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The purpose of Turbine Bypass to Condenser - 14 to 16 valves circuit - is to canalize the secondary circuit steam directly to condenser. The circuit allows evacuating up to 85% of reactor power (in case of load variation, turbine loss, in shutdown or restart phase).

On this type of plant, a default of tightness swiftly generate great financial loss in parts and in production.

Diagram of the Turbine Bypass Group to Condenser:

diagram of turbine bypass group

Combining the acoustic control and the "rate of decrease of pressure" test, MMC can determine the leaks discharge for each of 16 valves.

analysis grid
analysis table

The table below points that the elimination of the four most several leakages (repairing only 25% of the valves) would eliminate a minimum of 75% of the leakage on the set of 16 valves, saving 3097kg/h of steam.

before outage after outage
Before outage After outage

Two graphs below points the GCT 116 VV Valve signatures before and after intervention. We notice the differences of range between two black curves.

This method allows a significant reduction of efficiency losses in Nuclear Power Plants and of maintenance costs for the 16 Masoneilan valves.

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