Type: VVER-440 Model V213
Units: Four
Total megawatts (net): 1,730
Location: Paks, Hungary
Dates of initial operation:
For an overview of the principal strengths and deficiencies of Soviet-designed plants, see Soviet Nuclear Power Plant Designs.
The Paks plant has an essentially untroubled operating history, with a low number of unscheduled outages and reportable events. Between 1990 and 1994, the plant had an average capacity factor of 86.4 percent, and averaged 1 automatic scram per unit year. For 1995, the scram rate was zero. Over this period, the average outage for the plant as a whole lasted 179 days; this figure fell to 136 days in 1995.
Before MVM canceled its order in 1989 for two third-generation VVER-1000 units as the fifth and sixth units at the Paks site, it had awarded several contracts to Western companies for assistance in building the units.
Bechtel Power Corp. won a contract in 1988 to perform project management services for construction of Paks 5 and 6. Bechtel had already assessed management, organization and work flow at the four operating VVER-440 Model V213 units.
Finland's IVO International Ltd. was awarded a contract in 1988 to deliver project-management systems to the Paks construction project.
IVO International also signed a technical agreement with Paks management in 1988 under which IVO would participate in the construction and maintenance of the new Paks units.
Siemens/KWU experts cleaned the steam generators at Paks 1 in 1991, and Paks personnel used the Siemens chemical process to clean Unit 2's steam generators in 1992.
Plant Upgrades. The Paks plant has also contracted with Western firms for upgrades to the four VVER-440 Model V213 nuclear units. Finland's Nokia Oy was awarded an order for a plant full-scope simulator, and IVO International contracted to provide inspection and quality-control support, as well as safety and construction consulting, for all units at Paks. The simulator was completed in 1987. The plant has raised its performance level with the help of the new simulator, which Paks management uses not only to train staff but also to test emergency procedures. Following such a test in 1990, management made significant improvements to these procedures.
In 1990, Spain's Tecnatom signed a contract with the International Atomic Energy Agency (IAEA) to supply Paks with a system for acquiring and processing data from ultrasonic in-service inspection of pressure vessels and other components. The company carried out a partial inspection of Unit 3's reactor vessel in 1993 that showed the vessel to be in highly satisfactory condition, with no reportable defects in the inspected zones.
In 1992, the Hungarian Atomic Energy Commission launched a study--the Advanced General and New Evaluation of Safety (AGNES) study--of Paks to ensure that the plant meets Western safety standards. Nuclear experts headed by KFKI, the country's leading atomic energy research institute, reevaluated the systems, carried out new design-basis analyses as well as severe accident analyses, and completed a level-1 probabilistic safety assessment. The report on the AGNES study, issued in June 1994, made numerous safety proposals. One major task suggested in the report was upgrading the plant's seismic resistance. Under a Belgian-Hungarian energy agreement signed in May 1993, Belgium will contribute BF 20 million ($660,000) for safety and seismological tests to support safety systems and the construction of a waste storage facility.
Paks' safety enhancement program was reviewed on the basis of the AGNES study recommendations, and new priorities have been established for implementing safety measures. As a result, the training simulator's functions were extended, the steam generators were protected against overpressure in a cold state, diesel generator batteries were upgraded for earthquake resistance, and fireproof insulation was installed on the turbine hall support pillars.
In 1995, the instrumentation and control (I&C) and electrical panels and cabinets were improved, and the basic design for total separation of the auxiliary feedwater system from the normal and emergency feedwater system was completed. IVO International was awarded a contract to study the management of steam generator primary-to-secondary circuit leaks. IVO designed new clog-proof sumps for the confinement and the test of a prototype was successful. In addition, IVO was contracted to provide consultancy services on emergency procedures and severe accident management. Siemens was awarded a contract to deliver hydrogen recombiners for removing hydrogen generated in the confinement as a result of a severe accident.
The Paks plant spent $9.2 million on safety-related upgrades in 1995.
Studies, Training. Under a PHARE-funded project, expected to begin in early 1996, Siemens--together with the Czech Republic's Rez and Hungary's VEIKI--will supply computer models for severe accidents, training in their use, and a large program of analysis and development of VVER accident management programs. In addition, the plant has awarded a contract to the United Kingdom's NNC to provide an I&C training course for Paks operators.
WANO Exchange Visits. The World Association of Nuclear Operators (WANO) has coordinated several exchange visits involving the Paks plant. The plant has hosted personnel from the following plants:
In addition, personnel from Paks have visited the following plants:
Following the successful completion of a series of pilot peer reviews in 1992 and 1993, WANO launched a formal program of voluntary peer reviews of WANO member plants in 1994. Under the program, experienced operators from other plants offer independent observations on plant operations, make recommendations for improvements and identify good practices to share with operators worldwide. The first review in the pilot phase of this program was carried out at the Paks plant in February 1992.
Established Plant Exchanges. In addition to visits under the WANO exchange program, Paks maintains regular contact with several plants: Finland's Loviisa, Russia's Kola, Ukraine's Rovno, the Slovak Republic's Bohunice, the Czech Republic's Dukovany, Germany's Isar 2, and France's Blayais.
Plant Twinning. The Paks plant has been twinned with France's Blayais plant, Germany's Isar 2, and the Limerick and San Onofre plants in the United States.
International Safety Project. In early 1994, Paks launched a four-year safety project to establish a maintenance training center, introduce international training techniques and help to enhance the plant's safety culture. Funding for the $7 million project is provided by the International Atomic Energy Agency (IAEA) ($1.3 million), the U.S. government ($400,000), the European Union's PHARE program ($450,000) and Paks. Construction of the training center started in the summer of 1994.
IAEA Training Program. Paks will use the reactor pressure vessel, steam generator and auxiliary equipment from the canceled Zarnowiec VVER-440 Model V213 nuclear plant in Poland in an IAEA training program scheduled to begin in 1996.
Between 1984 and 1987, the Soviet nuclear equipment supplier carried out four reviews of the Paks plant. The aim of the reviews, requested by the plant, was to assess Paks' operation in light of Soviet requirements. Paks widened the scope of successive reviews, inviting not only specialists from the Soviet Union but also from other VVER-440 plants such as Finland's Loviisa and Czechoslovakia's Bohunice, and comparing the plant's performance with international standards. Hungary was the first Eastern European country to request IAEA inspection of one of its nuclear plants.
OSART Mission. An IAEA Operational Safety Review Team (OSART) mission visited Paks Nov. 14-Dec. 2, 1988, to review operating practices of Unit 3. The team reviewing Unit 3 in 1988 noted several indicators of good performance: The unit's cumulative availability was above 86 percent; the unit had no events requiring the use of redundant safety systems; and unplanned outages during 14 reactor-years of operation numbered 27, extremely low by international comparison. The team found safety performance at a high level and recommended a number of good techniques for worldwide use. The team also suggested improvements to enhance the plant's strong safety record: a strengthened operating organization, six-shift operation, additional independence in quality assurance, on-line chemistry control, and improved industrial safety.
Follow-Up OSART Mission. In 1989, Hungary asked IAEA for a follow-up inspection to review the plant's responses to the recommendations of the 1988 OSART mission. The follow-up team visited the plant Feb. 25-March 1, 1991, and found that of the 140 recommendations and proposals made by the OSART mission, 127 had been carried out or were well under way. The team noted that management-initiated plant modifications and upgraded procedures would help Paks maintain and improve its safety record. The team also noted that management had recognized the importance of nuclear information exchange and had begun several programs to increase the flow of operating experience among plant operators. The team added that Paks' management was committed to operating the plant at the highest possible safety levels. Some areas requiring improvement were mentioned, including the use of personal safety protection, the tagging process and handling human performance problems. The team underscored the progress made in fire protection and in improving operational procedures.
ASSET Mission. Hungary requested an Assessment of Safety Significant Events Team (ASSET) mission to Paks to review operating experience, assess the appropriateness of corrective actions, and exchange views on further enhancing incident prevention. The team, which visited the plant Nov. 2-13, 1992, said that Paks' operational statistics compared well with world averages, and the plant appeared to have entered a period of steady operation since the commissioning of Unit 4 in 1987. The team also found favorable the continuous backfitting of the plant on the basis of intensive exchange of experience with other Model V213 plants.
The team suggested, however, that there was room for improvement in the prevention of incidents. The total number of safety significant events was higher than expected, and the number of events found by surveillance was low compared with the number of events originating from the operational process. But the team did observe an increase in the percentage of events found by surveillance compared with the total number of events, from 5 percent in the 1987-1989 period to 14 percent in the 1990-1992 period.
The team identified three safety issues in its analysis of the plant's reported events: actions by staff that were contrary to written instructions or were carried out in the absence of written instructions; problems in plant operation associated with the vigilance of personnel and the safety culture; and problems associated with instrumentation and control equipment.
The team concluded that, while many improvements had already been made and others were planned, additional improvement of plant reliability and availability could be achieved by giving full attention to the team's recommendations, concentrating on all aspects of personnel proficiency and procedural guidance. It said a follow-up ASSET mission to the plant in two to three years would be advisable.
Follow-Up ASSET Mission. A follow-up ASSET mission visited the Paks plant March 6-10, 1995. The team noted that since 1992, the plant had carried out several safety upgrading measures, including:
The team reviewed plant events between June 1992 and December 1994. Of 160 events, the team determined that 131 were of safety relevance. Of those, six were classified as Level 1 on the International Nuclear Event Scale, and the remainder, as Level 0. The team noted that the number of safety-significant events was considerably reduced from the number reviewed in the 1992 mission, and the effectiveness of the plant's surveillance program had improved considerably since then.
The team identified several safety problems, and Paks personnel assessed the potential consequences of those problems, including:
The team concluded that the in-house ASSET review carried out by Paks was complete and comprehensive. The team made several recommendations to further enhance the prevention of incidents, including reviewing and evaluating safety culture enhancement practices from plants in other countries and formalizing procedure verification/validation arrangements in plant documentation.
Other Reviews. In addition to the IAEA reviews, Paks has hosted several other international reviews and inspections.
Operational Safety Review. In 1990, Paks invited an international team of experts to carry out a review similar to that of the IAEA OSART review, but with a limited scope. The review team focused on operation and technical support. Among the team's recommendations: widen the use of the full-scope simulator for preliminary checks of non-routine tests and verification of operating procedures and modify the auxiliary emergency feedwater system to avoid common-cause failures.
IVO Design Review. In 1991, a team of specialists from Finland's IVO carried out a design review of the Paks plant. Using the Loviisa safety report as a reference, the team reviewed the safety features system by system and recommended some safety upgrades. Among them: improve high-pressure emergency core coolant pump reliability, control cooling water temperature for the components that feed the emergency core cooling system heat exchanger, and analyze the possibility of common-cause failures in protection systems.
Hungarian Review. In 1991, Hungarian specialists carried out a review of the plant, including the reactor load, the plant's reporting activity to the Hungarian regulatory body, and plant safety. In their report of the review, the specialists said that plant safety should be upgraded in accordance with current international requirements. This review was one of the initiators of the AGNES study.
WANO Peer Review. In February 1992, the first WANO peer review was carried out at Paks. The review methodology was based on the plant evaluation practice of the U.S. Institute for Nuclear Power Operations. The team identified several strengths at Paks, including good performance indicators, professional control room operation, management commitment to follow best international practices, good training program and excellent housekeeping. The team identified some areas for improvement, including procedure use, safety tagging, shift turnover, overloaded electrical cable trays, and feedback on the use of industrial experience.
December 1995