[Korea`s nuclear technology (6)] Main players in world nuclear market

This is the sixth in a series of articles that highlight the challenges and opportunities facing Korea`s nuclear power industry. -- Ed.





By Kang Ki-Sig





Role of water cooled reactors in the future



Water cooled reactors have been the keystone of the nuclear industry in the 20th century. Many projections forecast significant growth in the use of nuclear energy both in countries currently taking advantage of it and in those considering its use for the first time. As we look into the future with the development of advanced and innovative reactor designs and fuel cycles, it seems clear that water cooled reactors will also play an important role in this future.

These interests have motivated both countries with existing nuclear programs and newcomer countries to consider the construction of new nuclear power plants, taking into account the desire to build capacity in terms of human resources, energy planning, regulatory capabilities and other infrastructure. Many of these new nuclear power plants will be water cooled reactors.

To support the future role of water cooled reactors, substantial design and development programs are underway in a few countries to incorporate evolutionary technology improvements into advanced nuclear power plant designs. The key technical features and specifications of the advanced water cooled reactors (AWCRs) currently available in the market are described in this article. Some of the design features available in many advanced reactor concepts include: a 60-year design life, four-train safety systems, more than 90 percent availability factors, full digital control systems, double containment with external impact protection and corium retention and stabilization systems.



In addition to their improved safety, most advanced water cooled reactor concepts have also achieved improved economics and performance by 1) decreasing construction costs through the optimization of conventional construction methods and the effective incorporation of recent advances in construction technologies; 2) shortening construction duration by using prefabrication, modularization, very heavy lift cranes, etc, while increasing quality; 3) applying modern information technologies and 3-D simulations during the design, construction, commissioning and operation of new nuclear power plants; 4) improving plant availability by enhancing operability and maintainability; and 5) increasing design plant lifetimes up to 60 years.



Development of advanced water cooled reactor designs



Common goals of AWCR designs are high availability, good operating features, competitive economics and compliance with internationally recognized safety objectives. For new plants, the basis for achieving high performance is being laid down during the design phase. For example, design for short outages, design for online maintenance, greater plant standardization and an overall goal of simplicity will contribute to high availability. A list of the AWCR designs is provided in Table I.





3. Overview of advanced water cooled reactor development

In France and Germany, AREVA has completed the basic design for the large size European Pressurized Water Reactor or EPR in 1998, which meets European utility requirements. The EPR`s higher power level relative to the latest series of PWRs operating in France (the N4 series) and Germany (the Konvoi series) has been selected to capture economies of scale.

In the United States, advanced boiling water reactor (ABWR), AP-600 and AP-1000 were certified by the U.S. NRC in August 1997, December 1999 and January 2006, respectively. General Electric is designing a large Economic Simplified Boiling Water Reactor (ESBWR) applying economies of scale together with modular passive safety systems.

In the Russian Federation, efforts continue on evolutionary versions of the currently operating WWER-1000 (V-320) plants. This includes the WWER-1000 (V-392) design, of which two units are constructing at the Novovoronezh site, two units in India and one unit in the Islamic Republic of Iran and two units are operating in China. Development of a larger WWER-1500 design has been initiated

AECL is developing the Advanced CANDU Reactor (ACR) to meet customer requirements for the next 20 years market. The ACR-1000 is 1200 MWe class heavy water reactor, designed to meet industry and public expectations for safe, reliable, environmentally friendly, low-cost nuclear generation.



4. Main players in world nuclear market



Advanced Boiling Water Reactor (General Electric, USA / Hitachi Ltd. and Toshiba Corp., Japan)



In Japan, benefits of standardization and construction in series are being realized with the ABWR units. Expectations are that future ABWRs will achieve a significant reduction in generation cost relative to the first ABWRs. The means for achieving this cost reduction include standardization, design changes and improvement of project management, with all areas building on the experience of the ABWRs currently in operation. The first two ABWRs in Japan, the 1,360 MW(e) Kashiwazaki-Kariwa 6 and 7 units, have been in commercial operation since 1996 and 1997, respectively. The design of the ABWR represents a complete design for a nominal 1,300 MWe power plant. The inclusion of such features as reactor internal pumps, fine motion control rod drives, multiplexed digital fiber-optic control systems and an advanced control room are examples of the type of advancements over previous designs that have been incorporated to meet the ABWR objectives.

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-- Core damage frequency of less than 10-5/ reactor year

-- 24 month refueling interval

-- personnel radiation exposure limit of 100 man-rem/year

-- Shortest construction time (37 months)

-- 4 units in operation (Kashiwazaki-Kariwa-6 & 7, Hamaoka-5 and Shika-2)

-- 7 units planned in Japan

-- Proposed for South Texas Project with construction expected to start in 2012



Advanced PWR (Mitsubishi, Japan)



The APWR has been developed, as a nuclear power plant for future use in Japan, as a joint international cooperative development project by several companies comprising the five PWR electric power companies (Hokkaido, Kansai, Shikoku, Kyushu Electric Power Company and Japan Atomic Power Company) and Mitsubishi Heavy Industries. In the APWR, advanced technologies based on the operational experience gained so far have been incorporated. Also safety, reliability, operability and the performance of the plant have been further increased and the construction cost has been further reduced due to the benefit of economy of scale resulting from the increase in capacity. The first APWR plant is adopted by the Japan Atomic Power Company, Tsuruga-3 and 4.





-- Core damage frequency of about 10-7/ry.

-- Reduction component number & capacity, efficient layout

-- Digital I&C System

-- Plate type heat exchangers

-- Utilization of Enriched 10B

-- Internals with neutron reflector

-- Advanced accumulator (Passive safety)

-- Refueling water storage pit in containment vessel

-- Steel containment structure employment for in-containment structure



EPR (AREVA, France/Germany)



The European Pressurized Water Reactor is the designation for a development effort by Nuclear Power International and its parent companies, Framatome and Siemens, whereas the nuclear part of both companies have merged as an entity in the Areva group. The project was performed in cooperation with Electricite de France and German Utilities, aiming at achieving a new improved nuclear power plant design that will become an acceptable and attractive alternative for meeting energy demands in the future. Following the conceptual design phase of the so-called common product conducted by NPI, Framatome and Siemens, from 1989 through 1991, Electricite de France (EdF) and several major German utilities decided to merge their own development programs -- the N4 Plus and REP 2000 projects on the French side and the further development of the KONVOI technology on the German side -- with the NPI project. From that time on, the NPI project became one single common development line for both countries, named EPR.



-- Very large core: 241 fuel assembly

-- Very high steam pressure: 77.2 bar

-- Computerized main control room

-- Military aircraft resistance

-- 4x100 percent independent Safety trains

-- Design basis accident: No spray system

-- Top mounted instrumentation in Reactor pressure vessel





AP-1000 (Westinghouse, USA)

The Westinghouse Advanced Passive PWR AP1000 is a 1117 MWe PWR based closely on the AP 600 design. The AP1000 design includes advanced passive safety systems and extensive plant simplifications to enhance the safety, construction, operation and maintenance of the plant. The plant design utilizes proven technology, which builds on approximately 40 years of operating PWR experience. PWRs represent 74 percent of all Light Water Reactors around the world and the majority of these are based on Westinghouse PWR technology.

The AP1000 is designed to achieve a high safety and performance record. It is conservatively based on proven PWR technology, but with an emphasis on safety features that rely on natural forces. Safety systems use natural driving forces such as pressurized gas, gravity flow, natural circulation flow and convection. Safety systems do not use active components (such as pumps, fans or diesel generators) and are designed to function without safety-grade support systems.



-- Predicted core damage frequency of 2.4x 10-07/yr

-- Net electrical power of at least 1117 MWe; and a thermal power of 3415 MWt

-- Short lead time (five years from owner`s commitment to commercial operation)

-- Occupational radiation exposure expected to be below 0.7 man-Sv/yr (70 man-rem/yr)

-- Core is designed for an 18-month fuel cycle

-- Seismic based on 0.3g ground acceleration



WWER-1200 (Atomenergoproject/Gidropress, Russian Federation)



Totally there are 51 nuclear power plant units with WWER in operation and accumulated operating life is more than 1,290 reactor-years. WWER-1200 is an evolutionary development with application of reference technical solutions based on VVER-1000 and a wide use of up-to-date knowledge and advanced technologies. The WWER-1200 is developed in accordance with the latest versions of the Russian safety regulations for NPPs by Atomenergoproject (Moscow) and EDO "Gidropress" under the scientific leadership of the Russian National Research Centre Kurchatov Institute. WWER -1200 increased up to 1200 MW and 60 years design service life.



-- Severe fuel damage does not exceed 1.0E-5 per reactor-year

-- probability of accidental radioactive releases does not exceed 1.0E-7 per reactor-year

-- load factor is increased to 90 percent.

-- load-follow conditions are provided in the design

-- usage of additional water inventory in hydroaccumulators of the second stage core cooling system

-- usage of passive elements, isolation, limiting and discharge devices



Advanced CANDU-1000



With a 60-year design life, the ACR-1000 reactor, with 1165 MWe gross output and 60 year design life, core consists of fuel and light-water coolant in pressure tubes with a heavy water moderator. Evolved from the well-established CANDU line of reactors, the ACR-1000 benefits from valuable project-based experience in the design, construction and operation of CANDU plants for utilities around the globe. The ACR-1000 design incorporates CANDU safety features that have provided decades of event-free nuclear power plant operation around the world. ACR-1000 safety systems are designed to prevent or mitigate severe accidents by ensuring reactor shutdown, removing decay heat and preventing radioactive releases. Following traditional CANDU practice, the ACR-1000 incorporates two passive, fast acting shutdown systems that are physically and functionally independent of each other.



-- Load following capability

-- On power refueling

-- Similar configuration/equipment as CANDU 6

-- Unique fuel cycle flexibility

-- Reactivity mechanisms operate in low temperature, low pressure environment

-- Two independent, fast, passively driven safety shutdown systems

-- Reactor building accessible for on-power maintenance

-- Integrated design, licensing construction, commissioning, operations, supporting development/qualification