Westinghouse RCP

A 4000hp motor???


(DelawareOnline) Eight thumb-sized, broken bolt-heads have sidetracked PSEG Nuclear's plans

for restarting its Salem Unit 2 nuclear reactor, as investigators work to find the breakaway spots and reasons for failure.

Discovery of the broken reactor coolant pump parts during a routine refueling outage prompted
Company spokesman Joe Delmar said Wednesday afternoon that PSEG was being conservative in delaying its restart to allow "additional internal inspections of the coolant pumps and make any repairs as needed." the company to extend the shutdown, which began April 14. It was the latest in a string of problems at the Salem/Hope Creek nuclear complex.
Nuclear Regulatory Commission spokesman Neil Sheehan said the bolt tops, each about an inch in diameter and 3 inches long, are likely from the area of one of four reactor coolant pump's impeller vanes, or blades.
Investigators consider "stress-corrosion cracking," – a kind of failure that occurs in some types of metals exposed to particular types of stress, temperature and corrosive conditions – as one of the potential causes for the breaks, Sheehan said.
"The concern is that if bolts holding the turning vane failed, the vane could drop and impact the rotating pump internals," Sheehan said.

According to this information release, the turning vane diffuser is the problem. There are bolts that secure the turning vane diffuser to the upper flange also hold the thermal barrier can assembly in place. The issue could end up being equal to a locked rotor accident, which has never happened. A locked rotor accident challanges the peak clad temperatures more than any one accident.
Flywheels on these 7-8K HP pumps are about the same weight as a heavy duty pickup, about 8K lbs. Not much can challange the costdown of these pumps, except a locked rotor. The lower radial bearing has been know to fail (ancient history), and the motor has enough power not phase it.
This is a very isolated issue, based on manufacture date and material used.

westinghouse

 

 

 

 

 Byron Jackson, CE