All it took was one sentence in President Obama's State of the Union Address last week, and an oft-maligned energy source was back on the map.
"To create more of these clean energy jobs, we need more production, more efficiency, more incentives," the president said. "And that means building a new generation of safe, clean nuclear power plants in this country."
A few days later, the White House budget was released and called for an increase in government loan guarantees for nuclear reactors from $18.5 billion to $54.5 billion.
Opponents of nuclear energy say that the power source is far from clean, and that spending the billions of dollars on renewable sources like wind and solar power would make a much bigger dent in carbon emissions without problematic issues of waste disposal and nuclear weapons proliferation.
Nonetheless, Energy Secretary Steven Chu and the president are making it clear that they intend to move forward. Thus, the question arises: After more than a decade without any new nuclear plants coming online in the U.S., what exactly would new nuclear power look like?
Slowed Momentum, Escalating Costs
The existing U.S. nuclear power industry provides about 20 percent of all electricity generated in the country. Nuclear has been largely quiet in recent years, though — the last nuclear reactor to come online was the Watts Bar plant in Tennessee, which began operation in 1996.
More recently, attempts to build new nuclear reactors have been stymied by skyrocketing cost estimates. In the most visible of those disputes, CPS Energy is suing NRG Energy and Toshiba for misleading officials on the cost of a reactor to be built near San Antonio, Texas. The cost estimates rose by about $4 billion from an initial estimate of $5.4 billion.
Such issues certainly call into question whether or not the $54.5 billion in loan guarantees that the Obama budget requests could really support the construction of 7 to 10 new reactors, as Chu asserted in budget discussions this week.
"It's really hard to tease out what these plants will actually cost from current information," says Edwin Lyman, a senior scientist in the Global Security program at the Union of Concerned Scientists.
In order to maintain the current share of electricity generation into the future, many more than just those 7 to 10 reactors would need to be built, he said.
Are New Plants Really That New?
Mixed in with all the recent discussion of "restarting" the U.S. nuclear program is the assumption — as stated directly in Obama's speech — that all these new reactors will be a next-generation fleet.
According to Lyman, the reactors currently proposed and those with even mild potential to be built within a decade involve only a few designs that are "just evolutionary variants of the current generation."
All of the reactor designs still involve pressurized water or boiling water cooling mechanisms, and there have been no major breakthroughs in methods to reduce waste or improve energy output, Lyman said. He said the one major difference from currently active plants is that the proposed reactors will likely be bigger, as the costs of reactors do not scale proportionally with the electricity output. The largest currently operating nuclear power plants peak at less than 1200 megawatts electric output, or enough to power about 750,000 households. Newer plants could exceed that significantly; one such example, the French company Areva's EPR, could scale up to 1650 MWe.
Lyman says that the only major area for improvements in soon-to-be-built reactors is in their degree of safety. Problematically, the Nuclear Regulatory Commission has a policy that does not require newer designs to be substantially safer than old designs, Lyman says. This can put reactors that incorporate extra safety features at a competitive disadvantage: They just cost more.
New reactor designs have begun utilizing what is known as passive safety. In the past, if the coolant that protects the nuclear fuel was somehow lost or compromised, various electric pumps would have to kick on in order to provide a huge quantity of water that could prevent a meltdown. In other words, an active power supply was needed in order to stop an accident. With passive safety, all that is needed is gravity. With a total power loss, water will simply flow downwards and stave off the meltdown.
There are differing views, though, on whether or not this is a safety improvement. Todd Allen, a nuclear engineer at the University of Wisconsin and the Idaho National Laboratory, says the passive safety does create a safer plant than active safety designs. "If you eliminate valves, you eliminate cables, you eliminate pumps, that is less things that can break."
Lyman, meanwhile, argues that there is a lack of experience with the passive designs. Active backup systems should be put in place, he argues, but they are not required and cost more money to build; the backup systems in some designs do not meet the requirements for being called nuclear safety grade, Lyman says.
The cost issues surrounding safety have already come up internationally. The United Arab Emirates awarded a high-profile contract for a new plant to a South Korean company late in 2009, after the French company Areva had been positioned as the front-runner. The Areva EPR reactor has some advanced safety features including a "core catcher" room that could help prevent compromised nuclear fuel from escaping the reactor, as well as an enforced shell that could theoretically withstand an airplane impact. It was speculated that those expensive features may have cost the company the UAE contract, and Areva has considered scaling back some of those additions for future designs.
Areva has also run into questions from regulators regarding the EPR's control and instrumentation systems in the United Kingdom. An example of that reactor (photo), under construction in Finland, has been delayed by at least three years and has more than doubled in price. The EPR is under certification review by the NRC in the United States.
Gen IV Nuclear Plants
Even if the $54.5 billion in loan guarantees is approved, it will only assist with the costs of building a few new plants within the near future. What about beyond 2015 or 2020 or even 2030? The current reactors are known as generation three, but there are a number of generation four possibilities that could theoretically be added to the mix later on this century.
The most likely candidate to be built first is a gas-cooled reactor that would probably use helium as the coolant. This would allow the reactor to operate at a much higher temperature than water-cooled plants, which could allow for use in functions beyond just electricity generation; these could include hydrogen production for vehicles and power for chemical plants.
"Some people say that they would be safer than water reactors because ... if there is an overheating or loss of coolant, the fuel would not necessarily leak fission products the way light water reactors would," Lyman says. "It wouldn't melt. But there are still a lot of technological issues to be solved with gas-cooled reactors."
Reactors that use molten metal, such as lead, would also reduce the possibility of a meltdown. The corrosive capability of the lead, though, creates materials problems that both Lyman and Allen say are far from being solved. "They may be 30 years out," Allen says. "It's a big research project."
Bury or Reprocess?
The other obvious issue with which all nuclear reactors have to contend is waste. The government will soon withdraw its license application with the NRC for the use of Yucca Mountain in Nevada as a spent fuel repository, and Chu recently announced the formation of a commission on nuclear waste to explore possibilities for the back end of the nuclear fuel cycle.
Some argue that if geologic repositories like Yucca Mountain are unsuitable, a type of reactor called a fast burner or fast breeder — which were essentially dismissed as far back as the Carter administration — should be reconsidered.
"If you want to build an overall fuel cycle where you're getting rid of as much waste as possible, then you actually want a fast reactor," Allen says.
By using coolants other than water — such as molten lead or sodium — the neutrons that fission off of uranium in a nuclear reaction do not slow down as rapidly. The end result is that the reactors could theoretically end up with less waste than a traditional reactor.
The main problem, though, is plutonium.
A fast breeder reactor can produce more plutonium than it consumes. Plutonium is weapons-usable nuclear material, while the traditionally used uranium-235 is not.
"If it were stolen by terrorists, it could be used in a crude nuclear bomb," Lyman says. "We don't think that the commercial nuclear industry needs to be saddled with that kind of responsibility, to have to protect weapons usable material from terrorists. But it looks like the Obama administration is still in love with fast reactors the way the Bush administration was, and they're asking for increased R&D money to pursue those types of reactors."
Allen says the possibility of fast reactors being built is still decades away.
"I think it becomes more of a research issue," he says. "If you assume for the moment that we won't have a Yucca Mountain, and we don't have these fast reactors, what is your third choice?"
Right now, spent nuclear fuel is stored on site at power plants, eventually being sealed in steel and cement casks that are considered generally safe storage options.
Whether or not the next generation of nuclear reactors joins the fray at some point beyond 2030, there is undeniable political momentum toward nuclear that will most likely see construction on new plants start by around 2013. Chu made it clear last week,
"The administration is committed to promoting nuclear power in the United States."
(Map: NRC; Photo of construction in Finland: Greenpeace/Nick Cobbing)