ML18038B181

LER 95-003-00:on 950207,test Results Showed That SRVs Failed Setpoint Test Acceptance Criteria.Caused by Corrosion Bond of SRV Pilot Disc/Seat Interface.Two out-of-tolerance Target Rock Valves Being Refurbished & retested.W/950307 Ltr

ML18038B181
Person / Time
Site:	Browns Ferry
Issue date:	03/07/1995
From:	Hsieh C, Machon R TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-95-003, LER-95-3, NUDOCS 9503140057
Download: ML18038B181 (16)

Text

P R.IC) RIDS PROCESSING)

R.IWY'ACCELERATED REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9503140057 DOC.DATE: 95/03/07 NOTARIZED: NO DOCKET g FACIL:50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee 05000260 AUTH. NAME AUTHOR AFFILIATION HSIEH,C.S. Tennessee Valley Authority MACHON,R.D.. Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 95-003-00:on 950207,test results showed that SRVs failed setpoint test acceptance criteria. Caused by corrosion bond of SRV pilot disc/seat interface.Two out-of-tolerance target rock valves being refurbished & retested.W/950307 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED: LTR ENCL j SIZE: 7 TITLE: 50.73/50.'9 Licensee Event Report (LER), ncident Rpt, etc.

NOTES RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-4-PD 1 1 WILLIAMS,J. 1 1 INTERNAL: ACRS 1 1 ~A'EODQSPD/RAB 1 1 AEOD/SPD/RRAB 1 1 ~FILE CENTE~R 02 1 1 NRR/DE/ECGB 1= 1 NRR/DE/EELB 1 1 NRR/DE/EMEB 1 1 NRR/DISP/PIPB 1 1 NRR/DOPS/OECB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRSS/PRPB 2 2 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 RES/DSIR/EIB 1 1 RGN2 FILE 01 1 1 EXTERNAL: L ST LOBBY WARD 1 1 LITCO BRYCE,J H 2 2 NOAC MURPHY,G.A 1 1 NOAC POORE,W. 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1

'NOTE TO ALL"RI DS" RECIPIENTS:

PLEASE HELP US TO REDUCE iVASTE! COYTACI THE DOCliIEYTCONTROL i!

DESK, ROONI P! -37 (EXT. 504.2083 ) TO EL! IRATE YOL'R WAFFIE FROil DISTRIBUTION LISTS I'OR DOCl.'ML'iTS YOL'Oi "I'LIED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED'TTR 27 ENCL 27

0 Tennessee vaaey Avtnon'y. post otfce Box 2000. Debtor. Ataoanta 35609-2000 R. D. (Rick) Machon Vice Pres!dani. Browne Ferry at~. Rant March 7, 1995 U.S..'Nuclear Regulatory Commission 10 CFR 50.73 ATTN: Document Control Desk Washington, D.C. 20555

Dear Sir:

BROWNS FERRY NUCLEAR PLANT (BFN) - UNITS 1q 2I AND 3 DOCKET NOS ~ 50-259~ 50-260'ND 296 - FACILITY OPERATING LICENSE DPR-33~ 52'ND 68 - LICENSEE EVENT REPORT 50-260/95003 The enclosed report provides details concerning the Unit 2 main steam safety/relief valves (SRVs) exceeding. the technical specifications setpoint limit during tests. A supplemental report will .be submitted after the test results of all 13 SRVs have been received.

This report is submitted in accordance with 10 CFR 50.73 (a)(2)(i)'(B) as a condition prohibited by the plant's technical specifications.

Mal ~>

R. D.- M on Site Vice President Enclosure cc: See page 2 A)gP

'st503140057 950307 PDR S

ADOCK 05000260 I~

PDR

U.S. Nuclear Regulatory Commission Page .2 March 7, 1995 Enclosure cc (Enclosure):

INPO Records Center Suite 1500 1100 Circle 75 Parkway Atlanta, Georgia 30339 Paul Krippner American Nuclear Insurers Town Center, Suite 300S 29 South Main Street West Hartford, Connecticut 06107.

NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637 Athens, Alabama 35611 Regional Administrator U.S. Nuclear Regulatory Commission Region'I 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. J. F. Williams, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 E. V. Imbro, NRR/RSIB U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 E. J. Leeds, NRR/DRPW U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland .20852

0 1

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I NRC FORH 366 U.S. N}CLEAR REGULATORY CQNIISS ION APPROVED BY (NHI NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE TO COHPLY lIITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.

LICENSEE EVENT REPORT (LER) FORlIARD COMHENTS RECARDING BURDEN ESTIHATE TO THE INFORMATION 'AND RECORDS HANACEMEHT BRANCH (HNBB 7714), U.S. NUCLEAR REGULATORY COMHISSION, (See reverse for required number of digits/characters for each block) NASHINGTON, DC 20555-0001 AND TO THE PAPERNORK REDUCTION PROJECT (3180-0104), OFFICE OF HANAGEHENT AND BUDGET IIASHINGTON OC 20503.

FACILITY NAHE (1> DOCKET IRNIBER (2) 'PACE (3)

Browns Ferry Nuclear Plant (BFN) Unit 2 05000260 1OF5 TITLE (4) Main Steam Safety/Relief Valves Exceeded the Technical Specifications Required Setpoint Limit as a Result of Disc/Seat Bonding DATE 5 LER }AMBER 6 REP(NIT DATE 7 OTHER FACILITIES INVOLVED 8 SEQUENTIAL REVISION FACILITY NAHE DOCKET NUMBER HO}ITH DAY YEAR 95'VENT YEAR HOHTH DAY YEAR NA NUMBER NUHBER FACILITY NAHE DOCKET NUHBER 02 07 95 003 00 03 07 NA OPERATING THIS REPORT IS SlÃNITTEO PINISUANT TO THE REQUIREMENTS OF 10 CFR = Check one or mor e 11 INX}E (9)

N 20.402(b) 20.405(c) 50.73(s)(2)(iv) 73.71(b)

P(NER 20.405(a)('l)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c)

LEVEL (10) 100 20.405(s)('1)(ii) 50.36(c)(2) 50.73(a)(2)(vii) OTHER 20.405(s)(1)(iii) X 50.73(a)(2)(i)(B) 50.73(a)(2)(viii)(A) (Specify in 20.405(a)(1)(iv) 50 '3(a)(2)(ii) 50.73(a)(2)(viii)(B) Abstract below and in Text, 20.405(s)(1)(v) 50 '3(a)(2)(iii) 50.73(s)(2)(x) NRC Form 366A LICENSEE CONTACT FOR THIS LER 12 NAME TELEPHONE NUHBER (Include Area Code)

Clare S. Hsieh, Compliance Licensing Engineer (205)729-2635 C(NPLETE ONE LINE FOR EACH IXNIP(NIENT FAILURE DESCRIBED IN THIS REPORT 13 SYS REPORTABLE +js:;t',i!i"'~!i"i'll: REPORTABLE CAUSE COMPONEN'I MANUFACTURER CAUSE SYSTEM COHPONENT MANUFACTURER TEH TO NPRDS TO NPRDS SB RV T020 SUPPLEMENTAL REPORT EXPECTED 14 EXPECTED MONTH OAY 'YEAR YES SISM ISS ION (If yes, complete EXPECTED SUBHISSION DATE). DATE (15) 04 10 95 ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

On February 7, 1995, Wyle Laboratories notified TVA that tests had been completed for 2 of the 13 Unit 2 main steam safety/relief valves (SRVs). The results of the tests showed that the SRVs failed the setpoint test acceptance criteria. The SRV setpoints were found outside the Technical Specification (TS) limit of +/- one-percent setpoint tolerance.

This condition is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by the plant's TS. The apparent cause was attributed to corrosion bonding of the SRV pilot disc/seat interface resulting in an upward setpoint drift. TVA will submit a supplemental report following receipt of the test results of the remaining SRVs. TVA has implemented one of the Boiling Water Reactor Owners Group's recommendations to reduce corrosion. During the Unit 2 Cycle 7 refueling outage, TVA removed the SRV pilot cartridges from the main steam SRVs and replaced them with cartridges refurbished with a 0.3 percent platinum alloyed stellite pilot disc.

HRC FORM 366 (5-92)

I' HRC FORH 366A ~ U.S. NUCLEAR REGULATORY C(HSIISSIOH APPROVED BY (HHI HO. 3150-0104 (5-92> EXP I RES 5/31/95 ESTIMATED BURDEN PER 'RESPONSE TO COHPLY llITH THIS INFORHATIOH COLLECTIOH REOUEST: 50.0 HRS. FORllARD COHHENTS REGARDING BURDEN EST INATE TO THE INFORHATIOH AND RECORDS NANAGEHEHT BRANCH (HNBB 771C), U.S. NUCLEAR REGULATORY CQQIISSION, LICENSEE EVENT REPORT MASHINGTON, DC 20555-0001, AHD TO THE PAPERllORK REDUCTIOH TEXT CONTINUATION PROJECT (3150-0104), OFFICE OF NANAGEHEHT AND BUDGET/

'LIASHINGTOH DC 20503 FACILITY WL% (1) DOCKET NHIBER (2) 'LER IRMBER (6> PAGE (3)

'YEAR SEOUEHT I AL REVISION NUHBER HUHBER Browne Ferry Unit 2 05000260 95 003 00 2 of 5 TEXT If more s ce is r ired use sdditionst co ies of HRC Form 366A (17)

I ~ PLANT CONDITIONS Unit 2 was operating at approximately 100 percent power. During the Unit 2 Cycle 7 refueling outage, the safety/relief valve (SRV) pilot cartridges were removed from the Unit 2 main steam (SB) SRVs (RV) for testing. Units 1 and 3 were shutdown and defueled.

DESCRIPTION OF EVENT Event:

On February 7, 1995, Wyle Laboratories notified TVA that the tests on the first 2 of the 13 Unit 2 main steam SRVs (Target Rock Two-Stage SRV Model No. 7576F) had been completed. The results of the tests showed that the SRVs failed the setpoint test acceptance criteria.

During the Unit 2 Cycle 7 refueling outage, the SRV pilot cartridges were removed from the Unit 2 main steam SRVs and sent to Wyle Laboratories for testing. On February 7, 1994, the first two SRV pilot cartridges were bench tested, and the test results showed that the pilot cartridges caused the SRVs to open outside the Technical Specifications (TS) limit of +/- one-percent of setpoint tolerance (i.e., the test results were +3.85 percent and +1.95 percent, respectively).

The above condition is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by the plant's TS.

B. Ino erable Structures Com onents or S stems that Contributed to the Event:

None.

C. Dates and A roximate Times of Ma'or Occurrences:

During the Unit 2 Cycle 7 outage (October 1, 1994 through November 23, 1994), SRVs pilot cartridges were removed from the Unit 2 main steam SRVs and shipped to Wyle Laboratories for testing. On February 7, 1995, TVA was notified on the results of the first two SRVs tested.

D. Other S stems or Seconda Functions Affected:

None.

0 l,

I

NRC F(RN 366A U.S. IQCLEAR REGULATORY C(WIISSION APPROVED BY (HB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN'PER RESPOHSE TO COHPLY UITH THIS INFORMATION COLLECT ION REQUEST: 50.0 HRS. FORllARD CONNENTS REGARDING BURDEN ESTIHATE TO THE INFORMATION AMD RECORDS MANAGEMENT BRANCH (HHBB 771C), U.S. NUCLEAR'EGULATORY COMMISSION, LICENSEE EVENT REPORT llASHIHGTON, DC 20555-0001 'MD TO THE PAPERNORK REDUCTIOM TEXT CONTINUATION PROJECT (3150-0104), OFFICE OF MANAGEMENT AMD BISGET, UASHINGTOH DC 20503 FACILITY KAID (1) DOCKET NWSER (2) LER IAHmER (6) PAGE (3)

TEAR SEOUENT IAL REVISION NUMBER NUMBER Browns Ferry Unit 2 05000260 95 003 00 3 of 5 TEXT If more s ce is r ired use additional co ies of MRC Form 366A (17)

E. Method of Discove The deviation from the SRV setpoints was identified during bench testing at Wyle Laboratories in Huntsville, Alabama.

F. . 0 erator Actions:

None.

Safet S stem Res onses:

None.

CAUSE OF THE EVENT Ao Immediate Cause:

The immediate cause was the deviation of SRV setpoints outside the testing setpoint 1'imit of +/- one-percent tolerance recpxired by TS 2.2.A.

B. Root Cause:

The apparent cause of this event was attributed to corrosion bonding at Target Rock two-stage SRV pilot disc/seat interface.

Since corrosion:bonding caused an increase in the valve opening pressure due to the need for additional opening force above the setpoint value, this resulted-in an upward setpoint drift.

IV ANALYSIS OF THE EVENT Thirteen main steam relief valves (MSRVs) on the main steam piping perform the safety/relief function for the primary reactor system

,boundary. Each valve is designed to open at a pressure sensed in the valve body of 1105, 1115, or 1125 psig providing a safety/relief function. The safety/relief function of the MSRVs is to limit primary reactor system pressure to <1375 psig in the event of a pressurization transient resulting from a turbine trip or a main steam isolation valve closure.

TVA has performed a cycle specific limiting pressurization transient analysis assuming a spectrum of MSRV failures and setpoint drifts.

Even if four MSRVs completely fail to open and the remainder operating ten percent above setpoint, the analysis conservatively

II Cl NRC FORN 366A U.S. IN)CLEAR REGULATORY CQHII SSI ON, APPROVED BY (NNI NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTINATED BURDEN PER RESPONSE TO CONPLY MITH THIS INFORHATIOH COLLECTION REOUEST: 50.0 HRS ~ FORllARD CONHENTS REGARDING BURDEN EST INATE TO THE INFORNAT ION AND RECORDS NAHAGENENT BRANCH (NHBB 7714), U.S. NUCLEAR REGULATORY COHNISS ION g LICENSEE EVENT REPORT 'ASHIHGTON, DC 20555-0001, AHD TO THE PAPERNORK REDUCTI OH TEXT CONTINUATION PROJECT (3150-0104), OFFICE OF NAHAGENENT AND BUDGET, WASHINGTON DC 20503.

FACILITY NAIK (1) DOCKET NLM8ER (2) LER IRMBER (6) PAGE (3)

YEAR SEQUENTIAL REVISION HUNGER NUNBER Browns Ferry Unit 2 05000260 95 003 00 4 of 5 TEXT lf more s ce is r ired Use additional co les of NRC Form 366A (17) shows that the primary reactor system pressure would not have exceeded 1355 psig. As this is within the safety limit of 1375 psig given in TS section 1.2.A, the plant and the public safety would not have been adversely affected and the safety of plant personnel was not compromised.

V CORRECTIVE ACTIONS Ao Immediate Corrective Actions:

The two out-of-tolerance Target Rock valves are currently being refurbished, retested, and recertified by Wyle Laboratories for use as spares.

B~ Corrective Actions to Prevent Recurrence:

The setpoint drift is a generic concern experienced by all utilities using this brand of SRV intheboiling water reactors BWR Owners'roup (BWR) and is being investigated by (BWROG)

SRV Drift Fix Development Committee and the manufacturer, Target Rock Corporation.

The Committee recommended replacing the existing stellite 6B pilot disc with a 0.3 percent platinum disc/seat alloyed stellite or installing several parts in the pilot area with catalyst plated platinum alloy to act as a recombiner of excess oxygen, thereby reducing the oxygen available for corrosion.

(Note: corrosion is being attributed to radiologically produced o'xygen collecting at the disc/seat interface.)

The Committee's recommendation on replacing the stellite 6B pilot disc with a platinum alloyed7 refueling stellite has been implemented at BFN. During the Unit 2 Cycle outage, TVA replaced the Unit 2'ain steam SRVs with a 0.3 percent platinum alloyed stellite pilot disc. Per TS requirements, the valves are bench tested and checked for any increased setpoint deviation or drift at the end of each Unit 2 operating cycle.

As a SRV Drift Fix Committee member, TVA is continuing to participate in the BWROG evaluation on the long term solution concerning the SRV setpoint drift problem.

TVA will provide a supplemental report after receiving the test results of all 13 Unit 2 SRVs from Wyle Laboratories.

0 II HRC F(XIH 366A U.S. is)CLEAR, REGULATORY C(HHISSIOH APPROVED BY 0$ NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE TO CDHPLY IIITH THIS IHFORHATIOH COLLECT ION REQUEST: 50.0 HRS ~ FORHARD COHHENTS REGARDING

'BURDEN'ST IHATE TO THE IHFORHATION AHD RECORDS HANAGEHEHT BRANCH (HHBB 7714), U.S. NUCLEAR REGULATORY COHHISSIOH, LICENSEE EVENT REPORT UASHINGTON, DC 20555-0001, AND TO THE PAPERMORK REDUCTION TEXT CONTZNUATZON PROJECT (3150-0104), OFFICE'F HANAGEHENT AND BISGET ~

UASHIHGTON DC 20503 FACILITY WVK (1) DOCKET IAMBER (2) LER INNER (6) PAGE (3)

TEAR SEQUENTIAL REVISION NUHBER NUHBER Browne Ferry Unit 2 05000260 95 003 00 5 of 5 TEXT lf more s ce is r ired use additional co ies of NRC Form 366A (17)

VZ ~ ADDITIONAL INFORMATION A. Failed Com onents:

Target Rock Two-Stage, SRVs Model 'No. 7567F.

B. Previous LERs on Similar Events:

Since the early 1980s, TVA has issued several LERs (e.g.,

296/81074, 259/83036, 260/87005, 259/88053, 260/93003) regarding MSRV setpoint drift due to disc/seat corrosion bonding. The BWROG and the valve manufacturer are pursuing corrective actions for the disc/seat corrosion bonding problem. TVA expects the corrective action of using platinum alloy for disc/seat interface should help toward reducing corrosion bonding and thus, decreasing setpoint drift problems in the future.

VZI. Commitments None Energy Industry Identification System (EIIS) system and component codes are identified in the text with brackets (e.g., [XX].

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