United States Nuclear Regulatory Commission - Protecting People and the Environment

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. 

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