The first power reactors (known as Generation I reactors) were low-power pro­totypes built in the 1950s and 1960s to prove the technology; not one of them is operating today in the United States. The reactors built in the 1970s and 1980s were of two main types—pressurized water reactors (PWR) and boiling water reactors (BWR)—and will be discussed in more detail in Chapter 10. These reac­tors are known as Generation II reactors (17). The basic design of PWRs was developed by Admiral Rickover for the US Navy nuclear reactor-powered sub­marines. The Wolf Creek Nuclear Plant is a PWR reactor, as are 69 of the 104 reactors operating through the end of 2012. The other 35 reactors are BWRs that were originally designed at Argonne National Laboratory. Either of these types of reactor works perfectly well. The preference just depended on the company that built them—Westinghouse built PWRs and General Electric built BWRs. This continued a competition between Thomas Edison (the founder of General Electric) and George Westinghouse (the founder of Westinghouse) that began in the 1890s. Edison developed the electric light bulb, but he built his electrical sys­tem on direct current (DC). Westinghouse put his money and prestige on alter­nating current (AC), based on the patent of Nikola Tesla, a brilliant but eccentric Serbian-American electrical engineer and inventor. Westinghouse ultimately won the battle for the electrical network because AC could be stepped up to higher voltages and transmitted over long distances with less loss of power (18).

In spite of there being just two main types of reactors, though, there were actu­ally 80 different designs for the specific reactors, so nothing was standardized (4). This is one of the main factors that led to cost overruns and delays in building the reactors. Another factor is that separate licenses were issued for construction and operation of a nuclear plant. As a result, construction could be finished but opera­tion could be—and sometimes was—halted, leading to extremely costly reactors and giving the whole process a bad name. Much of the delay was caused by anti­nuclear individuals and environmental groups who were adamantly opposed to nuclear power, especially after the accident at Three Mile Island (19). The high inflation rates in the 1980s made delays extremely expensive, with some reactors costing up to $9 billion (20).

Reactor design has not stopped. The next Generation III and III+ reactors have simpler, standardized designs to expedite licensing and to reduce the time and cost of construction, as well as simpler and more stable operation. They are designed for a longer initial lifetime of 60 years, instead of the 40 years for Generation II reactors. They are also designed with passive safety measures to make them much more resistant to accidental core meltdown and release of radiation, as has occurred on three occasions around the world (see Chapter 10 for a detailed dis­cussion of these accidents). Two standardized reactor designs have been approved by the NRC for new nuclear power plants in the United States, and 18 combined license applications have been received by the NRC for 28 reactors. A combined license (COL) reduces much of the time and cost for constructing reactors com­pared to the Generation II reactors because they authorize the licensee to both construct and operate a nuclear power plant at a specific site (21).

The NRC has approved the Westinghouse AP1000 Generation III+ design for a 1,150 MWe PWR reactor, two of which are currently under construction at the Vogtle plant in Georgia and two at the VC Summer plant in South Carolina. The first of these is to come online by 2017. The AP stands for “advanced passive" It incorporates an 800,000-gallon water tank sitting directly above the reactor containment shell to provide emergency cooling passively—even if the electric­ity goes out completely—for three days. This is the most critical time for cool­ing, since the heat output of a reactor drops off very rapidly in the first few days. It is also modular in design, about one-quarter the size of current BWRs, with half the number of valves and one-third fewer pumps, and uses about one-fifth as much steel and concrete (17, 20, 22). Mitsubishi designed another advanced PWR, known as the US-APWR for the US version, that will produce 1,629 MWe but is not yet approved by the NRC (17).

General Electric also continued work on advanced boiling water reactor (ABWR) designs in collaboration with Hitachi and Toshiba. Two GE-Hitachi and two GE-Toshiba reactors were operating in Japan, with two more under con­struction in Japan and two in Taiwan. The four operating reactors were built in 39 months, a huge reduction in construction time compared to existing reactors in the United States. Two are planned for construction in the United States. The ABWR produces about 1,400 MWe, substantially more power than current reac­tors. It is designed for a 60-year lifetime and incorporates passive safety features like the AP1000. It has also been approved by the NRC. An even newer and more economical version—the GE-Hitachi ESBWR (economic simplified boiling water reactor)—uses natural circulation for cooling, with fewer pumps and valves, and can run for six days without electricity (17). To improve security, critical compo­nents are located underground, such as the control room and used fuel cooling pool (20).

AREVA, a French public corporation that specializes in nuclear energy in France and internationally, is building a Generation III+ pressurized water reac­tor known as the European PWR or EPR that is designed to produce 1,750 MWe. The US version is the US-EPR, though the “E” has been changed from “European” to “Evolutionary" One unit is currently being built in Finland with large time and cost overruns, one in France, and two in China. It has four independent and redundant safety systems to minimize risk of an accident (17, 20).

And this is not the end of new designs. An international group of 13 countries currently using nuclear power are collaboratively designing Generation IV reac­tors that are not just evolutionary improvements in existing designs but involve new technologies. These technologies allow higher thermal efficiencies, use dif­ferent reactor physics to burn up nuclear waste, and can use uranium much more efficiently to extend supplies for hundreds of years. They are probably several decades away from commercial implementation, though (23, 24). These will be discussed in more detail in Chapter 11.

A significant new development is the design of smaller nuclear reactors that can be built as modular units in a factory (small modular reactors, or SMRs). These are intrinsically safe and are much smaller than conventional reactors—on the order of 50 to 300 MWe—though several of them might be clustered together. Numerous types of small reactors that incorporate novel features are being designed by the United States, Russia, China, South Korea, Japan, and France. None of these reac­tors has been submitted for licensing consideration to the NRC, though some are expected to be submitted in 2012 (25). NuScale Power has designed a modular 45 MWe reactor that would be built in a factory and then clustered in groups of 12 on site, for a total of 540 MWe, about half the size of a full-scale nuclear reac­tor. This might be useful for smaller cities, and NuScale claims it will be more cost-effective than large reactors—about $2.2 to $2.5 billion for the 540 MW— which would make funding considerably easier. That is not clear, though. David Crane, the CEO of NRG Energy, claims that large nuclear power plants are more economical because engineering and safety costs are spread out over many years (26, 27). A preliminary study of the economics of SMRs indicates that the cost of the reactors will fall substantially as the number of modular units built at factories increases (28). Only time will tell.

The DOE started a cost-sharing grant program to facilitate the development and licensing of SMRs and awarded the first grant to a consortium of Babcock & Wilcox, Tennessee Valley Authority, and Bechtel International in 2012 (29). Babcock & Wilcox makes a 180 MW reactor that is scalable from 1 to 10 or more reactors at a single site and runs for four years before refueling. A second tranche of funding is available for other innovative SMR designs for 2013 (30).