ML20011D335

LER 89-027-00:on 891120,chemical & Vol Control Sys Centrifugal Charging Pump 1B Declared Inoperable Due to Inability to Maintain Sufficient Charging Flow.Cause Not determined.Power-range Detector replaced.W/891222 Ltr

ML20011D335
Person / Time
Site:	Catawba
Issue date:	12/20/1989
From:	Glover R, Owen T DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-027-01, LER-89-27-1, NUDOCS 8912260177
Download: ML20011D335 (6)

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19 DUKE POWERJ December 22, 1989 i Document Control Desk

                 U. S. Nuclear Regulatory Commission Washington,'D. C.             20555

Subject:

Catawba Nuclear Station

                                      -Docket No. 50-413 LER 413/89-27 Genticmont Attached is Licensco Event Report 413/89-27, concerning Technical Specification required unit shutdown due to an inoperabic chemical and volume control contrifugal charging pump.

This event was considered to be of no significance with respect to the health and safety of the public. Very truly yours, I Tony B. Owen h Station' Manager kob\LER-NRC.TBO xc: Mr. S. D. Ebneter American Nuclear Insurers Regional Administrator, Region II c/o Dottie Sherman, ANI Library U. S. Nuclear Regulator Commission The Exchange, Suite 245 101 Marietta Street, NW, Suite 2900 270 Farmington Avenue Atlanta, GA 30323 Farmington, CT 06032 M & M Nuclear Consultants Mr. K. Jabbour U. S. Nuclear Regulatory Commission 1221 Avenues of the Americas Office of Nuclear Reactor Regulation New York, NY 10020 Washington, D. C. 20555 INPO Records Center Suite 1500 Mr. W. T. Orders 1100 Circle 75 Parkway NRC Resident Inspector Atlanta, GA 30339 Catawba Nuclear Station Q1% ) I\ 8912260177 891220 1" PDR ADOCK 05000413

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       ' b Es m m ,,,.. auseTro su,W35tDN DA fil                                          NO                                                                   0l5   0l 2 9 l0 Au T M AC T ,L        um .m.,  . . . ,.. e, ,,,-,        .. ..   .m,.~,.,     n el On November 20, 1989, at approximately 1650 hours, with Unit 1 in Mode 1, Power Operation, at 100% power, Chemical and Volume Control (NV) System Centrifugal Charging Pump 1B was declared inoperable due to its inability to maintain a sufficient charging flow. Subsequently, a work request was initiated to i                       investigate and repair NV Pump 1B. On November 22 at approximately 1400 hours, I                      with Unit 1 in Mode 1 at 100% power, the Control Room Operators (CR0s) commenced a power reduction as required by Technical Specifications due to the inoperability of r Pump 1B. On November 28, with Unit 1 in Mode 4, Hot Shutdown, NV Pump io repair work was completed and the pump was declared operable. The repair work involved replacing the pump's rotating element. The CR0s then proceeded to place the Unit in Mode 5, Cold Shutdown, for further outage related work. On November 30 at 2246 hours, Unit 1 entered Mode 1 and l                     -the CR0s began increasing Reactor power to 100%. This incident has been L

attributed to Equipment Failure. The root cause of this equipment failure has not been identified at this time. However, this report will be revised based on

t. a failure analysis report on the rotating element which was removed from NV Pump L IB.

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-                 BACKGROUND The Chemical'and Volume Centrol [EIIS:CB] (NV) Tystem is composed of three main                                            l subsystems:

1. Charging, letdown, and seal water

2. Chemical control, purification and makeup

3. Standby makeup The charging and letdown functions of the NV System are employed to maintain a programmed water level in the Pressurizer [EIIS:VSL], thus maintaining proper Reactor Coolant [EIIS:AB] (NC) System inventory. This is accomplished by a continuous feed and bleed process in which the feed flow is automatically ,

controlled by the Pressurizer level. The bleed rate can be chosen to suit , various plant operational requirements by selecting the proper combination of I letdown orifices in the letdown flow path. The charging pumps [E!!S:P] normally take suction from the Volume Control Tank (VCT) and return the Reactor Coolant to the NC System via the Charging System.- Charging flow may be delivered by a non-safety related Positive Displacement Charging Pump or either of two safety related Centrifugal Charging Pumps. Both Centrifugal Charging Pumps are required to be operable by Technical Specification 3.1.2.4. With one Centrifugal Charging Pump inoperable, there are 72 hours allowed to repair the pump or to start shutdown of the Unit. The charging flow rate for the Centrifugal Charging Pumps is controlled by INV294, NV Pumps A and B Discharge Flow Control Valve [EIIS:V]. A minimum flow for Centrifugal Charging Pump protection is continuously diverted from the charging pump discharge back to the VCT through the Seal Water Heat Exchanger [EIIS:HX]. EVENT DESCRIPTION On October 11, 1989, PT/1/A/4200/07B, Centrifugal Charging Pump 18 Test, was satisfactorily completed. On November 15, NV Pump 1B was placed in service and NV Pump 1A was removed from service per normal equipment rotation. . On November 20, at 1356 hours, with Unit 1 in Mode 1, Power Operation, at 100% power, NV Pump 1B was removed from service due to its inability to maintain a sufficient charging flow with INV294 at 100% demand. At this time, NV Pump 1A was placed in service. At approximately 1650 hours, NV Pump 1B was declared

                   -inoperable and Work Request (W/R) 52143 OPS was initiated to investigate and repair NV Pump 1B.
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                                                                                             '5^a      " Wif,','.     7A*.,3 C*tawba Nuclear Station, Unit I ftK1 (Jr neere essee e soge w ed, e,se smooner MC Fenn Jihd W (1h o l5 lo j o l0 l 4l113 819  -

012 l 7 - 010 Ol 3 0F 0l5 Under W/R 52143 OPS, Mechanical Maintenance (M/M) personnel hand rotated the pump and no-rubbing or binding was detected. Performance personnel measured bearing temperatures and vibration levels and reported higher than normal results. Performance then began preparation for a Head Curve Test per PT/1/A/4200/07B. At 2244 hours, the test was completed with satisfactory results. However, there was a noticeable decrease in discharge head pressure as compared to the previous test performed on October 11. After further troubleshooting, the decision was made to replace the pump's rotating element. On November 20, PIR 1-C89-0354 was initiated, requesting that Design Engineering provide justification for not performing a full flow balance after replacing the rotating element. On November 22, Design Engineering responded with the necessary test criteria which needed to be m9t in order to not perform a full flow balance test. On November 22, at approximately 1400 hours, the Control Room Operators (CR0s) commenced power reduction as required by Technical Specification 3.1.2.4. On November 23, at 0015 hours, the generator breakers [EIIS:BRK] were opened. Subsequently, Unit 2 entered Mode 2, Startup. At 0021 hours, Unit i entered Mode 3, Hot Standby. At 1536 hours, Unit 1 entered Mode 4, Hot Shutdown. On November 28, at 1828 hours, the repair was complete on NV Pump IB. Subsequently, the pump passed PT/1/A/4200/07B and was declared operable. At 1920 hours, the decision was made to proceed to Mode 5, Cold Shutdown, to replace a failed power range detector [EIIS:XT] (N-42). On November 29, at 0215 hours, Unit 2 entered Mode 5. The power range detector was replaced and Unit 1 entered Mode 4 at 1642 hours. Unit 1 entered Mode 1 at 2246 hours on November 30, and the CR0s began to increase Reactor power to 100%. Unit I reached 100% power at 1100 hours on December 3. CONCLUSION This incident has been attributed to equipment failure. The failure of NV Pump IB resulted in a Technical Specification required shutdown of Unit 1. The root cause of this equipment failure has not been identified at this time. However, this report will be revised based on a failure analysis report on the rotating element which was removed from NV Pump IB. During the incident, Design Engineering provided the necessary test acceptance criteria to not perform a flow balance test upon replacing the pump. It was concluded that a flow balance test was not required, because the head / flow characteristic curve of the replacement pump did not differ from the pump in place at the time of the last flow balance test by more than + 3% of t'eveloped head. The replaced pump satisfied this criteria and a flow balance test was not required.

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L Cmtawba Nuclear Station, Unit 1 o l6 j o l0 l o I 41113 819 - 0 l2 l 7 - 010 0 14 oF 015 TEXT kNNpt45089 4 N@taWWW. WAS SWdb8Dnel %4C #0m JUE41(17) NV Pump IB is manufactured by the Pacific Pumps Division of Dresser Industries. The failure of this pump is NPRDS reportable. In reviewing the NPRDS database, seven previous failures were noted which involved impeller replacement. However, these failures cannot be compared to this specific failure until the completion of the failure analysis report. It should be noted that Westinghouse has identified problems associated with the shaft manufacturing process and has taken appropriate actions to improve shaft reliability. The shaft replacement utilized in the repair of NV Pump 1B was of the improved type. During the incident, a power range detector, N-42, failed. This detector, model number WL23686, is manufactured by Westinghouse and is NPRDS reportable. The failure of this detector is unrelated to the failure of NV Pump 1B. A revh w of previous incidents showed that during the twenty-four months precediag this incident, there has been one Technical Specification required shutdown due to an equipment failure. On July 17, 1988, there was a plant shutdown due to the failure of NV Pump 2A (see LER 414/88-022). Therefore, this is a recurring event. To prevent a recurrence of this pump failure, an upgraded shaft war installed in NV Pump 2A. Recurring problem determination will be made e pending the results of the failure analysis report. CORRECTIVE ACTION SUBSEQUENT ! 1) NV Pump 1B was repaired.

2) PT/1/A/4200/07B was satisfactorily completed and NV Pump IB was l declared operable.

3) Power Range Detector (N-42) was replaced.

( PLANNED l l 1) A failure analysis report on the rotating element which was removed ! from NV Pump 1B will be provided.

2) This report will be revised based on the results of the failure analysis report.

SAFETY ANA. LYSIS The loss of one Chemical and Volume Control Centrifugal Charging Pump is a scenario encompassed by the Bases of Technical Specifications 3/4.1.2 and 3/4.5.2 for Boration Control Systems and Emergency Core Cooling Subsystems. In both Bases, one Centrifugal Charging Pump is required to assure single function capability with the other pump assumed to be inoperable because of a single failure consideration. g ow m. . a . c ns , u,..- s u e -

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0l2l7 - 010 01 5 oF 0l5 This incident duplicated the described scenarios. During the period of time l l that NV Pump IB was out of service, NV Pump 1A was operable or operating with all required subsystems, power supplies, and flow paths available. Required  ! boron concentrations and volumes were maintained in the Refueling Water Storage Tank and the Boric Acid Storage Tank. Diesel Generator [EIIS: GEN] 1A was  ! available to supply emergency power during this period if it had been required. l l When it became evident that NV Pump IB could not be restored to operability l within the 72 hours allowed by Technical Specifications, a Unit Shutdown was l commenced. The Unit reached shutdown and was borated to achieve the required J l shutdown margin within the allowable time. The health and safety of the public were not affected by this incident, i l l i l

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