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If there ever were a time that seemed ripe for nuclear energy, it's now.

For the first time in decades, popular opinion is on the industry's side. A majority of Americans thinks nuclear power, which emits virtually no carbon dioxide, is a safe and effective way to battle climate change, according to recent polls. At the same time, legislators are showing renewed interest in nuclear as they hunt for ways to slash greenhouse-gas emissions.

The industry is seizing this chance to move out of the shadow of Three Mile Island and Chernobyl and show that it has solved the three big problems that have long dogged it: cost, safety and waste. Researchers are working on reactors that they claim are simpler, cheaper in certain respects, and more efficient than the last generation of plants.

Some designs try to reduce the chance of accidents by automating safety features and minimizing the amount of hardware needed to shut down the reactor in an emergency. Others cut costs by using standardized parts that can be built in big chunks and then shipped to the site. Some squeeze more power out of uranium, reducing the amount of waste produced, while others wring even more energy out of spent fuel.

"Times are exciting for nuclear," says Ronaldo Szilard, director of nuclear science and engineering at the Idaho National Lab, a part of the U.S. Energy Department. "There are lots of options being explored."

But nuclear is far from a sure thing. Yes, the plants of tomorrow—some of which could enter construction as soon as 2012—go at least part way toward solving some of the problems of yesterday. But they are still more expensive than fossil-fuel plants, and they still generate waste that must be stored safely somewhere.

And while the industry is winning converts, plenty of powerful enemies remain. Many scientists and environmentalists still distrust nuclear power in any form, arguing that it can never escape its cost, safety and waste problems. What's more, critics say, trying to solve the problems in one area, such as safety, inevitably lead to more problems in another area, such as costs.

Here's a closer look at how the industry says it's addressing its longstanding problems—and where skeptics say nuclear energy is still coming up short.

For many people, talk of nuclear power conjures up memories of two accidents: the partial meltdown at the Three Mile Island plant in Pennsylvania in 1979 and the more extensive power surge that destroyed the reactor at Chernobyl, Ukraine, in 1986.

 

"A common theme of future reactors is to make them simpler so there are fewer systems to monitor and fewer systems that could fail," says Revis James, director of the Energy Technology Assessment Center at the Electric Power Research Institute, an independent power-industry research organization.

The current generation of nuclear plants requires a complex maze of redundant motors, pumps, valves and control systems to deal with emergency conditions. Generation III plants cut down on some of that infrastructure and rely more heavily on passive systems that don't need human intervention to keep the reactor in a safe condition—reducing the chance of an accident caused by operator error or equipment failure.

For example, the Westinghouse AP1000 boasts half as many safety-related valves, one-third fewer pumps and only one-fifth as much safety-related piping as earlier plants from Westinghouse, majority owned by Toshiba Corp. In an emergency, the reactor, which has been selected for use at Southern Co.'s Vogtle site in Georgia and at six other U.S. locations, is designed to shut down automatically and stay within a safe temperature range.

The reactor's passive designs take advantage of laws of nature, such as the pull of gravity. So, for example, emergency coolant is kept at a higher elevation than the reactor pressure vessel. If sensors detect a dangerously low level of coolant in the reactor core, valves open and coolant floods the reactor core. In older reactors, emergency flooding comes from a network of pumps—which require redundant systems and backup sources of power—and may also require operator action.

Another big concern is how well a plant can handle a terrorist attack, especially the nightmare scenario of someone flying a jetliner into the reactor area. The Evolutionary Power Reactor from France's Areva SA, another Generation III design, guards against such an accident by putting the reactor inside a double containment building, which would shield the reactor vessel even if the outer shell were penetrated. The design also boasts four active and passive safety systems—twice the number in many reactors today—that could shut it down and keep the core cool in case of a mishap. Areva's EPRs are being built in Finland, France and China and four are under consideration for construction in the U.S. The Union of Concerned Scientists, a group critical of nuclear expansion, considers this the only design that is less vulnerable to a serious accident than today's operating reactors.

Further out, Gen IV reactors, which use different fuels and coolants than Generation II and Generation III reactors, are designed to absorb excess heat better through greater coolant volume, better circulation and bigger containment structures. Advanced research into metal alloys that are resistant to cracking and corrosion should result in more suitable materials being used in plants, too, and giving them longer useful lives.

Still, Generation III reactors are incredibly complex systems, requiring the highest-quality materials, monitoring and training of personnel. Critics say it's unrealistic to think they can operate flawlessly. Corrosion of vital equipment remains a potential problem, especially if it goes undetected deep within parts of the reactor that are difficult or impossible to directly inspect.

What's more, none of the Generation III designs have been cleared for construction by the Nuclear Regulatory Commission. Some Generation IV concepts haven't even been presented to the NRC for review, and they still are years away from crossing that threshold.

"The designs are safer and the safety culture is better than 20 years ago," says Tom Cochrane, senior scientist with the nuclear-analysis team of the Natural Resources Defense Council, an environmental-advocacy group. But he's still not convinced reactors are safe enough to proceed. Critics remain concerned about possible physical breaches of security in the case of a terrorist attack.

Please see the second part tomorrow...