Steam Separator Replacement Project in Temelín NPP - Key Contribution by ŠKODA JS

30. 6. 2020

The Temelín Nuclear Power Plant modernization project includes a challenging partial project consisting in replacement of steam separators with new, more efficient equipment.

ŠKODA JS a.s. has entered the project as a principal local partner of the equipment manufacturer Balcke-Duerr. Our company was assigned to conceive a complete project implementation plan, to define internal transport and lifting operations, to map out the current state of the technology, and to draw up project and installation/implementation documentation focused on meticulous engineering preparation for all site activities. It also included setting up transport and handling plans to ensure occupational safety in handling the oversized equipment in a limited space, equipment setting in the final position with millimetric precision, and connection to the current technology.

The project and all preparatory works lasted 18 months. ŠKODA JS developed a 3D model, complete documentation, a construction organization project, and technological procedures. To eliminate any unexpected situations in installation during the power unit shutdown as much as possible, a trial assembly of the pipe bundle into the separator body was conducted together with the manufacturer and ČEZ. The separator replacement project consists of four such sophisticated operations per unit during the shutdown (each unit having 2 separators with 2 pipe bundles).

The project implementation process itself started with pre-shutdown works which consisted in piping prefabrication, production of assembly and fixation devices with the aim to ensure maximum safety at work and technology protection, and disassembly of a working platform in the Unit 2 machine house to free the transport corridor needed to transport the separators. Another crucial point of the project was turning the 114-ton separator shell with its length being 32.8 metres and height being 4.4 metres from the transport to the assembly position. These works lasted 7 hours, and they are now followed by a difficult operation of sliding the pipe bundles into the separator shells. The said pipe bundles were transported to the Temelín NPP from the manufacturing plant at the end of April. Each bundle weighs 32 tons and is 14 m long. The total number of pipe bundles is four, two for each steam separator-superheater. After installing the pipe bundles in the separator shells, the existing technology will have to be reconnected, which means connection of each separator to approximately sixty pipelines of diameters from 20 millimetres to 2.2 metres.

At the beginning, the works at the nuclear power plant were hindered by the measures taken in connection with the COVID-19 disease propagation. The restriction of people movement between the Czech and Slovak Republics, for instance, resulted in additional complications, but we managed to incorporate our qualified colleagues from the Slovak division of ŠKODA JS in the works to keep up with the time schedule. They contributed substantially with their professional knowledge to the so far successful course of the project implementation activities.

“The thorough engineering works were worth the trouble, as from the moment our workers took over the separators from the carrier in the nuclear power plant premises and started their works punctually with the beginning of the shutdown up to the present setting of the new separators in the final designed positions, we managed to control, coordinate and finalize all the activities in required quality and without any delay,” said the General Manager of ŠKODA JS František Krček. “Thus, our execution team succeeded in joining ideally the preparatory engineering works with the coordination of the executive units on site. This project is no exception for us in doing our best to keep our tradition to manage the modernization works of nuclear power plants in our country during their respective scheduled shutdowns.”

The schedule of ŠKODA JS installation works in this project comprises 488 partial activities to be performed and coordinated within the power plant’s shutdown regime. The works are performed in two 12-hour shifts. A 50 metres long trailer is used to transport the equipment, and a unique device manufactured for mechanical works on saturated steam supply piping of over 2 metres in diameter is used specifically to cut and chamfer nozzles of such dimensions. The execution works during unit shutdown are performed by a team of as many as 90 ŠKODA JS workers, consisting of coordinators, quality inspectors, welding supervisors, and 60 assembly workers – experienced pipe fitters and welders. In addition to them, teams of scaffolders and insulation workers are under the leadership of ŠKODA JS.

After finishing the steam separator replacement project at Unit 2 of the Temelín NPP, the same operation will follow at Unit 1, also during the regular scheduled shutdown.

Jan Stolár, spokesman, ŠKODA JS a.s.,  +420 605 221 093