Background
The aim of the on-site assistance (OSA) Large scale project for Kola NPP was to maintain a strong EU engagement in order to support the country efforts to deal with problems inherited from the past in the context of on-going budget difficulties.
The general objective of the on-site assistance was to combine the experience of TVONS as the Contractor (EU Utility) with the experience and needs of KOLA NPP (the beneficiary state Nuclear Power Plant), with a view to improve the operational safety of the NPP and to carry-out specific safety related projects, which include also equipment supplies. Rosenergoatom was pursuing a joint venture for production in Russia with Western valve manufacturers.
The project concerned a common problem with safety valves on SG (also on VVER 230, 1000 and RBMK SG).
Kola NPP, stage 2, has two identical 440MW units (units 3 and 4), with six steam generators belonging to each unit. Condenser by-pass valves, steam dump valves and safety valves were installed to protect the steam generators from excess of steam pressure. Two safety relief valves at each steam generator have the function to protect the vessel and live steam pipes from excess pressure during deviation from normal operation or in case of emergency. Because of the energy potential in the SG, the safety valve issue was considered of high importance.
To achieve the improvement of safety and reliability of Kola Nuclear Power Plant (End user) in the Russian federation, the program “TACIS 93/94 On-site assistance Kola NPP” provided the refitting of the safety relief valves for the steam generators of unit 3 and 4.
Objectives
The aim of the project was the replacement of the existing safety valves on the steam generators by modern safety valves.
Project Results
24 safety relief valves for two units, each provided with main and pilot valve, were installed under the Program “TACIS 93/94 On site assistance Kola NPP”.
The supplier (SEBIM) supplied for two units the complete set of safety relief valves, including pilot valves and control system (valves equipment, electrical control and diagnostic system, set of three rings for welder certification). Along with this, were provided spare parts and consumables, auxiliary equipment and tools for installation and normal operation, fatigue analysis, supervision of unpacking, supervision of the installation works by Kola staff, commissioning/ acceptance testing, training and instruction in the use of the supplies, a documentation package in English and Russian, after-sales services including maintenance and repair.
The kick off meeting was held at Kola NPP on 07.04.2000. Valve manufacturing for Sebim had been started already before the agreement was signed (the agreement concerning control system was signed on 12.04.2000).
Twelve Sebim Steam Generator Safety Valves with their control systems have been installed in Kola NPP unit 4 during outage on the 01.03 – 15.04.2001 and at Kola NPP Unit 3 in outage on the 03.08 – 13.09.2001. In frame of TACIS program, according to Contract NSP-038-KLA-001 the delivery of SG safety valves has been fulfilled by SEBIM in accordance with the agreed schedule.
Two of the SG pilot safety valves were found defected, and the defects needed to be eliminated during the next outage at Unit 3 in August 2002. The final acceptance for services, additional spare parts and consumables was submitted on the 09.01.2002.
During the outage 2002, surface shrinkage and cracks were detected in one safety valve. During the outage period August-September 2003, Sebim specialists decided to replace the body of the valve due to the manufacturing defect, but the extra equipment delivery caused customs clearance difficulties.
Sebim shipped a modified valve body to Kola NPP on 27.01.2004.
Kola NPP, task manager and TVONS decided in the meeting at Kola NPP on 15-16.01.2004 not to sign the FAC documents, because one valve body replacement was scheduled to be done during the outage in August 2004. The warranty period was prolonged until August 2005.
FAC was partially signed on 12.10.2005, not covering the valve ref. 18365 as it had been repaired during the warranty period.
Equipments were installed in normal condition. FAC was signed in August 2006, at the end of two year warranty, issued after the valve body replacement performed in August 2004.