ML17289A938

LER 92-039-00:on 920921,RWCS Isolated on High Differential Flow While ROs Were Attempting to Place filter-demineralizer RWCU-DM-1B Back Into Service.Caused by Inadequate Mgt Methods.Degraded Equipment Repaired & Procedures Updated

ML17289A938
Person / Time
Site:	Columbia
Issue date:	10/21/1992
From:	John Baker, Fuller R WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-92-243, LER-92-039, LER-92-39, NUDOCS 9210260292
Download: ML17289A938 (10)

Text

-, ACCELERATED DISTRIBUTION DEMONS'+ATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSIO'i$ NBR:9210260292 DOC.DATE: 92/10/21 NOTARIZED: NO DOCKET FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME AUTHOR AFFILIATION FULLER,R.E. Washington Public Power Supply System BAKER,J.W. Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 92-039-00:on 920921,RWCS isolated on high differential flow while ROs were attempting to place filter-demineralizer RWCU-DM-1B back into service. Caused by inadequate mgt methods. Degraded equipment repaired & procedures updated.

DISTRIBUTION CODE: IE22T COPIES 'RECEIVED:LTR ENCL ) SIZE: S 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 PD5 LA 1 1 PDS PD 1 1 DEANgW. 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 SD 1 1 NRR/DST/SICBSH3 1 1 NRR'/+)STj+PLBSD1 1 1 NRR/DST/SRXB 8E 1 1 02 1 1 RES/DSIR/EIB 1 1 RGN5 FILE 01 1 1 EXTERNAL'G&G BRYCEg J ~ H 2 2 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHYIG.A 1 1 NSIC POOREgW. 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK.

ROOM PI-37 (EXT. 504-2065) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 31 ENCL ,31

vi WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 + 3000 George Washington Way ~ Richland, Washington 99352 G02-92-243 October 21, 1992 Docket No. 50-397 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555

SUBJECT:

NUCLEAR PLANT WNP-2, OPERATING LICENSE NPI-21 LICENSEE EVENT REPORT NO. 92-039-00 Transmitted herewith is Licensee Event Report No. 92-039-00 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,

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

JWB/REF/lmr Enclosure CC: Mr. J. B. Martin, NRC - Region V Mr. W. Ang, NRC Resident Inspector (Mail Drop 901A, 2 Copies)

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

F Gt304, 92102602'P2 '221021 zpP PDR S

ADQCK 05000397 PDR

LIcENEEE EVEIOREPQRT (LER)

FACILITY NAME (1) DOCKET NUMB R ( ) PAGE (3)

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

REACTOR WATER CLEANUP ISOLATION DUE TO HIGH DIFFERENTIAL FLOW EVENT DATE (5 LER NUMBER 6) REPORT DATE (7) OTHER FACILITIES INVOLVED (B)

DAY YEAR YEAR SEC)VENT IAL EV I 5 ION MOHTH DAY YEAR FACILITY NAMES DOCKET NUMBERS(S)

MONTH NUHBER NUMBER 0 5 0 0 0 0 9 2 1 9 2 9 2 0 3 9 0 0 I 0 2 I 9 2 050 00 P ERAT ING HIS REPORT IS SUBHITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 5: (Check one or more of the following) (11)

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

(iO) 2O.4OS(a)(i)(i) 50.36(c)(1) 0.73(a)(2)(v) 73.73(c) 20.405(a)(1)(ii) 5O.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) below and in Text, NRC 20.405(a)(1)(iv) 50.73(a)(2)(ii) 50.73(a)(2)(viii)(B) Form 366A) 20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x)

LICENSEE CONTACT FOR THIS LER (12)

NAM E TELEPHOHE NUMBER REA CODE R.E. Fuller, Licensing Engineer - 4 8 5 0 9 7 7 4 1 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE SYSTEH COMPONENT MANUFACTURER EPORTABLE CAUSE S'YSTEH COMPONENT MANUFACTURER REPORTABLE TO NPRDS TO NPRDS SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED SUBMISSION MONTH DAY YEAR ATE (15)

YES (If yes, complete EXPECTED SUBHISSION DATE) x NO At 1248 hours0.0144 days <br />0.347 hours <br />0.00206 weeks <br />4.74864e-4 months <br /> on September 21, 1992, the Reactor Water Cleanup (RWCU) System isolated on high differential flow while Reactor Operators (RO) were attempting to place the filter-demineralizer (F/D)

RWCU-DM-18 back into service. This isolation occurs in response to a possible leak in the RWCU System and is considered an Emergency Safety Feature (ESF) actuation at WNP-2.

The isolation occurred as designed. This event resulted in no other actuation of Plant systems. No leaks were found upon inspection of RWCU piping. The isolations were reset and the RWCU System was returned to service.

The root causes of this event are inadequate management methods to initiate timely repair of degraded equipment and inadequate supervisory oversight. Contributing causes to the event consisted of inadequate self checking by an Equipment Operator (EO), and unclear wording of procedure instructions.

The corrective actions include repair of the degraded equipment, correction of the appropriate procedures to remove identified deficiencies, self-checking will be re-emphasized to operations personnel, and management expectations will be clarified with regard to RWCU high differential flow conditions and Control Room supervisory oversight. In addition, a review will be performed to identify similarly existing chronic problems. The review will assess the schedule for timely repair and ensure interim adequate administrative controls are in place to assure the equipment can be operated within preestablished limits.

LICENSEE EVENT REPORT R)

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

Year Number ev. No.

Washington Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 2 039 00 2 OF 8 TITLE (4)

REACTOR WATER CLEANUP ISOLATION DUE TO HIGH DIFFERENTIAL FLOW There is no safety significance associated with this event. There was no breach of the RWCU System that required the isolation valves to close. The event did not pose a threat to the health and safety of Plant personnel or the public.

Pln niin Power Level - 100%

Plant Mode - 1 (Power Operation)

Event Descri ti n At 1248 hours0.0144 days <br />0.347 hours <br />0.00206 weeks <br />4.74864e-4 months <br /> on September 21, 1992, the Reactor Water Cleanup (RWCU) System isolated on high differential flow while Reactor Operators (RO) were attempting to place the filter-demineralizer (F/D)

RWCU-DM-1B back into service. This isolation occurs in response to a possible leak in the RWCU System and is considered an Emergency Safety Feature (ESF) actuation at WNP-2.

Just prior to this event, the spent resin had been backwashed from the F/D and the F/D regenerated with fresh resin. This is known as backwash and precoat. Following precoat of RWCU-DM-1B, the RO initiated flow through the F/D per Plant Procedures to place the F/D into service. During this process, a high differential flow trip occurred indicating that the difference in volumetric flow between the inlet and outlet of the RWCU System exceeded the trip point of 58.5 gpm. If a high differential flow persists for longer than 45 seconds, a RWCU System isolation occurs. On this occasion, the high differential flow persisted, resulting in an ESF actuation (closing the Primary Containment isolation valves RWCU-V-1 and RWCU-V-4). A low flow condition resulted which caused pumps RWCU-P-1A and 1B to trip off.

The high differential flow trip is designed to isolate the RWCU System in the event of a breach in the system boundary. The trip time delay minimizes the probability of a spurious trip from momentary fluctuations in flow.

Immediate orrective Action The isolation occurred as designed. This event resulted in no other actuation of Plant systems. The RWCU System piping was inspected and no leaks were found. The isolation signals for RWCU-V-1 and RWCU-V-4 were reset and the RWCU System was returned to service.

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LICENSEE EVENT REPORT R)

TEXT CONTINUATION FACILITY NAHE (I) DOCKET HUHBER (2) LER HUHBER (8) AGE (3)

Year Number ev. No.

Washington Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 2 039 00 4 OF 8 TITLE (4)

REACTOR WATER CLEANUP ISOLATION DUE TO HIGH DIFFERENTIAL FLOW

3. As indicated above, several RWCU high differential flow conditions had occurred in the past without isolation caused by entrapped air during regeneration of RWCU-DM-1B. The Plant procedure used for regeneration of RWCU F/Ds and restoring them to service was revised September 17, 1992 to preclude the high differential flow condition.

The crucial steps to prevent air from leaking into the demineralizer RWCU-DM-1B included closing SA-V-251 and opening the air filter drain valve SA-V-23. Opening the air filter drain valve was to depressurize the SA header downstream of SA-V-251 and upstream of RWCU-V-213B.

On September 21, 1992, when the procedure directed the Equipment Operator (EO) to close SA-V-251, he found this valve and SA-V-23 closed. The next step of the procedure was to "Crack open SA-V-23 to depressurize the service air header." The EO interpreted this to mean that the valve was to be opened long enough to depressurize the header then reclosed.

The real intent was to leave the SA-V-23 open to ensure the header would not be repressurized from the leaking SA-V-251 valve. Because the EO found SA-V-251 already closed, he presumed that SA-V-23 had been opened, the header depressurized, and the valve reclosed. The EO did not notify anyone that he did not actually perform the crucial steps of the procedure, nor did he explain to anyone his interpretation of the procedure. No one could be identified as having manipulated the above indicated valves. Had the SA-V-23 valve been left open at the appropriate time in the process of regenerating the F/D, this event would not have occurred.

As a result of the leaking SA-V-251 and RWCU-V-213B valves, misalignment of the SA-V-3 and RWCU-V-230B valves created an air pocket in the RWCU-DM-1B tank. When bringing the F/D into service, the F/D inlet valve is opened to pressurize the F/D with the outlet valve closed. Normally there would be no flow of water into F/D tank because the tank would be vented and filled completely with water. In this case, because of the air pocket that had developed, water flowed into the tank when the F/D inlet valve was opened, compressing the air pocket to reactor pressure. The high differential flow condition occurred during the time the air pocket was being compressed.

5. Following completion of field valve manipulation, the evolution of placing in service the regenerated F/D requires an RO at the Control Room panel P602 and personnel in the Radwaste Control Room to control flow through the F/Ds. It had become common practice to station a person at a rear panel in the Control Room to monitor the status of the 45-second trip delay timer. There is some evidence that, in the event of persistent high differential flow, while placing a F/D into service, some Control Room personnel believed it appropriate to shutoff the RWCU pump(s) precluding an ESF actuation.

LICENSEE EVENT REPORT R)

TEXT CONTINUATION FACILiTY NANE (I) DOCKET NUMBER (2) LER NURSER (8) PAGE (3)

Year Number ev. No.

Washington Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 2 039 00 5 OF 8 TITLE (4)

REACTOR WATER CLEANUP ISOLATION DUE TO HIGH DIFFERENTIAL FLOW Prior to starting the evolution, an RO stationed himself at P602 and established communication with the Radwaste Control Room. The Control Room Supervisor (CRS) and other ROs were not aware that the RWCU-DM-1B F/D was being returned to service. Upon opening the inlet valve to RWCU-DM-1B by the Radwaste Control Room, the high differential flow annunciator alarmed and the trip delay timer initiated. This was not expected by the RO because he was aware that the procedures had been revised to preclude the high differential flow condition. The RO at P602 lost track of the elapsed time since the alarm actuated. While attempting to have another RO in the vicinity determine the status of the timer at the rear panel, the timer timed out and the isolation occurred.

There was no discussion prior to the evolution between the RO at P602 and other ROs to assist with the evolution. Although the CRS and the other ROs were aware that the RWCU-DM-1B F/D would likely be returned,to service some time during the shift, they were unaware that the evolution was in progress. This evolution was considered routine and the RO felt confident that the procedure revision would preclude the high differential flow condition.

6. The first root cause of this event was that management methods did not permit a timely response to repairing or replacing RWCU-V-213B and SA-V-251. Adequate time was available to obtain ASME qualified replacement parts for RWCU-V-213B or replace the valve. The SA-V-251 could have been repaired with minimal impact to Plant operations.

The second root cause of this event was that the supervisory oversight was less than adequate. The operating crew was not staged to assist in this evolution. Guidance and/or assistance from the other crew members may have precluded this event.

The first contributing cause of this event was that the EO did not apply self-checking to ensure the steps that he did not perform were actually performed correctly. A more questioning attitude may have resulted in proper depressurization of the SA header and correct interpretation of the step requiring the SA-V-23 be left open.

The second contributing cause of this event was the unclear wording of the procedure step requiring SA-V-23 to be opened. There was no clear statement that the valve was to be left open.

B. Further orrective Acti n Taken Plant Procedures have been changed to clarify the required position of SA-V-23.

Internal leakage of RWCU-V-213B was corrected on or about October 17, 1992.

LICENSEE EVENT REPORT R)

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

Year Number ev. No.

Washington Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 2 039 00 6 OF 8 TITLE (4)

REACTOR WATER CLEANUP ISOLATION DUE TO HIGH DIFFERENTIAL FLOW Further Corrective Action Correct the internal leakage of SA-V-251 by May 31, 1993.

2. Operations Management will re-emphasize procedural compliance with operating crews by November 30, 1992. The emphasis will indicate that the steps are to be completed prior to proceeding with the evolution. It is inappropriate to assume that a step has been performed without having personal knowledge of its correct execution.

3. Management expectations with regard to supervisory involvement in specific evolutions will be clarified by November 30, 1992.

4 Management will identify similar chronic problems and ensure the priority for resolution is commensurate with the problem's impact on Plant safety, availability and operation by November 15, 1992.

5. Management expectations will be formalized by November 30, 1992 with regard to Reactor Operator response to RWCU high differential flow conditions.

Safet Si nificance There is no safety significance associated with this event. There was no breach of the RWCU System that required the isolation valves to close. The event did not pose a threat to the health and safety of Plant personnel or the public.

imilar Event WNP-2 has had approximately thirty RWCU System isolations. One isolation similar to this event, documented in LER 84-97, occurred while restoring RWCU-DM-1B back to service following backwash and precoat. As a result, some modifications were made to the RWCU System.

LICENSEE EVENT REPORT R)

TEXT CONTINUATION AGILITY NAHE (I) DOCKET HUHBER (2) LER HUHBER (8) AGE (3)

Year Number ev. No.

Washington Nuclear Plant - Unit 2 3

0 5 0 0 0 9 7 2 039 00 7 OF 8 I'ITLE (4)

REACTOR WATER CLEANUP ISOLATION DUE TO HIGH DIFFERENTIAL FLOW EIIS Information Text Reference EIIS Reference

~Seem ~Com nen Reactor Water Cleanup System CE Reactor Water Cleanup System Valve CE V Reactor Water Cleanup System CE FDM Filter-Demineralizer Service Air System Valve LF V Breathing Air System LH

LICENSEE EVENT REPORT R)

TEXT CONTINUATION FACILITY HAME (I) OOCKET HUMBER (2) LER HUMBER (8) PAGE (3)

Year Number ev. Ho.

Washington Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 2 039 00 8 F 8 I'ITLE (4)

REACTOR WATER CLEANUP ISOLATION DUE TO HIGH DIFFERENTIAL FLOW RWCV-V-<52V RWCU OM 1A veNr I

PI I RwCU V 616V 79 Pl I 71 I AIR FILTER I RwCV V 213A RwCV-V-230A

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Rwcv-v-2300 I

I Rwcv v 2138 I

I RWCV V 617V veNr I

I Rwcv oM 18 I

RWCU V 653V I

SA SYSTEM RwCV SYSTEM I

RWCU BACh. WASH A R SUPPLY I SA/RWCU AIR SURGE FLOW DIAGRAM