Information Notice No. 81-24: Auxiliary Feed Pump Turbine Bearing Failures
SSINS No.: 6835 Accession No.: 8107270003 IN 81-24 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 August 5, 1981 Information Notice No. 81-24: AUXILIARY FEED PUMP TURBINE BEARING FAILURES Description of Circumstances: During an inspection of one auxiliary feed pump inboard turbine journal bearing to determine the cause of dirty oil, Baltimore Gas and Electric Company found the hearing damaged. The other auxiliary feed pump turbines were disassembled and similar damage was found on all inboard journal bearings. The turbines are Terry Turbine type GS-2. Bearing lubrication is accomplished by oil ring pick-up from reservoirs at either end of the turbine. Each reservoir is fitted with a sight glass about three inches long to monitor oil level. The damage has been attributed to a failure to maintain oil level within a narrow operating range (approximately 1/4 inch) within the sight glass. A similar instance of bearing failure was discovered by Northeast Utilities during an inservice inspection of the turbine bearings at Millstone Unit 2. Both facilities reporting the bearing failures have the Terry Turbine type GS-2 where bearing lubrication is supplied by oil ring pick-up only. The corrective actions taken have been to clearly mark the maximum and minimum allowed oil levels on the sight glass. A spot check of other facilities using Terry Turbines in PWR and BWR applications has revealed that the Terry Turbine types GS-2 and GS-1 can have a combination of force feed and oil ring pick-up lubrication. In these applications, the oil ring pick-up supplies lubrication during startup and coastdown of the turbine. A check of the Technical Manual has shown that proper oil level range for the oil ring pick-up was not addressed. However, the level should be maintained within a narrow range to provide adequate lubrication during startup & coastdown. No written response to this information is required. If you need additional information regarding this matter, please contact the Director of the appropriate NRC Regional Office. Attachment: Recently issued IE Information Notices
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Page Last Reviewed/Updated Tuesday, March 09, 2021