High performance generator stator leak monitoring system

1. A method of measuring hydrogen leakage from a generator core into generator coolant water flowing through the generator stator windings comprising the steps of:

providing a core hydrogen gas environment within the generator;

flowing coolant water in a flowpath through the generator stator windings and a conduit to a coolant water reservoir;

flowing air at a rate of less than 0.15 CFM into said conduit and the coolant water after the coolant water exits the stator windings; measuring the quantity of air flowing into said conduit and into the coolant water;

venting gas through a vent line from a contained vapor space over the coolant water within said coolant water reservoir; and

measuring the hydrogen content of the gas vented from the reservoir;

wherein flowing air at a rate of less than 0.15 CFM enables hydrogen leakage from the generator core environment through the stator windings into the generator coolant water to be determined in amounts down to about 0.2 CFD.

2. A method according to claim 1 wherein the step of flowing air into the coolant water includes inducing the flow of air through an opening in to said conduit and the coolant water by creating a low-pressure area in the flowpath of the coolant water within said conduit leading to the coolant water reservoir, the opening into the conduit being exposed to atmosphere.

3. A method according to claim 1 wherein the step of measuring includes providing a hydrogen gas analyzer in said vent line for sampling the gas vented from the reservoir to determine the fraction of hydrogen therein.

4. A method according to claim 1 comprising flowing air into said conduit at a rate of 0.10 CFD with said air filtered to remove CO2 as well as particulate and fluid contaminants.

5. A method according to claim 1 comprising activating a hydrogen gas alarm when the percentage of hydrogen in the air vented from the reservoir reaches no more than 4%.

6. A method according to claim 1 wherein the hydrogen gas alarm is activated when the percentage of hydrogen in the air vented from the reservoir reaches 1.33%.

7. A method of measuring hydrogen leakage from a generator core into generator coolant water flowing through the generator stator windings comprising the steps of;

providing a core hydrogen gas environment within the generator;

flowing coolant water in a flowpath leading from a coolant water source inlet, then through the generator stator windings and a conduit to a coolant water reservoir;

flowing air at a rate of between 0.1 and 0.15 CFD into the coolant water;

measuring the quantity of air flowing into the coolant water at an air sample rate of 1 CFH;

venting gas through a vent line from a contained vapor space over the coolant water within said coolant water reservoir; and

measuring the hydrogen content of the gas vented from the reservoir down to about 0.2 CFD±0.05 CFD.

8. A method according to claim 7 comprising activating a hydrogen gas alarm when the percentage of hydrogen in the air vented from the reservoir reaches no more than 4%.

9. A method according to claim 7 wherein the hydrogen gas alarm is activated when the percentage of hydrogen in the air vented from the reservoir reaches 1.33%.

10. A method according to claim 7 and further comprising implementing leak assessment guidelines based on hydrogen content in the gas vented from the reservoir.