ML17266A073

LER 79-017/03L-0 on 790509:1B Charging Pump Casing Block Contained Several Internal Cracks Centered Around Pressure Chambers.Caused by Suction Cavitation Resulting in Vibration.Pump Block Replaced

ML17266A073
Person / Time
Site:	Saint Lucie
Issue date:	06/07/1979
From:	Schoppman M FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML17206A852	List: ML17206A851 ML17266A073
References
LER-79-017-03L, LER-79-17-3L, NUDOCS 7906180555
Download: ML17266A073 (2)

Text

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REPORTABLE OCCURRENCE 335-79-17 LICENSEE EVENT REPORT PAGE TWO Additional Cause Descri tion and Corrective Action An engineering evaluation of the Charging and Volume Contro1 System (CVCS) operation and vibration was performed in September of 1977. This evaluation suggested that suction cavitation may be the cause of vibration within the system. Based on this,-plans were made to install pulsation dampening devices (accumulators) on the suction of each charging pump. Installation was scheduled to be performed during the 1980 refueling shutdown.

On 9-2-78, the 1A charging pump was found to have a cracked casing (see LER 335-78-34). The procurement of materials to install the suction pulsation dampening devices was placed on. an expedited basis. The cracked casing was replaced with a new casing on 1-9-79. On 3-16-79, the 1C charging pump was found to have' cracked casing (see LER 335-79-11).

Presently, the plant is shut down in the final stages of the 1979 refueling '

outage. Preliminary work on the CVCS was performed during this refueling outage to enable installation of the pulsation dampening devices during full power operation later this year. During power operation, only one charging pump at a time will be removed from servic'e to install the pulsation dampening device on that pump. This allows install ation during power operation while still fulfilling Technical Specification requirements for the CVCS. Delivery of the pulsation dampening devices is presently scheduled for September, 1979. The devices will be installed shortly after delivery.

Both the 1C and 18 Charging Pump Blocks were replaced during the 1979 refueling outage. The replacement blocks for all three pumps were of an improved design with fewer stress riser points (which reduces susceptability to cracking).