ML17289A352

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LER 92-003-00:on 920123,circulating Fan CAC FN-1B Failed to Start During Performance of Surveillance Test.Caused by Tripped Overloads.Thermal Overloads Reset & Surveillance Test performed.W/920220 Ltr
ML17289A352
Person / Time
Site: Columbia Energy Northwest icon.png
Issue date: 02/21/1992
From: John Baker, Fies C
WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-92-042, GO2-92-42, LER-92-003, LER-92-3, NUDOCS 9203030088
Download: ML17289A352 (10)
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Text

ACCELERATED DISTRIBUTION DEMONSTRATION SYSTEM REGULAT Z INFORMATION DISTRIBUTIO SYSTEM (RIDS)

'."1- ACCESSION NBR:9203030088 DOC.DATE: 92/02/21 NOTARIZED: NO DOCKET FA"IL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397

'UTH. NAME AUTHOR AFFILIATION FIES,C.L. Washington Public Power Supply System BAKER,J.W. Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 92-003-00:on 920123,circulating fan CAC FN-1B failed to start during performance of surveillance test. Caused by tripped overloads. Thermal overloads reset & surveillance test performed.W/920220 ltr.

DISTRIBUT10N CODE: IE22D COPIES RECEIVED:LTR ENCL SIZE:

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

NOTES:

RECIPIEN COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA .1 1, PD5 PD 1 1 ENG,P.L. 1 1 INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA 1 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/SELB 8D 1 . 1 NRR/DST/SICB8H3 1 1 RR SPLB8D1 1 1 NRR/DST/SRXB 8E 1 1 REG FIL 02 1 1 RES/DSIR/EIB 1 1 5 FILE 01 1 1 EXTERNAL: EGGG BRYCE,J.H 3 3 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHY,G.A 1 1 NSIC POOREgW. 1 1 NUDOCS FULL TXT 1 1 P 4/@733 e.fg NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM P 1-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 32 ENCL 32

ti WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 ~ 3000 George IVashington N'ay ~ Richland, 1Vashington 99352 February 20, 1992 G02-92-042 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.92-003 Transmitted herewith is Licensee Event Report No.92-003 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) qipqg3 ~if 9203030088 920221 PDR ADOCK 05000397 8 PDR

LICENSEE EVEN REPORT (LER)

FACILITY NAME (I) DOCKET NUHBER ( ) PAGE (3) ashington Nuclear Plant Unit 2 0 5 0 0 0 3 9 7 I OF 5 TITLE (4)

CONTAINMENTATMOSPHERE CONTROL (CAC) SYSTEM EVENT DATE 5 LER NUHBER 6 REPORT DATE 7 OTHER FACILITIES INVOLVED 8 MONTH DAY YEAR YEAR SEQUENTIAL E VISION HONTH DAY YEAR FACILITY NAHES 0 CKE NUHB R (5)

NUMBER NUHBER 5 0 0 0 0 I 2 3 9 2 9 2 0 0 3 0 0 0 2 2 1 9 2 5000 OPERATING HIS REPORT IS SUBHITTED PURSUANT TO THE REQUIREHENTS OF 10 CFR 5: (Check one or more of the following) (11)

MODE (9) I POMER LEVEL 20.402(b) 20.405(C) 50.73(a)(2)(iv) 77.71(b)

(10) 20.405(a)(l)(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, NRC 20.405(a) (I) I iv) 50.73(a)(2)(ii) 50.73(a)(2)(viii)(B) Form 366A) 20.405(a)(l)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUHBER REA CODE C. L. FIES, Compliance Engineer 5 0 9 7 7 - 4 1 4 7 COMPLETE DNE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE SYSTEM COMPONENT HANUFACTURER EPORTABLE CAUSE SYSTEH COMPONENT MANUFACTURER REPORTABLE 0 NPRDS To NPRDS SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED SUBHISSIDN MONTH DAY YEAR ATE (15)

YES (if yes, complete EXPECTED SUBHISSION DATE) X NO ABSTRACT (16)

On January 23, 1992 CAC Circulating Fan (CAC-FN-1B) failed to start during the performance of a routine surveillance test. Plant operators discovered the fan did not operate because of tripped overloads. It was then determined that Train B of the Containment Atmosphere Control (CAC) System had been inoperable longer than the 30 days allowed by the Technical Specifications. During the LER investigation it was determined that both CAC divisions were out of service for a 5-1/2 hour period due to testing of Train A.

Immediate corrective action was taken to reset the thermal overloads and the surveillance test was performed.

The Root Cause of this event was insufficient component monitoring. A second root cause was the fact the elementary drawing contained technical inaccuracies.

Further corrective action will be taken to correct the design and the design drawings associated with the CAC system. In addition a review will be performed of similar equipment/systems to prevent reoccurrence.

This event has minor safety significance.

LICENSEE EVENT REPORT ( )

TEXT CONTINUATION FACII.ITY NAME (I) DOCKET NUMBER (2) LER NUMBER (B) PAGE (3)

Year Number Rev. No.

Washington Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 92 003 00 2 F 5 TITLE (4)

CONTAINHENT ATHOSPHERE CONTROL CAC SYSTEH Power Level - 100%

Plant Mode - 1 On January 23, 1992 CAC Circulating Fan (CAC-FN-1B) failed to start during the performance of routine surveillance test PPM 7.4.6.6.1,2, CAC-HR-1B Preheater Operability. Plant operators discovered the fan did not operate due to phase A and C tripped overloads. Ori January 26, 1992 a Plant Technical Engineer determined that Train B of the Containment Atmosphere Control (CAC) System had been inoperable longer than the 30 days allowed by the Technical Specifications making this a reportable event.

At WNP-2 the CAC System includes redundant catalytic hydrogen recombiners provided to combine the hydrogen and oxygen in the Primary Containment during degraded post LOCA conditions. The recombiner subsystems (A and B) are located adjacent to the Primary Containment in the Reactor Building (Secondary Containment). Each redundant subsystem consists of a circulating fan, wet scrubber, electric heater, catalyst vessel, gas cooler and associated instrumentation, valves and piping. A constant speed fan is used to draw the atmosphere from the Primary Containment, process it through the equipment and return it back to the Containment.

Investigation revealed that the overloads were most likely tripped on December 17, 1991 when a CAC-HR-1B Recycle Flow Verification (PPM 8.3.229TP) test was conducted, Test procedure PPM 8.3.229TP was a special one time test conducted to verify that flow control valve CAC-FCV-6B could be controlled manually from the control room. As the flow control valve (FCV) closed, the flow decreased until flow switch CAC-FS-6B opened de-energizing the fan motor contactor. An auxiliary contact on the fan motor contactor de-energizes the contactors that supply 480 volts to the valve. With a loss of power, electro-hydraulic valve CAC-FCV-6B fails open. When the FCV opened, enough flow was present from the coast down of the fan to allow the flow switch to reclose and re-energize the fan motor contactor. The fan motor restarted and power was restored to the valves. Since the flow controller (CAC-FC-67B) had not been readjusted, the FCV reclosed. This cycle repeated three times before the system was turned off.

Plant Technical engineers consulted with Plant Operations and discussed the effects of the cycling on the fan motor. The elementary drawing (E545-10VB-1) showed the overloads in series with the control circuitry.

Control power was still energized, which led them to believe the overloads were closed. They decided that the motor was operational because the overloads did not trip and did not conduct any further investigation since they believed Train B was in operable status.

LICENSEE EVENT REPORT ( R)

TEXT CONTINUATION FACILITY NAHE (1) DOCKET NUHBER (2) LER NUHBER (8) PAGE (3)

Year Number Rev. No.

Mashin9ton Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 92 003 00 3 OF 5 I'ITLE (4)

CONTAINMENT ATMOSPHERE CONTROL CAC SYSTEM Imm ia e orrec ive Acti n Immediate corrective action was taken to reset the overloads and the surveillance test was continued on January 23, 1992.

Further Evaluation and rrec ive Ac i n A. Fu her Evaluati n

1. This event is reportable per 10CFR50.73(a)(2)(i)(B) as a condition prohibited by the Plant's Technical Specifications. Train B of the CAC system was inoperable from December 17, 1990 to January 23, 1992 while the Plant was in Mode 1. The Plant exceeded the Technical Specification Action requirements to restore the inoperable train of the CAC System within 30 days. In addition, during the investigation associated with this LER it was discovered that Train A of CAC was inoperable for a 5 I/2 hour period on December 19, 1991. The "A" Recycle Flow Verification Test was run on December 19, 1991 and CAC-HR-1A was inoperable from 1230 hours0.0142 days <br />0.342 hours <br />0.00203 weeks <br />4.68015e-4 months <br /> to 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br />.. Inoperability was a result of the test requirement to deactivate the containment isolation valves in a closed position as part of the test. With both trains out of service, this results in an "....event or condition that alone could have prevented the fulfillment of the safety function of structures or systems that are needed to...mitigate the consequences of an accident...." and is a four hour reportable event This item was called in at 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br /> on February 7, 1992. Further, with both under'0.72(b)(2)(iii)(D).

trains inoperable the Technical Specifications require LCO 3.0.3 to be entered along with the declaration of an unusual event.

2. CAC was purchased as a skid mounted system with control wiring installed and tested by the vendor.

The only external wiring was for indication, remote switches, controllers and power supplies.

Elementary diagram E545-10VB-1 is a copy of the vendor supplied drawing which is a schematic diagram showing the complete circuit, including the external wiring. This drawing shows a typical configuration of control power that has the fan overloads in series with the output of the control transformer. Since the power supplies were external to the skid, the vendor drawing did not show actual design configuration.

3. When the overloads were found tripped on January 23, 1992, Plant Technical conducted an investigation that found a discrepancy between the elementary diagram and the Electrical Wiring Diagram, EWD 22E067. The EWD showed the overloads in series with a 49X relay that would de-energize the fan motor contactor but was not in the control circuit. A physical check of the wiring confirmed the field configuration matched the EWD and the elementary diagram was wrong.

LICENSEE EVENT REPORT (L )

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

Year Number Rev. No.

Washington Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 92 003 00 4 F 5 TITLE (4)

CONTAINMENT ATMOSPHERE CONTROL CAC SYSTEM

4. The Architect Engineer issued drawing EWD 22E067 in 1983. The EWD showed the external wiring and connections but did not show the actual CAC skid wiring. The elementary drawing, which was issued in 1982, was not referenced on the EWD nor was it updated to show the correct configuration.

Subsequent revisions to both drawings failed to identify the discrepancy.

5. The design configuration of CAC system B gives no indication, through annunciation or lights, that the CAC-FN-1B overloads have tripped. BISI (Bypassed and Inoperable Status Indication) annunciator 2-1 (CAC-FN-1B Power Loss) CAC Division 2 BISI display did not alarm, nor did annunciator P811-KH2 drop 4-2 (CAC Div 2 Out of Service). A review of engineering drawings EWD 22E067 and E530 sheet 11 determined that the design did not include annunciation for an overload trip condition.
6. The Root Cause of this event was insufficient component monitoring as information on the tripped overloads should have been available to the plant operators. A second root cause was the fact that drawing E545-10VB-1 contained technical inaccuracies. This led to the decision not to investigate fan operability after the fan cycled three times on December 17, 1991.

B. Fur her rrec ive Action

1. The CAC system will be run every 30 days until the ongoing SSFI is complete and its recommen-dations are evaluated.
2. The CAC system design will be changed to place the spare 49X relay contact in series with the control power and BISI circuits to provide positive indication of system power alignment.
3. An as built inspection will be performed of the field wiring on each CAC skid.
4. Applicable drawings will be updated to reflect actual field wiring configuration of the CAC system.
5. Upgrade the as built corrected elementary drawing for the CAC skid to Top Tier status.
6. Perform a review of drawings for similar safety related equipment/systems and correct any discrepancies. From criteria previously established the following systems will be considered in the review; main steam leakage control, control room chillers, acoustic monitors, process-post accident sampling, and process radiation monitors.

Safet Si nificance Since both divisions of CAC were inoperable for a short period of time and there is a low probability of having an accident during this time, resulting in significant hydrogen production, this event is viewed as having minor safety significance. Plant operators were aware of the condition of Train A of CAC during this 5 1/2 hour test

LICENSEE EVENT REPORT R)

TEXT CONTINUATION FACILITY NAME (I) DOCKET NUMBER (2) LER NUMBER (B) PAGE (3)

Year Number Rev. Ho.

Mashlngton Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 92 003 00 5 OF 5 TITLE (4)

CONTAINMENT ATMOSPHERE CONTROL CAC SYSTEM period. A limited number of components were made inoperable by removing relays from the local control panel. This equipment included four containment isolation valves CAC-V-4, CAC-V-6, CAC-FCV-1A, and CAC-FCV-4A, the valve that provide water to the scrubber, CAC-FCV-SA, and the valves that provide air flow from and to the skid, CAC-V-2A and CAC-V-1A. There is a high likelihood that actions could have been taken to restore this equipment and the remainder of the CAC skid to operable status if it were needed to mitigate the consequences of an accident. There is some time available in the accident scenario since the system is not needed immediately for accident mitigation. This assumption on equipment availability is contingent on the availability of plant operators to be in the Reactor Building at the CAC local control panel to replace the relays.

imilar Events LER 84-013 reported the event where both hydrogen recombiner fan (CAC-FN-1A/B) motors tripped on electrical overload during preoperational testing at 18 psig containment pressure. The fuses and overloads installed had not been sized for the higher pressure conditions. LER 91-025 and 91-029 were recently written on the CAC system. Corrective actions as a result of these LERs are presently underway.

EIIS Informati n Text Reference EIIS Reference

~Sstem ~Com onen Containment Atmospheric Control (CAC) BB System Hydrogen Recombiner Circulating Fan BB BLO (CAC-FN-1B)

Hydrogen Recombiner (CAC-HR-1B) BB Recycle Flow Control Valve BB FCV (CAC-FCV-6B)

Recycle Flow Controller (CAC-FC-67B) BB FC Containment Isolation Valves (CAC-V-4, BB V CAC-V-6, CAC-FCV-1A, and CAC-FCV-4A)

Scrubber Cooling Water Valve BB FCV (CAC-FCV-5A)

CAC Air Flow Valves (CAC-V-21, BB V CAC-V-1A)

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