Trends and Innovations
Scaling Up Nuclear Power
After decades of languishing popularity, nuclear energy is back in favor among some politicians and researchers. For the first time since its establishment in 1974, the U.S. Nuclear Regulatory Commission issued a license on June 23 for a full-scale plant to enrich uranium — the low-cost fuel that powers nuclear power plants, which produce electricity without emitting carbon dioxide.
This “thermal-spectrum” nuclear power plant in Grundremmingen, Germany, is similar to most power plants in that it processes uranium only once before the radioactive waste is stored away. Researchers are now looking into technologies that can recycle that waste to recover more energy. Photograph is courtesy of IAEA.
Some policy-makers and scientists anticipate that it will take more than licenses, however, to jumpstart the nuclear industry. That’s why the Department of Energy (DOE) wants Congress to agree to the $250 million earmarked in the fiscal year 2007 budget for the new Global Nuclear Energy Partnership (GNEP) program. If funded, GNEP will help develop new nuclear technologies that reduce toxic waste and address proliferation issues associated with current power plants, DOE says.
The GNEP program poses “an opportunity for the United States to regain a leadership role in nuclear energy,” says Kathryn McCarthy, deputy manager of the GNEP Technology Demonstration Program at DOE’s Idaho National Laboratory. “And frankly, we’ve lost that,” she says.
Nuclear reactors first supplied energy to homes in 1954. The technology especially gained popularity between 1970 and 1975, when production grew an average of 30 percent per year, according to the International Atomic Energy Agency. But the nuclear trend lost steam and slowed during the late 1970s and 1980s after the Three Mile Island and Chernobyl accidents, and no new construction has started on a nuclear power plant in the United States since 1971, according to the U.S. Energy Information Administration.
Now, “we want to regain that leadership role and have an influence on what’s going on outside of the United States,” McCarthy says. Toward that effort, 10 national laboratories, along with universities and industry, plan to try to develop and demonstrate nuclear fuel recycling technologies.
Currently in the United States, reactors run on any number of variations of the “thermal-spectrum” reactor, in which neutrons bombard uranium atoms, sometimes breaking them apart. The process produces recoverable energy as well as additional neutrons to sustain the reaction. It also produces, however, a buildup of mildly radioactive fragments (about 4 percent of spent fuel), which limit the fuel’s lifetime in a reactor. Additional highly radioactive waste comes from atoms that do not break apart, but instead absorb the neutron and turn into what scientists call “transuranic” elements (about 1 percent of spent fuel).
All radioactive waste, now stored on a short-term basis, is planned to be stored in long-term repositories, such as the proposed Yucca Mountain repository in Nevada, where they can decay away. Also stored away, however, is the uranium, which accounts for the other 95 percent of the spent fuel, yet it is the same as when it entered the reactor. By recycling the spent fuel in new high-energy, fast-spectrum reactors, and using the transuranics from the spent fuel plus the uranium and the original ore, researchers think they can recover 100 times as much electrical power as with traditional reactors, McCarthy says.
Versions of fast reactors already exist, according to Burt Richter, a professor emeritus of physics at Stanford University in Palo Alto, Calif., who has chaired committees for DOE that looked into alternatives to traditional reactors and storage problems. But the fuel recycled in those reactors contained only plutonium and uranium, he says. Now, scientists want to put everything back into the reactor including the “nasty” transuranics: neptunium, americium and curium, he says. However, “you need to do some serious fuel testing to make sure that this is OK.”
The idea is that as fast reactors employ neutrons with higher energies, they are more likely to split transuranics and release that additional source of energy. Another benefit is that the once highly radioactive transuranics are torn into smaller, less-radioactive pieces — solving a major concern for waste storage. If the idea works, “one repository like Yucca Mountain would take care of all the spent fuel generated through the entire rest of the century, even with a big expansion of nuclear energy in the United States,” Richter says.
But first, researchers need to find out if they can take the technology, which has been performed only in small-scale tests in the laboratory, and demonstrate that it works on an industrial scale, McCarthy says. Chemical experts are typically confident that a chemical process will be successful at full scale if it can be demonstrated at 1 percent of full scale, Richter says. That means the United States, currently producing 2,500 tons per year of spent reactor fuel, needs to demonstrate plants capable of producing 25 tons per year, he says.
A scientist at Idaho National Laboratory conducts research on new technology for nuclear reactors. Funding from Congress will determine whether or not the proposed Global Nuclear Energy Partnership program moves forward with more research into advanced reactor technology. Photograph is courtesy of Idaho National Laboratory.
Readying the technology will take about 20 years, which is why “it is absolutely necessary that we start now,” McCarthy says. In a May 2006 report to Congress, DOE put forth a timeline of goals of the proposed GNEP technology demonstration program. Details to be worked out include showing that fuel will behave the way scientists think it will, even under higher-than-average temperatures, she says. And for safety concerns, the process will have to be completely automated, using robots to fabricate the lethal fuel.
Should the technology prove itself safe and economical in the three proposed test facilities, and the United States decides to move forward and deploy the technology on a larger scale, it would then take another 10 to 20 years for industry to build up the infrastructure, McCarthy says. “You can’t just snap your fingers and have a processing plant,” she says.
Whether the technology will be economical to deploy or not “depends on the situation 20 years from now,” McCarthy says, which is “hard to predict.” The cost of energy from gas-driven plants depends mostly on the cost of the fuel, which fluctuates, she says. Conversely, capital costs for nuclear reactors make up the bulk of the cost of electricity.
Although specific cost estimates are not yet available, some scientists suggest that no matter what comes out of the GNEP development and demonstration phase, fast-spectrum reactors will never be cost-competitive with current reactors. “Even the advocates admit that they will cost at least 50 percent more” than current reactors, says Ivan Oelrich, a nuclear physicist with the Federation of American Scientists in Washington, D.C., a group that carries out research related to global security and weapons proliferation.
But other factors could outweigh the costs, McCarthy says. In addition to solving waste-storage issues, the technology could reduce weapons proliferation risks, according to GNEP. The goal is to ramp up nuclear capabilities to make the United States, along with countries such as Russia, Japan and France, into “supplier states,” which will deliver enriched uranium to the user states and then reclaim the spent fuel and recycle it. “The idea is to convince nonfuel cycle states to forgo enriching,” McCarthy says; such states include Iran, which could use it to develop weapons.
Oelrich disagrees, and says that the proposed link between nuclear recycling plants and reducing weapons proliferation is “simply wrong.” To meet current proliferation goals, spent fuel need only exit the user country. After that, “I could recycle it, I could put it in a geological repository, I could launch it to the moon,” Oelrich says. How spent fuel is dealt with once back in the supplier country “doesn’t make any difference” from a nonproliferation standpoint, he says.
Whether GNEP gets funding to move forward with the technology demonstration depends on agreement in Congress. The House supports only $150 million, according to appropriations announced by the House May 17. That’s compared to support by the Senate for $279 million, $36 million above the president’s request, McCarthy says.
The biggest hurdle to the program, however, is public perception, McCarthy says. Edwin Lyman, a scientist with the Global Security Program, said in a June 29 statement that the reprocessing program is “dangerous, dirty and expensive,” according to the Union of Concerned Scientists.
But “the bottom line,” McCarthy says, is that all forms of energy production impact the environment, including energy from coal, water, wind or the sun. But the impact from nuclear energy, which doesn’t produce greenhouse gases, is much less than from other sources, she says. “The catch is convincing people that we know what we’re doing.”
In the meantime, Richter would like to see the United States move on with the fast-spectrum reactor research and development. “I think it’s a good idea and we ought to see if it works,” he says.