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TVA is planning to build two 180-megawatt small modular reactors on the Clinch River in Oak Ridge. (Rendering by Babcock & Wilcox Nuclear Energy)
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A single B&W mPower nuclear reactor module.
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Proposed small modular reactor

Name: mPower

Partners: Babcock & Wilcox, TVA and Bechtel

Site: Clinch River site in Oak Ridge

Size: Up to four SMR units, each capable of generating 180 megawatts of electricity

Schedule: Submit permit application to the U.S. Nuclear Regulatory Commission by mid 2014 for approval by 2018; commercial operation by October 2021.

Smaller reactor future Advantages:

• Most components are small enough to be built in factory and shipped for assembly on site

• Simpler and smaller design allows for reactor to be built underground and with passive cooling, eliminating need for so many pumps, valves and other equipment

• Smaller size should allow for quicker and easier construction and incremental additions that don't require as much one-time capital cost

• Small modular reactors could be air cooled, in some instances, allowing for locations away form rivers, lakes or oceans


• Technology is yet to be licensed by the Nuclear Regulatory Commission and there is no history of construction to test new design.

• Smaller size loses economies of scale possible with bigger reactors, pushing up labor costs per megawatt of power generated

• Distributed power from smaller units also increases number of targets for terrorist attacks or for public exposure to radiation leaks, if they occur

• Costs are still uncertain because there is no track record yet. Standardization will help, but there may still be competing and different designs for small modular reactors and utilities will have to order enough units to gain the efficiencies of mass factory production.


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The next new nuclear reactor for TVA may be built in a factory and shipped to the Tennessee Valley in a truck or railcar.

After more than three decades of building bigger and increasingly more expensive nuclear power plants, TVA officials are thinking small about their next potential nuclear unit.

The Tennessee Valley Authority is working with two of the world's biggest nuclear contractors -- Babcock & Wilcox and Bechtel Corp. -- to test a pilot small modular reactor known as mPower.

TVA has yet to decide if it will ultimately build the new type of reactor. But aided by up to $150 million of funding support from the federal government, TVA and its partners have agreed to be the first to test the mPower design and to submit plans for regulatory approval by next year to build a pair of the new reactors on the Clinch River in Oak Ridge.

If approved by regulators and the TVA board, the new 180-megawatt reactors could be producing enough power for all the energy needs of Oak Ridge by 2022.

Developers hope the smaller and simpler design will allow for factory fabrication of most plant components. The simpler and passive cooling design also should allow for reactors to be located underground and to be built quicker and with less cost.

Small modular reactors also offer the prospect of adding nuclear generation in incremental stages with less one-time capital costs than the current generation of nuclear plants.

"I think the small modular reactors can truly offer a new paradigm in the way we look at nuclear power in this country," said Dr. Peter Lyons, assistant secretary for nuclear energy at the U.S. Department of Energy. "There are many, many safety and security benefits from the small size and new design. From an economic standpoint the cost involved is much, much smaller."

But critics of small modular reactors question their economics and reliability.

"I think the industry is overhyping the benefits of small modular reactors because the technology is certainly not proven," said Ed Lyman, senior scientist for the Union of Concerned Scientists. "If you make reactors smaller and everything else is the same, you end up having to spend more per unit of electricity because the operating and maintenance costs don't necessarily go down just because the unit is smaller."

Lymans said some Department of Energy officials "are acting more like the Department of Commerce trying to sell" the technology around the globe.

Indeed, at the annual gathering of the Tennessee Valley Technology Corridor last week in Oak Ridge, DOE and Corridor leaders said the Tennessee Valley may be an ideal spot to manufacture key components for the new smaller, reactors.

Lyons said he was recently in China as part of the Obama administration's "Team USA" to develop and sell nuclear technology overseas. While U.S. manufacturers no longer fabricate some of the biggest components of today's nuclear reactors, the SMR design could spark a new industry in the Tennessee Valley, Lyons told government and business leaders in Oak Ridge last week.

"I'm hoping that the concepts we can bring to the market from our advance manufacturing can tip the sales over countries with lower wages," he said. "Yes, it is a challenge, but the government recognizes that challenge. Our goal with small modular reactors is to have them made in America and hopefully exported around the world from America."

Oak Ridge test Site

In response to DOE's funding offer to support new small modular reactors, four applicants applied to build one of the new smaller reactors. So far, the consortium between TVA, B&W and Bechtel is the only one picked by DOE for the government assistance.

TVA and B&W are scheduled to file an application for two of the mPower units by mid 2014, and the U.S. Nuclear Regulatory Commission is expected to decide on the request the next year.

The proposed small modular reactor designed by Babcok and Wilcox would rely upon a passive cooling system with water supplies above the reactor so that in an accident water could flood the reactor core without having to rely upon so many pumps, valves and pipes. The smaller design also could allow major components to be made in the factory and shipped to the site by truck or rail, rather than having to build the much larger and complex plants at the site.

TVA President Bill Johnson said building small modular reactors in Oak Ridge fits in with TVA's mission of being a living laboratory for energy and economic development.

"We have this mission for technology innovation and we see SMRs as part of that," he said.

Johnson said the mPower units could help TVA meet future power demand growth and make up for the planned closing of more aging coal-fired power plants.

"The reactors for SMRs are buried in the ground and it's almost impossible to uncover the core in this design," he said. "So they have some inherent safety advantages."

Only about 15 percent of the size of the 1,200-megawatt reactors at plants like Sequoyah near Soddy-Daisy and Watts Bar near Spring City, the small modular reactors also could be spread across a wider area and closer to where the power is needed.

"I think it's a good technology, especially as we think of the future and the possibility of distributed generation," Johnson said. "The capital costs should be much smaller, although we don't actually know the costs."

Johnson stressed that TVA is focusing its nuclear attention right now on finishing the Unit 2 reactor at Watts Bar by 2014 -- nearly 40 years after work on the unit first began.

"We want to make sure that Watts Bar Unit 2 is finished on schedule and on budget," Johnson said. "That's our No. 1 priority, and priority two is everything else."

Oak Ridge Mayor Tom Beehan said the community is eager for TVA to build the reactors on the site of the Clinch River Breeder Reactor that former President Jimmy Carter scrapped in the 1970s.

"We just have all of the right pieces in place," he said. "We have a site that is already approved and we want to be the energy capital of the world. If these type of units get preapproved and can be mass produced in a factory setting, it's incredible the potential this could have for our region."

Beehan noted that the Oak Ridge National Laboratory has the fastest computer in the world, but it is still running largely on coal-fired power. A nuclear reactor in Oak Ridge could help the DOE lab meet its goal of reducing its carbon footprint, Beehan said.

Contact Dave Flessner at or at 757-6340