Small Modular Reactors: A Potential Game-Changing Technology

Author: Dr. William Madia

There is a new type of nuclear power plant (NPP) under development that has the potential to be a game changer in the power generation market: the small modular reactor (SMR).  Examples of these reactors that are in the 50-225 megawatt electric (MW) range can be found in the designs being developed and advanced by Generation mPower, NuScale, the South Korean SMART reactor and Westinghouse.

Some SMR concepts are up to 20 times smaller than traditional nuclear plants

Today’s reactor designers are looking at concepts that are 5 to 20 times smaller than more traditional gigawatt-scale (GW) plants.

The reasons are straightforward; the question is, “Are their assumptions correct?” The first assumption is enhanced safety. GW-scale NPPs require sophisticated designs and cooling systems in case of a total loss of station power, as happened at Fukushima due to the earthquake and tsunami. These ensure the power plant will be able to cool down rapidly enough, so that the nuclear fuel does not melt and release dangerous radioactive fission products and hydrogen gas. SMRs are sized and designed to be able to cool down without any external power or human actions for quite some time without causing damage to the nuclear fuel.

The second assumption is economics. GW-scale NPPs cost $6 billion to $10 billion to build. Very few utilities can afford to put this much debt on their balance sheets. SMRs offer the possibility of installing 50-225 MW of power per module at a total cost that is manageable for most utilities. Furthermore, modular configurations allow the utilities to deploy a more tailored power generation capacity, and that capacity can be expanded incrementally. In principle, early modules could be brought on line and begin producing revenues, which could then be used to fund the addition of more modules, if power needs arise.

The third assumption is based on market need and fit. Utilities are retiring old fossil fuel plants.  Many of them are in the few hundred MW range and are located near load centers and where transmission capacity currently exists. SMRs might be able to compete in the fossil re-power markets where operators don’t need a GW of power to serve their needs.  This kind of “plug and play” modality for NPPs is not feasible with many of the current large-scale designs, thus giving carbon-free nuclear power an entry into many of the smaller markets, currently not served by these technologies.

There are numerous reasons why SMRs might be viable today.  

Throughout the history of NPP development, plants grew in size based on classic “economies of scale” considerations. Bigger was cheaper when viewed on a cost per installed kilowatt basis. The drivers that caused the industry to build bigger and bigger NPPs are being offset today by various considerations that make this new breed of SMRs viable.

Factory manufacturing is one of these considerations. Most SMRs are small enough to allow them to be factory built and shipped by rail or barge to the power plant sites.  Numerous industry “rules of thumb” for factory manufacturing show dramatic savings as compared to “on-site” outdoor building methods. Significant schedule advantages are also available because weather delay considerations are reduced.  Of course, from a total cost perspective, some of these savings will be offset by the capital costs associated with building multiple modules to get the same total power output. Based on analyses I have seen, overnight costs in the range of $5000 to $8000 per installed kilowatt are achievable. If these analyses are correct, it means that the economies of scale arguments that drove current designs to GW scales could be countered by the simplicity and factory-build possibilities of SMRs.

No one has yet obtained a design certification from the Nuclear Regulatory Commission (NRC) for an SMR, so we must consider licensing to be one of the largest unknowns facing these new designs. Nevertheless, since the most developed of the SMRs are mostly based on proven and licensed components and are configured at power levels that are passively safe, we should not expect many new significant licensing issues to be raised for this class of reactor.  Still, the NRC will need to address issues uniquely associated with SMRs, such as the number of reactor modules any one reactor operator can safely operate and the size of the emergency planning zone for SMRs.

To determine if SMRs hold the potential for changing the game in carbon-free power generation, it is imperative that we test the design, engineering, licensing, and economic assumptions with some sort of public-private development and demonstration program.  Instead of having government simply invest in research and development to “buy down” the risks associated with SMRs, I propose a more novel approach. Since the federal government is a major power consumer, it should commit to being the “first mover” of SMRs. This means purchasing the first few hundred MWs of SMR generation capacity and dedicating it to federal use. The advantages of this approach are straightforward.   The government would both reduce licensing and economic risks to the point where utilities might invest in subsequent units, thus jumpstarting the SMR industry. It would then also be the recipient of additional carbon-free energy generation capacity. This seems like a very sensible role for government to play without getting into the heavy politics of nuclear waste, corporate welfare, or carbon taxes.

If we want to deploy power generation technologies that can realize near-term impact on carbon emissions safely, reliably, economically, at scale, and at total costs that are manageable on the balance sheets of most utilities, we must consider SMRs as a key component of our national energy strategy.

Dr. William Madia serves as Chairman of the Board of Overseers and Vice President for the SLAC National Accelerator Laboratory at Stanford University.  Previously, he was the Laboratory Director at the Oak Ridge National Laboratory from 2000-2004 and the Pacific Northwest National Laboratory from 1994-1999.

Photo source: Tim Marss