With great pleasure, we'd like to proudly announce, that Koli Sp. z o.o., as a first nondestructive testing laboratory in Polish history, was approved and conducted inspection in closed turbine in nuclear powerplant.
Diagnostics were performed from 13th September to 4th October in Forsmark (Sweden), in the Unit 3 of Vattenfall group nuclear powerplant. Testing was performed on last stages (L-0) blades of 3 low-pressure rotors, without dismantling.
Rotor without blades removed, still being in it's own bearings, is a huge diagnostic challenge - blades roots are hidden by shaft grooves, making it impossible to see the surface of hooks, which are the areas to be most commonly exposed to stress-fatigue cracking. What's more, working on scaffoldings and testing such a big construction limits possibility to use standard solutions and, obviously, is exhausting for the operators.
Koli Team, during only 2 (!!!) months, created effective systems and procedures for blades aerofoils and roots testing using surface (visual VT, magnetic particle MT) and volumetric (ultrasonic phased array PAUT) NDT methods.
But the most unique thing about it is the Phased Array system, with full data recording, giving capability of scanning the most critical areas of blades roots, without removing them from rotor. Scanners, special delay lines (i.e. "continous wedge" - the wedge with variable geometry along the scan path), instrument set-ups and procedures were fully designed and assembled by Koli Sp. z o.o. inspectors.
All the procedures and inspection systems have been approved by general outage contractor - GE Power.
We are proud that our reputation and customers credits allow us to inspect the most critical constructions and objects in the world!
Nuclear powerplant turbine - 3 LP rotors
All 3 powerplant blocks - total generated power is 3,270 MW
Annual production of electrical energy is about 25 TWh