ML17266A073

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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 NextEra Energy icon.png
Issue date: 06/07/1979
From: SCHOPPMAN M A
FLORIDA POWER & LIGHT CO.
To:
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML17206A852 List:
References
LER-79-017-03L, LER-79-17-3L, NUDOCS 7906180555
Download: ML17266A073 (2)


Text

NRC PQRIrI 544 IT TTI LlCEIVSEE FVHIVT REPORT V.S NVCt 6AR RSOVLATOAY CO>>!MISSION

~o 3 CQN'T~O p 2 CQNTRQL, SLCCKI I I I I FILIS L ISI1Q20 0-9 UCLrr$44 CQCS I Ql" (PLEASS PRINT QR TYPS AI.L REQVIRSQ INPORMATIONI OI OIOI OIO-010 Qrt II Qi~IQi UCSIisa'i'IUM44R

'15 15 I aa-'454 TVPS i4 51~T 53!6 I I I I Qg 74 75 ilaPCrIT QAT4 0 Pum.casin block it was";;~lrQ 0 0 0>>Q~40 41 QQCK4 i HUMSSR 43 49 SVS>>T QATS 6VSNT QSSCRIPTIQN ANQ PRQIABL6 CQNS6QVSNC'6S QIQ Durin 1 armed re 1acement of the 1B Char in~02 found that the ol d block, contained several internal cracks centered around the um's ressure'hambers.

The cracks did not enetrate the block.This char in um block was bein re laced due to recent failures of the~as A an 1~pg T 3 9 Ia svsTau cAU54 cAU54 caMP.yALys CQQ4 cQQS suacaoa ccMpo>>SHTcaoa suacaoa suacaos S L<JS L~JS~+<"'r rS MES LrrS 9'0 II 11 11 1$'19 10$4CUa>>TIAI OCCUR IISNCS RSPQRT~.RSVISIQH 11 Ts 14 12, 15 11 11 ACTION PUTVRS SPPSCi sriUTQOWH+'TTACNM4>>T 4PRQW PRIMS COMP CQMPOHSHT TAKSH ACTICH CH PLANT A!4TIICO, NOVAS+22 SUSMITTSO PORlMSU8 SV JPLI4R MANUPAC VRrIR LrrS~xS.~iS MzS Lraoo.r EYES~YS~IQ~Ea 4 5 Q 14 15 14 3I S0 4 I 41 44 47'AVSS O6scRIPT!ON ANO CORRSCnv6 ACTIONS Q23 o.The cause.a ears to have-been-.vibration ca e b the um s.Suction dam enin devices accumulators will be install d all three um s to reduce cavitation.

Preliminar installation work to install these accumulators at ower is com lete'and these accumulators will be installed shortl after deliver.The 1B um block was re laced.I 4 9 P Ac I LI.Y.IQ MSTIICO QP ST*IUS'5 PCWSR QTIISR STATVS p/01$CQVSRY i LtuQrr~00 Qi NA~C(Dr 1 10'$11 SS 45 Ja ACTIVITY COHTSRT RSLSASSO 01 RSLSA54 AAIQUNI'QP

~iVITY QS 6~Z Q22~ZQ25 NA I 3 9 14 11 IA 49 psA50>>HSL axpa5VA45 r Loooo rQ>>2 Q>>'A 5 11 11 11 Psil$0>>>>SL IHIU>143~o'" o"o 8" NA 9 I I 11 LC5$QP CR QAMAC'4 ia SACIUTY Q42 VPS CSSCRIPTIQH Z'Q 1'0 pvaLIC.T.:ssuao 04$CRI pT!c>>Qas LN ISA 01$CQVSRY 045CIIIPTICH Q2 S ecial Ins ection LQCATIQV OP RSLSA$4 Q26 NA 30 g I 4!0~NBA!6 QP PRSPARSR>906'Z 80~~&NA NA H.A.Scho man ao 30 NRC LCK ONLY I-'ll 44,49 IO 305 552-3802 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).