ML18010A380

LER 91-016-00:on 910808,containment Cooling Water Pump B Started,Resulting in Momentary Pressure Spike Which Caused Three Relief Valves to Open.Caused by Error in Original Sys Design.Personnel Trained Re Valve setting.W/910909 Ltr

ML18010A380
Person / Time
Site:	Harris
Issue date:	09/09/1991
From:	Richey R, Verrilli M CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
HO-910133-(O), LER-91-016-01, LER-91-16-1, NUDOCS 9109190010
Download: ML18010A380 (7)

Text

ACCELERATED DISTRIBUTION DEMONSTRATION 'SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR: 9109190010 DOC. DATE: 91/09/09 NOTARIZED: NO DOCKET FACIL:50-400 Shearon Harris Nuclear Power Plant, Unit 1, Carolina 05000400 AUTH. NAME AUTHOR AFFILIATION VERRILLI,M. - Carolina Power & Light Co.

RICHEY,R.B. Carolina Power & Light Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 91-016-00:on 910808,containment coolinq water pump B started, resulting in momentary pressure spake which caused three relief valves to open. Caused by error in original sys D design. Personnel trained re valve setting.W/910909 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR I ENCL TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

L SIZE:

NOTES:Application for permit renewal filed. 05000400A D

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL D PD2-1 LA 1 1 PD2-1 PD 1 1 MOZAFARI,B. 1 1 INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DS P 2 2 NRR/DET/ECMB'9H 1 1 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 ~NRRy DSP/SBLQBD1 1 1 NRR/DST/SRXB 8E RES/DSIR/EIB 1

1 1

1

~EG RGN2 FILE~ 02 FILE 01 1

1 1

1 EXTERNAL EG &G BRYCE E J ~ H 3 3 L ST LOBBY WARD ,1 1 NRC PDR 1 1 NSIC MURPHY,G.A 1 1 NSIC POORE,W. 1 1 NUDOCS FULL TXT 1 1 D

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NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE ~VASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELlil!INATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 33 ENCL 33

Carolina Power 8 Light Company P.O. Box 165 ~ New Hill, N.C, 27562 R. B. RICHEY Vice President Harris Nuclear Proiect SfP - 9 199)

Letter Number: HO-910133 (0)

U.S. Nuclear Regulat:ory Commission ATTN: NRC Document Control Desk Washington, DC 20555 SHEARON HARRIS NUCLEAR, POWER PLANT UNIT 1 DOCKET NO. 50-400 LICENSE NO. NPF-63 LICENSEE EVENT REPORT 91-016-00 Gentlemen:

In accordance with Title 10 to the Code of Federal Regulat:ions, the

.enclosed Licensee Event Report is submitted. This report fulfills the requirement for a written report within thirty (30) days of a reportable occurrence and is in accordance with the format set forth in NUREG-1022, September 1983.

Very truly yours Vice President Harris Nuclear Project RBR:dmw Enclosure cc: Mr. S. D. Ebneter (NRC - RII)

Ms. B. L. Mozafari (NRC - RII)

Mr; J. 'E..Tedrow (NRC - SHNPP)

MEM/LER91-016/1/Osl i" I t 910ri900iO 910909 iV PDR S

ADOCK 0 't)0040'.t F'LlR

NRC FORM 366 US. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 31504104 (669)

EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50.0 HAS. FORWARD LICENSEE EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND RFPORTS MANAGEMENT BRANCH (P630), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31500104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (1) PA E Shearon Harris Nuclear Plant Unit f/1 0 5 0 0 0 4 P P 1 OF P 4 Potentially degraded residual heat removal capability due to CCW relief valve lifein and failing to reseat.'EPORT EVENT DATE (5) LFR NUMBER (6) DATE (7) OTHER FACILITIES INVOLVED (6) y~: SEQUENTIAL DAY YEAR FACILITYNAMES DOCKET NUMBEA(S)

MONTH DAY YEAR YEAR NVMSER gg REVEL MONTH 0 5 0 0 0 8 P 8 91 91 P 1 6 P PP9 P9 9 1 0 5 0 0 0 THIS REPORT IS SUBMITTED PURSUANT T0 THE REQUIREMENTS OF 10 CFA (): /Check One or more Of the follom'nfl l11 OPERATING MODE (9) 20.401 (5) 20.406(c) 60.73( ~ ) (2) (iv) 73.71(hl POWER 20.405(vill l(i) 6036(c) (I ) 60.73(e) (2)(v) 73.71(c)

LEVEL 1 p p 20.405(e) (I ) (iS I 50.36(cl(2) 50 73( ~ ) I1)(viil OTHER /Specify in AStrnct Oe/ovv end /n Text. /IRC Form 20.405( ~ l(1)(iii) 50.73(e) (1) IB 50,73( ~ l(1)(villi(A) 36SA/

20.405(e)(I ) (lv) 50.73( ~ l(2)(ill 50.73(el(2)(viiil(B) 20.405( ~ )(1)(v) 50.73(e) (2)(iiil 50.73( ~ ) (2) (el LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER AREA CODE Michael Verrilli Re ulaeor Com liance S ecialist 91 93 62- 23 P COMPLETE ONE LINE FOR EACH COMPONENT FAILUAE DESCRIBEO IN THIS REPORT (13)

CAUSE SYSTEM COMPONFNT MANUFAC.

TURER EPOATABLE

.~P@~c CAUSE SYSTEM COMPONENT MANUFAC.

TURER EPORTABLE TO NPADS N%R SUPPLEMFNTAL REPORT EXPECTED (14I MONTH DAY YEAR EXPECTED SV 6 MISSI ON DATE,(IS)

YES Ilf yet, complete EXPECTED SIISMISSIOff DATE/ NO ABSTRACT ILlmlt to /400 tpecer, I e., epproxlmetely fifteen tlnfrle tpece typewritten linnl (16)

On August 8, 1991 to support testing of a Component Cooling Water'CCW) flow indicator, the "B" CCW pump was started. (RA" CCW pump was already in operation).

The start of this additional pump created a momeneary pressure spike that caused three system relief valves to open. A decrease in surge tank level was also observed which indicated that at least one of the relief valves had not reseated.

This was determined to create a potential for degraded residual heat removal capability under cereain accident: conditions. There are two primary causes for this event. The cause for the relief valves lifting upon the start of the second pump was an error during initial system design. The cause for the relief valves not reseaeing was the improper setting of the relief valve nozzle ring adjustments during site maintenance activities. Immediate corrective action was to initiate CCW flow through the Residual Heae Removal (RHR) Heat Exchanger which lowered system operating pressure and would prevent lifting relief valves in the event of an automaeic second pump stare. Additional corrective actions included an inspection of CCW relief valves and personnel training on proper relief valve setting. Additional procedure guidance has been developed and plant modifications are being pursued to prevent recurrence. Further investigation was also undertaken to determine if similar problems exist in other plant syseems.

NRC Form 366 (669)

NRC FORM 366A UrL NUCLEAR REGULATORY COMMISSION (BJ)9) APPROVED OMB NO. 31500106 EXPIRES; 4/30/92

~ IMATED BURDEN PEA RESPONSE TO COMPLY WTH THIS LICENSEE EV T REPORT (LER1 INFOAMATION COLLECTION AEOUEST: 50.0 HRS. FORWARD COMMENTS REGAADING BURDEN ESTIMATE TO THE RECOADS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH IP430). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT (3(500104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR SEOUENTIAL MSI REVISION Shearon Harris Nuclear Plant Unit 81 r~@ NUMEER '.. 3 NUMBER TEXT /IIrr>>ro o/>>oo /s ter/rr/rorL I>>o or/orrT/or>>/NRC Form 36EAS/ ()7) 05000400 9 1 0 1 60 0 0 2 OF EVENT DESCRIPTION:

On August 8, 1991 trouble shooting was in progress on the Component Cooling Water (CCW) Flow Indicator (FI-688A) to the "A" Residual Heat Removal (RHR) Heat Exchanger. To provide additional flow for this process the "B" CCW pump was started, with the "A" CCW pump already in operation. The start of the second pump created a momentary pressure spike that lifted three system relief valves.

Shortly thereafter a decrease in surge tank level was observed by control room that gave indication that. one (or more) of these relief valves had, 'ersonnel failed to reseat. Subsequent investigation revealed that the CCW relief valve for the Boron Recycle Evaporator had opened and failed to reseat until the second CCW pump was secured. This was determined to create a potential for degraded residual heat removal capability during an accident due to a loss of CCW -

inventory from an unisolable relief valve that has failed to reseat. Immediate corrective actions included initiating and throttling CCW flow through the "A" RHR heat exchanger. This lowered system operating pressure to approximately 95.

psig so that in the event of an automatic start of the second pump, the resulting pressure spike would be below the relief valve setpoints. Additional corrective actions included an inspection of CCW system relief valves which revealed that the nozzle ring adjustments for the valves reseating pressures were not properly set. Prior to resetting the relief valves, training was conducted for applicable personnel to ensure that a complete understanding existed on the proper setting of relief valve nozzle rings.

There has been one similar event reported in LER ¹90-018.

CAUSE:

The two primary causes for this event are as follows:

The cause for the relief valves lifting during normal system operations (starting of second pump) can be attributed to a system design in which the CCW pump discharge dead head pressure exceeds the relief valve set pressures on several of the individual components in the system.

The cause for the relief valves failing to reseat was the 'improper setting of the relief valve nozzle ring adjustments during site maintenance activities. This was due to a lack of understanding on how to properly set these nozzle ring adjustments. This is based on an inspection that was performed by Technical Support and Maintenance personnel to determine CCW system relief valves were properly set.

if the reseating adjustments on The valves included in this inspection which were found to have incorrect nozzle ring settings were properly reset to their required value.

NRC Form 366A (6J)9)

0 S

NRC FORM 366A (BJ)9)

LICENSEE EVENT REPORT (LER)

U.S. NUCLEAR REGULATOAYCOMMISSION e APPROVED OMB NO. 31500106 EXPIRES: 6/30/92 ESTIMATED BURDEN PEA RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50A) HAS. FORWARD COMMENTS REGARDING BUADEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND AEPOATS MANAGEMENT BRANCH IP430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO 1HE PAPERWOAK REDUCTION PROJECT (3(604104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER I6) PAGE C))

YEAR  ::cM SEQUENTIAL <0 REVISION

?K?: NVM ER ~r?6 NVMSEII Shearon Harris Nuclear Plant Unit f/1 0 5 0 0 0 0 1 6 0 0 03 "0 4 TEXT //I more g>>ce /s ecto/red, u>> edd/0'or>>/NRC Fomr 36643/ lll)

SAFETY SIGNIFICANCE There were no significant safety consequences as a result of this event. The relieving setpoint for the CCW relief valves were properly set to provide maintained adequate system over pressure protection. Adequate CCW inventory was throughout the period of time while the relief valves were opened. This ensured that RHR was fully capable of performing its design function. During a postulated accident scenario the loss of CCW inventory through a relief valve would cause a low level CCW surge tank alarm on the main control board and would require operator action to make up to the CCW surge tank or terminate the inventory loss.

A new design is currently being developed that will reduce the potential for loss of CCW system inventory. Until this design is completed and implemented, the CCW system will'ontinue to be operated at the lower system pressure (approx. 95 psig) to ensure that an automatic start of the second pump will not result in the lifting of system relief valves.

This event is reportable per 10CFR50.73 (a) (2) (v) as an event which could have prevented the fulfillment of a safety function needed to remove residual heat.

CORRECTIVE ACTIONS:

CCW flow was initiated through the "A" RHR Heat Exchanger. This lowered system operating pressure to approximately 95 psig so that in the event of an automatic start of the second pump, the resulting pressure spike would be below the relief valve setpoints.

Training has been conducted for Maintenance and other applicable personnel to ensure that a complete understanding 'on interpreting relief valve test report data and how to properly set the nozzle rings is established.

3. Procedural guidance has been developed for setting the relief valve nozzle rings.

CCW system relief valves have been checked to ensure that their nozzle ring adjustments are properly set for the required reseating value.

Plant modifications are being aggressively pursued to provide an engineering solution to the system design, that will eliminate the need to throttle flow through the RHR heat exchanger.

Additional investigation will continue to identify similar relief valve problems on other plant systems.

NRC Form 366A (6J)9)

NRC FORM 366A UrL NUCLEAR REGULATORY COMMISSION (64)9) APPROVED OMB NO. 3)504)104 EXPIRES: 4/30/92 LICENSEE E T REPORT (LER) IMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50i) HRS. FORWARD TEXT CONTINUATION COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (P4)30), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31500104). OFFICE OF MANAGEMENTAND BUDGET. WASHINGTON, DC 20503.

FACILITYNAME (I) DOCKET NUMBER (2)

LE R NUMBER (6) PAGE (3)

YEAR SSQUSNTrAL 45vrsroN Shearon Harris Nuclear Plant Unit 81 NUM 64 NUMBER TEXT ///moro <<>>co iomr/rr/rod, oddidor>>/HRC 0 5 0 0 0 4 p p 9 1 P 1 6 pp p4 oFp 4 rroo  %%drrrr 3r/643/02)

EIIS CODE INFORMATION:

Component Cooling Water CC NRC Form 366A (669)