ML17291A406

LER 94-015-00:on 940704,actuation of HPCS Sys Diesel Engine & half-scram Condition Occurred Due to Tubing Valve Manipulation.Procedure Entitled, Startup Instrument Rack Valve Line-up Changed on 940706.W/940922 Ltr

ML17291A406
Person / Time
Site:	Columbia
Issue date:	09/22/1994
From:	Foley C, Parrish J WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-94-218, LER-94-015, LER-94-15, NUDOCS 9409290162
Download: ML17291A406 (7)

Text

'ACCELERATED RIDS PROCESSIX REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9409290162 DOC.DATE: 94/09/22 NOTARIZED: NO DOCKET ¹ FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME AUTHOR AFFILIATION FOLEY,C.J. Washington Public Power Supply System PARRISH,J.V. Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 94-015-00:on 940704,actuation of HPCS sys diesel engine

& half-scram condition occurred due to tubing valve manipulation. Procedure entitled, "Startup Instrument Rack Valve Line-up" changed on 940706.W/940922 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:

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

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD4-2 PD 1 1 CLIFFORD,J 1 1 XNTERNAL: ACRS 1 1 AEOD/ROAB/DSP 2 2 AEOD/SPD/RRAB NRR/DE/EELB 1

1 1 ~ILE CENTE~02 1 1 1 NRR/DE/EMEB 1 1 NRR/DORS/OEAB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HXCB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRSS/PRPB 2 2 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 NRR/PMAS/IRCB-E 1 1 RES/DSXR/EIB 1 1 RGN4 FILE 01 1 1 EXTERNAL EG &G BRYCE i J H 2 2 L ST LOBBY WARD 1 1 NOAC MURPHY,G.A 1 1 NOAC POORE,W. 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE iVASTE! CONTACTTHE DOCUWIENTCONTROL DESK. ROOM Pl-37 (E>:T. 504-2083 ) TO ELINIINATEYOUR NAXIE FROil DISTRIBUTION LISTS I'OR DOCUMENTS YOU DON "I'EED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 27 ENCL 27

vi WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 ~ 3000 George Washington Way ~ Richland, Washington 99352 September 22, 1994 G02-94-218 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. 94-015-00 Transmitted herewith is Licensee Event Report No.94-015 for the WNP-2 Plant. This report is submitted on a voluntary basis.

Should you have any questions or desire additional information, please call me or D.A. Swank at (509) 377-4563.

Sincerely,

. V. Parrish (Mail Drop 1023)

Assistant Managing Director, Operations JVP/CJF/my Enclosure CC: LJ Callan, NRC-RIV KE Perkins, Jr., NRC-RIV, Walnut Creek Field Office NS Reynolds, Winston & Strawn NRC Sr. Resident Inspector (Mail Drop 927N, 2 Copies)

INPO Records Center - Atlanta, GA DL Williams, BPA (Mail Drop 399) 9009290162 940922 PDR ADQCK 05000397 B PDR

L(CENSEE EVE EPORT (LER)

AGILITY NAME (1) DOCKET HUHB R ( ) PAGE (3)

Mashin ton Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 1 OF 4 ITLE (4)

VOLUNTARYREPORT OF A SPURIOUS ESF COMPONENT ACTUATION CAUSE BY TUBING VALVEMANIPULATION EVENT DATE 5) LER NUHBER 6 REPORT DATE 7 OTHER FACILITIES INVOLVED 8 MONTH DAY YEAR YEAR SEQUENTIAL EVI SION MONTH DAY FACILITY NAMES 0 CKE NUMB R (5)

NUMBER (x UMBER sc, 0 5 0 0 7 0 4 9 4 9 4 0 I 5 0 0 0 9 2 2 9 4 5 0 PERATING HIS REPORT IS SUBHITTEO PURSUANT TO TME REQUIREHEHTS OF 10 CFR 5: (Check one or more of the followin9) (ii)

ODE (9)

OWER LEVEL 20.402(b) 20.405(C) 0.73(a)(2)(iv) 77.71(b) 0.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.73(c) 20.405(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, HRC 20.405(a)(1)(iv) 0.73(a)(2)(ii) 50.73(a)(2)(viii)(B) orm 366A) 20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x) o1ontar LICENSEE CONTACT FOR THIS LER (12)

TELEPHONE HUHBER CJ Foley, Licensing Engineer REA CODE 5 0 9 7 7 - 4 3 2 5 COHPLETE ONE LINE FOR EACH COMPOHEHT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE STSTEH COHPONENl'ANUFACTURER EPORTABLE P ';::;";P'.:, CAUSE STSTEH COMPONENT MANUFACTURER REPORTABLE 0 NPRDS FN:;::;", TO NPRDS

.y3 HA SUPPLEHEHTAL REPORT EXPECTED (14) EXPECTED SUBMISSIOH HOHTH DAT TEAR ATE (15)

YES (If yes, complete EXPECTED SUBMISSION DATE) NO mACY n0)

This LER is being submitted as a voluntary report.

On July 4,1994, the plant was in an annual refueling/maintenance outage. An actuation of the High Pressure Core Spray System (HPCS) diesel engine and half-scram condition occurred at 2029 hours0.0235 days <br />0.564 hours <br />0.00335 weeks <br />7.720345e-4 months <br /> due to manipulation of instrument tubing valves in the reactor pressure vessel (RPV) level sensing instrumentation in preparation for reactor startup. No water was injected into the reactor pressure vessel (RPV) by the system because the HPCS pump had been properly removed from service. The actual water level in the RPV was normal. No plant condition existed that warranted actuation of the HPCS, and the actuation occurred as designed to the extent the existing system line-up permitted. The half-scram was reset and the diesel engine was shut down from the control room. The-cause was inadequate identification of the status of equipment undergoing a modification and testing process.

'LICENSEE EVENT REPORT R)

TEXT CONTINUATION FACILITY NAME (1) OOCKET NUMBER (2) LER NUMBER (8) PAGE (3)

Year umber ev. No.

Washington Nuclear Plant - Unit 2 0 5 0 0 0' 9 7

~4 0~1~5 0~0 2 OF 4 TITLE (4)

SPURIOUS ESF COMPONENT ACTUATION CAUSED BY TUBING VALVE MANIPULATION Event Descri i n On July 4, 1994, the plant was in an annual refueling/maintenance outage at 0% reactor power, operational mode 4 (cold shutdown). At 2029 hours0.0235 days <br />0.564 hours <br />0.00335 weeks <br />7.720345e-4 months <br />, invalid low reactor water level signals caused a half-scram condition and a start of the HPCS Diesel Engine. No water was injected into the reactor because control power fuses for the HPCS pump had been properly removed two days earlier in support of maintenance activities, preventing pump actuation. Control room operators verified that the reactor water level was normal and stable. At 2054 hours0.0238 days <br />0.571 hours <br />0.0034 weeks <br />7.81547e-4 months <br />, the half-scram was reset. At 2102 hours0.0243 days <br />0.584 hours <br />0.00348 weeks <br />7.99811e-4 months <br /> the HPCS diesel engine was shut down.

The NRC was notified of this event at 2240 hours0.0259 days <br />0.622 hours <br />0.0037 weeks <br />8.5232e-4 months <br /> pursuant to 10CFR50.72(b)(2). It was later determined

. that the notification had been unnecessary because 10CFR50.72(b)(2)(ii)(B)(1) exempts immediate reporting when the actuation is invalid and the system is properly removed from service. Subsequently, the event was determined to be non-reportable pursuant to guidance available in NUREG-1022 because the actuation was limited to elements of a train of ESF components and not an entire train. Additionally, the HPCS Diesel Engine is not classified as an ESF at WNP-2.

Further Ev I i n An immediate investigation revealed that two manual isolation valves in an instrument rack were opened by a technician under a procedure entitled "Startup Instrument Rack Valve Line-up." The purpose of this procedure is to align instrument systems at the end of an outage preparatory to plant startup. Due to the presence of a differential pressure across the valves resulting from existing plant conditions, opening the valves caused a fluid surge in the instrument tubing which includes the RPV level measuring instrumentation; this resulted in the invalid RPV low level signals, The valves were boundary valves for new features added by a plant modification to provide a continuous flow of water from the Control Rod Drive system to the reactor pressure vessel (RPV) water level sensing system to prevent saturation of the water in the instrumentation level reference "leg" by noncondensible gases. The two valves were not tagged or uniquely marked, but as boundary valves, had a different function than similar appearing valves in the instrument rack, This modification was made in response to NRC Bulletin 93-03 to address potential erroneous RPV level indications due to the release of noncondensible gases in the reference "legs" as saturation levels change during reactor depressurization. The two boundary valves had been temporarily included in a procedure entitled "Startup Instrument Rack Valve Line-up" in June of 1993 to reflect physical completion of the initial part of the modification in March of 1994. However, the required pre-operational testing had not been completed as of the date of the event. Upon completion of pre-operational testing, these two valves were to be deleted from the "Startup..." procedure and inserted into a new procedure entitled "RPV Level Instrumentation Reference Leg Purge System Operation" to provide detailed operating instructions for the modified equipment. The new procedure was required to provide more comprehensive control of the very sensitive new equipment than could be effected by use of the former procedure. The "Startup .. ~"

.0

'LICENSEE EVENT REPORT 8)

TEXT CONTINUATION AGILITY NAME (1) OOCKET NUMBER (2) LER NUMBER (8) PAGE (3)

Year Number ev. No.

Washington Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 i4 Oili5 Oio 3 OF 4 TiTLE (4)

SPURIOUS ESF COMPONENT ACTUATION CAUSED BY TUBING VALVE MANIPULATION procedure used by the technician had been changed on July 2, 1994 pursuant to the normal change process to reposition the boundary valves from "closed" to "open" to support reactor startup. However, the changed procedure pertained to equipment not under test, and the boundary valves were part of the equipment still in test status. Since the valves were not marked to differentiate them from valves in operational status, the cause of the event was inadequate identification of the status of equipment undergoing a modification and testing process.

orrec ive Acti n The procedure entitled "Startup Instrument Rack Valve Line-up" was changed on July 6, 1994 to remove the isolation valves from its scope. Preoperational testing was completed and the new system put in service on July 23, 1994 under the test procedure "Continuous Backfill from CRD-Preoperational and Startup." A new procedure entitled "RPV Level Instrumentation Reference Leg Purge System Operation" was issued on July 14, 1994 to cover operation of the instrument line purge system. This procedure alerts the user about the potential of perturbations in the system as may result from pressurized water trapped behind closed valves. Additionally, boundary valves associated with the purge system have been marked to differentiate them from similar appearing valves in instrument racks. A change will be made by October 31, 1994 to a procedure entitled "Plant Modifications" to provide enhanced guidance for release of equipment modifications to normal operation status.

S~iifi The event occurred when the reactor was shut down, and did not and could not have resulted in an increase in reactivity because the control rods remained inserted and the actual water level in the reactor was unchanged by the event. No radioactive releases or exposures to on-site or off-site personnel resulted or could have resulted from the event because the shutdown cooling systems remained in service. Technical Specification limits were not violated. No plant condition warranting actuation of the HPCS actually existed, and the actuation occurred as designed to the extent the existing system line-up permitted.

Consequently, this event is not safety significant.

imilar Even I.ER 89-025, "Engineered Safety Feature (ESF) Actuations During Excess Flow Check Valve Testing Due to Procedural Inadequacies" describes a similar actuation of the HPCS as caused by manipulations of valves in instrument tubing systems. However, in the LER 89-025 event instrument valves were opened in an incorrect sequence because of inadequate valve labeling, whereas in this event the valves opened were labeled adequately but had a different function than similar appearing valves in the instrument rack.

LICENSEE EVENT REPORT R)

TEXT CONTINUATION AGILITY NAHE (I) OOCKET NUHBER (2) LER NUHBER (8) PAGE (3)

Year Number ev. No Washington Nuclear Plant - Unit 2 0 ~

5 ~

0 ~ 0~ 0 ~

3 ~ 9 ~

7 4 OF 4 ITLE (4)

SPURIOUS ESF COMPONENT ACTUATION CAUSED BY TUBING VALVE MANIPULATION 8~It f Text Reference EIIS Reference Svstem Qgm~)~nen High Pressure Core Spray System BG Diesel Engine EK ENG Fuse FU HPCS Pump BG P Manual isolation valves ISV Tubing TBG