Posted: 08/10/2004 | Author: H. Sterling Burnett
Technological Breakthroughs May Bring Nuclear Power Out of the Mothballs
It has been 24 years since an accident at Pennsylvania’s Three Mile Island nuclear power plant brought the nuclear power industry to a grinding halt. While only minute levels of radiation – equal to about one x-ray per person – escaped the facility, the ensuing hysteria brought construction of nuclear power plants to a standstill.
Although it has been more than twenty years since the last nuclear power plant was granted a construction permit in the U.S., the nuclear power industry is far from dormant. Approximately 20 percent of the nation’s electricity comes from the 103 nuclear reactors still in operation. And the increased demands for energy to keep the economy growing, combined with problems of rising fuel prices and concerns about air pollution and global warming, nuclear energy seems likely to grow as a percentage of the nation’s energy mix. Even some environmental writers, like Sir Crispin Tickell and Time Magazine’s Eugene Linden, have seen the light, arguing that nuclear power has an important place in the world’s power mix.
Two hurdles limiting the growth of nuclear power are the exorbitant cost associated with construction and what to do with the nuclear waste. Concerning the former issue, while the reactors are by no means cheap, it is the costly containment facilities that really drive up the price of the project. It is estimated that the price tag for a new light water reactor (LWR) power plant, like those currently in use in the U.S., would range anywhere from $2 to $6 billion.
Because the initial costs for construction are so high, a completed reactor generates electricity at a cost of about 7 1/2 to 8 1/2 cents per kilowatt-hour. Coal powered plants on the other hand generate the same electricity at a cost closer to about 4 1/2 cents per kilowatt-hour. New technologies hold out the promise of bringing down the costs of producing this air quality friendly source of energy.
South Africa , for instance, is hoping to bring on-line the world’s first commercial Pebble Bed Modular Reactor (PBMR), a technology that could then be used in the U.S. The PBMR is a radical departure from the technology used in light water reactors, in that it uses helium gas instead of water to cool the nuclear fuel. This new process eliminates the plant’s need to be adjacent to a large water supply – making virtually any location feasible.
In addition, rather than using the uranium fuel rods, PBMR’s use thousands of ceramic covered uranium “pebbles” encased in graphite spheres to feed the reactor. This allows the plant to forego the typical containment facilities used in other reactors because, having a ceramic composition, a meltdown is virtually impossible. Moreover, this design change reduces the overall cost per unit of energy produced by more than 50 percent – which means cheaper power. And, the PBMR should be capable of extracting several times as much electricity from a ton of fuel as contemporary reactors – which means less radioactive waste. This will be especially important to those on Capitol Hill who are trying to solve the country’s nuclear waste problem.
Another potential innovation that could help revive the moribund nuclear industry are Accelerator-Driven Subcritical reactors (ADS). In c onventional nuclear reactors, energy is released by the splitting – “fission” – of uranium atoms. This process also releases neutrons capable of splitting further uranium atoms, triggering a chain “critical” reaction. In conventional reactors, the number of neutrons are kept just sufficient to keep the reaction in balance, resulting in a steady flow of power. An out of control chain reaction could have “explosive” results – thus costly and multiple redundant safety systems are built into each reactor which, of course, drives up the costs. In the ADS system, by contrast, the ADS reactor is “sub-critical:” its fuel does not generate a self-sustaining chain reaction. Instead, a particle accelerator is used to feed neutrons to the system. If this supply of neutrons is cut off for any reason, the reaction dies. This makes an explosive chain reaction impossible.
Better still, as the July 16, 2004 Financial Times reported, since chain reaction stability no longer depends on the type of fuel used, the ADS system is able to work with fuels that are wholly unsuited to weapons production, including radioactive waste from conventional reactors – obviating the need for long-term storage.
Though these systems are still in the testing stage and much work remains to be done before they see commercial use, these recent technological advances offer new hope for the future role of nuclear energy. Nuclear power isn’t a magic bullet, but with improved technologies it can be a clean source of energy fueling America’s future progress.