Near-term construction of large, new nuclear plants will address two of our nation’s top priorities: additional supplies of clean energy and job creation. Small modular reactors can complement these large-scale projects by expanding the level of deployment and application of carbon-free nuclear energy. Small-scale reactors provide energy companies and other users with a broader array of energy options.
Their small size—typically fewer than 300 megawatts (MW)—and modular construction will allow these reactors to be built in a controlled factory setting and installed module by module, reducing the financing challenge and matching a variety of needs for low-carbon energy.
The potential applications for small reactors include electricity generation. Small reactors may be more compatible with the needs of smaller U.S. utilities from the standpoint of generation, transmission and financing than large 1,400-megawatt (MW) plants. In some cases, the industry envisions modular reactors built in clusters, with modules added as needed to match growth in energy demand.
Small modular reactors could be used for industrial process heat applications, such as those used in the petrochemical industry, desalination or water purification. They also could power the development of liquid transportation fuels from North American resources of tar sands, oil shale and coal-to-liquids applications, reducing the overall life-cycle carbon footprint of these activities.
Designs Target Diverse Applications
Many small modular reactors designs are under development to meet specific U.S. and international market needs, and they are attracting considerable attention from the administration, Congress and the news media.
In March 2012, the administration announced a $452 million cost-shared program between the U.S. Department of Energy and the industry to develop up to two small reactor designs—300 megawatts or less—over five years. Several companies submitted designs for consideration. DOE selected B&W’s mPower reactor design as the first project and earlier this year announced a second solicitation for the program. DOE is seeking designs that can be in commercial operation by 2025. While that time frame tends to favor light water reactor technology, such as the mPower reactor, it does not preclude vendors from submitting other types of reactor designs that are well along in development.
The international community has been evaluating the feasibility of advanced reactor technologies for the past several years through the Generation IV International Forum, whose members include the United States.
The forum has identified six advanced reactor technologies for development. Four of them have small-reactor design options.
The Energy Policy Act of 2005 authorized research, development and construction of a prototype high-temperature gas reactor to provide high-temperature process steam for industrial applications and electricity production. DOE is pursuing this design through its Next Generation Nuclear Plant project, with AREVA’s 625-megawatt thermal steam cycle modular high-temperature gas-cooled reactor (SC-HTGR) selected as the reactor design concept.
Innovative Advanced Reactor Designs Offer a Range of Features
Light Water Reactors
Small light water reactors are designed to capitalize on the benefits of modular construction, ease of transportation and reduced financing, all of which could create a compelling business case. Since these designs typically are smaller than 300 megawatts-electric, they could replace older fossil-fired power stations of similar size that may no longer be economical to operate in a carbon-constrained world. The infrastructure, cooling water, rail and transmission facilities already exist at such facilities. Designs in development include:
“The reactor features a four-year operating cycle without the need for refueling, and is designed to produce clean, zero-emission operations. Generating capacity can be added in 180 [megawatts-electric] increments to match our customers’ load growth projections.” (Source: B&W website)
The SMR 160 is a 160-megawatt reactor that “uses gravitational force for running the reactor and safety functions, rather than large reactor coolant pumps. The rejection of reactor residual heat during shutdown also occurs by gravity-driven circulation, eliminating the need for off-site power supply.” (Source: Holtec website)
“The NuScale plant uses natural forces to operate and cool the plant. … Each NuScale Power Module generates 45 megawatts of electrical power.” (Source: NuScale website)
“The Westinghouse SMR is a >225 [megawatts-electric] integral pressurized water reactor with all primary components located inside the reactor vessel. It utilizes passive safety systems and proven components.” (Source: Westinghouse website)
High-Temperature Gas-Cooled Reactors
These reactors are especially well-suited for providing process heat for the industrial and transport sectors in the medium term and hydrogen in the longer term while reducing the carbon footprint of these activities.
The AREVA reactor design concept is the focus of an industry-government cost-shared program to assess the technology’s ability to create highly efficient electric power generation, cogeneration of thermal energy and electricity, and steam generation. DOE awarded $1 million in January 2013 for a 50/50 cost-shared program to continue business and economic analysis for using HTGR technologies. (Sources: AREVA and Next Generation Nuclear Plant Alliance websites)
The GT-MHR is “eliminates the need to make steam to produce electricity. … [It] includes one or more modular units in underground silos, each containing a reactor vessel and a power-production vessel.” (Source: General Atomics website)
“The Pebble Bed Modular Reactor (PBMR) Power Plant is a helium-cooled, graphite-moderated High Temperature reactor (HTR).” Modules can be added in 165-megawatt increments. (Source: PBMR website)
Liquid Metal and Gas-Cooled Fast Reactors
Liquid metal or gas-cooled fast reactor technologies hold the promise of distributed nuclear applications for electricity, water purification and district heating in remote communities. Fast reactors also could provide sustainable nuclear fuel cycle services, such as breeding new fuel and consuming recycled nuclear waste as fuel and could support nonproliferation efforts by consuming material from former nuclear weapons, thus eliminating them as a threat. Designs under development include:
“The PRISM (Power Reactor Innovative Small Modular) is GE Hitachi Nuclear Energy's next generation sodium-cooled reactor. … The PRISM reactor consumes transuranics in used nuclear fuel from water-cooled reactors, essentially turning waste into energy.” (Source: GE Hitachi website)
“The EM2 is a modified version of General Atomics’ high-temperature, helium-cooled reactor and is capable of converting used nuclear fuel into electricity and industrial process heat, without conventional reprocessing. Each module would produce about 240 MWe of power.” (Source: General Atomics website)
“The reactor, known as the Gen4 Module (G4M), designed to fill a previously unmet need for a transportable power source that is safe, clean, sustainable, and cost-efficient. The reactor has been designed to deliver 70 MW of heat (25 MW of electricity) for a 10-year lifetime, without refueling.” (Source: Gen4 Energy website)
“The 4S is a sodium-cooled fast reactor with a thermal rating of 30MWt or 135MWt that can supply not only electricity but also heat and/or steam.” (Source: Toshiba website)
Small, scalable nuclear power plants are an important addition to America’s energy mix, helping to keep the air clean and enhance energy security. Small reactors can replace inefficient fossil-fired facilities, provide process heat for diverse industrial applications and generate electricity for remote locations. Modules can be added as needed—built in controlled factory settings and easily transported to the site, where they will operate without refueling for anywhere from two to 10 years, depending on the design. Together with large reactors, they comprise a full product line of clean, safe, secure carbon-free energy sources.