Objective
Improvement of the secondary loop water quality by avoiding corrosion of the turbine condenser tubes.
One of the reasons for defects in the steam generators (Model PGV-1000) of the VVER-1000 plants is the infringement of water chemical conditions in the secondary circuit because of erosion-corrosion resulting from tube leakage of the steam turbine condensers.
The cooling tubes of condensers in Balakovo NPP are made of copper-nickel alloys (Cu-94%, Ni-5%, Fe-1%) and do not have the necessary resistance against corrosion. Corrosion arises under the micro and macro fouling on the inner side of cooling tubes of the condenser. Beside that even thin micro biological layers cause considerable output reductions of turbines and units.
Western NPP condensers are made increasingly of titanium and/or stainless steels or specific copper alloys depending on the water qualities and whether they are equipped with an efficient tube cleaning system.
The existing tube cleaning systems in RF was considered imperfect and does not guarantee the necessary cleaning.
At the same time it was considered necessary to install one debris filter system prior to each tube cleaning system to avoid jeopardizing the rubber ball cleaning system's proper functioning.
Result
A rubber ball condenser tube cleaning system has been supplied and installed on one of the 4 units in operation.
In addition (as project sub-part R1.02/92 A1) 4 debris filter systems have been delivered and installed.
R1.02/92A1 - Balakovo NPP: Main cooling water filters
Objective
Debris filters before the condenser were planned to be purchased within this project. These filters are recommended to operate the rubber ball cleaning system, supplied under Project R1.02/92A properly.
Result
The project was merged with project R1.02/92A, the supply of the condenser cleaning system (Project R1.02/92A) and has been installed together with the condenser cleaning system.