THE first commercial nuclear plant in the United States, commissioned in 1957, was just a scaled-up version of the reactors that powered submarines, and for decades afterward engineers made them bigger and bigger to maximize economies of scale.
But the hot idea now is to think small — small enough to fit a reactor on a railroad car or even a heavy-haul truck. Such a reactor could be built in a factory, sidestepping the problems of assuring high-quality fabrication in the field and allowing fast installation.
And such reactors would have a built-in safety feature: in an emergency, natural convection could help a small core cool faster than a big one, just the way a cup of coffee cools faster than a pot of coffee. Proponents say that makes meltdowns far less likely.
“They offer the potential for a new paradigm in how we think about construction of nuclear power plants,” Peter B. Lyons, the Energy Department’s assistant secretary for nuclear energy, said of the so-called small modular reactors, also known as S.M.R.’s. He is supervising a program under which the government will pay up to half of the development cost of two different models.
One manufacturer already has a contract to develop a plan for two small reactors in Tennessee. Because the plants could be safer as well as faster and easier to install, they do not have to surpass big reactors in cost per kilowatt-hour, Mr. Lyons said in an interview.
“If it is even equal, it is a winner,” he said. “If it’s better, it’s more than a winner.”
Rebecca Smith-Kevern, the Energy Department’s director for light water reactor deployment, estimated their cost at $800 million to $2 billion a unit, compared with $10 billion to $12 billion for a large reactor.
“Basically they’re not a bet-the-farm proposition for a utility,” she said.
Small modular reactors could serve as “starter reactors” for countries that have no nuclear power now, no budget for a standard behemoth-size model and grids too weak to tolerate one anyway, proponents say. (Put a standard, 1,200-megawatt reactor on a small grid, and it could trigger a nationwide blackout every time it shut down unexpectedly.)
In addition to being small enough to ship, the reactors are small enough to be installed underground, offering the advantage of earthquake protection; buried structures are less vulnerable than those above the surface. They may also be easier to defend from attack.
And the ability to air-cool the reactors further distinguishes them from big nuclear plants, which, like coal and most natural gas plants that make steam to drive a turbine, require copious amounts of water to condense the steam back to water. S.M.R.’s make steam, like other reactors, but can condense it back to water using something a bit like a car radiator.
The Obama administration, with nuclear power aims that have received less attention than its alternative energy initiatives, began a five-year program to develop reactors in 2012, planning to spend $452 million.
The budget outlook for the final three years is uncertain, but the incoming energy secretary, Ernest J. Moniz, speaking at his confirmation hearing on April 9, said of small modular reactors: “I think that it’s a very promising direction that we need to pursue. It’s where the most innovation is going on in nuclear energy.”
But new approaches to nuclear power have been forecast far more often than they have been realized, and some worry that small modular reactors could fall into that category.
Joyce L. Connery, an Energy Department nuclear expert assigned to the National Security Council, remarked at a nuclear power conference in March, “I hope that soon we populate the world with S.M.R.’s as much as we populate the world with conferences about S.M.R.’s.”
The economics may still be challenging even if the price tag is smaller, she said. “Clearly there is a need for nuclear energy for the environment, but the environment for nuclear energy is not so great right now,” she told a gathering of several hundred experts organized by the Nuclear Regulatory Commission.
Cheap natural gas in North America and global political fallout from the 2011 Fukushima nuclear accident in Japan are not helping, experts say.
And the regulatory structure is not so great for small reactors. Regulatory commission rules for control-room staff levels, emergency planning zones and security are all predicated on large, aboveground reactors.
A small one built mostly underground might logically have smaller requirements, but a potential buyer would be reluctant to build one under the current regulatory regime, experts say. Also, small reactors still face serious scrutiny for safety.
David Lochbaum, a nuclear engineer at the Union of Concerned Scientists, said that the nice thing about reactors that existed only on paper was that the worst damage risk is paper cuts; their weaknesses do not become evident until the design or construction is further along. But many potential manufacturers are advancing their designs.
Leading at the moment is the power plant company Babcock & Wilcox, which has a promise of aid from the Energy Department. The Tennessee Valley Authority wants two of the company’s mPower reactors for a site near the Oak Ridge National Laboratory and has agreed to pay for more detailed design work.
Babcock’s reactor, 13 feet in diameter and 83 feet high, can produce 180 megawatts of power, about 15 percent of the power of a large new reactor, but can run far longer before refueling is required: four years, the manufacturer says, versus one to two years for a standard reactor. When a utility company needs more power, it can order another.
Babcock refers to the basic design as a “two-pack,” as if the reactors were twin boxes of laundry soap. The reactor’s emergency cooling system consists of the natural circulation of air. Conventional reactors require operators to start up pumps and align valves, something that was impossible in the Fukushima accident, when a tsunami wiped out electric power.
Company executives hope to sell the mPower reactor to American military bases that would like to become more self-sufficient. At 180 megawatts, it could also be installed at the sites of 1950s-era coal plants that are being retired.
Some of the infrastructure in those places, like the transmission lines and transformers, are about the right size for that kind of plant, officials say.
But another major market would be exports. According to the Nuclear Energy Institute, the industry’s trade association, 5,000 to 10,000 jobs are created for every $1 billion spent in this country for nuclear technology that is exported.
Another major player is likely to be NuScale Power, which plans a module with an output of just 45 megawatts. Most reactors use pumps in their ordinary operation, to move the water they’ve heated into heat exchangers, which make clean steam for a turbine.
NuScale makes water run to its steam generator with natural circulation, eliminating the pump that is used in conventional plants for that function.
Such pumps are expensive and failure-prone. The reactor is small enough to provide the steam needed to run an oil refinery, or even heat for keeping buildings warm. It would sit inside something like a Thermos bottle, submerged in a pool of cold water that could accommodate up to 12 reactors.
In case of accident, that cooling water would last for months, the company says. “It needs no A.C. power, no D.C. power, no additional water, indefinitely,” said Michael McGough, a spokesman.
nytimes.com
But the hot idea now is to think small — small enough to fit a reactor on a railroad car or even a heavy-haul truck. Such a reactor could be built in a factory, sidestepping the problems of assuring high-quality fabrication in the field and allowing fast installation.
And such reactors would have a built-in safety feature: in an emergency, natural convection could help a small core cool faster than a big one, just the way a cup of coffee cools faster than a pot of coffee. Proponents say that makes meltdowns far less likely.
“They offer the potential for a new paradigm in how we think about construction of nuclear power plants,” Peter B. Lyons, the Energy Department’s assistant secretary for nuclear energy, said of the so-called small modular reactors, also known as S.M.R.’s. He is supervising a program under which the government will pay up to half of the development cost of two different models.
One manufacturer already has a contract to develop a plan for two small reactors in Tennessee. Because the plants could be safer as well as faster and easier to install, they do not have to surpass big reactors in cost per kilowatt-hour, Mr. Lyons said in an interview.
“If it is even equal, it is a winner,” he said. “If it’s better, it’s more than a winner.”
Rebecca Smith-Kevern, the Energy Department’s director for light water reactor deployment, estimated their cost at $800 million to $2 billion a unit, compared with $10 billion to $12 billion for a large reactor.
“Basically they’re not a bet-the-farm proposition for a utility,” she said.
Small modular reactors could serve as “starter reactors” for countries that have no nuclear power now, no budget for a standard behemoth-size model and grids too weak to tolerate one anyway, proponents say. (Put a standard, 1,200-megawatt reactor on a small grid, and it could trigger a nationwide blackout every time it shut down unexpectedly.)
In addition to being small enough to ship, the reactors are small enough to be installed underground, offering the advantage of earthquake protection; buried structures are less vulnerable than those above the surface. They may also be easier to defend from attack.
And the ability to air-cool the reactors further distinguishes them from big nuclear plants, which, like coal and most natural gas plants that make steam to drive a turbine, require copious amounts of water to condense the steam back to water. S.M.R.’s make steam, like other reactors, but can condense it back to water using something a bit like a car radiator.
The Obama administration, with nuclear power aims that have received less attention than its alternative energy initiatives, began a five-year program to develop reactors in 2012, planning to spend $452 million.
The budget outlook for the final three years is uncertain, but the incoming energy secretary, Ernest J. Moniz, speaking at his confirmation hearing on April 9, said of small modular reactors: “I think that it’s a very promising direction that we need to pursue. It’s where the most innovation is going on in nuclear energy.”
But new approaches to nuclear power have been forecast far more often than they have been realized, and some worry that small modular reactors could fall into that category.
Joyce L. Connery, an Energy Department nuclear expert assigned to the National Security Council, remarked at a nuclear power conference in March, “I hope that soon we populate the world with S.M.R.’s as much as we populate the world with conferences about S.M.R.’s.”
The economics may still be challenging even if the price tag is smaller, she said. “Clearly there is a need for nuclear energy for the environment, but the environment for nuclear energy is not so great right now,” she told a gathering of several hundred experts organized by the Nuclear Regulatory Commission.
Cheap natural gas in North America and global political fallout from the 2011 Fukushima nuclear accident in Japan are not helping, experts say.
And the regulatory structure is not so great for small reactors. Regulatory commission rules for control-room staff levels, emergency planning zones and security are all predicated on large, aboveground reactors.
A small one built mostly underground might logically have smaller requirements, but a potential buyer would be reluctant to build one under the current regulatory regime, experts say. Also, small reactors still face serious scrutiny for safety.
David Lochbaum, a nuclear engineer at the Union of Concerned Scientists, said that the nice thing about reactors that existed only on paper was that the worst damage risk is paper cuts; their weaknesses do not become evident until the design or construction is further along. But many potential manufacturers are advancing their designs.
Leading at the moment is the power plant company Babcock & Wilcox, which has a promise of aid from the Energy Department. The Tennessee Valley Authority wants two of the company’s mPower reactors for a site near the Oak Ridge National Laboratory and has agreed to pay for more detailed design work.
Babcock’s reactor, 13 feet in diameter and 83 feet high, can produce 180 megawatts of power, about 15 percent of the power of a large new reactor, but can run far longer before refueling is required: four years, the manufacturer says, versus one to two years for a standard reactor. When a utility company needs more power, it can order another.
Babcock refers to the basic design as a “two-pack,” as if the reactors were twin boxes of laundry soap. The reactor’s emergency cooling system consists of the natural circulation of air. Conventional reactors require operators to start up pumps and align valves, something that was impossible in the Fukushima accident, when a tsunami wiped out electric power.
Company executives hope to sell the mPower reactor to American military bases that would like to become more self-sufficient. At 180 megawatts, it could also be installed at the sites of 1950s-era coal plants that are being retired.
Some of the infrastructure in those places, like the transmission lines and transformers, are about the right size for that kind of plant, officials say.
But another major market would be exports. According to the Nuclear Energy Institute, the industry’s trade association, 5,000 to 10,000 jobs are created for every $1 billion spent in this country for nuclear technology that is exported.
Another major player is likely to be NuScale Power, which plans a module with an output of just 45 megawatts. Most reactors use pumps in their ordinary operation, to move the water they’ve heated into heat exchangers, which make clean steam for a turbine.
NuScale makes water run to its steam generator with natural circulation, eliminating the pump that is used in conventional plants for that function.
Such pumps are expensive and failure-prone. The reactor is small enough to provide the steam needed to run an oil refinery, or even heat for keeping buildings warm. It would sit inside something like a Thermos bottle, submerged in a pool of cold water that could accommodate up to 12 reactors.
In case of accident, that cooling water would last for months, the company says. “It needs no A.C. power, no D.C. power, no additional water, indefinitely,” said Michael McGough, a spokesman.
nytimes.com
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