Small modular reactors (SMRs) are nuclear generating units that are about the size of railroad cars and provide about one-tenth to one-fourth the power of full-size reactors. As a result, they cost a fraction of what full-size reactors cost. The reactors are designed to provide between 40 MW and 300 MW of electric power, compared with the 1,100 to 1,700 MW output of larger reactors. In addition, most are expected to cost under $1 billion, compared with the $5 billion to $10 billion price tags of the larger units.
Over the past decade, a number of companies have begun work on SMRs, including Westinghouse, Toshiba, GE Hitachi Nuclear, Babcock & Wilcox, NuScale Power, PBMR, Hyperion Power, Areva and General Atomics.
Westinghouse was one of the earliest to develop the technology. “We have been working on SMRs since 1999,” reports Michael Anness, manager, advanced reactors, for Westinghouse in Pittsburgh, Pa. Initially, these were in the range of about 200 MW. However, the designs have evolved over the years, with multiple power levels. “The more we learn about them, the more we learn how to streamline the design,” he explains. “We are now working on the optimum configuration for SMRs, and we are currently in the conceptual design phase.” Anness says one such design, the International Reactor Innovative and Secure (IRIS), is about 10 years from its first actual deployment.
Utilities are beginning to express interest in the potential for SMR technology. In February 2010, Tennessee Valley Authority, FirstEnergy and Oglethorpe Power signed an agreement with Babcock & Wilcox (B&W), a subsidiary of McDermott International, creating a consortium that’s committed to getting B&W’s SMR, called mPower, approved for commercial use in the United States. “Some other utilities have expressed interest, and some are getting ready to sign up with the consortium,” says Christofer Mowry, president of Modular Nuclear Energy, the small reactor division of B&W. “However, at this point, they want to keep a low profile.”
Interest is growing beyond just a few vendors and utilities, though. Microsoft founder Bill Gates, for example, is negotiating with Toshiba to develop plants based on the company’s Traveling-Wave Reactor technology. As envisioned, such a reactor would use depleted uranium and would operate for 100 years without refueling.
“There have been a lot of conferences recently on small modular reactors, and they have been well attended by vendors and utilities,” says Michael Mayfield, director of the advanced reactor program at the Nuclear Regulatory Commission.
Moreover, the U.S. government is responding to this rising interest in SMRs. “The Department of Energy is working on this, as is the Nuclear Energy Institute,” Mayfield says. “In addition, the NRC created the Advanced Reactor Program to provide an organization within the office of new reactors to focus on this technology in order to provide appropriate attention, while at the same time not distract resources or attention from the large light-water reactors.”
According to Mayfield, there are at least three different technologies in the class of SMRs.
One is labeled integral pressurized water reactors. These are light-water cooled and light-water moderated reactors. The NRC currently is studying three of these: B&W’s mPower design; Westinghouse’s IRIS; and a third called NuScale, being developed by NuScale Power. “We are having some limited pre-application discussions with all three of these vendors,” Mayfield says, adding that NuScale and B&W have been most active recently. “We’ve had discussions with Westinghouse over a longer period of time,” he explains. “During all of these discussions, we become more familiar with the technologies, and the vendors better understand the regulatory requirements and how they might apply to that technology.”
A second technology area is labeled high-temperature gas-cooled reactors. Westinghouse, General Atomics, PBMR Ltd., and Areva are working on these designs. Instead of using water as the coolant and moderator, this technology uses high-temperature helium. “We are currently looking at the pre-conceptual designs and conceptual designs of these,” Mayfield says. “Under the Energy Policy Act of 2005, the notion is that the prototype reactor would be built and licensed in the U.S.” The DOE is working on the specifics, and the NRC is working with DOE on generic aspects of these reactors, looking at policy issues, and discussing the early pre-application process without choosing a specific design, because DOE hasn’t yet made that selection.
A third technology category involves liquid-metal reactors. “There are a number of variations of designs on these,” Mayfield says. “The more common ones are liquid-sodium cooled.” Toshiba is advancing one such design called the Super-Safe, Small and Simple (4S) reactor, and GE Hitachi Nuclear is backing the Power Reactor Innovative Small Modular (PRISM). “We’re having very limited pre-application discussions with them,” Mayfield says. (For more information, see “Pocket Nukes Come On Strong,” Fortnightly.com.)
SMRs have a number of technical benefits compared to full-size nuclear reactors. For one, most of them can be manufactured quickly. For example, while traditional built-on-site plants can take about five years to construct, the mPower units that would be built in B&W factories are estimated to take about half that time, and then be shipped by rail or barge to the sites.
Another particularly appealing feature of SMRs is their lower requirements for cooling water, and even the ability to use air-cooled condensers. “This could offer a unique application for us in locations where water may be a limitation,” says Ashok Bhatnagar, TVA nuclear’s senior vice president, nuclear generation development and construction.
Additionally, plant safety is an appealing feature. Most of the SMRs utilize a simpler design than standard-sized reactors, and have fewer moving parts that could fail. They also contain a smaller nuclear reaction and generate less heat. All of this means they are designed to be easier to shut down if malfunctions occur.
Security benefits also make SMRs an attractive option. “These are as safe as existing large plants,” Mowry says. “We can also make some enhancements to the technology to make these units even more secure.” For example, all the safety systems and reactor containment would be located underground, and thus easier to protect. Likewise, with the mPower design, used fuel would be stored underground in the containment structure for the entire life of the plant. The mPower reactor is designed to be refueled about every four-and-a-half years, he says, which involves replacing the entire core.
Such a refueling cycle offers its own potential benefits. “If the refueling cycle is every four to five years, and if four of these units are in place at one site, then each year one of the units would come off-line to refuel, while the other three continue to generate power,” says Todd Schneider, a spokesperson for FirstEnergy. “This would be an alternative to having to take one huge unit off-line, and we see this as very beneficial.”
Mowry says the value proposition for mPower comes down to three things. “One is cost certainty, the second is schedule certainty, and the third is affordability,” he says. “You didn’t hear me say anything about technology. That is, we aren’t about a science project. We are in business to repackage the best of proven technologies and make it more affordable by creating an incremental nuclear option. You don’t have to bet your company to deploy a nuclear plant.”
A key feature of SMR projects involves flexibility in siting and development.
“What got us interested was that, as we look into the future, we realize that there may be situations where we don’t need a large amount of new power at one time,” Bhatnagar says. “Rather, we may need small increments of power over multiple years.” The idea of having individual modules that TVA could implement over time seems like a good option.
While some utilities might be interested in SMR technology as a way to more easily create greenfield nuclear sites, utilities and vendors alike see substantial opportunities to install them at existing coal or nuclear facility sites. “Our fossil fleet is fairly old—about 45 to 47 years old,” Bhatnagar says. “As we look into the future, especially in terms of some of these smaller units, there could be an opportunity to repower these fossil fuel sites by installing new reactors and new turbine combinations.” And, of course, he adds, these sites already will have water, transmission, and other infrastructure. “This strategy could help to reduce our carbon footprint over time,” he says.
Replacing older coal-fired capacity might become a sweet spot in the market for SMRs. “These locations already have cooling water available, as well as substations and transmission lines,” Mowry says. He also sees potential for the units on existing brownfield nuclear sites, which, for example, might have been designed for four large units, but have only two up and running. “Utilities have the opportunity to incrementally build these out in bite-sized chunks,” he says. “Then, once they get revenues from the first installation, they can begin work on the next.”
Still another placement option and benefit, according to Westinghouse’s Anness, is that certain portions of the grid are incapable of handling more than a few hundred megawatts of power at one time. “Small reactors provide an option for these utilities,” he says.
Despite these advantages, SMRs seem unlikely to replace large nuclear plant technology. “There will always be demand and room for large nuclear plants,” Mowry says. “Large utilities can afford [large reactors] and continue to be interested in them. As such, we don’t see ourselves as competing with large nuclear plants. Rather, we complement them.”
Because none of the designs has yet been approved by the NRC, it’s difficult to assess the implications of SMRs for permitting, financing, regulatory approvals and ratemaking. However, Mowry believes sponsors will have an easier time getting an SMR project built. “For example, we believe that PUCs will be more open to these, because they have shorter construction times and smaller investments,” he says. “In addition, we’re excited because the DOE has a new program in the fiscal 2011 budget to provide cost-sharing for small modular reactors.”
Jim Hempstead, a senior vice president with Moody’s Investor Service, believes it’s too early to predict how Wall Street will react to SMRs. “These new small technologies are further away on the radar screen,” he says. “It will be a number of years before the NRC will be ready to talk about the designs. As such, from a credit perspective, we haven’t spent a lot of time on it yet.”
Obviously, everything hinges on NRC approval for one or more of the SMR designs. To date, according to NRC’s Mayfield, none of the vendors has submitted a specific design certification application, nor does the NRC have any formal combined licensed applicants referencing a small modular reactor.
And even before it can address new SMR technologies in detail, the NRC must address some other issues. “Many policies and licensing requirements are geared to large reactors,” Bhatnagar says. “There are a lot of new issues with the smaller reactors related to security, fee payment, emergency planning, common control rooms, operator staffing, and so on. We are in early discussions on these with the NRC.”
Many such issues relate to policy more than technology, explains Scott Burnell, an NRC public affairs officer. “One of the most pressing examples will be in the licensing fee area,” Burnell says. “For example, does it make sense to charge the same licensing fee for a small reactor that only puts out 45 MW as we do for a baseload reactor putting out 1,600 MW? At this point, we don’t know.” The NRC might need to review many of its rules and standards to determine, from a policy standpoint, whether small reactors merit a different set of requirements.
All this will take time, but the technology companies remain optimistic. B&W’s goal is to have its first SMR plant up and running by 2020. “We think this is a necessary goal if the technology is really going to be a near-term solution to carbon-free baseload generation,” Mowry says. “As a result, we are in the process of submitting materials to the NRC and expect to get the final formal application in within the next two to three years.”