NUCLEAR FACTS

Business of nuclear

Advanced-design nuclear power plants
(May 2001)

Key Facts

n	The U.S. nuclear energy industry has been developing and improving light water reactor technology for more than four decades. Most of the plants built using this proven technology are virtually one-of-a-kind, custom designs.
n	For new nuclear plants, the nuclear industry is firmly committed to developing standardized designs instead of the customized designs used in the past. These advanced nuclear power plants contain many features that make them even safer and more efficient than today's plants. These standardized designs will significantly reduce construction and operating costs.
n	Three standardized advanced light water plant designs have been certified by the Nuclear Regulatory Commission (NRC).
n	New initiatives are focused on innovative reactor designs, including gas-cooled reactors, although these designs are not yet certified by the NRC.

Today's nuclear power plants: Customized designs
The light water reactor-so called because its coolant is ordinary water-is the work-horse of the nuclear energy industry in the United States and overseas. There are two types: pressurized water reactors (PWRs) and boiling water reactors (BWRs). Nearly two-thirds of the world's nuclear plants are PWRs.

The U.S. nuclear industry has learned many important lessons from the construction and operation of today's nuclear power plants-how to improve safety, economics, construction management and practices, operation and maintenance.

One of the most important lessons-that customized designs can create inefficiencies, duplication of effort and higher costs-brought about a fundamental change in industry practice: design standardization. Most of America's operating nuclear power plants are virtually one-of-a-kind, because they were designed and built at a time when regulatory requirements, licensing standards and the technology were evolving rapidly.

New nuclear power plants: Safer, simpler
For future plants, the U.S. electric utility industry is firmly committed to using standardized designs. The new designs will incorporate the latest technologies, and will be easier to operate and faster to build. These plants will achieve even higher safety ratings than today's plants. Standardization simply means that reactors will be built in families of the same design, except for a limited number of site-specific differences. Standardization will reduce construction and operating costs, and lead to greater efficiencies and simplicity in all aspects of nuclear plant operations, including safety, maintenance, training and spare parts procurement.

Demonstrated benefits—Experience overseas demonstrates the benefits of standardization. The French nuclear program is based on standardized nuclear plant designs. Over nearly two decades, the French built 34 standardized 900-megawatt units and 20 1,300-megawatt units, which now supply about 75 percent of that country's electricity.

By using standardized designs, the French were able to cut construction times significantly. The first reactors in the 900-megawatt series took about seven years to build; the last reactors, only five years. Because of standardization, the cost of nuclear power plants in France is among the lowest in the world.

The Republic of Korea's nuclear energy program, with eight reactors using Westinghouse's System 80 plant design, is another example of the benefits of standardization. Each successive project has experienced reduced construction and start-up schedules. Further reductions are expected in four units under construction.

The United States has three standardized designs available for new plant orders. Two are large 1,350-megawatt "evolutionary" designs, and one is a smaller 600-megawatt design. The 600-megawatt design employs conventional reactor and power generation technology, but uses features such as stored water and gravity for safety functions as opposed to systems that use pumps and motors to move the water.

A 1,000-megawatt version of the 600-megawatt design is undergoing a design review that may lead to certification.

Large "evolutionary" nuclear plants—Two nuclear companies-Westinghouse and General Electric Co.-have designed large (1,350-megawatt) light water reactors. The Nuclear Regulatory Commission issued design certification for these plants in 1997.

They are called "evolutionary" designs because they build directly on a previous design and on the experience and lessons learned from plants already operating around the world. The "evolutionary" designs optimize the light water reactor, producing a plant that is simpler, easier to operate and maintain, and costs less to build. Safety studies indicate that these designs will be able to meet safety goals that are more than 100 times better than current plants.

Since today's nuclear plants were designed and built, there have been tremendous strides in many technological areas. Electronic control systems are a good example. Today's nuclear power plants have miles of control cable. New plant designs will greatly reduce the amount of cabling required through the use of multiplexed, digital control systems, including state-of-the-art fiber optic technology. The new control systems are more compact, easier to operate and thus safer. They're also simpler, which cuts construction time and cost.

The revolution in electronic controls extends into the control room: Display panels and controls have been completely redesigned.

Advanced Boiling Water Reactor. General Electric's design for the advanced boiling water reactor (ABWR) differs from today's reactors in a number of ways. Here are just a few:

Kashiwazaki-Kariwa 6, the first of two GE ABWRs in Japan and whose design is similar to that certified in the United States, began generating electricity in January 1996. Construction was completed in 52 months-10 weeks ahead of schedule. Kashiwazaki-Kariwa 7 began commercial operation in mid-1997.

System 80+ Advanced Pressurized Water Reactor. Westinghouse developed the System 80+ advanced PWR, evolving from the proven System 80 design. Three System 80 reactors are in operation at the Palo Verde Nuclear Generating Station in Arizona, the nation's largest nuclear facility. Eight additional units using the System 80 design and incorporating several System 80+ advancements are in operation or under construction in the Republic of Korea. In 1997, the Republic of Korea selected the System 80+ design as the technology base for the advanced Korean nuclear program. The System 80+ design is engineered to achieve improvements in cost and safety with a number of significant features:

Smaller, simpler nuclear plants
In 1984, EPRI started a program to develop a new generation of mid-size nuclear plants (in the 600-megawatt range). The goal: To achieve even greater simplification in nuclear plant designs as a way of reducing cost and enhancing safety. Utility requirements for performance, operation, maintenance and construction were developed for these passive designs, just as they were for the evolutionary designs.

Although the AP600 is quite different from today's large plants, it will use proven light water technology and tested systems and components as much as possible. Its design relies on natural forces like convection and gravity flow of emergency cooling water, reducing or minimizing reliance on pumps, valves, emergency diesel generators and other components that ensure safety in today's plants.

In addition, the AP600 incorporates improved automatic safety features. It has several large tanks of emergency cooling water inside the containment structure above the reactor vessel. During an emergency, pressure and gravity would force this water into the vessel to cool the core. Compared to today's plants, the AP600 will need 50 percent less building volume, 50 percent fewer valves, 80 percent fewer pipes, 35 percent fewer large pumps and 70 percent less control cable.

Because of their simplicity, the smaller plants can be built much faster than recent U.S. nuclear plants. Quick construction is possible because many systems and subsystems will be assembled in the factory, not on the plant site. The goal is a construction time of three years.

Design certification timetable
Both standardized 1,350-megawatt evolutionary plants received design certification from the NRC in 1997 and the Westinghouse AP600 in 1999.

In 1992, the Department of Energy and a consortium of electric utilities called the Advanced Reactor Corp. signed a contract to launch a five-year, cost-shared program to do detailed "first-of-a-kind engineering" on two standardized advanced plants. This detailed program completed most of the standardized engineering work that goes beyond what the NRC requires to conduct safety reviews, and will provide the level of information needed by potential buyers to estimate construction costs and schedules with a high degree of certainty.

In 1993, two designs-GE's 1,350-megawatt ABWR and Westinghouse's 600-megawatt AP600-were picked by the Advanced Reactor Corp. to share first-of-a-kind engineering support. The engineering design on the ABWR was completed in 1996, and first-of-a-kind engineering for the AP600 was completed in 1998.

Investments made by the nuclear industry and DOE to develop first-of-a-kind engineering will be recouped through royalties from the sale of these plants.

Beyond today's certified designs
Companies in both the United States and abroad are pursuing other advanced reactor designs that could be brought to market in the next few years.

Westinghouse, for example, is exploring options for the AP1000-a large-scale version of its AP600. The AP1000 incorporates many of the same design and safety features as the AP600. In addition, Exelon has entered into an agreement with the South African utility, Eskom, to pursue deployment of the Pebble Bed Modular Reactor, a 110-megawatt, helium-cooled reactor. The pebble bed's modular design, small size and simple design are expected to help reduce construction time and cost, and add flexibility by allowing companies to add reactors to sites incrementally as needed.

A detailed feasibility study is under way in South Africa. It is scheduled for completion in June 2001. Exelon separately will decide whether to proceed with initial licensing and construction in the United States.

If early demonstrations of the reactor are successful, construction of a prototype reactor in South Africa could begin by the middle of 2002, with completion in about 36 months. After a one-year testing period, commercial operation could begin there as early as 2006.

A continuum of nuclear plant designs
Operating nuclear power plants-known as Generation II designs-are today's industry workhorses. Most of these plants will renew their operating licenses for an additional 20 years, thus maximizing their value.

The advanced light water reactors-the evolutionary and passive designs-are known as Generation III. The lessons learned from these designs are being used. Efforts are under way to make the Generation III designs-developed during the regulated utility era-more cost competitive in a deregulated marketplace.

The next generation of nuclear plants-Generation IV-include such designs as gas-cooled reactors. The cost reductions identified through work on Generation IV plants could be applied to Generation III designs.

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