Nuclear, Reactors

Future of SMR technology

Issue 4 and Volume 4.

By Christofer M. Mowry, president of Babcock & Wilcox Nuclear Energy Inc.

The global emphasis on clean energy technologies continues to grow as power demand worldwide continues to expand. As a result, the bright future of small modular reactor (SMR) technology is getting increasing attention from the energy industry.

That interest is growing because SMRs directly address several key challenges in today’s market, including financing risk, safety and clean energy production. A significant economic advantage of SMRs is the ability to match customer requirements and infrastructure constraints. Not every utility has the capital, electric grid and water resources to build a large reactor, nor does every utility need the capacity of a large reactor. In these cases, which represent numerous utilities across the country and many more around the world, more affordable SMRs offer attractive alternatives to large reactors.

Improved financing reduces costs, while individual modules provide utilities the flexibility to replace aging fossil plants with carbon-free nuclear power using existing grid and site assets, reducing costs even further. This is achievable through a paradigm shift from “economies of scale” to factory assembly of simplified, integral reactors in a manufacturing setting.

Safety In Light of a Fukushima-Type Event

Safety continues to be a primary factor in nuclear energy production. Current and next-generation U.S. large reactor designs operate at a remarkable level of safety, making the U.S. the global leader in nuclear safety and security. While the current fleet is considered very safe, in the wake of the earthquake and tsunami in Japan and the resulting emergency at Fukushima-Daiichi nuclear plant, the nuclear community is evaluating what additional layers of safety are appropriate to mitigate the potential for these types of challenges. SMRs offer significant safety enhancements to Nuclear Regulatory Commission (NRC) safety goals through the use of an inherently safer plant architecture, simplified design and defense-in-depth safety systems.

This enhanced safety performance is achieved through a number of critical design features. Each SMR design is different, but key features in the B&W mPower reactor illustrate the safety features in SMRs. For example, the B&W mPower reactor uses an integral nuclear steam supply system, so there are no large reactor penetrations in the primary cooling circuit. The integral design eliminates the possibility of a worst-case design basis accident occurring from an accident in which a loss of cooling water to the reactor is caused by a break in the reactor system piping.

Demonstrating the defense-in-depth principle, the B&W mPower integral reactor module is isolated from external events in a steel containment structure, which is itself enclosed within a reinforced concrete reactor building that is fully embedded underground. This watertight reactor building contains all emergency cooling water sources, isolates all safety equipment from natural disaster and creates an auxiliary containment for the protected underground spent fuel pool. This underground configuration also offers inherent protection against external man-made threats such as aircraft.

In addition, the emergency core cooling system is powered by gravity; natural circulation removes decay heat and a gravity-drained heat sink tank supplies water to cool the reactor core in an emergency.

Meeting industry’s needs

Interest among utilities continues to grow, as is evidenced by their willingness to participate in advisory committees that provide input to SMR vendors about design necessities and deployment options. For example, B&W has formed a consortium of 15 U.S. utilities and an advisory council of 26 utilities. We are working closely with these member utilities to validate the economic value of our reactor and incorporate their valuable input.

Utilities are also highly interested in maximizing manufacturing efficiencies as a means of reducing risk and managing cost. The modular approach to SMR manufacturing means that vendors expect to be able to achieve “nth-of-a-kind” costs in a relatively small number of modules, rather than thousands as some SMR opponents have implied. Understandably, utility customers also require that SMRs be competitive on a per-kilowatt basis with large reactors. This is achievable through modular, integral design and factory assembly for a fully manufactured product; the ability to maintain a skilled workforce in a manufacturing setting; improved quality, efficiency and process standardization in factory settings; and simplified construction on-site. An additional element of cost control is to design SMRs not only to have a reasonable capital cost, but also to be cost competitive on an operating and maintenance cost basis. Utility advisors have been invaluable in sharing their views on methods to reduce and control operations and maintenance costs.

Innovative SMR designs have the potential to operate at high levels of safety while offering a competitive source of near-term, domestically produced, clean energy. Turning this innovation into reality will depend on leadership and foresight from the nuclear industry in delivering this promising technology to the world.

About the author: Christofer M. Mowry is the President of Babcock & Wilcox Nuclear Energy, Inc., an operating group of The Babcock & Wilcox Co. Mr. Mowry also serves as Chairman of the Board of Generation mPower LLC, a joint company formed by B&W and Bechtel to design, license and build the next generation of nuclear power plants based on B&W mPower reactor technology.

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