A nuclear power plant case study…
Nuclear plants need to function effectively and have reliable systems. The equipment and manpower that keep the equipment functioning is crucial not only to the continued ability to provide power services, but to the safety of all of us. All nuclear power plants are required to maintain and regularly test their pumps to ensure operability in the case of a nuclear event or emergency. If they didn’t, the potential outcomes could range anywhere from the inability to produce electric energy to the occurrence of a catastrophic nuclear incident, potentially affecting many thousands of people. Simply put, nuclear power plants cannot afford to have malfunctioning equipment.
An auxiliary feedwater (AFW) system is one of the important features of a pressurized water reactor (PWR) nuclear power plant. This system serves two functions:
- During normal startup and shutdown operations, the AFW system provides a reliable source of water for cooling the plant steam generators.
- Following a reactor trip, the AFW system will provide an emergency source of cooling water to the steam generators in order to remove the heat generated by the decay of fission products in the nuclear fuel.
Both of these functions are crucial, and the pump must be at peak performance in either case.
The Problem
A nuclear utility was experiencing repetitive maintenance and operational issues on its AFW pumps, reducing both system and unit availability. The issues included high thrust-bearing temperatures, black oil or oil discoloration and vibration amplitudes exceeding acceptable limits for operability. These pumps were Ingersoll-Rand Model HMTA, 10 Stage, Horizontal split case designs. The utility had worked over a period of several years to resolve the reliability issues with no success. Continue reading