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| Entered date | Event description | |
|---|---|---|
| ENS 40610 | 25 March 2004 17:56:00 | Subject:Roots Blower on OP Engines On March 23, 2004, Fairbanks Morse Engine evaluation determined a potential safety hazard exists for blowers (P/N 16609294) on OP engines. It is possible that the aluminum rotors can slip on the steel shaft and cause rotor-to-rotor or rotor-to-housing contact which could cause blower failure and inability of engine to perform its safety function. The defect was caused by improper cleaning of the shaft prior to casting the rotor onto the shaft. This causes an inadequate bond and allows the aluminum rotor to move axially on the steel shaft. Sample testing of rotors has found this condition to exist to varying degrees on approximately 75% of rotors produced between 1998 and 2003. (4) blowers were shipped to nuclear utilities that may be affected: Utility Site Blower S/N Exelon Limerick (RB813A, RB3871, RB816) Entergy ANO-2 (RB814) To date, no engine failures have been experienced as a result of this problem. However, the potential exists. All slipped rotors have been found during routine maintenance inspections. This condition has been found to manifest itself within a low number of hours of operation. Therefore, the longer the rotors run and maintain proper clearance, the less likely they are to be affected by this condition. The affected utilities will be notified to evaluate inspection results and replace as necessary. |
| ENS 40524 | 16 February 2004 14:57:00 | On February 12, 2004, Fairbanks Morse Engine evaluation determined a potential safety hazard associated with the use of ABB turbocharger model VTC-304 on OP engines only. Torsional resonance has been found in the rotating assembly which is excited by exhaust pulses. The resonance manifests itself as either a bent or broken shaft, slipped compressor wheel, cracked compressor wheel or complete rupture of the compressor set. Once failure occurs, engine power cannot be sustained. This condition is corrected by machining the rotating assembly to tune the natural frequency away from operating conditions. The only affected site is Crystal River 3. (6) turbos have been shipped to this site. None of the turbos have been installed and all are in storage. The FM parts department will arrange to have the turbos returned to the factory to have the necessary machining performed. |