These components relate to the key elements of the NPP safety system. They are capable of performing their function without operator’ attendance and even without power supply.
Eight PCFS hydro accumulators were installed in the design position in the reactor building of Power Unit 2. The full cycle of equipment installation took nine days.
The hydro accumulator is a thick-walled stainless-steel vessel weighing 77 tons (96 tons with a support part) and a volume of 120 cubic meters. During the power unit operation, each of them will be filled with boric acid solution. In the event of s primary pressure drop of the reactor plant below the preset values, the solution is automatically fed to the core, cooling the reactor.
The equipment was installed using the Open Top process — through the open top of the reactor building. This method, used for installation of large-sized elements at the early stages of the power unit construction, requires high accuracy, careful preparation of the installation area and well-coordinated work of all participants.
According to specialists, installation of hydro accumulators became an important stage in shaping the safety systems for the reactor plant of Power Unit 2.
Sergey Kizhapkin, Head of MAW Department, T2IC, noted: “Installation of hydro accumulators of the passive core flooding system is one of the key stages in shaping the safety systems for the reactor plant of Power Unit 2 Each accumulator has a significant weight and dimensions, so the work requires high accuracy and strict adherence to the installation process of large-sized equipment. All operations were performed in accordance with the schedule and requirements of the design documentation.”
Dmitry Plotnikov, Head of heat equipment section of nuclear island, TSM Enerji, stated: “The total weight of all hydro accumulators together with fasteners is 768 tons. Our mission included preparation and installation of embedded parts for accurate placing of equipment in the design position. The success of such large-scale works directly depends on the vast experience of each specialist and the flawless coordination of the installation team. Particularly difficult is the unpacking of hydro accumulators. This operation requires use of heavy cranes and the highest competence of personnel, so we pay special attention to training and inspection at each stage.”
Completion of the hydro accumulators installation allows to proceed to the next stage of construction of Power Unit 2 — installation of the sixth tier and the dome part of the reactor building inner containment.
For information:
The TITAN-2 Holding is a Russian group of companies that builds nuclear facilities. Organisations of the Holding perform the whole cycle of works, from development of basic design documentation to facility commissioning.
The TITAN-2 Holding is the general contractor for construction of the new power units of the Leningrad NPP. At the construction site, the organisations of the Holding perform all civil construction, installation, and electric installation works.
The Holding participates in the construction of Akkuyu NPP in Turkey, Paks II NPP in Hungary and El-Dabaa NPP in Egypt.