ML17285B405

LER 90-014-00:on 900703,HPCS Sys Pump Suction Switchover from Condensate Storage Tanks to Suppression Pool Occurred Due to Suppression Pool High Water Level Condition.Caused by Procedural Inadequacy.Procedures modified.W/900802 Ltr

ML17285B405
Person / Time
Site:	Columbia
Issue date:	08/02/1990
From:	Arbuckle J, John Baker WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-014, NUDOCS 9008080204
Download: ML17285B405 (12)

Text

ACCELERATED DISTRIBUTION DEMONSTRATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9008080204 DOC.DATE: 90/08/02 NOTARIZED- NO DOCKET FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME AUTHOR AFFILIATION ARBUCKLE,J.D. Washington Public Power Supply System BAKER,J.W. Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION R '

SUBJECT:

LER 90-014-00:on 900703,HPCS sys pump suction valve switchgear actuation on high suppression pool level. D W/9 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 D PD5 LA 1 1 PD5 PD 1 1 ENG,P.L. 1 1 D INTERNAL: ACNW 2 2 ACRS 2 2 S AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DET/ECMB 9H 1 1 NRR/DET/EMEB9H3 1 1 -NRR/DLPQ/LHFB11 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB11 1 .1 NRR/DREP/PRPB11 2 2 NRR/DST/SELB 8D 1 1 NRR/DST/SICB 7E 1 1 NRR/~BST/ LB8D1 1 1 NRR/DST/SRXB 8E 1 1 02 1 1 RES/DSIR/EIB 1 1 RGN5 FILE 01 1 1 EXTERNAL EG&G BRYCE i J ~ H 3 3 L ST LOBBY WARD 1 1 LPDR'. 1 1 ~ . NRC PDR 1 1 NSIC MAYS,G 1 . 1 NSIC MURPHY,G.A 1 1 NUDOCS FULL TXT 1 1 P ogB5oAw)g D P

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NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US.TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM PI-37.(EXT. 20079) TO ELIMINATEYOUR NAME FROM DISI'RIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED! S'ULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 34 ENCL 34

WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 ~ 3000 George Washington Way ~ Richland, Washington 99352 Docket No. 50-397 August 2, 1990 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

NUCLEAR PLANT NO. 2 LICENSEE EVENT REPORT NO.90-014

Dear Sir:

Transmitted herewith is Licensee Event Report No.90-014 for the WNP-2 Plant.

This report is subm'itted in response to the report requirements of 10CFR50.73 and discusses the items of reportability, corrective action taken, and action taken to preclude recurrence.

Very truly yours, J. . Baker (H/D 927M)

WN -2 Plant Manager JWB:lr

Enclosure:

Licensee Event Report No.90-014 cc: Mr. John B. Hartin, NRC Region V Mr. C. J. Bosted, NRC Site (M/D 901A)

INPO Records Center Atlanta, GA Hs. Dottie Sherman, ANI Hr. D. L. Williams, BPA (H/D 399)

( qg,A(5 9008080204 '$00g02 PDR ADOCK 05000397 PDC

NRC FORM %38 U.S. NUCLEAR REGULATORY COMMISSION APPAOVEO OMB NO. 31504) I04 (569)

EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REGUEST: 50.0 HRS. FORWARD LICENSEE EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (F630), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWOAK REDUCTION PROJECT (31500104), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

PA 5 FACILITY NAME (ll DOCKET NUMBER (2)

Washington Nuclear Plant - Unit 2 0 5 0 0 03 97>OFO sg ressure ore pray ys em ump uc son a ve w> c over Actuation on High Suppression Pool Level due to Procedural Inadequacy EVENT DATE (5) LER NUMBER (5) REPORT DATE (7) OTHER FACILITIES INVOLVED (SI

'j'j SEavsrevraL DOCKET NUMBER(s)

MONTH OAY YEAR YEAR a: NUMBER SAR:

REVISrON Yg NUMBER MONTH OAY YEAR FACILITY NAMES 0 5 0 0 0 0 7 03 90 9 0 1 4 0 0 08 2 9 0 0 5 0 0 0 THIS REPORT IS SUBMITTED PURSUANT T 0 THE RLOUIREMENTS OF 10 CFR (Ir IChech one or more ol the Iollowlnol (11)

OPERATING MODE (9) 20.402(S) 20.405(c) 50.73( ~ ) l2) liv) 73.71(S)

POWER 20A05 (e) III I 0 5035(c) III 50,73(el(2)(v) 73.71(cl LEvEL 0 0 0 20.405(e)((IBI) 50M(c) l2l 50.73( ~ l(2) IvS) OTHER ISpeclly in Ahrrrect Silovr end In Text, ArRC Form 20.405(el(1)(iii) 50.73(e) l2) li) 50,73(el(2((xiii)(BI 50.73( ~ ) (2) (viii) (Al 3rrr)A) 20A05 4) (1)(iv) 50.73(e l(2) (Ii) 4,(k~ r.. &4 20.405(e) (I wvl 50.73(el(2)(IIB 50.73( ~ ) (2) (xl LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER AREA CODE J. D. Arbuckle, Compliance Engineer 50 937 7- 11 CAUSE SYSTEM COMPONENT MANUFAC.

TURER AEPORTAB'LE TO NPROS

)r 8 0 '::

COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCAIBEO IN THIS REPORT l13),

>r'""r'r ".

Qvr(.

CAUSE SYSTEM COMPONENT MANUFAC.

TURER EPORTABI.E TO NPAOS

~(. N SUPPLEMENTAL REPORT EXPECTED (14) MONTH OAY YEAR EXPECTED SUBMISSION DATE HSI YES Illyet, complete EXPECTED SVBhrlSSIOII DATE) NO ABSTRACT I(.lmlt to l400 tpecet, I e., epproxlmetely lilreen tinole.gece type>>mitch Iinetl (15)

On July 3, 1990 at 1713 hours0.0198 days <br />0.476 hours <br />0.00283 weeks <br />6.517965e-4 months <br /> while the Plant was shutdown for maintenance, a High Pressure Core Spray (HPCS) System pump suction switchover from the Condensate Storage Tanks to the Suppression Pool occurred due to a Suppression Pool high water level condition.

Plant configuration at the time was such that HPCS suction was lined up to the Condensate Storage Tanks (CSTs) with CST Suction Valve HPCS-V-1 open and Suppression Pool Suction Valve HPCS-V-15 closed, the normal system lineup (reference Figure 1).

The switchover, an Engineered Safety Feature (ESF) actuation, was the automatic closure of HPCS-V-1 and the opening of HPCS-V-15.

During the event period, Plant Control Room Operators were monitoring Suppression Pool water level because it had been on a gradual, increasing trend for approximately one and a half days due to Excess Flow Check (EFC) Valve testing that was in progress. The level increase was due to water draining through the Main Steam Safety Relief Valves (MSRVs) during the EFC valve testing. During this period the Suppression Pool high level alarm annunciator had been sealed in t.the alarm annunciates at +0.5 inches (0.5 inches above normal pool level)j. When Suppression Pool water volume reached approximately +3.1 inches indicat'ed level, the automatic switchover occurred. The normal setpoint for an automatic transfer on high Suppression Pool level is +5 inches.

NRC Form 355 (589)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 31600104 (FI 89)

EXPIRES: 1/30/92 TED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVE REPORT ILER) INFORMATION COLLECTION REOUEST: 500 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH IP830), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (3150010i). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1 I DOCKET NUMBER (2) LER NUMBER (5) PAGE (3)

SEOVENTIAL RSV8 ION NVMSSR NVMQSII Mashin ton Nuclear Plant TEXT ///morr <<woo /J nqvked, uw ~ - Unit HRC FomI 36649/ (17) 2 o s o o o 397 90 0 1 4 00 2oF 0 6 Abstract (contd.)

As an immediate corrective action, Plant Control Room Operators took action to lower Suppression Pool level and then realigned the HPCS suction from the Suppression Pool to the Condensate Storage Tanks (HPCS-V-15 was closed and HPCS-V-1 was re-opened).

The cause of this event is procedural inadequacy in that the annunciator response procedures did not provide sufficient guidance to alert Plant Operators of the possibility of an HPCS suction transfer during Operational Mode 4 (Cold Shutdown).

As further corrective action, the annunciator response procedures will be modified to provide additional guidance and actions for those conditions when an HPCS suction valve switchover could occur.

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

Plant Conditions Power Level - OX Plant Mode - 4 (Cold Shutdown)

~E On July 3, 1990 at 1713 hours0.0198 days <br />0.476 hours <br />0.00283 weeks <br />6.517965e-4 months <br /> a High Pressure Core Spray (HPCS) System pump suction switchover from the Condensate Storage Tanks to the Suppression Pool occurred while the Plant was shutdown for maintenance. The switchover occurred as the result of a Suppression Pool high water level condition.

configuration at the time was such, that 'lant HPCS suction was lined up to the Condensate Storage Tanks (CSTs) with CST Suction Valve HPCS-V-1 open and Suppression Pool Suction Valve HPCS-V-15 closed, the normal system lineup (reference Figure 1).

The switchover, an Engineered Safety Feature (ESF) actuation, was the automatic closure of HPCS-V-1 and the opening of HPCS-V-15.

NRC Form 356A (589)

0 II g

NRC FORM 388A UA. NUCLEAR REGULATORY COMMISSION APPROVEO 0MB NO. 31600)04 (84)9)

EXPIRESI 4/30/92 TED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVE REPORT ILER) INFORMATION COLLECTION REQUEST: 60.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH IP4)30), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31504)104), OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, OC 20503.

FACIUTY NAME (1) DOCKET NUMBER (2) LER NUMBER (8) PAGE (3)

SEQUENTIAL REVISION YEAR gg NUMSSR EBB/I NUM SR Mashington Nuclear Plant TEXT /J/ANSe g>>Ce JI ISEMPed, IISS SI/SSR4/NRC %%dnn

- Unit 38849/ ((7) 2 <<<< o 3 9 7 9 0 01 40 0 3 oFO During the event period, Plant Control Room Operators were monitoring the Suppression Pool water level because it had been on a gradual, increasing trend for approximately one and a half days due to Excess Flow Check (EFC) Valve testing that was in progress. The level increase was due to water draining through the Main Steam Safety Relief Valves (MSRVs) during the EFC valve testing. During this period the Suppression Pool high level alarm (annunciator) had been sealed in,[the alarm annunciates at +0.5 inches( 0.5 inches above normal pool level)j. Plant Control Room Operators continued to monitor the level increase; however, when Suppression Pool water volume reached approximately +3.1 inches indicated level, the automatic switchover occurred. The Suppression Pool high level trip setpoint which would automatically cause a suction transfer is +5 inches. However, because the tolerance band (accuracy) for the level instrumentation is plus or minus two inches, the automatic switchover could occur as low as +3 inches or as high as +7 inches.

Therefore, with the setpoint that actually existed, the suction transfer occurred at the low end of the instrument tolerance band, instead of the automatic suction valve transfer setpoint of +5 inches.

Although the switchover was unexpecte'd, the closure of HPCS-V-1 and the opening of HPCS-V-15 was by Plant design. Plant Control Room Operators took action to lower Suppression Pool level and, at 1028 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91154e-4 months <br /> on July 5, 1990, the system was restored to the pre-event lineup status. ll Immediate Corrective Action Plant Control Room Operators responded in an appropriate and timely manner by taking action to lower Suppression Pool level and realigning the HPCS Suction from the Suppression Pool to the Condensate Storage Tanks (HPCS-V-15 was closed and HPCS-V-1 was re-opened).

Further Evaluation and Corrective Action A. Further Evaluation

1. This event is reportable under 10CFR50.73(a)(2)(iv) as an event or condition that resulted in manual or automatic actuation of any Engineered Safety Feature.

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

)SR C Form 388A (889)

NRC FORM 388A (LS. NUCLEAR REGULATORY COMMISSION APPROVEO 0MB NO. 31500104 (889)

EXPIRES: 4/30/82 E ED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVE REPORT (LER) INF MATION COLLECTION REQUEST: 50J) HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION ANO REPORTS MANAGEMENTBRANCH (P430). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (3(504)104). OFFICE OF MANAGEMENTANO BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1 l DOCKET NUMBER (2) LER NUMBER (8) PAGE (3)

YEAR SEQUENTIAL +??( REVISION gg~ NVMSEA 4?? NVMSEA Washin ton Nuclear Plant - Unit dI//oo4/HRC Foeo 35843/ (12l 2 05000397 9 0 01 4 0 0 <<0 6 TEXT ///IINvoEpeco /4 IPEMPPIL 844

3. The circuit operation is such that the HPCS switchover logic is designed to actuate based on either low Condensate Storage Tank or high Suppression Pool levels. Once initiated, the logic opens Suppression Pool Suction Valve HPCS-V-15. When HPCS-V-15 is full open, design logic closes Condensate Storage Tank Suction Valve HPCS-V-1. These valves are interlocked in this manner to prevent losing suction to pump HPCS-P-l.

There are two magnetically-activated float switches (HPCS-LS-2A and HPCS-LS-2B) that actuate on high Suppression Pool level. Because of the one-out-of-one logic, either switch can initiate opening of the Suppression Pool suction valve.

4~ The cause of this event is less than adequate procedures. Plant Annunciator Response Procedures (PPMs) 4.601.All and 4.601.A12, "Annunciator Panel Alarms" for Suppression Pool Level, require that when level is greater than +0.5 inches, Plant Control Room Operators are to lower the Suppression Pool level by means of aligning the Residual Heat Removal (RHR) System to the radwaste system. However, at the time of the event, the RHR System was already in service and providing for shutdown cooling. The alternate method of lowering the pool by means of Suppression Pool Cleanup was also not available because of a high silica condition in the Condensate Storage Tanks.

Plant Control Room Operators are aware of the trip setpoint (+5 inches) for an HPCS auto suction switchover;however, the procedure did not reference this value or provide guidance that the suction transfer can occur within plus or minus two inches of this setpoint. Plant Control Room Operators are not normally expected to know the administrative tolerances (accuracy) of instruments unless they are specifically called out by procedure.

Furthermore, Plant Control Room Operators confirmed that there were no Suppression Pool high level limits for Operational Mode 4 (Cold Shutdown).

B. Further Corrective Action Plant Procedure (PPM ) 7.4.3.3.1.60, NHPCS High Suppression Pool Level Actuation - CFT/CC,N was successfully completed on July 5, 1990. This procedure is a monthly Channel Functional Test/Channel Calibration of Suppression Pool Water Level Monitors HPCS-LS-2A and HPCS-LS-2B to demonstrate operability within the High Pressure Core Spray System.

2. Plant Procedures (PPMs) 4.601.A11 and 4.601.A12 will be modified to provide additional guidance and actions for those conditions when an HPCS suction valve switchover could occur.

NRC Form 388A (888)

0 0 Q/

IL

NRC FORM 366A UJL NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 31500104

,IBJIBI EXPIRES: 4/30/92 TED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVE REPORT ILER) IN MATION COLLECTION REOUESTI 50O HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH IP4130I, U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555, AND TO 3'HE PAPERWORK REDUCTION PROJECT I315001041, OFFICE OF MANAGEMENT ANO BUDGET, WASHINGTON, DC 20503.

FACILITYNAME 111 DOCKET NUMBER 111 LER NUMBER (SI PAGE 131 SEOUENTIAI P~S* REVISION NUMBEII 48 NUMSSR Mashin ton Nuclear Plant - Unit 2 o s o o o 397 90 01 4 00 0 5oFO 6 TEXT (8'mcvo spoco Js IoqIdmd, Uoo oddIdonol NRC FonII 36BABJ (171 Safet Si nificance There is no safety significance associated with this event. All systems operated as designed to cause a HPCS System pump suction valve switchover on the high Suppression Pool water level condition. In addition, there are no Suppression Pool high level restrictions during .Operational Mode 4 (Cold Shutdown) because there is insufficient energy in the reactor during this condition to place significant loads on the containment. Furthermore, Plant Control Room Operators responded by lowering the Suppression Pool and realigning the system to pre-event status. Accordingly, this event posed no threat to the health and safety of either the public or Plant personnel.

Similar Events There have been two other HPCS pump suction transfers from the Condensate Storage Tanks to the Suppression Pool;however, neither of these events had the same root cause as this event.

EI IS Information EI IS Reference System Component High Pressure Core Spray(HPCS) System BG HPCS-V-1 BG V HPCS-V-15 BG V Excess Flow Check (EFC) Valve NH V Main Steam Safety Relief Valves (MSRVs) SN RV Suppression Pool NH WW Condensate Storage Tank KA TK HPCS-P-1 BG P HPCS-L IS-2A BG LIS HPCS-L IS-2B BG LIS Residual Heat Removal (RHR) System BO NRC Form 368A IBBBI

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