ML17348B008

LER 90-014-01:on 901107,crack Discovered in Coolant Water Flexible Hose Weld.Caused by Manufacturing Defect.New Flexible Cooling Water Hoses Successfully Retested During Remaining EDG Acceptance tests.W/910722 Ltr

ML17348B008
Person / Time
Site:	Turkey Point
Issue date:	07/22/1991
From:	Plunkett T, Dawn Powell FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-91-196, LER-90-014, LER-90-14, NUDOCS 9107290073
Download: ML17348B008 (12)

Text

ACCELERATED DISTRIBUTION DEMONSTPATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9107290073 DOC.DATE: 91/07/22 NOTARIZED NO DOCKET g FACIL:50-251 Turkey Point Plant, Unit 4, Florida Power and Light C 05000251 AUTH. NAME AUTHOR AFFILIATION POWELL,D.R. Florida Power & Light Co.

PLUNKETT,T.F. Florida Power & Light Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 90-014-01:on 901107,crack discovered in coolant water flexible hose weld. Caused by manufacturing defect. New flexible cooling water hoses successfully retested during remaining EDG acceptance tests.W/910722 ltr.

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

L, SIZE:

NOTES:

RECIPIENT COPIES'TTR RECIPIENT COPIES ID CODE/NAME ENCL ID CODE/NAME LTTR ENCL PD2-2 LA 1 1 PD2-2 PD 1' AULUCK,R 1 1 INTERNAL: ACNW 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 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 SD 1 1 NRR/DST/SICB8H3 1 1 NR~R DST/SPLBSD1 1 1 NRR/DST/SRXB 8E 1 '1 02 1 . 1 RES/DSIR/EIB 1 1 RGN2 FILE 01 1 1 EXTERNAL: EG&G BRYCE,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 NOTE TO ALL "RIDS" RECIPIENTS:

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

P FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIFQ REQUIRED: LTTR 31 ENCL 31

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P.O. Box 029100, Miami, FL, 33102-9100 FPL JUL 22$ 91 L-.91-196 10 CFR 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Gentlemen:

Re: Turkey Point Unit 4 Docket No. 50-251 Reportable Event: 90-014-01 Date of Event: November 7, 1990 4 B Emergency Diesel Generator (DG) Cooling Water Flexible Hose Weld Crack Could Prevent DG From Performing Intended Safet Function The attached supplemental voluntary Licensee Event Report 251-90-014-01 is being provided for information purposes only following the guidance provided by NUREG 1022, Supplement 1, Item 19.1. This supplement contains a revised safety analysis.

If there are any questions please contact us.

Very truly yours, T. F. Plunkett Vice President Turkey Point Nuclear TFP/JEK/jk enclosures cc: Stewart D. Ebneter, Regional Administrator, Region II, USNRC, Senior Resident Inspectorr USNRCI Turkey Point Plant I-'. VVU~ 'i 9 gp7,~V>>

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LICENSEE EVENT REPORT (LER)

FACILITY NAYE (1)

DOCKET NUHSER (2) PACE (I)

TURKEY POINT UNIT 4 05000251 oF 4 4 B EMERGENCY DIESEL GENERATOR,(DG) COOLING WATER FLEXIBLE .HOSE WELD CRACK COULD PREVENT DG FROM PERFORMING INTENDED SAFETY FUNCTION RPT DATE (I) OTHER FACILITIES INV. (S)

EVENT DATE (5) LER NUMBER (6) sEO 6 DOCKET 6 (S)

MON YR NAME 07 90 90 014: 01 07 10 91 OPERATINO NODE (S) 10 CFR POSER LEVEL (10) 100 OTHER Voluntar (Speclty In Abstract belce and In text)

LICENSEE CONTACT FOR THIS LER (12)

David R. Powell, Superintendent of Licensing TELEPHONE NUF~R 305-246-6559 COHPI,ETE ONE LINE FOR EACH COHPONENT'FAILURE DESCRIBED IN THIS REPORT (1S)

SYSTEH NPRDS EK P SP X9 9 9 N EXPECTED SUPPLEHENTAL REPORT EXPECTED (16) SUBHISSION DATE (15) MONTH DAY YEAR (II yes. ccnplete EXPECTED SUBMISSION DATE)

S

. ABSTRACT (16)

This supplemental voluntary LER is being submitted .to revise the safety analysis.

On November 7; 1990, with both units operating at 100 percent power, a crack approximately three inches long was discovered in a coolant water flexible hose flange weld. The crack was found during installation of one of the four six inch flexible hoses in the new 4B Emergency Diesel Generator (EDG) coolant system. This inspection was being, performed in preparation for part of phase 1 of the FPL acceptance testing prior to turnover to the plant. The two new EDGs are being installed as part of the Emergency Power 'Systems Enhancement Project (EPS) . The two new EDGs are scheduled for turnover to the plant in the summer of 1991. The cause of the weld crack was a manufacturing defect. The wrong materia'l was used in the flexible hose stub by the manufacturer. New flexible hose assembl'ies were received and installed on both the 4A and 4B EDGs. The new assemblies incorporate a design that does not require the welds which cracked.

The existing. flexible hoses were removed and returned to the vendor.

The new flexible cooling water hoses were successfully retested during the remaining EDG acceptance tests. FP&L Quality Assurance (QA) and Nuclear Engineering are reviewing the generic implications of this event to determine if additional corrective actions are necessary.

il II LZCENSE~VENT REPORT (LER) TE CONTZNUATZON FACILITY NAME DOCKET NUMBER LER NUMBER PAGE No.

TURKEY POINT UNIT 4 05000251 90-014-01 02 oF 04 I. EVENT DESCRIPTION This supplemental voluntary LER is being submitted to revise the safety analysis..

On November 7, 1990, with both units operating at 100 percent power, while preparing for Emergency Diesel Generator (EK) (EDG) acceptance tests, a crack approximately three inches long was discovered in a coolant water flexible'hose flange weld. The crack was found during installation of one of four six inch flexible hoses in the new 4B Emergency Diesel Generator (EDG) coolant system. This inspection was being performed in preparation for part of phase 1 of the Florida Power and Light (FPL) acceptance testing before turnover to t'e.

plant. The two new EDGs are being installed as part of the Emergency Power Systems Enhancement Project (EPS) . They are scheduled for turnover to the plant in the summer of 1991.

IX. EVENT CAUSE

a. Immediate Cause The immediate cause of this event was a crack in the weld connecting the flexible hose pipe stub (EK) (FCON) and the flange.

b. Immediate Cause The manufacturer of the flexible hoses was different from that specified on the drawing received from the vendor.

c. Root Cause The cause of this event was a manufacturing error. Two samples of the weld material from the defective flexible hose were analyzed for chemical composition by Florida Power and Light.

This analysis and subsequent discussions with the vendor, Morr'ison-Knudsen Company, Inc., determined that the wrong material had been used by the manufacturer in the flexible hose stub. The filler metal to be used for welds is determined by chemical compatibility and thermal expansion compatibility with the metals being welded. The metals being welded were different from those called for in the plans. Therefore, the weld filler material called for in the plans was no longer applicable. This metal incompatibility resulted in the crack formation and propagation.

III. EVENT SAFETY ANALYSIS The Emergency Diesel Generators are necessary to provide on-site.-

power to required safety related loads during a loss of off-site power. An engineering evaluation of this event by FPL engineering concluded that the loss of engine coolant due to the leakage described above could eventually result in engine failure by engine overheating.

LZCENSEEVENT REPORT (LER) TEX+CONTZNUATZON FACILITY NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 4 05000251 90-014-01 03 oF 04 The defect was discovered and corrected prior to turn-over of the subject EDG to the plant. EDGs 3A and 3B have a different type of flexible hose that has not experienced this type of failure.

Pre-operational inspections and tests were developed to locate infantile problems similar to the crack discussed above. The tests and inspections are performed before the equipment can be declared operational.

At the time of this event, with both uni:ts cooperating, EDGs 3A and 3B were operable as required by Technical Specifications. The Dual Unit Outage had not yet begun and the Emergency Power Systems Enhancement Project EDGs 4A and 4B were still undergoing pre-operational and acceptance testing. If off-site power had been lost to Turkey Point Nuclear Power Plant, at that time, the site had available the two safety related diesels (3A and 3B), which are designed to auto start and provide power to the safety related emergency buses. Thus, the health and safety of the public were not affected by this events IV. CORRECTIVE ACTIONS The defective flexible hose and one of the other three flexible hoses associated with the 4B EDG were returned to the vendor for analysis and replacement on January 30, 1991.

2. The vendor supplied a complete set of new flexible hose assemblies for both 4A and 4B EDGs. The new assemblies were manufactured by the company specified on the vendor new assemblies incorporate a design that uses a floating drawings'he coupling in place of the weld that cracked. The new flexible hoses were installed on both 4A and 4B EDGs. The old flexible hoses were removed and returned to the vendor.

3. The new flexible cooling water hoses were successfully retested during the remaining EDG acceptance tests (phase II testing) .

The Turkey Point Independent Safety Engineering Group (ISEG) has independently reviewed documentation of this event and recommended further review of quality activities and possible generic implications. The final determination .of further corrective actions by FP&L Quality Assurance (QA) and Nuclear Engineering is scheduled to be completed by July 31, 1991.

ii LICENSE VENT REPORT, (LER) TE CONTXNUATZON FACILITY NAME DOC ET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 4 05000251 90-014-01 V. ADDITIONAL INFORMATION Similar LERs:

Voluntary LER 251-90-012-00 issued March 15I 1991I also reported problems with the coolant water system on the new EDGs.

2. Vendor/Manufacturer:

Florida Power & Light Turkey Point EDGs,4A and 4B were assembled by Morrison-Knudsen Company, Inc. The diesel portion of the EDG was manufactured by the Electro-Motive Division of General Motors. The engine is a 20 cylinder, skid-mounted diesel. The engine model number is 20-645F4B. The failed flexible hose assembly was manufactured by Air Craft Metal Products. The replacement assembly and the 'one called Sor in the vendor drawings was manufactured by Flexonics.

The generator portion of the EDG was manufactured by NEI Peebles-Electric Products.

The vendor, Morrison-Knudsen Company,, has worked .with FPL during this event.

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