Balakovo NPP: Supply of safety related steam blow off valves type BRU-A Description Introduction Balakovo nuclear power station (Russian: Балаковская АЭС) is located in the city of Balakovo, Saratov Oblast, Russia, about 900 kilometers south-east of Moscow. It consists of four operational reactors. Owner and operator of the nuclear power station is Rosenergoatom. The plant has four VVER-1000 reactors (1000 MW each). All units are VVER- 1000 model V320. These units were connected to the grid in May 1986 and January 1988 for Units 1 and 2 and in April 1989 and December 1993 for units 3 and 4. Background The On-Site Assistance (OSA) programmes are a corner stone of the Tacis nuclear safety co- operation with the Russian Federation. Companies or consortia with experience of NPP operation in the EU are contracted by the EC to work on site at a nuclear power plant of the Beneficiary country. The aims are to provide the transfer of know-how, in particular through soft assistance, which addresses the human element of safety (i.e. safety culture, quality assurance, maintenance, management and training,…) and to upgrade the safety of the plant through the supply of equipment. At the time of this contract, OSA contracts were in place at seven NPPs in Russia (Kola, Balakovo, Kalinin, Leningrad, Smolensk, Beloyarsk and Novovoronezh). BRU-A valves are used to dump steam from steam generators to the atmosphere in case turbine is not available and steam pressure is too high. Each unit is equipped with 4 steam dump valves, one for each main steam line. According to the investigations performed by IAEA, one of the deficiencies of the dump valves (BRU-A) installed in the Russian Units was their missing qualification for operation with water and steam mixture. In case of leak from primary to secondary circuit, the water from primary circuit may fill in the SG and steam piping before BRU-A. Missing qualification of the valve operability under water or mixed steam and water release conditions could result into non closing of the valve after their opening. Failure to close BRU-A may result to containment by-pass, core over cooling and as a consequence to core damage. Missing qualification of BRU-A operability seriously affect the 3rd level of defence in depth and was a deficiency of the design. Based on the above mentioned, IAEA suggested the stations to conduct a series of activities to solve this problem. BRU-A valves originally installed in the units at Balakovo NPP were manufactured by Chekhov power machines producing plant, Russia. The initial analysis demonstrated that it was reasonable to replace BRU-A valves against more reliable valves qualified to work with steam-water and water. Objectives Supply and replacement of 8 BRU-A valves (4 for unit 1 and 4 for unit 2), including electrical actuators, sensors and interface with existing piping flanges. Project Results – Achievements (With reference to the TOR) In the frame of this project 8 BRU-A valves (4 for unit 1 and 4 for unit 2), including electrical actuators, sensors and interface with existing piping flanges and spares were supplied and installed on Balakovo Units 1 and 2. The Supply contract was awarded to Framatome ANP in September 2001 with Chekhov PEP as a subcontractor for the new BRU-A valves and Sipos Aktorik for the actuators. The valves were installed on Unit 2 during outage in June 2005 and on Unit 1 during outage in June 2006. Final acceptance certificate of the whole equipment was signed in June 2006, and final technical report was issued in May 2007. Comments (Quality of the results, Lesson learnt, Recommendations for follow-up) In course of the project implementation both administrative and technical problems arose: ● The requirement to Electro Magnetic Compatibility (ECM) were set in force in Russia after the project technical Specification had been developed and approved. This lead to additional testing of the actuators themselves and study of the rooms where the valves would be installed. That influences both the dates of project implementation and induced extra expenditure to finance the related activities. ● In 2005 during the testing of BRU-A electric motors a defect of electromagnetic brake diode was detected of the motor 1LC3133, plant number E0210/28753501010. The defected electric motor was repaired following the procedure and using the spare parts, sent by AREVA, the supplier of BRU-A valves. ● Operating the new valves in manual control was found difficult due to the great loads at the beginning. Tools were developed to facilitate the BRU-A valves control in manual mode. ● After the start-up of Unit 2, leakages were detected on 3 BRU-A valves. The valves were disassembled during next outage (one year later) and the defects on the sealing surfaces were removed. Further Information This project was similar to the other projects: - R1.01/94C (Kola NPP) - R1.02/94E (Balakovo NPP) - R1.05/94 D (Smolensk NPP) � General Information Title: Balakovo NPP: Supply of safety related steam blow off valves type BRU- A Programme: TACIS Status: Closed Amount: € 959.470,00 Old reference: ITALTREND 5455 (contact PA) Budget year: 1995 Countries: Russia Project R1.02/95B reference: Nature: Supply Decision number: multi annual Types of Equipment Supply activities: Method of Special Fund procurement: (Procurement Agent) NPP: Balakovo IAEA: III Duration 57 (months): Procurement ITALTREND 5455 Agent contract: Contracting Special Fund (EC) authority: Procurement NSP-015-BAL-005/95 Agent reference: Partner Rosenergoatom (Beneficiary): Procurement 18/07/2005 Agent provisional Contractors: Framatome acceptance: Procurement 30/06/2006 Agent Final acceptance: Signature date: 11/09/2001 Effective contract 11/09/2001 date: Contract end 30/06/2006 date: Closure date: 30/06/2006.