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Main Condenser Repair: Tube Insert Installation and Tubesheet Coating
South Ukraine Nuclear Power Plant, Unit #3 — Ukraine
South Ukraine Nuclear Power Plant, Unit #3 · Ukraine
The Problem
Three Concurrent Condenser Failure Modes
Inlet-End Tube Erosion
Erosion at the inlet end of the tubes was causing leaks across a number of tubes.
Tube-to-Tubesheet Joint Leaking
General leaking at the tube-to-tubesheet joint across the condenser.
Outlet Tubesheet Scaling
Scale accumulating at 3–5 millimeters per year, progressively degrading heat transfer performance.
Specification
CuNi Tube Inserts + Epoxy System, Spray Applied
Application
Condenser Tubes & Tubesheets
Substrate
Carbon Steel Tubesheets
Total DFT
50 mils (25 primer + 25 topcoat)
Tube Inserts
6-to-8 inch 90/10 CuNi metal inserts installed in all leaking tubes. Expanded into existing tubes using a deep roll to ensure a smooth transition into the existing tube bore.
Surface Preparation
Tubesheets plugged and abrasive blasted to SSPC SP-5 White Metal.
Primer
25-mil epoxy primer applied by heated plural component sprayer. Pits and stripped weld seams filled with epoxy rebuilding compound.
Topcoat
25-mil epoxy topcoat spray applied for a total DFT of 50 mils.
The Result
Immediate Performance Recovery — Units #1 and #2 Subsequently Completed
June 1995 Inspection
95% of tube leaks remedied. Tube-to-tubesheet leaking eliminated. Outlet scaling easily removed by water blast.
December 1995 Inspection
No coating damage. Continued outstanding performance.
Following successful completion of Unit #3, Units #1 and #2 were subsequently completed on the same specification.
High-performance epoxy systems for industrial repair and protection.
