ML17289A629

LER 92-014-01:on 920326,920414 & 920512,engineers Identified TS Violations Associated W/Flow Measurements in Hpcs,Lpcs & RHR Sys,Respectively.Caused by Inadequate Design Analysis. Tests Performed to Verify flows.W/920611 Ltr

ML17289A629
Person / Time
Site:	Columbia
Issue date:	06/11/1992
From:	John Baker, Fies C WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-92-140, LER-92-014, LER-92-14, NUDOCS 9206230155
Download: ML17289A629 (8)

Text

ACCELERATED >DISTRIBUTION DEMON+RATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDE)

ACCESSiON NBR:9206230155 DOC.DATE: 92/06/ll NOTARIZED: NO DOCKET FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH, NAME AUTHOR AFFZLZATION FIES,C. Washington Public Power Supply System BAKER,J.W. Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 92-014-01:on 920326,920414 & 920512,Engineers identified TS violations associated w/flow measurements in HPCS,LPCS &

RHR sys,respectively. Caused by inadequate design analysis.

Tests performed to verify flows.W/920611 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), ncident Rpt, etc.

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 DEANFW. 1 1 INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2. NRR/DET/EMEB 7E 1 1 NRR/DLPQ/LHFB10 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB 1 1 NRR/DREP/PRPB11 '2 2 NRR/DST/SEL'B SD 1 1 NRR/DST/SICB8H3 1 1 NRR/DST/SPLBSD1 1 1 NRR/DST/SRXB 8E 1 1 R'E 02 1 1. RES/DSIR/EIB 1 1 RGN5 FILE 01 '1 1 EXTERNAL: EGSG BRYCE,J.H 3 3 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHYFG.A 1 1 NSIC POOREFW. 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSiON REQUIRED TOTAL'UMBER OF COPIES REQUIRED: LTTR 32 ENCL 32

WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 ~ 3000 George Washington Way ~ Richland, Washington 99352 June 11, 1992 G02-92-140 Docket No. 50-397 Document Control Desk U. S. Nuclear Regulatory Commission Washington, D. C. 20555

SUBJECT:

NUCLEAR PLANT WNP-2, OPERATING LICENSE NPF-21 LICENSEE EVENT REPORT NO. 92-014-01 Transmitted herewith is Licensee Event Report No. 92-014-01 for the WNP-2 Plant. This report is submitted in response to the report requirements of 10CFR50.73 and discusses the items of reportability, corrective action taken, and action taken to preclude recurrence.

Sincerely, J. W. Baker WNP-2 Plant Manager (Mail Drop 927M)

Enclosure CC: Mr. John B. Martin, NRC - Region V Mr. C. Sorensen, NRC Resident Inspector (Mail Drop 901A, 2 Copies)

INPO Records Center - Atlanta, GA Ms. Dottie Sherman, ANI Mr. D. L. Williams, BPA (Mail Drop 399)

~ 0155 920611 cs'206~30 PDR ADOC ~ 05000397 8

LICENSEE EVENT REPORT (LER)

AGILITY NAME (I) DOCKET NUMB R ( ) PAGE (3)

Washington Nuclear Plant Unit 2 0 5 0 0 0 3 9 7 I OF 6 ITLE (4)

HIGH PRESSURE CORE SPRAY (HPCS), LOW PRESSURE CORE SPRAY (LPCS), AND RESIDUAL HEAT REMOVAL (RHR) FLOW SETPOINT ERROR EVENT DATE (5 LER NUMBER 6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8 MONTH OAY YEAR YEAR -'..;. SEQUENTIAl EVI SION MONTH OAY YEAR FACILITY NAMES DOCKET NUMB RS(S)

-'I NUMBER NUMBER 0 3 2 6 9 2 9 2 0 I 4 0 1 0 6 I 1 9 2 PERATING MIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 5

(Check one or more of the following). (11)

ODE (9) I OWER LEVEL 20.402(b) 20.405(C) 50.73(a)(2)(iv) 77.71(b)

(io) 20.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.73(c) 0.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vii) THER (Specify in Abstract 20.405(a)(1)(iii) 50.73(a)(2)(i) 50.73(a)(2)(viii)(A) elow and in Text, NRC 20.405(a)(1)(iv) 50.73(a)(2)(ii) 50.73(a)(2)(viii)(B) "orm 366A) 20.405(a)(1)(v) 50.73(a)(2)( << I) 50.73(a)(2)(x)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER Carl Fies," Compliance Engineer REA CODE 5 0 9 7 7 - 4 1 4 7 COMPLETE OHE LINE FOR EACH COMPONENT FAILURE DESCRIBED IH TNIS REPORT (13)

CAUSE SYSTEM COMPONENT MANUFACTURER EPORTABLE CAUSE SYSTEM COMPOHEH'I MANUFACTURER REPORTABLE 0 HPRDS TO HPRDS SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED SUBMISSIOH MONTH DAY YEAR ATE (15)

YES (If yes, complete EXPECTED SUBMISSIOH DATE) X HO BSTRACT (16)

On March 26, April 14, and May 12, 1992, contract engineers working in the Setpoint Methodology Program identified Technical Specification violations associated with flow measurements in the High Pressure Core Spray (HPCS), Low Pressure Core Spray (LPCS), and Residual Heat Removal (RHR) systems, respectively. The violations occurred because the instrumentation associated with the flow measurements assumed a higher water temperature than that present during testing or postulated initial accident conditions. This temperature difference caused the actual flow conditions to be lower than the indicated flow.

The root cause of this event was inadequate design and analysis. There was an analysis deficiency in that the previous setpoint calculations did not adequately address the temperature effects on setpoint accuracy.

Corrective actions included changes to the setpoints of impacted instrumentation, corresponding changes to surveillance test procedures, and reperformance of tests to verify flows.

This event has no safety significance and posed no threat to the health and safety of either the public or Plant personnel.

LICENSEE EVENT REPORT ( ER)

TEXT CONTINUATION FACILITY NAME (I) DOCKET NUMBER (2) LER NUMBER (8) AGE (3)

Unit 2 ear ,'lumber ev. No.

Washington Nuclear Plant 0 5 0 0 0 3 9 7 2 14 01 2 F 6 ITLE (4)

HIGH PRESSURE CORE SPRAY (HPCS), LOW PRESSURE CORE SPRAY (LPCS), AND RESIDUAL HEAT REMOVAL RHR FLOW SETPOINT ERROR Plant Conditions Power Level - 100%

Plant Mode - 1 Event Descri tion On March 26, April 14, and May 12, 1992, contract engineers working in the Setpoint Methodology Program identified Technical Specification violations associated with flow measurements in the High Pressure Core Spray (HPCS), Low Pressure Core Spray (LPCS), and Residual Heat Removal (RHR) systems, respectively, The violation occurred because the instrumentation associated with the flow measurements were calibrated for a higher water temperature than that present during testing or initial postulated accident conditions. This temperature difference caused the actual flow conditions to be lower than the indicated flow.

'he HPCS flow orifice (HPCS-FE-007) is sized to provide the design differential pressure for a fluid temperature of 212'F. Actual water temperature could be as low as 60'F. The HPCS flow required by the Technical Specifications is equal to or greater than 6350 gpm (4.5.1.b.3). The minimum flow required is equal to or greater than 1200 gpm (Table 3.3.3-2.C.l.f). The minimum flow valise is established to prevent pump damage during low flow operation. For the HPCS system the flow orifice, HPCS-FE-007, transmits a signal to Flow Indicating Switch, HPCS-FIS-6. HPCS-FIS-6, controls the operation of the minimum flow valve, HPCS-V-12. This valve opens as necessary to maintain a minimum flow of 1200 gpm through the pump. With calibration and drift errors taken into account, in addition to temperature, the minimum flow may have been as low as 1150 gpm and system flow could have been as low as 6200 gpm. At 1540 hours0.0178 days <br />0.428 hours <br />0.00255 weeks <br />5.8597e-4 months <br /> on March 26 the HPCS was declared inoperable and Technical Specification Action Statements 3.3.3.a and 3.5.1.C.1 were entered. After additional testing was completed to assure flow was adequate HPCS was declared operable at 0615 hours0.00712 days <br />0.171 hours <br />0.00102 weeks <br />2.340075e-4 months <br /> on March 28. Although declared inoperable the HPCS was maintained in a ready status, fully capable of automatic actuation, throughout the period of technical inoperability.

The LPCS flow orifice (LPCS-FE-002) is sized for a fluid temperature of 170'F. The actual water temperature could be as low as 60'F. The LPCS system flow required by the Technical Specification is 6350 gpm (4.5.1.b.1). With the calibration, drift, and temperature errors the actual system flow could have been as low as 6200 gpm. At 1328 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.05304e-4 months <br /> on April 14 LPCS was declared inoperable and Technical Specification Action Statement 3.5.1.D.2 was entered. After additional testing to reverify its ability to provide 6,350 gpm LPCS was declared operable at 2130 hours0.0247 days <br />0.592 hours <br />0.00352 weeks <br />8.10465e-4 months <br /> that same day. Although declared inoperable the LPCS was maintained in a ready status, fully capable of automatic actuation, throughout the period of technical inoperability.

LICENSEE EVENT REPORT R)

TEXT. CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (8) AGE (3)

Unit 2 Year umber ev. No.

Washington Nuclear Plant 2 014 Di 3 OF 6 TITLE (4)

HIGH PRESSURE CORE "SPRAY (HPCS), LOW PRESSURE 'CORE SPRAY (LPCS), AND RESIDUAL HEAT REMOVAL RHR FLOW SETPOINT ERROR The RHR flow orifices (RHR-FE-14A, B, and C) are sized for a fluid temperature of 120'F. The actual water temperature could be as low as 60'F. The RHR system flow required by the is 7450 gpm (4.5.1.b.2). With the calibration, drift, and temperature errors taken into .

Technical'pecifications account the actual system flow for RHR Loops A and B met the Technical Specification requirement.

However, the RHR'Loop C corrected flow of 7417.gpm was not acceptable. The problem with RHR flow was discovered when the plant was in a.refueling outage. Thus no immediate corrective action was needed.

Immediate Corrective Action On March 27 Instrument Setpoint Change Request (ISCR) 1115 was approved to increase the trip setpoint for the Flow Indicating Switch (HPCS-FIS-6).

On March 28-Plant Procedure PPM 7.4.5.1.11, HPCS System Operability Test was changed and performed. It demonstrated HPCS flow complied with the Technical Specification requirements with the temperature corrected 'flow rate.

On April 14 Plant Proc'edure PPM 7.4.5.1.7, LPCS System Operability Test, was changed and performed.

It verified the LPCS flow met the Technical Specification requirements with the temperature corrected flow rate.

Further Evaluation and orrective Action A. Further Evaluation A four hour verbal notification was made to the NRC at 1730 hours0.02 days <br />0.481 hours <br />0.00286 weeks <br />6.58265e-4 months <br /> on March 26, 1992, pursuant to the requirements of 10CFR50;72(b)(2)(iii)(A). The inoperability of HPCS (a single train system) resulted in a condition that alone could have prevented the fulfillment of a safety function needed to shut down the reactor and maintain it in a shutdown condition.

This written report is required by 10CFR50.73(a)(2)(i)(B) as the events described herein were a condition prohibited by the plant's Technical Specifications in that minimum and system flows did not meet requirements. It is also required by 10CFR50.73(a)(2)(v) since the inoperability of HPCS.

(a. single train system) resulted in a condition that alone could have prevented the fulfillment of a safety function needed to shut down the reactor and maintain it in a shutdow(I condition.

LICENSEE EVENT REPORT R)

TEXT CONTINUATION FACILITY NAME (I) OOCKET NUMBER (2) LER NUMBER (8) AGE (3) ear umber ev. No.

Washington Nuclear Plant Unit 2 0 5 0 0 0 3 9 7 2 0 1 4 0 1 4 OF 6 ITLE (4)

HIGH PRESSURE CORE SPRAY (HPCS), LOW PRESSURE CORE SPRAY (LPCS), AND RESIDUAL HEAT REMOVAL RHR FLOW SETPOINT ERROR Further evaluation was performed on the Technical Specification requirements for LPCS minimum flow. The LPCS minimum. flow, allowable value required by the Technical Specifications is less than or equal to 900 gpm (Table 3,3.3-2.A.l.c). The minimum flow value is established to prevent pump damage during low low operation. An allowable value that is "less than or equal" is an error in the Technical Specifications as it would allow minimum flow values as low as zero flow. The trip setpoint value listed in the Technical Specifications is greater than or equal to 770 gpm. For the LPCS system the flow orifice, LPCS-FE-002, transmits a signal to Flow Indicating Switch, LPCS-FIS-4. LPCS-FIS-4, which controls the operation of the minimum flow valve, LPCS-V-11. With the temperature error the actual minimum flow could have been as low as 627.9 gpm. However, this is not a Technical Specification violation as it is lesS than or equal to 900 gpm.

Further evaluation was'performed on the Technical Specification requirements for RHR minimum flow. The RHR minimum flow required by the Technical Specifications is greater than or equal to 650 gpm (Table 3.3.3-2.B.l.e). Even with the temperature error the actual minimum flow was well above this limit.

The root cause of this event was inadequate design and analysis. There was an analysis deficiency in that the previous setpoint calculations did not adequately address the temperature effects on setpoint accuracy.

There were no structures, systems, or components inoperable prior to the start of this event that contributed to the event.

1 B. Further orrective Action

1. Plant Procedure PPM 7.4.3.3,1.63, HPCS Flow Rate Low (Minimum Flow)-Channel

-'unctional Test/Channel Calibration for HPCS-FIS-6 was modified to the new setpoint value.

This action was completed on March 27, 1992.

2. An Instrument Setpoint Change Request (ISCR-1119) was written to increase the trip setpoint for LPCS-FIS-4. This action was completed on May 13, 1992.

3. Plant Procedure PPM 7.4.3.3 1.6, ECCS-LPCI (A) and LPCS Pump Discharge Low

~

(Minimum Flow) - Channel Functional Test - Channel Calibration for LPCS-FIS-4 was modified to a new setpoint value. This action was completed on May 27, 1992.

4 An investigation of the temperature conditions associated with flow measurements on the Residual Heat Removal (RHR) Pumps was performed. The results of this investigation are being reported in this LER revision.

LICENSEE EVENT REPORT ER)

TEXT CONTINUATION AGILITY NAHE (i) DOCKET NUHBER (2) LER NUHBER (8) PAGE (3)

Year umber ev. No.

Washington Nuclear Plant Unit 2 0 5 0 0 0 3 9 7 2 14 01 5 OF 6 ITLE (4)

HIGH PRESSURE CORE SPRAY (HPCS), LOW PRESSURE CORE SPRAY (LPCS), AND RESIDUAL HEAT REMOVAL RHR FLOW SETPOINT ERROR

5. Plant Procedure PPM 7.4.5.1.10, RHR Loop C Operability, was changed to correct for the reduced water temperature during testing. This action was completed on May 30, 1992.

6. Plant Procedure PPM 7.4.5.1.10 will be performed to verify RHR Loop C flow meets the Technical Specification requirements. This will be completed by June 30, 1992.

S~fi if'he HPCS and LPCS pump minimum flow requirements were evaluated against actual flow conditions to assure no pump damage occurred due to the lower than expected flows.

The HPCS minimum flow evaluation by the pump supplier states the minimum flow for short periods (three hours or less) may be as low as 400 gpm. Therefore, pump damage could not have occurred due to this condition since the HPCS flow with 60'F water would be no lower than 1150 gpm.

Likewise, the LPCS minimum flow evaluation by the pump supplier states the minimum flow for short periods is 570 gpm. Therefore, pump damage could not have occurred since the LPCS flow with 60'F water would be no lower than 761 gpm.

The small deviations in system flows for HPCS, LPCS and RHR are not considered significant when compared to the flows and overall conservatism assumed in LOCA accident analysis. In addition, the small variance in total flow is not significant for heat removal capability.

Both the HPCS and LPCS remained aligned and available for automatic vessel injection in the event of an accident during the period of technical inoperability.

There was no safety significance associated with this event.

Similar Events The new setpoints described in this LER are a result of the Supply System efforts to improve the level of confidence in the Technical Specification related setpoints; Other events resulting from the setpoint program may be reported as revisions to this LER.

The Supply System has identified several setpoint problems previously reported in LERs. These include LER 92-002 dealing with the Main Steam Isolation Valve Leakage Contr61 System, and LER 92-006 dealing with the Reactor Building to Suppression Pool Vacuum Breaker valves. Technical Specification setpoints continue to be evaluated as part of the Setpoint Methodology Program to ensure WNP-2 setpoints incorporate the necessary conservatism and modern analytical setpoint calculation techniques.

LICENSEE EVENT REPORT R)

TEXT 'CONTINUATION AGILITY KAME (1) DOCKET KUMBER (2) LER KUMBER (8) AGE (3)

Unit 2 umber ev. Ko.

Washington Nuclear Plant 0 5 0 0 0 3 9 7 2 i 4 i 6 OF 6 ITLE (4)

HIGH PRESSURE CORE SPRAY (HPCS), LOW PRESSURE CORE SPRAY (LPCS), AND RESIDUAL HEAT REMOVAL RHR FLOW SETPOINT ERROR II Infrm i n ~Salem Text Reference ~EII R I

~m~nen High Pressure Cdre Spray (HPCS) BG Low Pressure Core Spray (LPCS) BM Residual Heat Removal (RHR) BO HPCS Flow Orifice (HPCS-FE-007) BG FE HPCS Flow Indicating Switch (HPCS-FIS-6) BG FIS HPCS Minimum Flow Valve (HPCS-V-12) BG V LPCS Flow Orifice (LPCS-FE-002) BM FE LPCS Flow Indicating Switch (LPCS-FIS-4) BM FIS LPCS Minimum Flow Valve (LPCS-V-11) BM V RHR Flow Orifices (RHR-FE-14A, B, and C) BO FE