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Small Modular Nuclear Reactors

Reactor Building Cross Section - NuScale nuclear power reactors are housed inside high strength steel containment vessels and submerged in a large steel-lined pool of water below ground level in the Reactor Building.  The Reactor Building is designed to withstand earthquakes, tsunamis, tornados, hurricane force winds and aircraft impact.  The fuel pool and control room also are housed below ground level. © 2013 NuScale Power, LLC. All Rights Reserved

Reactor Building Cross Section - NuScale nuclear power reactors are housed inside high strength steel containment vessels and submerged in a large steel-lined pool of water below ground level in the Reactor Building. The Reactor Building is designed to withstand earthquakes, tsunamis, tornados, hurricane force winds and aircraft impact. The fuel pool and control room also are housed below ground level. © 2013 NuScale Power, LLC. All Rights Reserved

The development of clean, affordable nuclear power options is a key element of the Department of Energy’s Office of Nuclear Energy (DOE-NE) Nuclear Energy Research and Development Roadmap. As a part of this strategy, a high priority of the Department has been to help accelerate the timelines for the commercialization and deployment of small modular reactor (SMR) technologies through the SMR Licensing Technical Support program.  Begun in FY12, the DOE Office of Nuclear Energy’s Small Modular Reactor Licensing Technical Support program will advance the certification and licensing of domestic SMR designs that are relatively mature and can be deployed in the next decade. 


Small modular reactors offer the advantage of lower initial capital investment, scalability, and siting flexibility at locations unable to accommodate more traditional larger reactors.  They also have the potential for enhanced safety and security.

Modularity: The term “modular” in the context of SMRs refers to the ability to fabricate major components of the nuclear steam supply system in a factory environment and ship to the point of use.  Even though current large nuclear power plants incorporate factory-fabricated components (or modules) into their designs, a substantial amount of field work is still required to assemble components into an operational power plant. SMRs are envisioned to require limited on-site preparation and substantially reduce the lengthy construction times that are typical of the larger units. SMRs provide simplicity of design, enhanced safety features, the economics and quality afforded by factory production, and more flexibility (financing, siting, sizing, and end-use applications) compared to larger nuclear power plants. Additional modules can be added incrementally as demand for energy increases.  

Lower Capital Investment: SMRs can reduce a nuclear plant owner’s capital investment due to the lower plant capital cost.  Modular components and factory fabrication can reduce construction costs and duration. 

Siting Flexibility: SMRs can provide power for applications where large plants are not needed or sites lack the infrastructure to support a large unit. This would include smaller electrical markets, isolated areas, smaller grids, sites with limited water and acreage, or unique industrial applications. SMRs are expected to be attractive options for the  replacement or repowering of aging fossil plants, or to provide an option for complementing existing industrial processes or power plants with an energy source that does not emit greenhouse gases.

Gain Efficiency: SMRs can be coupled with other energy sources, including renewables and fossil energy, to leverage resources and produce higher efficiencies and multiple energy end-products while increasing grid stability and security.  Some advanced SMR designs can produce a higher temperature process heat for either electricity generation or industrial applications.

Nonproliferation: SMRs also provide safety and potential nonproliferation benefits to the United States and the wider international community.  Most SMRs will be built below grade for safety and security enhancements, addressing vulnerabilities to both sabotage and natural phenomena hazard scenarios. Some SMRs will be designed to operate for extended periods without refueling. These SMRs could be fabricated and fueled in a factory, sealed and transported to sites for power generation or process heat, and then returned to the factory for defueling at the end of the life cycle. This approach could help to minimize the transportation and handling of nuclear material.  

International Marketplace: There is both a domestic and international market for SMRs, and U.S. industry is well positioned to compete for these markets. DOE hopes that the development of standardized SMR designs will also result in an increased presence of U.S. companies in the global energy market. 

SMR Licensing Technical Support  Program 

To date, none of the existing SMR concepts  have been designed, licensed or constructed. DOE believes that  SMRs may play an important role in addressing the energy, economic and climate goals of the U.S. if they can be commercially deployed within the next decade. 

The mission of the SMR Licensing Technical Support program is to promote the accelerated deployment of SMRs by supporting certification and licensing requirements for U.S.-based SMR projects through cooperative agreements with industry partners, and by supporting the resolution of generic SMR issues. DOE anticipates continuing efforts toward a 6-year $452 M program.

mPower America Partnership: The first agreement, awarded to the mPower America team of Babcock & Wilcox, Tennessee Valley Authority, and Bechtel, includes efforts to complete design certifications, site characterization, licensing, first-of-a-kind engineering activities, and the associated Nuclear Regulatory Commission (NRC) review processes. The goal of this program is to support commercial operations of an SMR by 2022; the mPower team has developed a plan that expects to achieve a commercial operation date (COD) of October 2021.

Key Activities for the mPower America team include:

  • Submit Design Certification application to the Nuclear Regulatory Commission (NRC) by late-2014 for approval by 2018
  • Perform site characterization at TVA’s Clinch River Site
  • Submit a Construction Permit Application to the NRC by mid-2015 for approval by 2018
  • Advance the balance of plant design
  • Grow the U.S. based supply chain by mitigating challenges to domestic market entry and broad commercialization

NuScale Power Partnership:  DOE selected NuScale Power under a second SMR funding opportunity announcement that sought innovative and effective solutions for enhanced safety, operations and performance beyond designs currently certified by the NRC. The NuScale SMR design offers an impressive mix of safety, scalability, transportability, and economics, as well as an advanced state of design maturity that should achieve commercial operation in the 2025 timeframe. DOE continues to work with NuScale to execute a cooperative agreement and measurable project goals.

Key Activities included in the agreement include:

  • Complete the preliminary design by the first quarter of 2015
  • Execute testing programs in support of design development and NRC review requirements
  • Submit Design Certification application to the NRC by late-2016
  • Complete reactor module final design by mid-2019

Support in Resolving Generic SMR Issues: DOE recognizes the need to support industry in addressing the licensing hurdles that will be faced by all potential licensees. Issues involving the treatment of unique SMR source term evaluations or operations, maintenance and security staffing requirements may require experimentation and analysis that DOE laboratories may have capabilities and resources to address. DOE intends to support the development of such experimentation and analysis as required.

DOE also intends to support efforts to improve the commercialization potential for SMRs both domestically and internationally. DOE is supporting economic and business case studies that will improve the modeling of the economic potential of SMRs. DOE is also supporting the Electric Power Research Institute in developing a Utility Requirements Document for SMRs to help establish a generic set of design requirements for the SMR industry and improve the licensing framework.

Advanced SMR R&D

SMRs designed from advanced and innovative concepts, using non-LWR coolants such as liquid metal, helium or liquid salt, may offer added functionality and affordability. This program element will support laboratory, university, and industry projects to conduct nuclear R&D on capabilities and technologies that are unique and support development of advanced SMR concepts for use in the mid to long term.

Advanced SMR R&D activities will focus on four key areas:

  • Developing assessment methods for evaluating advanced SMR technologies and characteristics;
  • Developing and testing of materials, fuels and fabrication techniques;
  • Resolving key regulatory issues identified by NRC and industry; and
  • Developing advanced instrumentation and controls and human-machine interfaces.

This program element may also include evaluations of advanced reactor technologies that offer simplified operation and maintenance for distributed power and load-following applications, and increased proliferation resistance and security.