Temelin project moves forward8 January 1999
Westinghouse Electric Company’s work at the Temelin nuclear power station in the Czech Republic has recently been extended under terms of a new contract. This report by Westinghouse is an update of the project and explains the basis for the upgrades being undertaken and how this work provides an experience base for similar work in Eastern Europe and beyond.
Temelin has provided Westinghouse with a unique experience. Beginning in 1993, Westinghouse was awarded five contracts for work at the Temelin nuclear power station, a twin-unit site consisting of two 1000 MWe Russian-designed pressurised water reactors. The contracts included the replacement of the entire instrumentation and control (I&C) system, the supply of nuclear fuel and associated components, the diagnostic and monitoring system, and the radiation monitoring system. Westinghouse was also asked to help the Czechs develop emergency operating procedures for the plant.
With the implementation of the new I&C system and utilisation of advanced fuel, Temelin will be on a level with any advanced nuclear power plant in the world.
One contract was for nuclear fuel fabrication of the first core load and four subsequent reloads of Western design fuel. The first core shipments were completed in the spring of 1998 and placed in the New Fuel Handling Facility.
Along with high performance fuel, Westinghouse provides technical services that maximise the operating efficiency and safety of the VVER plant. BEACON™, for example, is a 3-dimensional on-line monitoring system that provides precise knowledge of current core power, flux distribution and core peaking factors as well as core analysis and predictions of how operating decisions will affect plant availability.
ADVANCED CONTROL SYSTEMS
To date, all of the 600 control cabinets for Unit 1 have been shipped and are nearing installation at Temelin. The next major milestone will be to incorporate the latest software, followed by an aggressive testing programme in the factory and at site. As anticipated, unit 2 is slightly behind unit 1 in implementation; all the control system cabinets are on-site and are now in the process of being installed.
Temelin’s distributed digital control and information system meets all international nuclear plant safety and equipment design standards. The reactor protection and redundant plant control and limitation systems use the proven Eagle™ family of hardware. The plant control and computer information systems use the WDPF II™ distributed process control family of hardware and software.
The integrated I&C system at Temelin consists of several subsystems. The Reactor Protection System includes the trip logic and provides basic monitoring and protection of the reactor. The Redundant Reactor Control System controls the nuclear reactor and provides critical limitation and monitoring functions. The Plant Control System controls and monitors non-reactor control-related plant functions.
The Computer Information System monitors all plant systems and provides plant operators with operational assistance using modern information presentation techniques including both standard and custom graphics. The Control Room is ergonomically designed using human engineering, with “soft” and “hard” alarm systems.
“The Temelin project, while challenging, has given us the skills and experience to implement similar projects in Central and Eastern Europe,” said Tom Markovich, Westinghouse’s managing director, Temelin.
TEMPLATE FOR INNOVATION
In many cases, the Temelin upgrade forms the basis for new products and processes. Westinghouse has developed a new reactor protection system used for the Diverse Reactor Protection System, a much higher-density data highway with revolutionary diagnostics and monitoring systems, and soft controls for plant operators.
A new protection system runs in parallel with the Eagle primary reactor protection system. This protection system incorporates commercially available hardware which has been validated to meet the stringent nuclear requirements and has a sizable reduction in cabinets compared to Eagle. Such “open” systems will be the standard for nuclear plants in the future.
Another major step forward involves the data highway. Standard non-Temelin-type systems can handle 60 to 80 points per second on the highway; far too few for systems as complex as this one. The new fibre distributed data interchange (FDDI), enhanced with a proprietary, deterministic protocol, supports a much denser and faster Information System to avoid bottlenecks. This new WESNET III™ system can handle 200 000 points per second; so every point on the system can be updated once per second. This information system is really the heart of the Temelin upgrade. The original I&C system at Temelin was made-up of a number of near-stand-alone systems, each designed to perform a single function. Now the Information System processes data from various protection and control subsystems throughout the plant and integrates this into a universal data set accessible by any of the system’s users. The relational database contains well over a million pieces of information documenting everything from the simplest piece of data – such as instrument identification – to intelligence that produces cable block diagrams automatically. The WEStation drops (individual computers) distributed throughout the plant perform functions used to assist the operators and plant engineers in plant monitoring, control, performance analysis and maintenance.
A third major innovation is soft controls. Although other industries, including fossil power plants, rely on CRT-based controls, the nuclear industry has stayed with hardwired, control systems. This is the first nuclear plant to have soft controls everywhere except for reactor protection, which has both hardwired and soft controls.
Temelin’s unit 1 is scheduled for provisional system acceptance with 100% power testing in May 2001. Unit 2 is approximately 15 months behind in implementation; it should receive provisional system acceptance with 100% power testing in August 2002.
The Temelin project proved the capability of implementing such a vast, complex technology integrated into a Russian reactor: the ability to marry two very different design technologies.
The more modern of the Russian VVERs may be retrofitted with upgraded safety systems, particularly control systems, to bring them up to acceptable standards.
“One of Westinghouse’s goals is to take advantage of upgrade opportunities in Central and Eastern Europe,” says Mike Comiskey, general manager of the Westinghouse Nuclear Projects Division. “ In the future, many similar Russian-built VVER pressurised water reactors in Hungary, Bulgaria and other countries will need to be retrofitted or upgraded with advanced safety and control systems. With our experience at Temelin, Westinghouse will already be high on the learning curve.”
Beyond this, Temelin coincides with the upgrading and modernisation of a number of nuclear plants in the United States as well as in Europe. Many older plants are poised to take the leap in technology that will provide them with microprocessor-based control systems.