Czech Temelín uses new metal deposition method as one of the first in the world

Temelín nuclear power plant has used a new method of depositing metals at supersonic speeds. Temelín is among the first nuclear power plants in the world to use the technology, known as Cold Spray, which enables repairs without heat, flames or the risk of material damage. It is working with the Research and Testing Institute (VZÚ) Plzeň to introduce the method. The main benefit is savings in both time and costs, plant spokesperson Marek Sviták told journalists today.

Some time ago, the plant’s engineers tested the new method while repairing a high-pressure component of the second unit’s turbine and electric generator. Now, in cooperation with VZÚ Plzeň, they want to qualify the modern method, which makes it possible to add missing material with an accuracy of hundredths of a millimetre without conventional welding, for repairing sealing surfaces as well as heat exchangers and valves.

"We are introducing new technologies and procedures, and the Cold Spray method clearly belongs among them, although we always proceed conservatively and verify the safety parameters, reliability and effectiveness of new methods," said Bohdan Zronek, a member of the ČEZ board and director of the nuclear energy division.

The principle of Cold Spray technology does not lie in melting, but in enormous kinetic energy. Metal powder particles are accelerated by a carrier gas to supersonic speed. When they strike the base material, the particles mechanically anchor themselves and form an extremely strong layer. "The base material remains almost untouched, which is crucial when repairing sensitive plant components. No heat-affected zone is created as in welding, and there is no oxidation or thermal stress," said Zdeněk Čančura, director of the nuclear power plants’ quality management department.

For the plant, the main benefit is savings in both time and costs. The method makes it possible to repair even minor defects directly on site, without having to replace entire expensive parts. The resulting coating is very thin and easy to machine. If necessary, technicians can add to the layer at any time without any thermal preparation. The introduction of Cold Spray technology is another step towards ensuring the long-term operation of the Temelín units.

Since the start of the year, Temelín plant has generated 5.6 terawatt-hours of electricity. ČEZ will invest CZK 3.8 billion in modernising the plant this year. That is CZK 700 million more than last year.