Type: VVER-440 Model V213
Units: Four
Total megawatts (net): 1,560
Location: Dukovany, Moravia, Czech Republic
Dates of initial operation:
For an overview of the principal strengths and deficiencies of Soviet-designed plants, see Soviet Nuclear Power Plant Designs.
Dukovany's operating history has been essentially free of controversy. An International Atomic Energy Agency (IAEA) mission to the plant in 1989 described it as having high availabilities and load factors, with a low--and decreasing--number of unplanned shutdowns. According to the IAEA team, the number of reportable events was within the normal range, and radiation exposure of plant employees was extremely low.
Attempts to build an interim storage facility for spent fuel at the plant, however, encountered local opposition. Although the Czech Ministry of Environment publicly expressed support for the facility and the Atomic Energy Commission approved the proposal, the licensing process required public discussion and an environmental impact study. An environmental group appealed the granting of a construction permit, but in June 1994, the Czech Economics Ministry upheld the permit, clearing the way for construction to begin. The facility began trial operation in September 1995. The casks--designed by Germany's Gesellschaft für Nuklear Behälter--are being made by Skoda Plzen in the Czech Republic.
The Dukovany units are based on the second-generation VVER-440 design and share many of the generic deficiencies common to this design. Plant management and the Czech utility have turned to Western companies for help in upgrading Dukovany in an attempt to address some of these deficiencies.
Between 1984 and 1986, Germany's Siemens/KWU supplied loose-parts monitoring systems and component-vibration monitoring systems to all four Dukovany units.
Following an analysis of Dukovany's Soviet-designed instrumentation and control (I&C) system, plant management recommended replacement with a Western-designed system. Siemens/KWU was awarded a contract in 1990 to supply a new I&C system. However, the Czech and Slovak Federal Republic (CSFR) government said in April 1992 that a study of I&C system replacement in VVER-440 Model V213 reactors would be carried out under the European Communities' PHARE program. The study found that extensive I&C refurbishing or replacement was needed at Dukovany, and a contract was signed with the U.K.'s NNC Ltd. in 1993 to provide full technical specification of the I&C system. The replacement itself will be funded by CEZ, which expects to complete the work before the year 2000.
Also under the PHARE program, NNC Ltd. is leading a consortium that will prepare the data packages needed to develop software for a simulator. The simulator is expected to be supplied by 1998.
Another PHARE-funded project, expected to begin in early 1996, entails the supply of computer models for severe accidents, training in their use, and a large program of analysis and development of VVER accident management programs.
The Czech Republic's Nuclear Research Institute carried out a probabilistic safety assessment (PSA) of Dukovany in 1993, which indicated areas that needed upgrading. Much of the upgrading work was carried out during the PSA, including extending the scope of the emergency operating procedures and redesigning the emergency power supply system. The PSA was then extended, incorporating equipment qualification, more detailed recognition of human factors, internal flooding and fires. In 1995, the focus was the plant's low-power and shut-down phases. The Institute and plant personnel, together with the U.S. company Science Applications International Inc., will complete the first applications in the near future.
A major overhaul of Dukovany Unit 3, including a number of modifications to upgrade operational safety, was completed in 1992. Between 1994 and 1996, the plant plans to evaluate the integrity of all units' primary circulation, steam and feedwater piping. According to plant management, major upgrading of all four units, based on a probability safety assessment, is planned for 1996. The plant is also carrying out extensive reconstruction of electrical supply and distribution systems, replacing some equipment.
Another major undertaking is the plant's aging control program, aimed at ensuring safe operation over the plant's design lifetime. A basic part of this program entails the systematic monitoring and evaluation of such equipment as the reactor pressure vessel, accident localization system, steam generators, main recirculation pump and turbine generator. The program is being audited both internally and externally. The external audit is focusing on the plant's mechanical systems. It is being funded with 1 million ECU ($1.26 million) from the EU's PHARE program, and was scheduled to be completed by the end of 1995.
Dukovany's control room operators are writing more than 200 new operating procedures. Because the four units vary somewhat from one another, each unit will have its own documentation. Plant operators are writing the emergency operating procedures in cooperation with the U.S. company Westinghouse; these procedures should be completed by the end of 1996.
Dukovany has awarded a contract to NNC of the United Kingdom to review the plant's emergency operating procedures and to provide consultancy services in quality assurance.
CEZ, together with SEP, has bought some 400 unused fuel assemblies from the closed Greifswald plant in eastern Germany. About 200 of the assemblies will be used at Dukovany.
WANO Exchanges. Under the auspices of the World Association of Nuclear Operators, Dukovany hosted personnel from the U.S.'s Grand Gulf nuclear plant in 1990, and staff from Dukovany visited the Grand Gulf plant in 1990, the U.S.'s San Onofre plant in March 1992 and Japan's Tsuruga plant in June 1992.
Plant Twinning. The Dukovany plant has been twinned with France's Saint Alban plant and Germany's Obrigheim plant.
IAEA Training Seminar. An IAEA training seminar is scheduled to be held at the Dukovany plant Dec. 3-5, 1996, to review the findings of the October 1996 ASSET peer review mission.
OSART Mission. In September 1989, an IAEA Operational Safety Review Team (OSART) mission reviewed safety practices at Dukovany 3.
It found highly qualified management and a well-trained workforce, aware of health and safety practices. The team called Dukovany's operating history impressive and said exemplary safety practices would be communicated to other plants.
Among the team's recommendations were limited streamlining of Dukovany's organizational structure and strengthening of the quality-assurance function. In addition, the team recommended an increase in control room personnel and said that operating procedures should be upgraded and expanded.
Follow-Up OSART Mission. After a November 1990 follow-up visit, the team noted that improvements had been made at Dukovany: A new organizational structure was being developed, quality assurance was being improved, and more efficient feedback of operational experience was being organized.
At the same time, the team found areas where little progress had been made: an on-site plant-specific simulator for training control room personnel, recording capability for plant disturbances, and an advanced training facility for firefighters.
OSART Technical Exchange Mission. An IAEA Technical Exchange Mission--part of the OSART program--visited Dukovany Oct. 14-25, 1991, to review the plant's maintenance practices. The team's overall impression was favorable. It noted that the plant's management had made major efforts to develop a modern approach to maintenance, and said that the maintenance policy compared well with those at Western plants. The team also noted that the plant's preventive maintenance program is comprehensive and effectively supports nuclear safety.
The team suggested that plant management make efforts to develop a comprehensive predictive maintenance program to optimize its preventive maintenance program and the cost-effectiveness of maintenance activities. It also suggested that management use critical path analysis in the scheduling and follow-up of refueling outages.
ASSET Mission. An IAEA ASSET mission visited the Dukovany plant Oct. 11-22, 1993, to assess the effectiveness of the plant's policy on incident prevention. The team reviewed 476 events reported between April 1988 and March 1993. Of these, 383 were considered to be of safety relevance; one event was classified as Level 2, 19 were classified as Level 1 and the rest as Level 0. The team observed that the number of reported events rose slightly between 1988 and 1990, but fell in 1991 and again in 1992.
The team identified five pending safety problems:
The team noted that electrical system weaknesses such as cable insulation will continue to undermine the reliability of essential electrical supplies until planned improvements are implemented. The team also identified deficiencies in the quality of the procedures, maintenance and testing of 400 kV circuit breakers and their associated protective equipment.
In addition, the team stated that the plant's analysis of events is inconsistent in its thoroughness, and observed that failure to effectively analyze events would undermine the plant's reliability.
Among the team's comments:
The plant has carried out a significant number of improvements and is to be commended for its progressive attitude, but more needs to be done.
When investigating events, more attention needs to be paid to procedural aspects.
CEZ's electrical transmission department and the plant need to develop an interface and a surveillance program to identify deficiencies in investigative procedures.
The plant is to be commended for its willingness to enlist expert support from external sources.
The team made a number of recommendations to management, including:
implement plans to replace 6 kV cables and install 400 kV circuit surge suppressors,
improve means of indication that a diesel generator is not in the normal stand-by mode,
improve the procedures for investigating unusual events to obtain results more quickly,
improve quality assurance measures that ensure goods and services provided to the plant are suitable for their intended purpose,
cooperate with other VVER-440 Model V213 plants to improve the mutual exchange of operating experience, and
review reporting criteria with the aim of streamlining the level of reporting.
The team noted that many of the recommendations apply to improvements under way at the plant, and suggested a follow-up ASSET mission to Dukovany in 18-24 months. The team also suggested that Dukovany request an ASSET seminar on the INES rating system and ASSET root-cause analysis tailored to the plant's needs.
Safety Review Mission. An IAEA Safety Review Mission visited the Dukovany plant in November 1995 to review the plant modernization program prepared by Dukovany in cooperation with other Czech and international organizations. The team found that all safety issues identified by the IAEA for the VVER-440 Model V213 had been addressed by the plant with specific safety improvement measures. According to the team, the most important activities planned for the near future include: qualification of safety valves for steam-water flow, and installation of additional relief valves qualified for water flow both on the pressurizer and steam generators.
The team found that issues in the area of component integrity were especially well addressed, and that a considerable amount of work had already been done. According to the team, the measures related to strengthening the bubbler condenser structure needed reconsideration so that weak mechanical points could be strengthened. Dukovany asked the IAEA to send a mission to review the scope of measures aimed at strengthening the bubbler condenser structure.
Planned ASSET Mission. An ASSET peer review mission to Dukovany is scheduled for Oct. 7-11, 1996. The mission will review the plant's self-assessment of operational safety performance based on ASSET procedures.
January 1996
