ML17241A489

LER 99-004-00:on 990912,noted That MSSV Surveillance Was Outside of TS Requirements.Caused by Setpoint Drift.Subject MSSVs Are Being Refurbished & Retested Prior to Unit Startup from SL1-16 Refueling Outage.With 991007 Ltr

ML17241A489
Person / Time
Site:	Saint Lucie
Issue date:	10/07/1999
From:	Frehafer K, Stall J FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-99-219, LER-99-004-01, NUDOCS 9910140083
Download: ML17241A489 (10)

Text

MMJ;NVUlC Y' REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9910140083

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DOC.DATE: 99/10/07 NOTARIZED: NO

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FACIL:50-335 St. Lucie Plant, Unit 1, Florida Power & Light Co.

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DOCKET ¹

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05000335 AUTH.NAME . 'AUTHOR AFFILIATION FREHAFER,K.W. Florida Power & Light Co.

STALL,J.A. , Florida Power & Light Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 99-004-00:on 990912,noted that MSSV surveillance was outside of TS requirements. Caused by setpoint drift. Subject MSSVs are being refurbished & retested prior to unit startup from SLl-16 refueling outage. With 991007 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR I ENCL I SIZE:

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

NOTES:

'ECIPXENT COPIES RECIPIENT 'OPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL LPD2-2 1 1 GLEAVES,W 1 1 INTERNAL: ACRS 1 1 1 1 NRR/DIPM/IOLB 1 1 NRR/DRXP/REXB 1 1 NRR/DSSA/SPLB 1 1 RES/DET/ERAB 1 1 RES/DRY/OERAB 1 1 RGN2 FILE 01 1 1 EXTERNAL: L ST LOBBY WARD 1 1 LMXTCO MARSHALL 1 1 NOAC POORE,W. 1 1 NOAC QUEENER,DS 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE. TO HAVE YOUR NAME OR ORGANIZATION OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR REMOVED FROM DISTRIBUTION LIST DESK (DCD) ON EXTENSION 415-2083 ORGANIZATION, CONTACT T THE DOCUMENT CONTRC FULL TEXT CONVERSION REQUIRED TOTAL, NUMBER OF COPIES REQUIRED: LTTR 16 ENCL 16

Florida Power St Light Company, 6351 S. Ocean Drive, Jensen Beach, FL 34957 October 7, 1999 FPL L-99-219 10 CFR $ 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Re: St. Lucie Unit 1 Docket No. 50-335 Reportable Event: 1999-004-00 Date of Event: September 12, 1999 Main Steam Safety Valves Surveillance Outside Technical S ecification Re uirements The attached Licensee Event Report 1999-004 is being submitted pursuant to the requirements of f

10 CFR 50.73 to provide notification of the subject event.

Very truly yours, J. A. Stall Vice President St. Lucie Nuclear Plant JAS/EJW/KWF Attachment cc: Regional Administrator, USNRC, Region II Senior Resident Inspector, USNRC, St. Lucie Nuclear Plant 99i0140083 991007 05000335 PDR ADOCK PDR an FPL Group company

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3160-0104 EXPIRES 06/30/2001 I6.1999)

Estimated burden per response to comply with this mandatory information collection request: 50 hrs. Reported lessons teamed are incorporated into the licensing process and fed back to industry. Forward comments regarding LICENSEE EVENT REPORT (LER) burden estimate to the Record. TAanagement Branch {TW F33), U.S. Nuclear Regulatory Commission, Washington, Dc 205554001, and to the Papenvork Reduction Project (31504104j, Office of Management and Budget, (See reverse for required number of Washington, DC 20503. If an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, digits/characters for each block) and a person is not required to respond to, the Information collection.

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

St. Lucie Unit 1 05000335 Page 1 of 5 TITLE (4)

Main Steam Safety Valves Surveillance Outside Technical Specification'equirements EVENT DATE (6) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

SEQUENTIAL REVISION FACIUTYNAME DOCKET NUMBER MONTH DAY YEAR YEAR MONTH DAY NUMBER NUMBER FACIUTYNAME DOCKET NUMBER 09 12 1999 1999 - 004 - 00 10 07 1999 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQ UIREMENTS OF 10 CFR 5: (Chock ono or more) (11)

MODE (9) 20.2201 (b) , 20.2203(a)(2)(v) X 50.73(a)(2)(i) 50.73{a) (2)(viii)

POWER 20.2203(a) {1) 20.2203 (a) (3) {I) 50.73(a) (2)(ii) 50.73(a) (2)(x)

LEVEL {10) 070 20.2203(a)(2) (i) 20.2203{a) (3)(ii) 50.73(a) (2)(iii) 73.71 20.2203{a) (2) (ii) 20.2203(a) (4) 50.73(a) {2)(iv) OTHER 20.2203(a) (2)(iii) 50.36(c){1) 50.73(a)(2) (v) Specify In Abstract below or 20.2203(a) {2)(iv) 50.36(c) (2) 50.73(a) (2) {vii) in NRC Form 366A LICENSEE CONTACT FOR THIS LER {12)

NAME TELEPHONE NUMBER unaluda Araa Coda)

Kenneth W. Frehafer, Licensing Engineer (561) 467 7748 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 13)

CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE REPORTABLE To EPIX CAUSE SYSTEM COMPONENT MANUFACTURER To EPIX SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY EXPECTED YES SUBMISSION (tf yes, c'omplete EXPECTED SUBMISSION DATE). X No ,

DATE (16)

ABSTRACT /Limit to 1400 spaces, i.e., approximately 15 singlewpaced typewritten lines/ (16)

On September 12, 1999, St. Lucie Unit 1 was in Mode 1 and holding at. approximately 70 percent reactor power for testing'f the main steam safety valves (MSSVs) in accordance with proceduze 1-MSP-08.07, "Main Steam Sa'fety Setpoint Surveillance."

Three train A and one train B MSSVs lifted low, outside of the required Technical Specification pressure setpoint range of +/- 1 percent. Prior to testing, the reactor trip setpoints were reduced to allow continued operation with two MSSVs per train out of service. The set pressure of one of the train A MSSVs was reset to allow continued operation.

The apparent cause of the MSSV surveillance failures was setpoint drift. Per ASME code considerations, a formal root cause is not required. The safety significance of the low as-found MSSV setpoints was evaluated and found to be insignificant.

The subject MSSVs are being refurbished and retested prior to unit startup from the SL1-16 refueling outage. FPL is considering whether a change to the St. Lucie Technical Specifications or TS bases is appropriate to address the differences between NUREG-1432 and the St. Lucie Technical Specifications concerning as-found and as-left

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safety relief setpoints.

NRC FORM 3BB IB.1999)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6-1998)

LlCENSEE EVENT REPORT (LER)

TEXT CONTINUATION DOCKET PAGE (3)

FACILITY NAME (1) LER NUMBER (6)

NUMBER (2)

SEQUENTIAL REVISION NUMBER NUMBER St. Lucie Unit 1 05000335 004 - Page 2 of 5 1999 00 TEXT (Ifmore space is reriuired, use additional copies of IVRC Form 366A) (17)

Description of the Event On September 12, 1999, St. Lucie Unit 1 was in Mode 1 and holding at approximately 70 percent reactor power for testing of the main steam safety valves (MSSVs)

(EIIS)SB)RV) during the downpowex for the SL1-16 refueling outage. The following MSSVs lifted outside of their Technical Specifications (TS) required pressure range.

Additionally V8213 lifted outside of the +/- 3% ASME code allowed range by 0.6 psig low. This surveillance testing of the MSSVs'etpoints was performed in accordance with procedure 1-HSP-08.07, "Hain Steam Safety Setpoint Surveillance."

Measured Deviation Valve Train Lift TS Limit From TS Sepoint Pressure Limit (() )

(psia)

V8201 986.9 1000 +/- 1% 1 '1 V8202 982. 9 1000 +/- 1() -1071 V8211 1025.5 1040 +/- 1() -1.45 V8213 1008.7 1040 +/- 1'h -3013 MSSVs V8201, V8211, and,V8213 were left inoperable and out of service at the completion of testing. V8202 was restored to OPERABLE stats by setpoint adjustment within the action time of Technical Specification 3.7.1.1. Prior to testing the MSSVs, the reactor trip setpoints had been reduced to allow continued operation with two MSSVs per train out of service pex work ordex (WO) 98023939-02. No more than two valves per train were out of service and the reactor trip setpoints were properly adjusted in accordance with Te'chnical Specification 3.7 '.1, therefore there were no operability concerns.

Cause of the Event The as-found set pressure deviations were relatively minor and similar to those found in past cycles. The apparent cause is setpoint drift and/or the use of the new test methods. As described below, a formal root cause is not required by ASME/ANSI OM-1987, part l.

Per ASME/ANSI OM-1 'tt1.3.3.1(e)(2) and Code Interpretation 92-8, a Class 1 pressure relief valve with an as-found setpoint outside the acceptance range of the setpoint on the minus side is not considered a failure. As a consequence, additi.onal testing for valves failing outside the negative acceptance criteria is not required by the ASME Code. FPL quality instruction (QI) 11-PR/PSL-7, "Control of Code Safety and Relief Valves," contains additional criteria within 95.5.3 that generally requires additional testing for valves failing the negative tolerance criteria. The QI criteria are based on the adverse system functional issues resulting from relief valve seat leakage and premature lift. However, per the QI, the criteria for additional testing of valves faili.ng the negative tolerance acceptance criteria may be waived or altered based on an evaluation of the as-found test pressure, valve inspection, system requirements and histori.cal records. The expansion of testing scope due to the failure of V8213 was waived based on the small amount of deviation (3.13% vs. 3%), the acceptable results of the other'alve tests with respect to ASME NRC FORM 388A 18.1898)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION I 6-1 888)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION DOCKET PAGE (3)

FACILITY NAME (1) NUMBER (2)

LER NUMBER (6)

SEQUENTIAL REVISION NUMBER NUMBER St. Lucie Unit 1 05000335

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Page 3 of 5 1999 004 00 TEXT llfmore specs is required, use addi tionel copies of NRC Form 366A ) (17)

Cause of the Event (cont'd) criteria, the absence of recent problems with MSSV seat leakage and premature lift, and the insignificant effect of a small negative set pressure deviation in a high bank MSSV relief valve. The MSSVs are being refurbished and retested.

Analysis of the Event This event is reportable under 10 CFR 50.72 (a) (2) (i) (B) as "any operation or condition prohibited the plant's Technical Specifications." The St. Lucie Unit 1 Technical Specifications differ from NUREG-1432r "Standard Technical Specification Combustion Engineering Plants," in that an as-found MSSV setpoint tolerance is not included in the St. Lucie Technical Specifications.

FPL is considering whether a change to the St. Lucie Technical Specifications oz TS bases is appropriate to address this Technical Specification difference.

Analysis of Safety Significance The MSSVs must open to provide overpressure protection for the steam generators and relief capacity to remove decay heat. The MSSVs are classified as Safety-Related, Quality Group B components.

Per TS table 3.7-1 the maximum allowable power level high trip setpoint with two inoperable steam line safety valves on either operating steam generator is 79.8%

Effect on Safet Anal ses Valves V8201, V8202, V8211 and V8213 lifted outside the TS limit of +/- 1 percent. However, these lift lift setting tolerance setting failures were greater than the

-1 percent limit. Valves V8205 and V8216 lifted within the tolerance limit specified in the TS. It will be assumed for the purpose of this evaluation* that all the remaining valves would have lifted within their tolerance limits.

The only FSAR analyzed events that could potentially be affected by the deviations in the MSSV setpoints are the loss of exterhal load (LOEL) and the small break, LOCA (SBLOCA).

The loss. of external load event, including the case of inoperable MSSVs, relies on the MSSVs to release the system energy so as to prevent the primary and the secondary side pressures from exceeding the overpzessurization criteria. The analysis of this event assumes conservatively that the MSSVs begin to open at the TS allowed maximum lift pressure corresponding to a tolerance of + 1 percent. Opening of the valves at a pressure lower than that assumed in the safety analysis would be beneficial for this transient and the results would remain bounded by the FSAR results.

In the analysis of the small break LOCA event, open at a lift it is- assumed that the MSSVs begin to pressure corresponding to a tolerance of + 3 percent. The as-found set pressures therefore would, not have any adverse 'impact on the small break LOCA analysis results, as presented in the FSAR.

Other FSAR events including the steam generator tube rupture (SGTR) event are not impacted by the variations in the MSSV lift pressure.

FSAR conservatively assumes the opening of the atmospheric dump valves (ADVs) to The SGTR event analyzed in the NRC FORM 3BBA (6-1888)

NRC FORM 366A U.S. I'IUCLEAR REGULATORY COMMISSION Is-1998)

LICENSEE EVENT REPORT (LER)

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

SEQUENTIAL REVISION NUMBER NUMBER St. Lucie Unit 1 05000335 Page 4 of 5 1999 004 00 TEXT (If more speceis required, use eddi tionel copies of NRC Form 366AJ (17)

Analysis of Safety Significance (cont'd) release the steam from the ruptured steam generators. The identified MSSVs'etpoint pressure deviations thus would not impact the FSAR conclusions for this event.

'he opening of MSSVs at pressures lower than the lift pressure corzesponding to -1 percent tolerance is thus determined to'have no adverse impact on the safety analysis, including deviations outside -3.percent. A much lower negative valve

'tolerance limit, although acceptable from safety analysis considerations, may have operational impact as the margin to operating pressure gets reduced.

The MSSVs's-found set pressure values (specified above) were outside the tolerance limits specified in the St. Lucie Unit 1 Technical Specification 3.7.1.1. This degraded condition however did not compromise plant safety. The evaluation performed using the as-found setpoints concludes that, Cycle 15 operation had remained within the design basis of the plant for all analyzed FSAR events. No safety criteria would have been violated due to the identified condition of the MSSVs.

Se oint Drift Considerations The below chart shows the MSSV tests in the last 3 cycles for unit 1. Not'all of the valves were tested during these cycles. The As-Found () Failure column is shown for the cycles that were evaluated. They represent the percentage from nameplate setpoint that the valve was out of tolerance. The none in the column means, that the test was satisfactory. The percent Drift between Cycles .column is the percentage change that the valve experienced over one cycle taken from the 2"e as-left setpoint test and the next as-found test of the valve. I Valve S/N Unit Date As-Pound  %

Date As-Pound  %  % Drift between 1

'ailure Pailure cles N55128-00-0001 1996 none 1999 -1.71 -1.62 N55128-00-0002 1996 none 1999 -1.31 -1.93 N55128-00-0003 1996 1.4 1997 -1.03 -1. 12 N55128-00-0004 1996 none N55128-00-0005 1996 -1.52 1999 none -0.20 N55128-00-0006 1996 ~

1.83 1997 1.62 1.52 N55128-00-0007 1996 1.93 N55128-00-0008 1996- 2.54 N55128-00-0009 1996 none 1997 none -.50 N55128-00-0010 1996 none 1997 none -.19 N55128-00-0011 1995 none 1996 1.37 1. 17 N55128-00-0011 1999 -1.45 -2. 13 N55128-00-0012 1996 none 1997 none - 68

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N55128-00-0013 1996 1.95 1999 -3.13 -3.50 N55128-00-0014 1996 1.27 1997 none -1.35 N55128-00-0015 1996 1.17 1997 none .10 N55128-00-0016 1996 none 1999 none -0.87

NRC FORM 366A U.S: NUCLEAR REGULATORY COMMISSION (8-1998)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME {1) DOCKET NUMBER I2 LER NUMBER I6) PAGE I3)

SEQUENTIAL REVISION NUMBER NUMBER St. Lucie Unit 1 05000335 Page 5 of 5 1999 004 00 TEXT (Ifmore spaceis required, use additional copies of NRC Form 3MAJ (17)

Analysis of Safety Significance (cont'd)

These data are from the Relief Valve Database. This evaluation does not take into account the instrument inaccuracies or the difference in readings between'the 1" and 2"" tests done to accept the valves.

The test methodology was changed for Unit 1 for the 1999 testing. The plant started using computer operated test machine vs. the previous manual test method. Both test techniques use a lifting device but the newer system's ramp rate and setpoint interpretation are less subjective and operator dependent which provide for more consistent and accurate readings.

FPL concluded that the relief valves setpoint drift is mostly scattered data with no dominant trending setpoint drift for any valve over the cycles analyzed. Therefore, there is no concern pertaining to the downward drift of the MSSV setpoints.

Based on the above, this event had no impact on the health and safety of the public, Corrective Actions

1. The subject MSSVs are being refurbished by Wyle Labs via WO 98018487.

2. The subject MSSVs will be reworked and retested per WO 98018488.

3. FPL is considering a change to the St. Lucie Technical Specifications to address the differences between NUREG-1432 and the St. Lucie Technical Specifications concerning as-found and as-left safety relief valve setpoints.

Additional Information Failed Com onents Identified Based on ASME code considerations, there were no MSSV test failures.

Similar Events LER 50-389/1999-004-00 and 50-389/1999-004-01, "As Found Cycle 10 Pressurizer Safety Valve Setpoints Outside Technical Specification Limits, " was issued for Unit 2 pressurizer code safety surveillance failures.

NRC FORM 3BBA IB.1898)

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