, a barrel of synthetic oil made from American shale or Canadian tar sands with massive inputs from domestic nuclear power begins to look like a bargain.
If we had leaders interested in our sovereignty and prosperity, that's the message they'd be pushing. But alas, we have leaders who secretly serve other agendas.
2005-10-05 18:29 | User Profile
Molten salt breeder reactors.
2005-10-05 19:40 | User Profile
[QUOTE=Walter Yannis]The nuclear power industry has an enormous task before it to convince the general public that nuclear power is clean and safe. No doubt about that. Uh Walter, it's been trying for the last 40 years
[QUOTE]Just getting that nuclear waste site approved in NV cost enormous political capital.
But I'm thinking that the time is ripe to raise the issue. Nuclear power is very competitive, at least in those plants now in operations. They're real cash cows, as they've learned to make them run very efficiently. You're right about the start up costs, but like I say it's a public relations problem. That's where they really need to invest.[/QUOTE]They've been trying. But the anti-nuclear environmental groups have much deeper pockets
[QUOTE]I think the hook is that cheap electricity from a few hundred new nuclear power plants would allow us to tap our enormous synfuels potential, begin to develop ultra-clean hydrogen technology, and wean us off imported oil before we find ourselves in the middle of a major conflagration.
The problem is folks don't really count the beans. The price of a barrel of oil on the Chicago commodities exchange doesn't reflect the cost of keeping the military in the middle east, or the billions we pay Israel and Egypt each year. Not to mention unquantifiable security issues. If you really do the accounting right, a barrel of synthetic oil made from American shale or Canadian tar sands with massive inputs from domestic nuclear power begins to look like a bargain.[/QUOTE]Its cheaper and safer, sho nuff. Realistically though, if opening up some barren desert in the southwest or frozen tundra in Alaska in this day of $3 gasoline or $14 natural gas is still controversial, I doubt there's a big sea change imminent toward nuclear.
I think its the sort of controversial issue our modern democratic society in its present form is able to handle. Just like immigration reform or social breakdown.
If we had leaders interested in our sovereignty and prosperity, that's the message they'd be pushing. But alas, we have leaders who secretly serve other agendas.[/QUOTE]Such as? Be specific Walter. If you can only hint vaguely at the answer even on this board, how do you expect that our society is going to make substantive material progress which presupposes such a wider understanding?
The way it is, I think your goal of reimplementing the Inquisition is more attainable.
2005-10-06 01:40 | User Profile
Walter,
I think there is a good chance by next spring after a winter of high fuel costs due to the shut down of refining on the Gulf coast that I think folks will be alot more receptive to building nukes.
2005-10-06 03:17 | User Profile
PBMR's might just be the ticket; ORNL types say they are much safer and can be more efficient than the molten salts...
see also: "Let A Thousand Reactors Bloom" [url]http://www.wired.com/wired/archive/12.09/china.html?pg=1&topic=china&topic_set=[/url]
Pebble bed reactor From Wikipedia, the free encyclopedia. [url]http://en.wikipedia.org/wiki/Pebble_bed_reactor[/url]
The pebble bed reactor is an advanced nuclear reactor design. This technology claims a dramatically higher level of safety and efficiency. Instead of water, it uses pyrolytic graphite as the neutron moderator, and an inert or semi-inert gas such as helium, nitrogen or carbon dioxide as the coolant, at very high temperature, to drive a turbine directly. This eliminates the complex steam management system from the design and increases the transfer efficiency (ratio of electrical output to thermal output) to about 50%.
The technology was first developed in Germany but political and economic decisions were made to abandon the technology. In various forms, it is currently under development by MIT, the South African company PBMR, General Atomics (U.S.), the Dutch company Romawa B.V., Adams Atomic Engines, a U.S. Company, and the Chinese company Chinergy, working with Tsinghua University.
Basic design The reactor provides heat, which is used to turn a generator. However, there are a number of different design choices.
The uranium, thorium or plutonium fuels are in oxides (ceramic form) contained within spherical pebbles made of pyrolitic graphite (see discussion below).
The pebbles are in a bin or can. An inert gas, helium, nitrogen or carbon dioxide, circulates through the spaces between the fuel pebbles to carry heat away from the reactor.
Ideally, the heated gas is run directly through a turbine. However, if the gas from the primary coolant can be made radioactive by the neutrons in the reactor, it may be instead brought to a heat exchanger, where it heats another gas, or steam. The exhaust of the turbine is quite warm and may be used to warm buildings or chemical plants, or even run another heat engine.
The primary advantage of a pebble bed reactor is that it can be designed to be inherently safe. As the reactor gets hotter, the rate of neutron capture by U-238 increases, reducing the number of neutrons available to cause fission. This places a natural limit on the power produced by the reactor. The reactor vessel is designed so that without mechanical aids it loses more heat than the reactor can generate in this idle state. The design adapts well to safety features (see below). In particular, most of the fuel containment resides in the pebbles, and the pebbles are designed so that a containment failure releases at most a 0.5 mm sphere of radioactive material.
A large advantage of the pebble bed reactor over a conventional light-water reactor is that it operates at higher temperatures. The reactor can directly heat fluids for low pressure gas turbines. The high temperatures let a turbine get more mechanical energy from the same amount of thermal energy; therefore, the power system uses less fuel per kilowatt-hour.
A significant technical advantage is that some designs are throttled by temperature, not by control rods. The reactor can be simpler because it does not need to operate well with the varying neutron profiles caused by partially-withdrawn control rods. For maintenance, many designs include control rods, called "absorbers" that are inserted through tubes in a neutron reflector around the core.
If throttled by temperature, the reactor can change power quickly, just by changing the coolant flow rate (this is patented). A coolant-throttled design can also change power more efficiently (say, for utility power) by changing the coolant density or heat capacity.
Another advantage is that fuel pebbles for different fuels might be used in the same basic design of reactor (though perhaps not at the same time). Proponents claim that some kinds of pebble-bed reactors should be able to use thorium, plutonium and natural unenriched uranium, as well as the customary enriched uranium. There is a project in progress to develop pebbles and reactors that use the plutonium from surplus or expired nuclear explosives.
[edit] Stationary designs and history In most stationary pebble-bed reactor designs, fuel replacement is continuous. Instead of shutting down for weeks to replace fuel rods, pebbles are placed in a bin-shaped reactor. A pebble is recycled from the bottom to the top about ten times over a few years, and tested each time it is removed. When it is expended, it is removed to the nuclear waste area, and a new pebble inserted.
The concept was invented by Professor Dr. Rudolf Schulten in the 1950s. The basic concept was to make a very simple, very safe reactor, with a commoditized nuclear fuel. The crucial breakthrough was the idea of combining fuel, structure, containment, and moderator in a small, strong sphere. The concept was enabled by the realization that engineered forms of silicon carbide and pyrolytic carbon were quite strong, even at temperatures as high as 2000 ðC. The natural geometry of close-packed spheres then provides the ducting (the spaces between the spheres) and spacing for the reactor core. To make the safety simple, the core has a low power-density, about 1/30 the power density of a light water reactor.
The core generates less power as its temperature rises, and therefore cannot have a criticality excursion when the machinery fails. At such low power densities, the reactor can be designed to lose more heat through its walls than it would generate. In order to generate much power it has to be cooled, and then the power is extracted from the coolant.
The "modular" concept of the pebble bed reactor uses several small reactors in a large power plant. This is convenient because new investment can be gradual, and tuned to the actual demand for electric power. Sites that require larger generation capacity can simply install more reactors. Depending on the design, there also can be economies of scale and better reliability when several reactors share equipment, and can switch sets of equipment when some part fails.
The modular design also allows a small reactor to be mass-produced, reducing the life-cycle costs of safety-certification and design qualification.
In modular systems, the equipment to cool the turbine's exhaust must be adapted to the site. The cooling equipment adaptable to the most sites is a cooling tower. However, near water, water cooling is far less expensive because the larger heat capacity of water permits the equipment to be much smaller.
[edit] History [edit] Germany A 15 megawatt (electric) demonstration reactor, Arbeitsgemeinschaft Versuchsreaktor (AVR - roughly translated to working group test reactor), was built at the nuclear research center Kernforschungszentrum in Jülich, West Germany. The goal was to gain operational experience with a high-temperature gas-cooled reactor. The unit's first criticality was on August 26, 1966. The facility ran successfully for 21 years, and was decommissioned on December 1, 1988, in the wake of the Chernobyl disaster.
The AVR was originally designed to breed uranium 233 from thorium 232. Thorium is about three times as abundant in the Earth's crust as uranium, and an effective thorium breeder is therefore considered valuable technology. However, the fuel design of the AVR contained the fuel so well that the transmuted fuels were uneconomic to extract—it was cheaper to simply use natural uranium isotopes.
The AVR used helium coolant. Helium has a low neutron cross-section. Since few neutrons are absorbed, the coolant remains less radioactive. In fact, it is practical to route the primary coolant directly to power generation turbines. Even though the power generation used primary coolant, it is reported that the AVR exposed its personnel to less than 1/5 as much radiation as a typical light water reactor.
[edit] China China has licensed the technology of the AVR, and is actively developing a pebble-bed modular reactor for power generation [1]. The 10 megawatt prototype is called the HTR-10. It is a conventional helium-cooled, helium-turbine design. The program is at Tsinghua University in Beijing. The first 200 megawatt production plant is planned for 2007. There are firm plans for thirty such plants by 2020 (6 gigawatts). By 2050, China plans to deploy as much as 300 gigawatts of reactors. If PBMRs are successful, there may be a substantial number of reactors deployed. This may be the largest planned nuclear power deployment in history.
Tsinghua's program for Nuclear and New Energy technology also plans in 2006 to begin developing a system to use the high temperature gas of a pebble bed reactor to crack steam to produce hydrogen. The hydrogen could serve as fuel for vehicles, reducing China's dependance on imported oil. Hydrogen can also be stored, unlike electricity, and distribution by pipelines may sometimes be more efficient than conventional power lines.
[edit] South Africa Pebble Bed Modular Reactors Pty. Ltd. (PBMR) in South Africa may be the current technology leader. It is developing a modular pebble-bed reactor. On June 25, 2003, the South African Republic's Department of Environmental Affairs and Tourism approved a prototype 110MW pebble-bed modular reactor for Eskom at Koeberg, South Africa. PBMR also has approval for a pebble-bed fuel production plant in Pelindaba. The uranium is to be imported from Russia through the S. African port of Durban.
PBMR's primary coolant is helium. The helium directly turns low-pressure turbomachinery, without intervening losses from heat-exchangers. Helium is well-favored because it is chemically inert, and neutrons do not transmute it to a radioactive element. This means that the turbomachinery does not become radioactive, even though it operates on primary coolant. One disadvantage is that the turbine must be somewhat larger, and therefore more expensive.
The turbine's compressors are decoupled from the turbine, which permits the turbine's pressurization to be decoupled from the generator speed. Utility generators must be synchronized to the power grid. The prototype test of the closed-cycle helium system including compressors, turbine and recuperator has been developed in the engineering lab at Potchefstroom University.
Helium is lighter than air, so air can displace the helium if the reactor wall is breached. Pebble bed reactors need fire-prevention features to keep the graphite of the pebbles from burning in the presence of air. Luckily, these are not difficult.
The pebble bed reactor's design can be throttled in real time to meet peak electric power loads just like conventional reactors, where power follows steam demand in seconds. The modular design also supports the speculation that it will be useful in building peak load plants. South Africa lacks fossil fuels for the gas turbines that normally power peak loads, but it exports uranium and thorium.
The S. African module's capacity is 165 MWe. The reactor could be a significant export item for South Africa.
PBMR's web site has also said that the reactor was designed to desalinate seawater, to help with South Africa's continuing lack of fresh water.
An inherently safe modular reactor that can provide peaking-power and fresh water would be a genuinely useful addition to the market, and a valuable export item. If the trial is successful, PBMR says it will build up to ten local plants on South Africa's coast. PBMR also wants to export up to 20 plants per year. The estimated export revenue is 8 billion rand (roughly US$ 1.2 billion)/yr, and could employ about 57,000 people. The program's total cost is about US$ 1 billion, and the developers estimate that about 30 plants will need to be produced to break even.
The environmental group Earthlife Africa (website) filed a court challenge to the EIA approval of the Koeberg reactors in September 2003, which it won in January 2005 [2]. The Cape Town city government and other civic and environmental groups also say they oppose the plant. In July 2003, following the approval of the environmental impact assessment, there were public demonstrations against the project in both Johannesburg and Cape Town. Earthlife Africa also opposes the Pelindaba fuel plant.
[edit] Mobile power systems Pebble-bed reactors can plausibly power vehicles. There is no need for a heavy pressure vessel. The pebble bed produces gas hot enough that it could directly drive a lightweight gas turbine.
[edit] Romawa Romawa B.V., the Netherlands, promotes a design called "Nereus". This is a 24 thermal-megawatt reactor designed to fit in a container, and provide either a ship's power plant, isolated utilities, backup or peaking power. It is basically a replacement for large diesels and gas turbines, but without fuel transportation expenses or air pollution. Because it requires external air, Romawa's design limits itself only to environments in which diesel engines are already possible.
Romawa's reactor heats helium, which in turn heats air that drives a conventional gas turbine. The Romawa design cleverly reduces the size and expense of heat exchangers. The main heat exchangers, the reactor and air-heater, operate at very high temperatures, and should therefore be small, inexpensive and efficient. The large, inefficient, expensive low-temperature steam condenser (the largest part of a light water reactor—the big cooling tower) is avoided by exhausting the air from the turbine.
Romawa proposes two types of throttling. For vehicular power, they advocate a reliable, quick-acting, inexpensive valve between the turbine and reactor. For efficient utility-style throttling, they advocate a system that reduces the density of helium in the coolant loop that connects the reactor to the turbine.
The basic design is at least as safe as a light water reactor, because only the helium passes through the reactor. The design attempts to reproduce the very safe operational experience of the AVR by using helium as the primary coolant.
The air passing through the turbine never passes through the reactor, and is therefore never exposed to neutron flux, and therefore particles and gasses cannot become radioactive. The turbine is likewise not part of the primary loop, and uses air as its working fluid. The technology is therefore very standard. Most moving parts do not touch the primary loop, and therefore service should be relatively easy and safe.
Romawa also proposes a clever refueling and maintenance plan, based on "pool service." Users of large gas turbines customarily pool their repair resources to minimize expensive equipment, spares and training. By shipping entire reactors, Romawa plans to eliminate on-site service, and provide all service in one or a few centralized, very capable workshops.
Romawa has a business agreement with Adams Atomic Engines in the U.S., which promotes a similar reactor system.
[edit] Adams Atomic Engines AAE's engine is completely self-contained, and therefore adapts to dusty, space, polar and underwater environments. The primary coolant loop uses nitrogen, and passes it directly though a conventional low-pressure gas turbine. Nitrogen and air are almost identical, so a turbine designed for air should work well almost without changes. Though AAE's design seems to require a larger secondary condenser, a sea-water-cooled condenser might be small enough to be inexpensive, or a stationary installation might afford a small cooling tower.
AAE holds the patent on direct throttling of a turbine heated by a pebble-bed reactor.
[edit] Other Issues Both Romawa and AAE plan to use neutron reflectors (graphite) and shields (heavy metals) that are bins of balls. This means that the shielding need not have complex ducting to cool it.
One proposed design of nuclear thermal rocket uses pebble-like fuel containers in a fluidized-bed to achieve extremely high temperatures.
[edit] Safety Features When a pebble-bed reactor gets hotter, the more rapid motion of the atoms in the fuel decreases the probability of neutron capture by U-235 atoms by an effect known as Doppler broadening. When the uranium is heated, its nuclei move more rapidly in random directions, and therefore see and generate a wider range of relative neutron speeds. U-238, which forms the bulk of the uranium in the reactor, is much more likely to absorb fast-moving neutrons.[3] This reduces the number of neutrons available to cause U-235 fission, reducing the power output by the reactor. This natural negative feedback places an inherent upper limit on the temperature of the fuel, without any operator intervention.
The reactor is cooled by an inert, fireproof gas, so it cannot have a steam explosion as a light-water reactor can.
The coolant has no phase transitions—it starts as a gas and remains a gas.
The moderator is solid carbon. It does not act as a coolant, move, or have phase transitions (i.e. between liquid and gas) as the light water in conventional reactors does.
A pebble-bed reactor thus can have all of its supporting machinery fail, and the reactor will not crack, melt, explode or spew hazardous wastes. It simply goes up to a designed "idle" temperature, and stays there. In that state, the reactor vessel radiates heat, but the vessel and fuel spheres remain intact and undamaged. The machinery can be repaired or the fuel can be removed.
These issues are not just theory. This exact test was performed (and filmed!) with the German AVR reactor (See link below). All the control rods were removed, and the coolant flow was halted. Afterward, the fuel balls were sampled and examined for damage. There was none.
PBRs are intentionally operated above the annealing temperature of graphite, so that Wigner energy is not accumulated. This solves a problem discovered in a famous accident, the Windscale fire. One of the reactors at the Windscale site in England (not a PBR) caught fire because of the release of energy stored as crystalline dislocations (Wigner energy) in the graphite. The dislocations are caused by neutron passage through the graphite. At Windscale, a program of regular annealing was put in place to release accumulated Wigner energy, but since the effect was not anticipated during the construction of the reactor, the process could not be reliably controlled and led to a fire.
The continuous refueling means that there is no excess reactivity in the core. Continuous refueling also permits continuous inspection of the fuel elements.
[edit] Containment Most pebble-bed reactors contain many reinforcing levels of containment to prevent contact between the radioactive materials and the biosphere.
Each seed, from the inside out, consists of:
Some authorities say that pyrolytic graphite can burn in air, and cite the famous accidents at Windscale and Chernobyl—both graphite-moderated reactors. Others insist that it cannot, and cite engineering studies of high-density pyrolytic carbon. Of course, all pebble-bed reactors are cooled by inert gases that prevent fire. However, all pebble designs also have at least one layer of silicon carbide that serve as a fire break, as well as a seal.
The fissionables are also stable oxides or carbides of uranium, plutonium or thorium. These cannot burn, and have a higher melting point than the metals. The fission materials are about the size of a sand grain, so they are too heavy to be dispersed in the smoke of a fire.
The layer of porous pyrolytic graphite right next to the fissionable ceramic absorbs the radioactive gases (mostly xenon) emitted when the heavy elements split. Most reaction products remain metals, and reoxidize. A secondary benefit is that the gaseous fission products remain in the reactor to contribute their energy. The low density layer of graphite is surrounded by a higher-density nonporous layer of pyrolytic graphite. This is another mechanical containment. The outer layer of each seed is surrounded by silicon carbide. The silicon carbide is nonporous, mechanically strong, very hard, and also cannot burn.
Many authorities consider that pebbled radioactive waste is stable enough that it can be safely disposed of in geological storage. Thus used fuel pebbles could just be transported to disposal.
[edit] Production of Fuel Most authorities agree (2002) that German fuel-pebbles release about 3 orders of magnitude less radioactive gas than American, which is not surprising in view of the Germans' longer operational experience.
All kernels are precipitated from a sol-gel, then washed, dried and calcined. U.S. kernels use uranium carbide, while German (AVR) kernels use uranium dioxide.
The precipitation of the pyrolytic graphite is by a mixture of argon, propylene and acetylene in a fluidized-bed coater at about 1275 ðC. The fluidized bed moves gas up through the bed of particles, "floating" them against gravity. The high-density pyrolytic carbon uses less propylene than the porous gas-absorbing carbon. German particles are produced in a continuous process, from ultra-pure ingredients at higher temperatures and concentrations. U.S. coatings are produced in a batch process. Although the German carbon coatings are more porous, they are also more isotropic (same properties in all directions), and resist cracking better than the denser American coatings.
The silicon carbide coating is precipitated from a mixture of hydrogen and methyltrichlorosilane. Again, the German process is continuous, while the American is batch-oriented. The more porous German pyrolitic carbon actually causes stronger bonding with the silicon carbide coat. The faster German coating process causes smaller, equiaxial grains in the silicon carbide. Therefore, it may be both less porous and less brittle.
Some experimental fuels plan to replace the silicon carbide with zirconium carbide to run at higher temperatures.
[edit] Criticism Several critics of pebble bed reactors have claimed that encasing the fuel in potentially flammable graphite poses a hazard. The reactor's use of an inert gas as a coolant possibly alleviates this issue.
Additionally, some designs for pebble bed reactors lack a containment building, potentially making such reactors more vulnerable to outside attack and allowing radioactive material to spread in the case of an explosion. However, an explosion would most likely be caused by an external factor, as the design does not suffer from the steam-explosion vulnerability of water-cooled reactors.
Since the fuel is contained in graphite pebbles, the actual volume of radioactive waste is greater, although the waste tends to be less hazardous. Defects in the production of pebbles may also cause problems.
The strength of silicon carbide is known from its use in abrasion and compression, but public debators may misrate this material by quoting not its strength against expansion and shear force but its hardness. Crystalline materials such as diamond can be cut with a sharp blow, and since the disintegration products such as Xenon have a limited absorbance in carbon, after some point the nugget accumulates a large amount of gas and may rupture. The system needs to be actively purged of oxygen, and the points at which the fuel pellets inserted, and more importantly, are removed, are an opportunity for disastrous introduction of air, and need to be specifically and sturdily enclosed. The containment structure must be capable of serving as a secondary tank capable of containing the hot reaction products that would result from a breach of the primary container, should oxygen enter the system. High temperature for extended periods may produce gas reactions that may have not been well studied because of the expense of maintaining such conditions over long periods of time.
Critics also often point out an accident in Germany in 1986, which involved a jammed pebble. This accident released radiation into the surrounding area, and led to a shutdown of the research program by the West German government.
2005-10-06 03:22 | User Profile
Probably one of the finest live albums of the last thirty years...
[url]http://www.amazon.com/exec/obidos/tg/detail/-/B0000A430W/002-9748263-4376808?v=glance[/url] NO NUKES Video Springsteen Raitt J Taylor J Browne The greats of the 1970’s and 1980’s in a rare collaborative feat. As Rolling Stone raved, "The MUSE NO NUKES Concerts of 1979 were a high-water mark of inspiration and optimism...a stunning testimony to the depth of the shared beliefs of the generation which came of age in the sixties." Musicians United for Safe Energy (MUSE) is a group of artists and activists working for a non-nuclear future. Their inspiring collaboration to bring five nights of concerts to Madison Square Garden and to organize a 200,000 person rally in Battery Park City has been distilled into an unprecedented film, documenting forever that elusive moment when artist, audience, and important cause were perfectly in sync. James Taylor and Carly Simon create their unique harmony in ‘Mockingbird’ and ‘The Times They Are A Changing’. Jackson Browne performs two of his most celebrated songs, ‘Running on Empty’ and ‘Before the Deluge’ and Bruce Springsteen brings down the sold out house with ‘Thunder Road’ and ! ‘The River’. Rounding out the extraordinary proceedings are Bonnie Raitt, The Doobie Brothers, Jesse Colin Young, Crosby, Stills and Nash, John Hall and Gil Scott-Heron.
POWER John and Johanna Hall [url]http://gratefuldread.nstemp.net/act/protest/john%20hall%20-%20power.txt[/url]
Just give me the warm power of the sun Give me the steady flow of a waterfall Give me the spirit of living things as they return to clay Just give me the restless power of the wind Give me the comforting glow of a wood fire But won't you take all your atomic poison power away G - - - / Bm - - - / Em - - - / D - - - / Am - < - / C - - - / G - - - / D - - - / G - - - / Bm - - - / Em - - - / D - - - / Am - < - / C - D - / G - CG/ // Everybody needs some power I'm told To shield them from the darkness and the cold Some may seek a way to take control when it's bought and sold I know that lives are at stake Yours and mine of our descendants in time There's so much to gain and so much to lose Everyone of us has to choose é 1979 Siren Songs (BMI):: on their "No Nukes" (Muse), and on Holly Near "Speed of Light"
2005-10-06 04:18 | User Profile
[QUOTE=weisbrot]Probably one of the finest live albums of the last thirty years...
[url]http://www.amazon.com/exec/obidos/tg/detail/-/B0000A430W/002-9748263-4376808?v=glance[/url] NO NUKES Video Springsteen Raitt J Taylor J Browne The greats of the 1970ââ¬â¢s and 1980ââ¬â¢s in a rare collaborative feat. As Rolling Stone raved, "The MUSE NO NUKES Concerts of 1979 were a high-water mark of inspiration and optimism...a stunning testimony to the depth of the shared beliefs of the generation which came of age in the sixties." Musicians United for Safe Energy (MUSE) is a group of artists and activists working for a non-nuclear future. Their inspiring collaboration to bring five nights of concerts to Madison Square Garden and to organize a 200,000 person rally in Battery Park City has been distilled into an unprecedented film, documenting forever that elusive moment when artist, audience, and important cause were perfectly in sync. James Taylor and Carly Simon create their unique harmony in ââ¬ËMockingbirdââ¬â¢ and ââ¬ËThe Times They Are A Changingââ¬â¢. Jackson Browne performs two of his most celebrated songs, ââ¬ËRunning on Emptyââ¬â¢ and ââ¬ËBefore the Delugeââ¬â¢ and Bruce Springsteen brings down the sold out house with ââ¬ËThunder Roadââ¬â¢ and ! ââ¬ËThe Riverââ¬â¢. Rounding out the extraordinary proceedings are Bonnie Raitt, The Doobie Brothers, Jesse Colin Young, Crosby, Stills and Nash, John Hall and Gil Scott-Heron. [/QUOTE] Wessy, tell me, how is a group of fuddy duddy engineers with pencils stuck behind their ears gonna compete with a group like that.
You can't hug your child with nuclear arms. No nukes is good nukes!
2005-10-06 04:21 | User Profile
[QUOTE=weisbrot]PBMR's might just be the ticket; ORNL types say they are much safer and can be more efficient than the molten salts...
see also: "Let A Thousand Reactors Bloom" [url]http://www.wired.com/wired/archive/12.09/china.html?pg=1&topic=china&topic_set=[/url]
Pebble bed reactor From Wikipedia, the free encyclopedia. [url]http://en.wikipedia.org/wiki/Pebble_bed_reactor[/url]
The pebble bed reactor is an advanced nuclear reactor design. This technology claims a dramatically higher level of safety and efficiency.......
.[/QUOTE]Fascinating. But how long does it take you guys to learn, you can't reason with irrationality. No matter how safe the technology, you will always be able to find some flaws.
You engineerophile types remind me of the aggie at the hanging, whose last words were, "doggonit, don't you know that trap door might work half-decently if you put a little grease on it" :lol:
2005-10-06 04:21 | User Profile
[QUOTE=Okiereddust]Wessy, tell me, how is a group of fuddy duddy engineers with pencils stuck behind their ears gonna compete with a group like that.
You can't hug your child with nuclear arms. No nukes is good nukes![/QUOTE]
Hey Todd, the ketamine seems to be kicking in a bit hard tonight...
2005-10-06 04:27 | User Profile
[QUOTE=Walter Yannis]They're building 30 new nuclear power plants but their energy consumption is growing so fast (to fuel manufacturing) that nuclear power is projected to grow as a percent of total output only by a very small margin. [/QUOTE] I should have mentioned Walter, I read they and India between them are also building [B]800 [/B] new coal fired plants.
Looks like the nukes are just a tiny salve to their global CO2 consciences. I suspect before India and China finish our CO2 levels will be up about twenty times, and people will be planting palm trees in Alaska.
2005-10-06 04:40 | User Profile
[QUOTE=Okiereddust]I should have mentioned Walter, I read they and India between them are also building [B]800 [/B] new coal fired plants.
Looks like the nukes are just a tiny salve to their global CO2 consciences. I suspect before India and China finish our CO2 levels will be up about twenty times, and people will be planting palm trees in Alaska.[/QUOTE]
Okie: what you said above, I don't think we disagree. Nukes are a great idea, but there's a huge PR problem. Weisbrot's links really bring that home. I mean, the Boss says they're bad, so what's a little science got to do with it? The reason that this may be an auspicious time to tackle the PR problem is that with the Global Warming thing, people are looking for a way to feel good about running their air conditioner overtime. Nukes make that possible.
And there's movement now on the chic left in favor of nukes as the only viable alternative to burning massive amounts of coal as you point out, for example in China and India (which has huge coal deposits, or so I'm told).
It won't be easy, but it could be done if we had the committment. But we don't, because - in so many words - the Jews want to keep us involved in the Middle East for Israel's sake, and making America energy independent would remove the only real vital interest we have there, thereby leaving the Shitty Little Country as the sole reason for staying. That would in turn create a huge PR problem for the Yahoodis and security problems for Zhidostan as our attention drifted back toward home. It follows that there can be no real move toward American energy independence, at least on their watch.
2005-10-06 05:03 | User Profile
[QUOTE=weisbrot]Hey Todd, the ketamine seems to be kicking in a bit hard tonight...[/QUOTE]OK, I admit I am being a little abrubt. What I am really trying to point out to you is there are fundamental issues here, that don't admit to technical solutions. This guy's article contains some of these.
[QUOTE]One can take issue with Davison's critique of Heidegger (for a completely different perspective on Heidegger's importance to ecological thought, see Michael Zimmerman's various articles on the subject). Heidegger urged that, due to the very danger that modern technology presents by creating an increasingly incoherent world, it represents an epic opportunity for modern people to experience the need they have for a deeper, more poetic relationship with the earth, one that will | in his splendid phrase | let Being be (even more splendid das Sein sein," in the original German). Davison's objections to the contrary, Heidegger does in fact appear to make a cogent distinction between craft and modern technology, between a way of existence represented by wooden windmills as opposed to power plants (to use the example Davison discusses from \The Question Concerning Technology").
The Trumpeter Book Review: Technology and the Contested Meaning of Sustainability 3
Furthermore, this distinction seems to accord with everyday experience, not mere nostalgia: [B]power plants raise issues of the domination of nature with us, in terms of pollution, integration with central authority, sheer ugliness, [/B] while windmills do not and,historically, never did. More to the point, Davison's dismissal of those who view modern technology as inherently bad, a la Heidegger, remains ill-defined. Why isn't it possible that modern technology, due to its ubiquity if nothing else, is irredeemably inimical and worthy of simple scorn? Quantity has not only a quality all its own, but an ontology all its own. [B]I for one have no problem saying nuclear power plants are bad in fundamental ways that windmills are not,[/B] leaving aside the issue of whether I'd want a windmill in this or that particular place. This is all the more true when a small, elite class siphons of most of the benefits of pervasive technology, while passing the detriments on to the rest of us. In short, many readers may feel that Davison's \philosophically rich" approach to technology lets it B off the hook too easily[/B].[url]http://trumpeter.athabascau.ca/content/v18.1/manes_review.pdf[/url][/QUOTE]
So if you technology backers are going to be let off the hook, think again. What you are pushing is "irredeemably inimical (I think evil is the more accurate word for what he means) and worthy of simple scorn" He's not going to let you off the hook. :tongue:
OK now I'll repeat it
[CENTER][SIZE=6] [COLOR=Red]"[B][I]No Nukes is Good Nukes![/I][/B]"[/COLOR] [/SIZE][/CENTER]:tongue:
2005-10-06 05:21 | User Profile
[QUOTE=Walter Yannis]Okie: what you said above, I don't think we disagree. Nukes are a great idea, but there's a huge PR problem. Weisbrot's links really bring that home. I mean, the Boss says they're bad, so what's a little science got to do with it? See my link below for a little theory on the nature of the PR problem
[QUOTE]The reason that this may be an auspicious time to tackle the PR problem is that with the Global Warming thing, people are looking for a way to feel good about running their air conditioner overtime. Nukes make that possible.
And there's movement now on the chic left in favor of nukes as the only viable alternative to burning massive amounts of coal as you point out, for example in China and India (which has huge coal deposits, or so I'm told).
It won't be easy, but it could be done if we had the committment. [/QUOTE] See the link below about trying to be let off the hook. > But we don't, because - in so many words - the Jews want to keep us involved in the Middle East for Israel's sake, and making America energy independent would remove the only real vital interest we have there, thereby leaving the Shitty Little Country as the sole reason for staying. That would in turn create a huge PR problem for the Yahoodis and security problems for Zhidostan as our attention drifted back toward home. It follows that there can be no real move toward American energy independence, at least on their watch.[/QUOTE]The middle east question is apprapo, but I see a larger issue, which is simply the type of society we have become (losing our coherent base). As a result, we no longer have the inner unity and self discipline to approach difficult communitarian issues rationally and in a spirit of self-sacrifice. Environmental issues especially personify this problem with communitarian issues.
Therefore I doubt that technology will go anywhere. In this state, difficult issues can only be overcome by rather obvious overt manipulation, as was done with Iraq. Iraq was a "chic war" (avenging all those kisch eating yuppies in the twin towers) and maybe we'll have chic nuclear power now. I didn't go along with the first, why should I go along with the second?
2005-10-07 13:55 | User Profile
[QUOTE]One could vigorously respond to Davison that before we can make technology moral, we may have to first wrest control of it from the elite that disproportionately benefits from a certain kind of technological development, one that is centralized, complex, interconnected, mass produced, and profitable.[/QUOTE]
Manes has been talking to Walter.
This "chic" war is chic among a certain elite. I doubt that Southern Baptists consider the illegal invasion of Iraq to be "chic"; to them it's a Crusade ordained straight from the Big Cuddly Promise Keeper/Avenger in the Sky.
If these people can be brought to an understanding of how their Gospel is being twisted to maintain one SLC and its far-flung children, perhaps there could be some changes in their understanding of what needs to be done to deal with the demands of an energy-starved world.
We're only 150 years removed from Darby's fantasyland beginnings. Why accept the apocalyptic views of the Bush Base as unchangeable? Once their attachment to the SLC is broken, progress on other fronts could be made.
What say we start with a space-station-visible bonfire of all "Left Behind" material that can be confiscated?