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LER 87-014-00:on 871008,unidentified RCS Leakage Greater than Tech Spec Limit Discovered.Caused by Weld Joint Failure Due to Previous Misalignment of Listed Flanges.Reactor Shut Down & Required Repairs performed.W/871106 Ltr
	ML17221A497
Person / Time
Site:	Saint Lucie
Issue date:	11/06/1987
From:	Woody C; FLORIDA POWER & LIGHT CO.
To:	; NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
	L-87-456, LER-87-014-02, LER-87-14-2, NUDOCS 8711100366
	Download: ML17221A497 (6)
	v • d • e

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REGULA Y INFORMATION DISTRIBUTION -SYSTEM (RIDS)

ACCESSION NBR: 8711100366 DOC. DATE: 87/11/06 NOT*R IZED: NO DOCKET FAClL: 50-335 St. Lucie Planti Unit ii Florida Power h Light Co. 05000335 AUTH. NAME *UTHOR *FFILI ATION WOODY'. O. Florida Poeer h Light Co.

REC IP. NAME RECIPIENT AFFILIATION

SUBJECT:

LER 87-014-00: on 871008'nidentified RCS leakage greater than Tech Spec= limit discovered. Caused bg meld point failure due to previous misalignment of listed flanges. Reactor shut doen 0 required repairs performed. W/871106 ltr.

DISTRIBUTION CODE: IE22D COPIES RECEIVED: LTR I ENCL I SIZE:

TITLE: 50. 73 Licensee Event Report (LER)i Incident Rpti etc.

NOTES:

RECIPIENT COPIES REC IP IENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-2 LA 1 1 PD2-2 PD 1 TOUR IGNYi E 1 1 INTERNAL: ACRS MICHELSON 1 1 ACRS MOELLER 2 2

'1 AEOD/DOA 1 1 AEOD/DSP/N*S 1 AEOD/DSP/ROAB 2 2 AEOD/DSP/TPAB 1 1 ARM/DCTS/DAB 1 1 DEDRO 1 1 NRR/DEST/ADS 1 0 NRR/DEST/CEB 1 1 NRR/DEST/ELB 1 1 NRR/DEST/ICSB 1 1 NRR/DEST/MEB 1 1 NRR/DEST/MTB 1 1 NRR/DEST/PSB 1 1 NRR/DEBT/RSB 1 1 NRR/DEST/SGB 1 1 NRR/DLPG/HFB 1 1 NRR/DLPG/GAB 1 1 NRR/DOEA/E*B 1 1 NRR/DREP/R*B 1 1 NRR/DREP/RPB 2 2 NR+iDR'I~S I B 1 1 NRR/PMAS/ ILRB 1 1 02 1 RES DEPY GI 1 1 RES TELFORD) J 1 1 RES/DE/EIB 1 1 RGN2 FILE 01 1 1 EXTERNAL: EGS(G GROHz M 5 5 H ST LOBBY WARD 1 1 LPDR 1 1 NRC PDR 1 1 NSIC HARRIS' 1 1 NSIC MAYST G 1 1 TOTAL NUMBER OF COPIES REQUIRED: LTTR 45 ENCL 44

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NRC Form 355 V.S. NUCLEAR REGULATORY COMMISSION (943)

APPROVED OMB NO, 3)50410l LICENSEE EVENT REPORT (LER) EXPIRES: 5/31/SS FACILITY NAME 0) DOCKET NUMBER l2) PACE 3 St. Lucie Unit 1 0 5 0 0 0 3 3 5 1 OF 0 4 UNIDENTIFIED REACTOR COOLANT SYSTEM LEAKAGE GREATER THAN TECHNICAL SPECIFICATION LIMIT RESULTS IN REACTOR SHUTDOWN EVENT DATE (5) LER NUMBER (5) REPORT DATE (7) OTHER FACILITIES INVOLVED IS)

MONTH DAY YEAR YEAR Ss>r ssoUsrevrAL R e vrslorr OAY FACILITYNAMES

oQI NUMBER rrUMSSR MONTH YEAR DOCKET NUMB E R(S)

NA 0 5 0 0 0 10 088 7 8 7 014 0 0 Og 87 0 5 0 0 0 OPERATINO THIS REPORT IS SUBMITTED PURSUANT T0 THE REQUIREMENTS OF 10 CFR (): ICneee One Or mOre Of the IOIIOwifrpl (Ill MODE (9) 20A02(tr) 20A05(cl 50,73(e) (2)(N) 73.71(O)

POWER 20AOS(el(1)(5 SOW(c) (I ) 50.73(el(2)(v) 73.71(cl LEYEL (10) 1 0 0 20AOS(e) l1) (5 I 50.35(c)(2) 50.73(e) l2)(vill OTHER ISpecivy in Apttrect Oeiorv enrt In Text, NRC Form 20A05(el(1) lii)) 50.73(el(2)li) 50.73(e) (21(villi(A) 3SSAI 20A05 (e I lll I ivl 50 73(el(2)(ill 50.73(el(2((viiil(B) 20A05 (el II IN) 50,73(el(2) liii) 50.73(e) (21(x)

LICENSEE CONTACT FOR THIS LER (121 NAME TELEPHONE NUMBER Shift Technical Advisor V. N. Mendoza, 305465-3550 AREA CODE COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE SYSTEM COMPONENT MANUFA(r EPORTABLE MANUFAC. EPORTABLE TURER TO NPRDS CAUSE SYSTEM COMPONENT TVRER TO NPRDS ereTnf XZ~:i' BABSEAL B 5 8 0 Yes 44%5>>4'P~%!c(%

Z'J~~P+oZe AMKi SUPPLEMENTAL REPORT EXPECTED (Ill MONTH DAY YEAR EXPECTED SU 5 MISSION DATE (15)

YES fifycL comprere EIIPECTED SVSl(ISSIOH DATEI NO ABsTRAcT (Limit to te00 totter, I.e., epproximetery fifteen tinpie.epece typevrritten Iineri (15)

On October 8, 1987, St. Lucie Unit 1 was at Mode 1, 100% power and at steady state conditions. While performing a routine 2-hour leak rate surveillance, it was discovered that there was an unidentified reactor coolant system (RCS) leakage greater than one gallon per minute (GPM)'(1.09 GPM). At 0529, the Nuclear Plant Supervisor (NPS) declared an Unusual Event. Operations personnel made a containment entry to investigate the source of leakage. At 0612 hours0.00708 days 0.17 hours 0.00101 weeks 2.32866e-4 months , a controlled reactor shutdown was started so further investigations could be performed. During this investigation, the sources of the leakage were identified and determined to be less than the 10,GPM allowed by the Technical Specifications.

The Unusual Event was terminated at 1405 on October 8, 1987.

Cause of the event was due to leaking check valve bonnet and a cracked pipe in the heat affected zone on the 1Al reactor coolant pump (RCP) lower cavity seal nozzle weld. The root cause of the weld joint failure was due to the previous misalignment of the seal injection piping flange and the RCP lower cavity seal nozzle flange.

For corrective actions, the unit was shutdown and required repairs were performed and completed. The remaining reactor coolant pumps, lA2, 1Bl, and 1B2 were inspected for proper alignment of the seal injection and lower cavity seal nozzle flanges. Inspection revealed satisfactory alignment.

This event is reportable under 10 CFR 50.73 (a) (2) (i) (A), the completion of any nuclear plant shutdown required by the plant's Technical Specifications.

NRC Form 355 8711100366 871106 (9 53 I PDR ADOC)(, 05000335 8 PDR

t'4ii NRC Form 35SA U.S. NUCLEAR REOULATORY COMMISSION (94)3)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION APPROVEO OMS NO. 3150-0104 EXPIRES: 5/31/55 FACILITY NAME (1) OOCKET NUMBER (2) LER NUMBER (5) PACE (3)

SEOUENTIAL REVISION YEAR gg NUMSER NUM ER St. Lucie Unit 1 o so oo335 8 7 0 1 4 0 0 0 2 OF 0 4 TEXT ///morc 4/Mcc /4 /cr/rr/rod, o>> oddr)/ooo/HRC Form 35549/ O7)

DESCRIPTION OF EVENT On October 8, 1987, Unit 1 was at Mode 1, 100% power and at steady state conditions.

All controls were in their normal steady state condition lineup. While performing a routine 2-hour leak rate surveillance, it was discovered that there was Reactor Coolant System (RCS) (EIIS:AB) unidentified leakage greater than one gallon per minute (GPM) (1.09 GPM). At 0529, the Nuclear Plant Supervisor (NPS) declared an Unusual Event. State and local agencies along with the Nuclear Regulatory Commission (NRC) and plant management were notified. Operations personnel made a containment entry at 0530 to investigate and possibly identify the source of leakage. Another RCS leak rate calculation was performed to verify the leak rate. Also, operations personnel investigated other possible sources of leakage outside of containment. A report from the team of operators who made the containment entry verified a leak in the area of the reactor coolant pumps (RCP). At 0612, a controlled reactor shutdown was started so further investigations could be performed. At 0930, another containment entry was made by a team of operations and maintenance personnel to re-assess the leak.

From this investigation, it was discovered that the 1A1 RCP vapor seal was spraying a mist of water, the lA2 vapor seal was showing possible signs of leakage, the 1Bl charging system (EIIS:CB) header to the 1B1 loop was leaking, and the safety injection (EIISEBQ) line to the 1B2 loop was suspected to be leaking. Because the exact sources of the leakage could not be identified, it was determined to remain in the unusual event. The shutdown to Mode 3 (Hot Standby) was continued. At 0913, the turbine was removed from the grid. At 1205/ the reactor was shutdown and in Mode 3 ~ A task team was formed and assigned to evaluate the situation and prepare a plan to positively identify the leakage sources and arrange for the required repairs. The team decided to stop the 1A1 RCP so that a closer investigation could be performed on the RCP area leaks.

Also, arrangements were made to remove the insulation off the lines where leakage was suspected in order to positively identify the leakage sources.

The following sources of leakage were identified:

1) The lAl RCP leak was from a cracked weld joint on the RCP lower cavity seal nozzle connection. This was determined as a minor source of the leakage.

2) The 2-inch charging line to the 1Bl loop check valve V-2432 was leaking around the cover plate gasket. This was determined as the major source of the leakage.

The above leakage paths were estimated to be 0.5 GPM total.

At 1405, the Unusual Event was terminated because the leakage sources were identified and the leakage rate was determined to be less than 10 GPM of identified leakage as allowed by the plant's Technical Specifications. The unit was brought to Mode 5 (cold shutdown) at 1000 hours0.0116 days 0.278 hours 0.00165 weeks 3.805e-4 months on October 9, 1987 to perform the required repairs.

NRC FORM 355A (94)3)

NRC Form 366A U.S. NUCLEAR REOULATORY COMMISSION (943) .

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION APPROVED OMS NO. 3(SOMISE EXPIRES: 8/3(/88 FACILITY NAME (() DOCKET NUMSER (2) LER NUMBER (6) PACE (3)

YEAR SEOUENTIAL ??~e REVISION NUMBER 4IIr NVMSER St. Lucie Unit 1 0 5 o 0 o 3 3 5 8 7 0 1 4 0 0 0 3 OF 0 4 TEXT /lfmore tpeoF /F rer/u/red, u>> edono///RC Form 3//SAM (17)

CAUSE OP THE EVENT:

The cause of the event was the leakage on the check valve bonnet and the leakage from the cracked weld joint on the RCP lower cavity seal nozzle flange. The root cause of the cracked weld joint was due to the previous misalignment of the RCP lower cavity seal nozzle flange and the RCP lower cavity seal injection line flange. Due to this misalignment, the weld joint was stressed until the weld joint failed. The contributing factor for the weld joint failure could be attributed to the inherent vibration of the RCP. The root cause of the leakage on the check valve bonnet was due to the slight loosening of some of the bonnet bolts, which resulted in insufficient compression of the bonnet gaskets.

ANALYSIS OP THE EVENT:

Technical Specifications 3.4.6.2.b and 3.4.6.2.d, require that the reactor coolant system leakage shall be limite'd to: 1 GPM unidentified leakage, and 10 GPM identified leakage from the Reactor Coolant System, while plant is at Modes 1, 2, 3, & 4. Since the plant was at Mode 1, this report is being submitted under 10 CFR 50.73 (a)(2)(i)(A), the .completion of any nuclear plant shutdown required by the plant's Technical Specifications. Immediately upon the discovery of the excess RCS leakage, operations personnel investigated the situation and proceeded to perform a controlled reactor shutdown within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months and 22 minutes from the time of discovery in order to correctly identify and determine the amount of leakage. This was a conservative measure taken by operations personnel to ensure that the health and safety of the general public was not affected. Engineering evaluated the 1Al RCP flange misalignment and provided the resolution to correct the problem. The remaining reactor coolant pumps 1A2, 1Bl, and 1B2 were inspected for proper seal flange alignment and were found to be properly aligned.

NRC FORM 366A ISSSI

I Wo NRC Form 366A 1 U.S. NUCLEAR REGULATORY COMMISSION (943)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION APPROVEO OMB NO, 3150-0104 EXPIRES: 5/31/BB FACILITY NAME (1) OOC K ET NUMBE R (3) LER NUMBER (5) PAGE (3)

YEAR SEQUENTIAL REVISION NVM SR NVMSSR St. Lucie Unit 1 3 3 5 8 7 0 1'4 0 0 4 0 p 5 p p p OF TEXT ///II>>re e/>>o<< ie reeokrd, Iree eddiiior>>////IC Form 365/(3/ (IT)

CORRECTIVE ACTIONS:

1) Containment entry was made by operations and maintenance personnel to investigate and assess the situation to determine sources of leakage.

2) Once leakage sources were identified, repairs were performed on the identified leaking check valves. New gaskets were installed and valve bonnet bolts were properly torqued.

3) The lA1 RCP seal assembly was replaced, and the RCP lower cavity seal nozzle and the RCP lower cavity seal injection line flange were re-aligned to achieve a proper flange face matchup.

4) The RCP lower cavity seal flange and seal injection flange of the three remaining RCP were inspected for proper flange alignment and all were found to be properly aligned.

5) The lAl and lA2 RCP vapor seal drain lines were flushed and were found to be free of blockage.

6) All the RCP areas were inspected for signs of boric acid build-up as a preventive measure.

7) The other 2-inch charging line check valve, V-2433 was inspected as a preventive measure. The valve bonnet bolts were re-torqued.

8) The pressurizer Power Operated Relief Valve (PORV) V-1402 flange gasket was replaced and flange bolts were torqued. As a preventive measure, the other PORV, V-1404 was inspected and the inlet flange bolts were re-torqued.

9) As an additional preventive measure, the following were inspected for signs of boric acid build-up:

a) The 12-inch safety injection line to the 1B2 loop check valve V-3247 and was found to have sign of slight boric acid at the hinge pin gasket; The gasket was replaced.

. b) The 2-inch pressurizer auxiliary spray line check valve V-2431 was found to have signs of slight boric acid build-up around the bonnet gasket. The gasket was replaced and bonnet bolts were torqued.

c) The 3-inch 1B1 loop pressurizer main spray line check valve V-1249 was found to have signs of slight boric acid build-up around the bonnet gasket. The gasket was replaced and the bonnet bolts were torqued.

d) Valve V-3815 had a very minor packing leak. The valve packing gland was tightened to correct the leak.

ADDITIONAL INFORMATION:

FAILED COMPONENT IDENTIFICATION:

COMPONENT: RCP Seal Assembly MODEL NO./ Serial No.: 681-N-0448 MANUFACTURER: Byron Jackson PREVIOUS SIMILAR EVENT:

The most recent similar event on Unit 1 was an RCS leakage greater 'than 1 GPM submitted under LER I)335-82-014.

NRC FORM 366A (943)

P. OX 14000, JUNO BEACH, EL 33408 0420 NOVEMBER 0 6 1987 L-87-456 10 CFR 50.73 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Gentlemen:

Re: St. Lucie Unit I Docket No. 50-335 Reportable Event: 87-I4 Date of Event: October 8, I 987 Unidentified Reactor Coolant System Leakage Greater Than Technical S ecification Limit Results in Reactor Shutdown The attached Licensee Event Report is being submitted pursuant to the requirements of IO CFR 50.73 to provide notification of the subject event.

Very truly yours, C. 0. ody

< Group Vice President Nuclear Energy CO W/GRM/gp cc: Dr. J. Nelson Grace, Regional Administrator, Region ll, USNRC Senior Resident Inspector, USNRC, St. Lucie Plant Attachment an FPL Group company GR M5/062/ I

ML17221A497

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