New nukes is bad nukes
Bush's plan for your radioactive future
keep our economy growing, we also need reliable supplies of affordable,
environmentally responsible energy. (Applause.) Nearly four years ago,
I submitted a comprehensive energy strategy that encourages
conservation, alternative sources, a modernized electricity grid, and
more production here at home including safe, clean nuclear energy.
(Applause.) My Clear Skies legislation will cut power plant pollution
and improve the health of our citizens. (Applause.) And my budget
provides strong funding for leading-edge technology from
hydrogen-fueled cars, to clean coal, to renewable sources such as
ethanol. (Applause.) Four years of debate is enough: I urge Congress to
pass legislation that makes America more secure and less dependent on
foreign energy. (Applause.)”
George Bush, 2005 State of the Union Address
Boiled long enough, even the toughest nut will eventually soften. Faced with criticism from a united global community and an increasing portion of the US business community as well as burgeoning scientific unanimity on climate change, the Bush Administration has finally begun to retreat from its position that “more study” is needed before we reduce our profligate consumption of carbon fuels. Even longtime oil industry insiders such as Bush crony James Baker have started to express reservations about burning all that oil. In a speech to Texas oilmen at the Houston Forum Club on March 3, Baker went so far as to say, “When you have energy companies like Shell and British Petroleum, both of which are perhaps represented in this room, saying there is a problem with excess carbon dioxide emission, I think we ought to listen.”
The problem for Bush in retreating from a fossil-fuel economy, of course, is that many climate-friendly alternative energy paths solar, wind, and (most importantly in the short term) conservation are not exactly amenable to centralization. This means that energy companies stand to lose control of their markets. Burning oil or coal or natural gas to produce electricity favors the development of large generating plants and expansive, “gameable” grids. Wind power development can be centralized, but people can also put windmills in their backyards. Solar electric, due to the low amount of energy per square foot of generator, fairly demands decentralization: rooftops are about the only environmentally neutral surface area available in sufficient quantity to power most cities. And conservation is the least profitable strategy of all, at least until the energy companies figure out a way to charge you for turning lightbulbs off.
In an age in which more and more people agree we must drastically cut our use of fossil fuels to mitigate the damage weve done to the climate, where can the energy lobby turn to protect its profitability?
Enter nuclear power. Or perhaps that should be “re-enter.” Widely considered a dead industry since the 1979 partial meltdown at Three Mile Island and the subsequent Chernobyl disaster solidified its bad reputation, the nuclear power industry is poised to make a post-Kyoto comeback as a putative “clean” source of energy. Thats right: “Clean, safe nuclear power,” just like the president said.
Of course, this is the same president that talks about “Clear Skies” initiatives and “clean coal.”
No new nuclear power plants have been built in the US since the Three Mile Island incident. Many of the USs existing plants were designed for a 40-year operating life, which for the youngest plants would end in 2019 or so. But the Nuclear Regulatory Commission has already granted 20-year extensions to 26 of the nations 103 operating nuclear power plants, with another 42 extensions in the works.
|Aerial view of Yucca Mountain in Nevada, proposed site of a dump for high-level nuclear waste. Reuters photo|
The Bush administration wants to make new nuclear power plants a federal priority, and its putting our money where its mouth is. A proposed 2006 budget, which featured massive cuts in almost every social program, grants a $25 million increase to the Department of Energy (DOE)s Nuclear Energy, Science and Technology division, $20 million of that for research and development. An Advanced Fuel Cycle initiative, the brainchild of nuke-friendly Senator Pete Domenici (R-NM), would receive $2.5 million more than in 2005 to research reprocessing of nuclear waste into fuel an increase of four percent over the 2005 budget. “Nuclear Power 2010,” a Bush initiative to promote new nuke plant site permits and operating licenses, won a 13 percent budget increase to $56 million in 2006. Twenty million dollars, up from nine million last year, will go to promote nuclear generation of hydrogen gas to fuel what Bush bizarrely referred to in the 2004 debates as “hydrogen-generated automobiles.”
And the 2006 budget also includes a $5.3 million boost for research into new nuclear reactor technologies, called “Generation IV” reactors.
But lest you get the impression that no part of the federal nuclear power budget suffered cuts, you can rest easy. The overall 2006 DOE budget was cut by $475 million relative to 2005, and a significant portion of that cut will affect cleanup of sites contaminated by radioactive waste.
Brave nuke world
In late February, the Bush Administration signed onto the Generation IV International Forum (GIF), a multilateral partnership with Canada, Japan, France, Argentina, Brazil, South Africa, South Korea, Switzerland, Britain, and the EU as a whole to research and promote six Generation IV reactor designs. The designs differ in a number of respects from the nuclear reactors currently producing 17 percent of US electricity.
The new reactor technologies the Gas-Cooled Fast Reactor, the Sodium Fast Reactor, the Lead-Cooled Fast Reactor, the Molten Salt Reactor, the Supercritical Water Reactor, and the Very High Temperature Reactor each have their proponents and their detractors. To distinguish among them, lets first describe the method by which present-day nuclear power plants, of a type known as “thermal” or “slow” reactors, operate.
Nuclear power plants, like coal-, oil-, or gas-fired power plants, operate by heating water (or some other fluid) that then turns turbines to generate electricity. While fossil-fuel plants heat the water through direct combustion, nuclear fuel (usually uranium, sometimes plutonium or thorium) generates heat when the unstable, radioactive substances in the fuel “decay” their atoms split apart, releasing energy.
Heat isnt the only energy produced when the atoms split: radioactive decay releases electromagnetic radiation (from long-wave types such as visible light to energetic gamma rays) and subatomic particles. Among those particles are neutrons, one of the basic building blocks of the atomic nucleus. The guiding principle of all nuclear reactors is to assemble sufficient nuclear fuel in a tight enough pile so that each neutron released by a decaying atom stands a good chance of smacking into another atom of fuel, splitting that atom, which releases more heat (which drives the turbines) and more neutrons, which strike more nuclei. This is what nuclear physicists mean by the phrase “chain reaction.”
“The hydrogen economy is really a nuclear economy.”
The problem is that a chain reaction in a large enough quantity of nuclear fuel is the precise mechanism behind nuclear weapons as well. The trick is to keep the chain reaction humming along just fast enough to keep the turbines moving, but not so fast that the whole pile goes up in a blinding flash. The solution first implemented successfully by Enrico Fermi at the University of Chicago in 1942 is to include a neutron-absorbing substance to control the chain reaction. These are traditionally used in the form of “control rods” that can be slid into and out of the reactor core to fine-tune the rate of reaction. Graphite, a form of carbon, was first used for this purpose, and still is in some reactors. Control rods of other materials such as boron compounds are also used.
Uranium-fueled reactors generally rely on the unstable isotope Uranium 235 as the most important fissile material in the pile. Unfortunately, U-235 is far less common in uranium ore than the more stable isotope U-238, and “enriching” uranium to increase the percentage of U-235 is messy and expensive. To reduce the degree to which the fuel needs to be refined, most older reactors incorporate “moderator” substances that slow down neutrons, increasing the likelihood that any particular neutron will strike an atom of U-235, to drive the chain reaction.
The basic premise is simple enough. Protecting the outside world from the reaction products, however, introduces a bit of complexity. Water heated by the reactor core becomes highly radioactive, and so it is generally used to heat theoretically uncontaminated water in a heat exchanger: the clean water drives the turbines. Decades of bombardment by neutrons can make steel containment vessels brittle and more likely to rupture under extremes of temperature. As happened at Three Mile Island, if temperature control systems fail, the nuclear fuel can overheat and melt, breaching containment and causing catastrophic release of radiation into the environment. The control rods become highly radioactive after some time: storage is a problem. And of course, spent fuel rods pose an extreme threat, with no acceptable current solution to the problem of storage for the many thousands of years it would take the waste to decay to a minimally safe level.
Fast, cheap, and out of control rods
Many Generation IV nukes are “fast reactors” they maintain chain reactions with “fast” neutrons that have not been slowed down by a moderator. As water slows neutrons, GIV reactors must use other substances as coolants an important consideration as the new reactors generally operate at much higher temperatures from 700° to 1,000° Fahrenheit than do conventional light water reactors, which max out at about 300°F. Alternative coolants under study include lead, sodium, and uranium salts all of which would be used in molten form and non-reactive gases such as helium, nitrogen or carbon dioxide.
Backers claim that these high temperatures suit many of the designs for direct production of hydrogen, through thermal hydrolysis heating water molecules until they break apart into hydrogen and oxygen, in a more efficient method than the typical running of an electric current through water. As Financial Times columnist John Dizard put it in a January essay:
[H]ydrogen isnt a source of fuel its a storage medium. It is produced by expending some other primary source of energy. The source the government, energy industry, and the automotive industry has in mind [for Bushs hydrogen car initiative] is nuclear power. We are talking about literally thousands of new nuclear facilities dedicated to the production of hydrogen through fission powered electrolysis (the splitting of water into hydrogen and oxygen gas).
The hydrogen economy is really a nuclear economy. Investors and the rest of corporate America may not realise how close the country is to making a gigantic bet on a nuclear future.
Though each design has its fans, the model that seems to excite the most interest and that the Bush administrations nuclear advisors seem to be considering most closely is a type of Very High Temperature Reactor called the “pebble bed reactor.” Rather than being assembled into long fuel rods, the nuclear fuel in a pebble bed reactor is contained in small, tennis-ball-sized “pebbles.”
Backers of pebble bed technology claim significant improvement in reactor safety over traditional designs. The nuclear fuel is fabricated into very small grains, each with a hard coating, and folded into a matrix of pyrolitic graphite for inclusion in each pebble. Pyrolitic graphite is a theoretically fire-resistant carbon polymer often used in missile nose cones. The pebbles, each of which contain many thousand fuel grains, are coated with a highly protective silicon carbide coating that seals the graphite and fuel granules away from exposure to the reactor coolant, typically helium.
A much-touted key safety feature of the pebble bed design lies in the configuration of the fuel. Pebble bed reactors actually use the U-238 as stopgap “control rod.” When core temperatures pass a certain point, causing the uranium atoms in the fuel to vibrate more rapidly, the U-238 atoms offer a wider “profile” to the neutrons zipping around the reactor core a phenomenon called “Doppler broadening.” As the U-238 absorbs more of the neutrons, the chain reaction slows, shutting down the reactor. This safety protocol was actually tested with a live reactor at the Center for Nuclear Research in Jülich, Germany. The reactor was allowed to overheat and shut itself down; the experimenters claimed success.
|Fallout from the pebble-bed
reactor mishap was high enough
to initially be blamed on Chernobyl.
Germany isnt the only place where pebble-bed reactors are gaining serious attention from nuclear power generators. Beijings Tsinghua University is heading a project to build a 10-megawatt prototype pebble bed reactor, with a 200-megawatt production plant planned for 2007, and 29 more in the next 15 years. Chinese officials say they hope to build as much as 300 gigawatts worth of nuclear generating capacity 1,500 plants the size of the 200-megawatt reactor slated for 2007. Theyre eyeing the plants as a source of hydrogen for automobiles as well as for electrical generation.
South Africa is another current center of pebble-bed activity, with Eskom Holding Co. planning to start building a demonstration “modular” pebble bed reactor near Cape Town in 2007. The modular form of the reactor would allow for mass production, a notion appealing to developing nations nervous about their carbon emissions. Eskom says the plant and its successors will be used to desalinate seawater, also a tempting lure for poor countries.
The South African plant has attracted a firestorm of opposition, with Earthlife Africa, the government of the city of Cape Town, and many other local groups protesting the siting. Opposition to the Chinese plants is rather hard to gauge. And environmental concern forced the shutdown of the German plant after an incident subsequent to the test described above in which a pebble got stuck in a fuel-reloading tube. Operator error during attempts to fix the problem caused damage to the pebble and subsequent release of radioactive material into the surrounding environment. As the Nuclear Information and Resource Service describes the incident, the fallout in the region was high enough to initially be blamed on Chernobyl.
Despite the German incident, pebble-bed backers still herald their design as safer than conventional Generation III reactors. Strictly speaking, they are not entirely wrong. The design is certainly more elegant than the multiply redundant GIII reactors, and taking advantage of Doppler broadening is a sensible touch. But safety depends on the world outside the lab. Though pyrolytic graphite is called “fireproof” by reactor backers, not all scientists agree, and thus reactor fire-safety measures have to be implemented in case the inert helium coolant is replaced by oxygen-containing atmosphere. Further, the very convection-cooled design that leads to claims of enhanced safety precludes, in many pebble-bed models, the inclusion of a containment facility, which would hinder airflow around the reactor core.
Another claimed safety feature is the dispersal of fissile fuel in tiny, sand-grain-sized seeds throughout the pebbles, making it impractical to extract weapons-grade material from the nuclear fuel a setback for would-be nuclear proliferators. But the sheer volume of material used to fuel a pebble bed reactor, and the fuels easy portability each pebble the size of a tennis ball may make radioactive “dirty bombs” that much easier to assemble for any terrorist with access to a waste holding area.
Further, each of the pebbles must be built to amazingly exacting specifications. Variations in pebble shape too small to be seen by the unaided human eye could result in unforeseen problems with the reaction. Could a failure of a misshaped pebble to reach operating temperature interfere with the vital Doppler broadening safety function? The technology exists to make each pebble meet required specifications. But when were talking about millions of pebbles over the lifetime of each reactor (about a third of a million inside the reactor core at any one time) and companies looking to cut costs, one can assume that flawed pebbles are a near inevitability.
|Nuclear waste storage casks. Nuclear Regulatory Commission photo|
Would you trust this manufacturer?
In fact, Exelon, one of three US companies at the center of the fledgling pebble-bed reactor industry and a former partner in the South African project, has been credibly accused of cutting corners on a much less exacting nuclear technology with far greater potential risk per individual failure. In 2003, Exelon employee Oscar Shirani accused his employer of failing to meet government safety specs in purchasing its high-level nuclear waste containers. These casks, used to store spent fuel on-site at power plants until a permanent waste repository is opened and to transport the fuel to the repository afterwards, were designed by the Holtec company and fabricated by US Tool and Die. Shirani, a quality assurance engineer at Exelon, says he reported to his superiors that unqualified workers performed welding of critical seams in the casks, and that Holtec failed to report holes in the casks neutron shielding. He went so far as to issue a “stop work order” to Holtec in May 2000. For his trouble, Shirani was reassigned to Exelons finance department and then laid off. The casks remain in service, with only faulty welds protecting the environment from the hellishly hot nuclear waste inside.
If Exelon has that much trouble making sure a few thousand large concrete-lined casks are built to specs, how will they fare when supervising the manufacture of millions upon millions of fuel pebbles?
What a waste
The biggest liability to pebble-bed reactors, however, is the nuclear waste they produce, a significantly higher amount per megawatt of energy produced than conventional reactors do.
Pebble-bed reactors are designed for continuous refueling. Unlike Generation III reactors, which need to be shut down to remove spent fuel rods, a pebble bed reactor continuously cycles the pebbles through the core. As pebbles reach the bottom of the core, they fall into a bin where they are sorted. Pebbles with some life left in them are dumped back into the reactor core, while spent pebbles are dumped into an Exelon cask.
The very coating and cladding that allows nuclear engineers to claim increased reactor safety increases the amount of nuclear waste generated by the reactors. As the pebbles pass through the core time and time again, the pebbles graphite and cladding become highly radioactive.
Existing US nuclear power plants now store their nuclear waste on-site in casks. Though aboveground storage in secure facilities at the point of production is likely the least unsafe method of handling nuclear waste second to not producing it in the first place the expense has been a thorn in the side of the nuclear industry and an obstacle to siting new plants. Corporations have lobbied intensely for a disposal site run at government expense, to which they would ship the waste on public highways and rail.
For a number of years, Yucca Mountain was seen as that publicly funded solution. The mountain, in Nevadas northern Mojave Desert 100 miles north of Las Vegas, has been touted as the best possible dump site for wastes that will remain deadly for hundreds of thousands of years. But the Yucca Mountain dump, long anathema to Nevadans, looks increasingly like a loser for the nuclear industry. It was revealed in March that government employees may have falsified documents relating to the hydrology of the site, of concern when not “if” the dump leaks waste into the Mojave soil. Several different presidential administrations have claimed that scientific study of the site shows that no water could ever leach from the dump site into nearby aquifers, due to the geology of the mountain and the extreme aridity of the site.
This is laughable, as anyone with the slightest familiarity with the Mojaves history will tell you. The wastes in question will remain dangerous for perhaps 300,000 years, and the National Academy of Sciences advocated designing Yucca Mountain to as close as possible to a 100,000-year safety standard. (The EPA countered with a 10,000-year plan, based on its experience with the Waste Isolation Pilot Project in New Mexico.) But a mere 15,000 years ago, the Mojave was much wetter. A deep lake filled Death Valley then, and the Amargosa River wet year-round even today flowed off the slopes of Yucca Mountain. Assuming the climate will not change as radically in the next 100,000 years as it has in the last 10,000 is foolish. Even without climate change, instruments in test shafts inside the “arid” mountain rusted out within a year, and there is evidence of recent hot spring intrusion into the rock layers planned to house the dump. These would release the waste to flow out among the many faults in the mountains rock found by geologists over the last decades.
Add to all this the revelation that a US Geological Survey employee had fabricated documentation of his work on the mountains hydrology, and even backers of the site began to admit that it wouldnt open by the 2010 deadline. The nuclear industry, which had maintained that no new nukes could be commissioned until an offsite storage repository was established, began to turn to other possibilities. The chief contender at this writing is on the Skull Valley Goshute reservation in Utahs West Desert, where a tribal council desperate for income is proposing to lease land to a company called Private Fuel Storage a consortium of eight nuclear companies for “temporary” above-ground storage of high-level waste. Anti-nuclear dissidents among the tribes two dozen members are trying to block the dumpsites lease, and the future of the project is far from certain.
The federal government, in other words, is hard pressed to set aside even enough long-term storage for existing nuclear power plants, and Yucca Mountain would be filled to capacity within three decades of opening. Imagine if a new wave of nuclear power plants came on line, each of them spitting out highly radioactive tennis-ball-sized waste pebbles by the thousands! This reactor “so safe you can walk away from it and let it shut down on its own,” as one backer puts it, will leave a legacy of dangerous waste for our great-grandchildren to manage. Perhaps a better plan is to walk away from the notion of nuclear power altogether.