Test report: Generator stator bar leak quantification and pinpointing.

摘要

Tests to detect generator stator bar leaks were conducted at the Union Electric Labadie Power Plant during a two-day period in January. The stator bar assembly of the unit No. 4 generator was pressurized to 5 psi with nitrogen containing 300 ppm of PMCP (perfluoromethylcyclopentane). The presence of the tracer in the generator shell was discovered with passive samplers that were attached to stator bars on both ends of the assembly. The arrangement allowed the detection of areas of increased concentration necessary for subsequent pinpointing of leaks. Leak pinpointing was achieved by sampling air in these areas of higher concentration with the Dual Trap Analyzer. A second tracer, PMCH (perfluoromethylcyclohexane), contained in a l-liter cylinder with a known emission rate was used to quantify the leak rates from the stator bar assembly. The average leak rate was determined to be 50 liters/day (about 2 ft(sup 3)/day) at a nominal pressure of 100 psi. Investigation of several accessible leaks showed leak rates about 1000 times smaller than the overall leak rate. Hence, none of the leaks in the upper accessible half of the generator shell was the major leak. 1 fig., 2 tabs.