ML17290A521

LER 93-025-00:on 930615,Group 1 Nuclear Steam Supply Shutoff Sys Isolation Occurred During Performance of TS Surveillance Test on Turbine Throttle Valves.Caused by Procedure Deficiency.Procedure changed.W/930715 Ltr

ML17290A521
Person / Time
Site:	Columbia
Issue date:	07/15/1993
From:	Fies C, Parrish J WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-93-184, LER-93-025, LER-93-25, NUDOCS 9307220304
Download: ML17290A521 (8)

Text

ACCELERAT .D DOCUINENT DIST'TION SYSTEM REGULA INFORMATION DISTRIBUTIO SYSTEM (RIDS)

ACCESSION NBR:9307220304 DOC.DATE: 93/07/15 NOTARIZED: NO DOCKET FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME AUTHOR AFFILIATION FIESPC.L. Washington Public Power Supply System PARRISH,J.V. Washington Public Power Supply System RECIP.NAME RECIP1ENT AFFILIATION

SUBJECT:

LER 93-025-00:on 930615,Group 1 nuclear steam supply shutoff sys isolation occurred during performance of TS survei'llance test on turbine throttle valves. Caused by procedure deficiency. Procedure changed.W/930715 ltr.

DISTRIBUTION CODE: IE22T TITLE: 50.73/50.9 Licensee Event Report (LER), J IncidentQRpt, etc.

COPIES RECEIVED:LTR ENCL SIZE:

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PDV LA 1 1 PDV PD 1 1 CLIFFORDIJ 1 1 INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DE/EELB 1 1 NRR/DE/EMEB 1 1 NRR/DORS/OEAB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRIL/RPEB 1 1 NRR/DRSS/PRPB 2 2 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 ~~gEG ~EX- E 02 1 1 RES/DSIR/EIB 1 1 RGN5 FILE 01 1 1 EXTERNAL: EG6G BRYCE,J.H 2 2 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHYPG.A 1 1 NSIC POOREPW. 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL"RIDS" RECIPIENTS:

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WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 ~ 3000 George Washington Way ~ Richland, Washington 99352 July 15, 1993 G02-93-184 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.93-025 Transmitted herewith is Licensee Event Report No.93-025 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.

J. V. Parrish (Mail Drop 1023)

Assistant Managing Director, Operations JVP/CLF/my Enclosure CC: Mr. B. H. Faulkenberry, NRC - Region V Mr. R. Barr, NRC Resident Inspector (Mail Drop 901A, 2 Copies)

INPO Records Center - Atlanta, GA Mr. D. L. Williams, BPA (Mail Drop 399) 2XQ006 9307220304 930715 PDR ADDCK 05000397 8 PDR

LICENSEE EVAREPORT (LER)

AGILITY NAHE (1) DOCKET NUMB R ( ) PAGE (3)

Washin ton Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 I OF ITLE (4)

ENGINEERED SA'FETY FEATURE (ESF) ACTUATION CAUSED BY SURVEILLANCE TESTING EVENT DATE 5) LER NUHBER 6) REPORT DATE (7) OTHER FACILITIES INVOLVED (6)

HONTH OAY YEAR YEAR g SEOUENTIAL EV I SION HONTH OAY YEAR FACILITY NAMES CKE NUMBER (5)

NUMBER UMBER 8>

5 0 0 6 5 9 1 3 9 3 0 2 5 0 0 0 7 1 5 9 3 50 PERATING HIS REPORT IS SUBHITTEO PURSUANT TO THE REQUIREMENTS OF 10 CFR E: (Check one or more of the following) (11)

OOE (9) 4 ONER LEVEL 20.402(b) 20.405(C) X 50.73(a)(2)(iv) 77.71(b)

(10) 20. 405(a) (1) ( I ) 50.36(c)(1) 50.73(a)(2)(v) 73.73(c)

20. 405(a) (1) ( I I) 50.36(c)(2) 50.73(a)(2)(vii) THER (Specify in Abstract 20.405(a) (I) (i i I) 50.73(a)(2)(i) 50.73(a)(2)(viii)(A) elow and in Text, NRC 0.405(a)(l)(iv) 50.73(a)(2)(ii) 50.73(a)(2)(viii)(B) orm 366A) 0.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x)

LICENSEE CONTACT FOR THIS LER ( 12)

TELEPHONE NUHBER C. L. Fies, Licensing Engineer REA CODE 5 0 9 7 7 - 4 1 4 7 COHPLETE ONE LINE FOR EACH COHPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE SYSTEH COHPONENT HANUFACTURER EPORTABLE CAUSE SYSTEM COHPONENT MANUFACTURER REPORTABLE 0 NPRDS TO NPRDS h

SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED SUBMISSION MONTH DAY YEAR ATE (15)

YES (If yes, complete EXPECTED SUBMISSION DATE) NO BlACT eel At approximately 1850 hours0.0214 days <br />0.514 hours <br />0.00306 weeks <br />7.03925e-4 months <br /> on June 15, 1993, a Group 1 Nuclear Steam Supply Shutoff System (NS')

isolation occurred during the performance of a Technical Specification surveillance test associated with the Turbine Throttle Valves. The test involved calibration of position switches on the valves associated with the NS'ogic. During shutdown conditions there is no main condenser vacuum. The NS4 logic is configured in a manner where exercising each Turbine Throttle valve to the open position initiates a half Group 1 isolation. During the surveillance test a second Throttle Valve was opened without resetting the (NS4) logic after testing the first valve. This resulted in a Group 1 isolation which is considered an ESF actuation.

The root cause of this event was a procedural deficiency.

Immediate corrective action was taken to stop work on the surveillance and investigate the cause. Further corrective action was taken to change the surveillance procedure to require a reset of the logic after the switches on each valve are calibrated.

The event posed no threat to the health and safety of either the public or plant personnel.

LICENSEE EVENT REPOR1kR)

TEXT CONTINUATION AGILITY HAKE (1) OOCKET KUMBER (2) LER HUHBER (8) AGE (3) ear Kumber ev. Ho.

Washington Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 3 025 0 2 OF 5 iTLE (4)

ENGINEERED SAFETY FEATURE ESF ACTUATION CAUSED BY SURVEILLANCE TESTING Pln niin Power Level - 0%

PlantMode -4 Even Descri i n At approximately 1850 hours0.0214 days <br />0.514 hours <br />0.00306 weeks <br />7.03925e-4 months <br /> on June 15, 1993, a Group 1 Nuclear Steam Supply Shutoff System (NS')

isolation occurred during the performance of a Technical Specification surveillance test associated with the Turbine Throttle Valves. The test was being performed in accordance with plant procedure PPM 7.4.3.1.1.18, Turbine Throttle Valves - System A/B - Channel Calibration. The surveillance provides for the calibration of position switches associated with the closure of the Throttle Valves, During power operation, above 30 percent, these switches initiate a scram when the valves are greater than or equal to five percent closed.

These switches are also used as part of the NS4 logic. During shutdown conditions there is no main condenser vacuum. The NS4 logic is configured in a manner where exercising each Turbine Throttle valve to the open position initiates a half Group 1 isolation. During the surveillance test a second Throttle valve was opened without resetting the NS4 logic after testing the first valve. This resulted in a Group 1 isolation involving a closure signal to the Main Steam Line Isolation Valves and the Main Steam Line Drain Valves.

This is an ESF actuation.

mmediate rrec iv Ac ion Immediate corrective action was taken to stop surveillance testing and investigate the cause of the event.

Further Evalu ion R t Cau e and rrective Action A. Further Evaluation

1. This event is being reported per the requirements of 10CFR50.73(a)(2)(iv). This event was verbally reported as a non-emergency event under 10CFR50.72(b)(2)(ii) at 2241 hours0.0259 days <br />0.623 hours <br />0.00371 weeks <br />8.527005e-4 months <br /> on June 15, 1993.

2. Further evaluation showed the electricians assigned to perform the throttle valve surveillance had not previously performed the surveillance. In a pre-job briefing, the craft supervisor told them that stroking a throttle valve would cause a half scram. They were also told that the control room must be notified before starting the surveillance and after completing calibration of each throttle valve. They notified the control room prior to starting the surveillance and also after completing each valve. The electricians believed they could cause a half scram and they knew the procedure addressed the MSIVs. However, they did not know the difference between a half

LICENSEE EVENT REPORR)

TEXT CONTINUATION AGILITY KAHE (i) DOCKET HUHBER (2) LER KUHBER (B) ABE (3)

Year umber ev. Ko.

Washington Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 3 025 00 3 OF 5 ITLE (4)

ENGINEERED SAFETY FEATURE ESF ACTUATION CAUSED BY SURVEILLANCE TESTING scram and a half isolation and did not realize that they were effecting two separate logic trains when they manipulated the position switches. Actually, the surveillance cannot cause a half scram because RPS relay contacts for the throttle valves are bypassed when the reactor is below 30% power.

3. The precautions and limitations section of the procedure states, "Throttle valve sections may be done in any order however, all steps in each section are to be performed in sequence. Only one instrument channel is to be in a state of test at any time. When a channel is returned to service, verify with the Control Room that all trips, alarms and computer points are cleared before proceeding to the next channel test." In addition, a procedural precaution states in part; "Ifthe RPS-K10 relays are energized with low condenser pressure, MSIVs will get a fast closure signal if more than one throttle valve is open at a time," However, the precaution does not inform the user that a NS'alf isolation occurs when only one throttle valve is open. It is apparent that the procedural instruction intended to inform the control room of the need to reset appropriate logic.

However, the direction was not as specific as it should have been and was not included as a step in the body of the procedure.

4. Operations personnel cannot remember when or if the NS'ogic was reset during the throttle valve calibration. At the same time they were conducting several other surveillance tests including Turbine Governor Valve (TGV) Fast Closure Response Time Testing and the MSIV Logic System Functional Test. The TGV fast closure surveillance introduces an actual half scram in the RPS logic and both A and B divisions were tested while the throttle valve procedure was in progress. Performance of these surveillances concurrently should not present a problem but in the absence of specific instruction to reset the logic, other surveillances may have diverted the operator's attention from resetting the NS4 half isolation. Also, an operations shift change occurred near the end of the surveillance.

5. A review of procedures that can initiate a scram or isolation revealed that procedures performed by the Instrument and Controls (I & C) shop are written to be logic safe. The I & C procedures separate the divisions so a full scram or isolation cannot be initiated with a single procedure.

There are relatively few procedures of this type performed by the Electrical shop. They have not been subject to this logic safe format. The Maintenance Procedures Department has identified three additional electrical procedures that could possibly cause a full scram or isolation.

6. A review was performed of the development of PPM 7.4.3.1.1.18. Revision 0 of the procedure was written in June 1985. In this revision the test was limited to Throttle Valves 1 and 3. In February 1986 the procedure was revised to include all four throttle valves. The statements in the precautions and limitations sections of these early revisions to the procedures are similar to the current version. A formal validation and verification has not been performed on this procedure. Thus, the procedure has been defective since inception.

LICENSEE EVENT REPORThR)

TEXT CONTINUATION AGILITY NAME (1) OOCKET HUHBER (2) LER HUHBER (8) AGE (3)

Year umber ev. Ho.

Washington Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 3 25 00 4 F 5 rTLE (4)

ENGINEERED SAFETY FEATURE ESF ACTUATION CAUSED BY SURVEILLANCE TESTING B. Root Cause The root cause of this event was a procedural deficiency. The omission of a required action to reset the NS4 logic after completing each valve calibration caused the Group 1 isolation. It is recognized that this problem did not occur during previous performances of this surveillance. As discussed above, under further evaluation, there were additional complications that were present when the event occurred.

C. Further Corrective Actions

1. PPM 7.4.3.1.1.18 was changed on June 16, 1993, to include steps in each section of the procedure to reset the NS4 logic and verify the annunciators have cleared before proceeding to the next valve.

2. Plant Procedures PPM 7.4,3.1.1.18, 7.4.3.1.1.10A, 7.4.3.7.5.44, and 7,4.3.7.5.45 will be revised into logic safe procedures. This will be completed prior to their use during the next refueling outage.

3. An evaluation will be performed to determine the need for additional training for electrical shop personnel involved with Technical Specification Surveillances. This will be completed by Qff October 1, 1993.

This is no safety significance associated with this event. The plant was in mode 4 and the MSIVs were closed prior to the isolation.

imil r Event Group 1 isolations have occurred previously at WNP-2. These events are documented in LERs87-021 and 88-010. However, these isolations were not caused by surveillance testing associated with the Throttle Valves.

LICENSEE EVENT REPORTER)

TEXT CONTINUATION ACIL1TY NAME (1) 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 3 025 00 5 F 5 ITLE (4)

ENGINEERED SAFETY FEATURE ESF ACTUATION CAUSED BY SURVEILLANCE TESTING EIIS Information T~Rf EIIS Reference

~Stem ~Com anent Nuclear Steam Supply Shutoff System (NS') BD Turbine Throttle Valves SB V Turbine Throttle Valve Position Switches SB 33 Main Steam Line Isolation Valves SB V Main Steam Line Drain Valves SB V