ML18038B605

LER 95-008-01:on 951004,reactor Zone Isolation Dampers Failed to Close.Caused by Black Residue on core-plugnut Interface Inside Solenoid Valves.Removed/Replaced Solenoid valves.W/960130 Ltr

ML18038B605
Person / Time
Site:	Browns Ferry
Issue date:	01/30/1996
From:	Machon R, Jay Wallace TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-95-008, LER-95-8, NUDOCS 9602090077
Download: ML18038B605 (20)

Text

CATEGORY 1~

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ACCFSSION NBR:9602090077 DOC.DATE: 96/01/30 NOTARIZED: NO DOCKET ¹ FACII'.50-260 Browns Ferry Nuclear Powe" Station, Unit 2, Tennessee 05000260 AUTH. NAME AUTHOR AFFILIATION WALLACE,J.E.. Tennessee Valley Authority MACHON,R.'D. Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

.LER 95-008-01:on 951004,reactor zone isolation dampers failed to close. Caused black residue on core-plugnut interface inside solenoid valves. Removed/replaced solenoid valves.W/960130 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR t ENCL ~ SIZE:

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

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME ITTR ENCL ID CODE/NAME LTTR ENCL PD2-3-PD 1 1 WILLIAMS,J. 1 1 INTERNAL: ACRS 1 1 2 2

'AEOD/SPD/RRAB 1 1 1 1 NRR/DE/ECGB. 1 1 NRR/DE/EELB 1 1 NRR/DE/EMEB 1 1 NRR/DRCH/HHFB 1 1

'RR/DRCH/HICz~ 1 1 NRR/DRCH/HOLB 1 1 NRR/DRCH/HQMB 1 1 NRR/DRPM/PECB 1 1 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 . 1 RES/DSIR/EIB 1 1 RGN2 FILE 01 1 1 D EXTERNAL: L ST LOBBY WARD 1 1 LITCO BRYCE,J H 2 2 NOAC MURPHY,G.A 1 1 NOAC POORE'gW. 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 N

NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM OWFN SD-5(EXT. 415-2083) TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: L'FTR 26 ENCI 26

Terlessee Vatey Authortty. Pos; Otfce Box 2000, Decatur. Atabatta 35609 2000 R. D. (Rick) Machon Vce Presrcertt, Browses Ferry Nuc'ear Ptartt January 30, 1996 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 1~ 2'~ AND 3 - DOCKET NOS. 50-259~ 50-260'~ AND 50-296 FACILITY OPERATING LICENSES DPR-33'2'ND 68 - LICENSEE EVENT REPORT 50-260/95008 R1 This LER is a voluntary revision to LER 50-260/95008 dated November 2, 1995. This report provides additional details concerning the failure of several reactor zone isolation dampers to close. In the initial LER, we stated that two dampers failed. However, since transmitting the initial LER, two additional failures have occurred. The dampers failed to close because the solenoid valves were sticking. The solenoid valves became stuck at the core-plugnut interface as a result of an adhesive residue. At this time, TVA has replaced 14 of the 24 similar solenoid valves and plans to replace the remaining 10 solenoid valves. TVA and the valve vendor (ASCO) are still investigating the source of the residue.

The initial report was submitted in accordance with 10 CFR 50.73(a)(2)(v) and 10 CFR 50.73(a)(2)(vii) as (1) an event or condition that alone could have prevented the fulfillment of a safety function of structures or systems that are needed to control the release of radioactive material or mitigate the consequences of an accident, and (2) an, event where a single cause or condition caused two independent trains or channels to become inoperable in a single system designed to control the release of radioactive material or mitigate the consequences of an accident.

'7602090077 960i30 PDR ADGCK 05000260 s .PDR

U.S. Nuclear Regulatory Commission Page 2 January 30, 1996 The enclosure contains the supplemental response. The revision bars in the right hand-margin identify the revised text.

Sincerely, Enclosure cc (Enclosure):

INPO Records Center 700 Galleria. 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 10833 Shaw Road Athens, Alabama 35611 Regional Administrator U.S. Nuclear Regulatory Commission Region II Marietta Street, NW, Suite. 2900 101 Atlanta, Georgia 30323 Mr. J. F. Williams, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852

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NRC FORH 366 U.S. NUCLEAR REGULATORY COHlllSSION APPROVED BY OHB NO. 3150.0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE'O CONPLY IJITH THIS INFORHATION COLLECTIOH REQUEST: 50.0 COHHEHTS REGARDING BURDEN ESTIHATE TO LICENSEE EVENT REPORT (LER)

BR'ORNARD THE IHFORHATIOH AND RECORDS HANAGEHEHT BRAHCH (HNBB 7714), U.S. NUCLEAR REGULATORY COHHISSIOH, NASHINGTON, OC 20555 0001 AND TO THE PAPERNORK (See reverse for required number of digits/characters for each block) REDUCTION PROJECT (31j0-0104), OFFICE OF HANAGEHENT AND'BUDGET llASHINGTON DC 20503.

FACI" ITY NAME (1) DOCKET NUHBER (2) PAGE (3)

Browns Ferry Nuclear Plant (BFN) Unit 2 05000260 1 OF 7 TITLE (4) Reactor zone isolation dampers failed to close.

EVENT DATE '(5) LER NUNBER '(6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

SEQUENTIAL REVISION FACILITY NAHE DOCKET NUHBER MONTH DAY YEAR YEAR NORTH DAY YEAR NA NUHBER NUNBER FAG I L I 'I'Y NAHE DOCKET NUHBER 10 04 95 95 008 01 01 30 96 NA OPERATIHG THIS REPORT IS SUBNITTED PURSUANT TO THE REQUIREHEHTS OF 10 CFR 5: (Check one or mor e) (11)

NODE (9) N 20.402(b) 20.405(c) 50 '3(a)(2)(iv) 73.71(b)

PONER 20.405(a)(1)(i) 50.36(c)(1) X 50.73(a)(2)(v) 73.71(c)

LEVEL'10) 100 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vii) OTHER 20.405(a)(1)(iii) 50.73(a)(2)('I) 50.73(a)(2)(viii)(A) (Specify in 20.405(a)(1)(iv) 50.73(a)(2)(ii) 50.73(a)(2)(viii)(B) Abstract and in Text, below 20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x) NRC Form 366A)

LICENSEE CONTACT FOR THIS LER (12)

NAHE TELEPHONE NUNBER (Include Area Code)

James E. Wallace, Compliance Licensing Engineer (205)729-7874 COHPLETE ONE LINE FOR EACH COHPONENT FAILURE DESCRIBED IN THIS. REPORT (13)

SYS REPORTABLE CAUSE SYSTEH COHPONENT RE~TABLE CAUSE HANUFACTURER TEH COHPONEHI'SV TO NPRDS TO 0 "VA A610 N NPRDS'UPPLEHENTAL REPORT EXPECTED (14) EXPECTED NORTH DAY YEAR YES SUBHISSION (If yes, coapiete EXPECTED SUBHISSIOH DATE).

X NO DATE (15)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typeNritten lines) (16)

On October 4, 1995, at 0145 hours0.00168 days <br />0.0403 hours <br />2.397487e-4 weeks <br />5.51725e-5 months <br />, while performing a scheduled weekly routine of alternating the reactor zone supply fans, the dampers failed to close. Limiting Condition for Operation (LCO) 3'.7.C.2 was entered. At 0211 hours0.00244 days <br />0.0586 hours <br />3.488757e-4 weeks <br />8.02855e-5 months <br />, the dampers were closed after the solenoid valves on the air supply were lightly tapped. At 0214 the LCO was exited. As a result of this event, at 0511 hours0.00591 days <br />0.142 hours <br />8.449074e-4 weeks <br />1.944355e-4 months <br /> CST, a four-hour nonemergency notification was made to the NRC. The apparent cause for the dampers failing to close was black residue on the core-plugnut interface inside the solenoid valves. Since this LER was first transmitted, additional solenoid valve failures have occurred. TVA is continuing, its investigation of this event. Interim corrective actions include: (1) removed/replaced the solenoid valves, (2) increased test frequency when dampers fail, and (3) return any further damper failures that are on the increased test frequency to operable status. Any further corrective actions that are developed as a result of TVA's investigation will be implemented in accordance with TVA's corrective action process. This report is submitted in accordance with 10 CFR 50;73(a) (2)(v) and 10 CFR 50.73(a)(2) (vii) as (1) an event or condition that alone could have prevented the fulfillment of a safety function of structures or systems that are needed to control the release of radioactive material or mitigate the consequences of an accident, and (2) an event where a single cause or condition caused two independent trains or channels to become inoperable in a single system designed to control the release of radioactive material or mitigate the consequences of an accident.

NRC FORH 366 (5-92)

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NRC FORM 366A U.S. NUCLEAR REGULATORY CQNIISSION APPROVED BY (NS NO. 3150-0104 (5 92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPOHSE TO COMPLY WITH THIS INFORNATIOM COLLECT ION REOUEST: 50.0 HRS. FORMARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AHD RECORDS MANAGEMENT BRANCH (HHBB 7714), U.ST HUCLEAR REGULATORY CONHISSION, LICENSEE EVENT REPORT MASHIHGTOH, DC 20555-0001, AMD TO THE PAPERIR)RK REDUCTIOH TEXT CONTINUATZON PROJECT (3150-0104), OFFICE OF NAHAGEMEHT AND BUDGET, NASHINGTON DC 20503 FACILITY NAME (1) DOCKET MQQER (2) LER MQIBER (6) PAGE (3)

YEAR SEOUEHI'IAL REVISION NUMBER NUMBER Browns Ferry Unit 2 05000260 95 008 Ol 2 of 7 TEXT If more s ce is r ired Use edditionsl co ies of NRC Form 366A (17)

I ~ PLANT CONDITIONS At the time this event occurred, Unit 2 was at 100 percent power.

Unit 3 and Unit 1 were shutdown and defueled.

DESCRIPTION OF EVENT'

~ Event:

On October 4, 1995, at 0145 hours0.00168 days <br />0.0403 hours <br />2.397487e-4 weeks <br />5.51725e-5 months <br /> CST, while performing a scheduled weekly routine of alternating the reactor zone (VA) supply fans, the inboard and outboard isolation dampers [BDMP) for the reactor zone supply fan failed to close. Because the dampers failed to close, this event resulted in the loss of secondary containment. Limiting Condition for Operation (LCO) 3.7.C.2 was entered. An Assistant Shift Operations Supervisor (utility, licensed) and Assistant Unit Operators (utility, nonlicensed) were dispatched to the field to investi-"te the event. At 0211 hours0.00244 days <br />0.0586 hours <br />3.488757e-4 weeks <br />8.02855e-5 months <br />, the dampers closed after the solenoid valves (FSV] on the air supply to the inboard and outboard d'ampers were lightly tapped. At 0214 hours0.00248 days <br />0.0594 hours <br />3.53836e-4 weeks <br />8.1427e-5 months <br /> after the dampers were successfully cycled'hree times, the LCO was exited.

As a result of this event, at 0511 hours0.00591 days <br />0.142 hours <br />8.449074e-4 weeks <br />1.944355e-4 months <br />, a four-hour nonemergency notification was made to the NRC. This report is submitted in accordance with 10 CFR 50.73(a)(2)(v) and 10 CFR 50.73(a)(2)(vii) as (1) an event or condition that alone could have prevented the fulfillment of a safety function of structures or systems that are needed to control the release of radioactive material or mitigate the consequences of an accident, and (2) an event where a single cause or condition caused two independent trains or channels to become inoperable in a single system designed to control the release of radioactive material or mitigate the consequences of an accident. The vendor is addressing any 10 CFR Part 21 requirements.

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

Automatic Switch Company (ASCO) was the manufacturer of the solenoid valves. These valves were model number X-206-832-3RF-15385.

II NRC FORH 366A U.S. NUCLEAR REGULATORY CQSIISSI ON APPROVED BY CKB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE TO COHPLY HITH THIS INFORHATION COLLECTION REQUEST: 50.0 HRS. FORllARD COHHENTS REGARDING BURDEN EST IHATE TO THE IHFORHAT ION AND RECORDS HANAGEHENT BRANCH (HNBB 7714), U.S. NUCLEAR REGULATORY COHHISSION, LICENSEE EVENT REPORT IIASHINGTON, DC 20555-0001, AND TO THE PAPERNORK REDUCTION TEXT CONTINUATION PROJECT (3150.0104), OFFICE OF HANAGEHENT AND BUDGET, HASHING'TON DC 20503 FACILITY NAHE (1) DOCKET NQIBER (2) LER NLNBER (6) PAGE (3)

YEAR SEQUENTIAL REVISION NUHBER NUHBER Browns Ferry Unit 2 05000260 95 008 01 3 of 7 TEXT If more s ce is r ired use sdditionsi co ies of NRC Form 366A (17)

Ci Dates and A roximate Times of Ma'or Occurrencest On October 4, 1995 At 0145 hours0.00168 days <br />0.0403 hours <br />2.397487e-4 weeks <br />5.51725e-5 months <br /> CST Reactor zone supply isolation dampers failed to close, and LCO 3.7.C.2 was entered At 0211 hours0.00244 days <br />0.0586 hours <br />3.488757e-4 weeks <br />8.02855e-5 months <br /> CST Dampers were closed At 0214 hours0.00248 days <br />0.0594 hours <br />3.53836e-4 weeks <br />8.1427e-5 months <br /> CST Dampers successfully cycled three times, and LCO exited At 0511 hours0.00591 days <br />0.142 hours <br />8.449074e-4 weeks <br />1.944355e-4 months <br /> CST Four-hour nonemergency notification made to the NRC D. Other S stems or Seconda Functions Affected:

As expected, the temperature in the Unit 2 main steam tunnel elevated to the alarm point of 1604F following a loss of the reactor building ventilation. This alarmed condition subsequently cleared following restoration of the reactor building ventilation.

E. Method of Discove This condition was discovered when the Unit Operator (UO)

[utility, licensed) did not receive the green indicating lights to signify that the dampers were closed.

F. 0 erator Actions:

When the UO noticed the inboard and outboard damper green indicating lights were not lit, operations personnel were dispatched to investigate why the dampers did not close. At that time, LCO 3.7.C.2 was entered. After the damper solenoid valves were lightly tapped, the dampers closed.

Safet S stem Res nses:

The reactor zone supply inboard and outboard isolation dampers failed to close. All other safety systems responded as designed for this type of event.

IN NRC FORli 366A 'U.S. NUCLEAR REGULATORY CQBIISSIOH APPROVED BY MB Ie. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE TO COHPLY MITH THIS IHFORHATION COLLECTION REQUEST: 50.0 NRS. FORllARD COHHENTS REGARDING BURDEN ESTIHATE TO THE INFORHATIOH AND RECORDS HAHAGEHEHT

'LICENSEE EVENT REPORT BRANCH (HNBB 771C), U.S. NUCLEAR REGULATORY COHHISSIOH, llASHINGTON, DC 20555-0001, AND TO THE PAPERNORK REDUCTION TEXT CONTINUATION PROJECT (3150-0104), OFFICE OF HANAGEHENT AND BUDGET, 1IASHINGTON DC 20503 FACILITY HAHE (1) DOCKET NIRIBER (2) LER NIMBER (6) PAGE (3)

YEAR SEQUENTIAL REVISION NUHBER NUHBER Browns Ferry Unit 2 05000260 95 008 01, 4 of 7 TEXT tf more s ce is r ired use additional co ies of NRC Form 366A (17)

III'AUSE OF THE EVENT Ao Immediate Causes The immediate cause of the event was sticking of the solenoid valves.

B~ A arent Cause:

TVA has concluded from its analyses that the solenoid sticking phenomena has been definitely identified to occur at the core-plugnut interface (CPI). TVA also concluded that the residue found on the surface is adhesive and causes the solenoid core to stick to the plugnut. Other conditions which may have contributed to the sticking problem include:

(1) The smooth, flat. surface associated with the AC coil construction at the CPI provides a relatively large area for adhesion to occur.

(2) The low differential'perating pressure at which the valve operates. High differential operating pressures across the valve exhaust disc tend to aid the valve in shifting position.

(3) High temperature at the CPI associated with the AC'odel NP-206.

(4) The valve will not develop the sticking problem until after about 12 months of operation-Currently, ASCO is performing detailed valve testing and further chemical analysis on the core/plugnut residue in an effort to determine the source of the black residue.

C~ Contributin Factors:

None.

IV. ANALYSIS OF THE EVENT The inboard and outboard damper valves are redundant for secondary containment purposes. This simultaneous failure resulted in loss of secondary containment integrity. Technical Specification (TS) 3.7.C.1 states, in part, that secondary containment integrity shall be maintained in the reactor zone at all times except as specified

~i NRC FORH 366A U.S. NUCLEAR REGULATORY CGWISS ION ~

APPROVED BY (WB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN-PER RESPONSE TO COMPLY WITH THIS INFORHATIOH COLLECTIOM REQUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN EST'IHATE TO THE IMFORHATIOH AND RECORDS HANAGEHENT BRANCH (HNBB 7714), U.S. NUCLEAR REGULATORY COHHISSIOHg LICENSEE EVENT'EPORT WASHINGTON, DC 20555-0001,, AMD TO THE PAPERWORK REDUCTION TEXT CONTINUATION PROJECT (3150 0104), OFFICE OF HANAGEHEHT AND BUDGET, IIASHINGTON DC 20503 FACILITY NAHE (1) DOCKET NINBER (2) LER NIMBER,(6) PAGE (3)

'YEAR SEQUENTIAL REVISIOH NUMBER NUHBER Browns Ferry Unit 2 05000260 95 008 Ol 5 of 7 TEXT If more s ce is r uired use additional co ies of NRC Form 366A (17) in TS 3.7.C.2. TS 3.7.C.2 requires, in part, reactor zone secondary contai.nment integrity be restored within four hours, or place reactors in at least a hot shutdown condition within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in a cold shutdown condition within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

This failure to maintain reactor zone secondary containment integrity lasted approximately 26 mi.nutes. During this time, no conditions were identified that would have resulted in the release of radioactive material. Therefore, this event did not adversely affect plant personnel or the public.

V~ CORRECTIVE ACTIONS A Immediate Corrective Actionst Operations personnel di.spatched to the field tapped the solenoid valves and the dampers closed.

B. Corrective Actions to Prevent Recurrence:

The two solenoid valves which failed were replaced. The other secondary isolation dampers were tested and one additional failure on the Unit 1 supply outboard damper occurred due to binding in the limit switch. The limit switch was ad)usted.

Subsequent to this testing, the Unit 1 supply outboard damper failed to close when it received a containment isolation signal.

This was also due to a sticking sc,.lenoid valve which was also removed.

As a result of the valve failures, TVA increased the test frequency from weekly to daily for the failed dampers. Because the solenoids were replaced, TVA returned to a weekly testing frequency for the dampers. To date, a total'f four similar failures have occurred. As compensatory actions, should additional failures. occur, their testing frequency will be increased'o daily. If any further failures occur on the dampers with increased test frequency, the failed dampers will be returned to operable status by establishing measures in accordance with Generic Letter 91-18.'s a result of these failures, TVA determined that the 24 ASCO solenoid valves should be replaced. Currently, 14 valves have been replaced. Two solenoid valves. were replaced with the same Generi.'c Letter 91-18 provides guidance for the resolution of the degraded and nonconforming condition and for ensuring the functional capability of a. system or component.

II NRC FORH 366A U.S. NUCLEAR REGULATORY CONNISSION APPROVED BY OHB NO. 3150.0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE TO COHPLY 'WITH THIS INFORHATION COLLECTION REQUEST: 50.0 HRS. FORNARD COHHEHTS REGARDING BURDEN EST IHATE TO THE IHFORHATION AND RECORDS NANAGEHENT BRANCH (NNBB 7714), U.S. NUCLEAR REGULATORY CONHISSIOH, LZCENSEE EVENT REPORT llASHINGTOil, DC 20555 .:"1, AND TO THE PAPERHORK REDUCTION TEXT CONTINUATION PROJECT (3150.010C), OFFICE OF NANAGENEHT AND BISGETg WASHINGTON DC 20503 FACILITY NAHE (1) DOCKET NURSER (2) LER NUHBER ( ) PAGE ( )

YEAR SEOUEHTIAL REVISION NUHBER NUNBER Browns Ferry Unit 2 05000260 6 of 7 TEXT If more s ce is r ired use sdditionsi co ies of NRC Form 366A (17)

ASCO model NP-206 assembled with DC550 lubricant. TVA plans to use the latter model for future replacements since no significant failures were previously noted when BFN used that model from 1988 to mid-1994. As a short term resolution, TVA plans to replace the 24 solenoids with the latter model approximately every 12 months until the solenoid valves are replaced with:a different model.

VZ. ADDZTZONAL ZNFORMATZON A. Failed Co onents:

ASCO was the manufacturer of the solenoid valves. The failures have been limited to model number X-206-832-3RF-15385. Failures have only occurred in this design which are 120 VAC powered, continuously energized in their normal position and are supplied low pressure air (less than 25 psig). The identified failure mechanism has not been identified on DC powered solenoids of the same valve design, AC valves of the same design which are intermittently energized, or continuously energized AC powered valves which are used to control high pressure air sources. On valves used in high pressure applications, the high differential exhaust pressure creates a large force on the valve's exhaust port disc which aids in shifting the valve when it vents.

B. Previous LERs on Similar Events:

LER 296/92003 was written when the Unit 3 reactor zone exhaust fan isolation solenoid valves failed to close the exhaust dampers. As part of the corrective actions for LER 296/92003, the existing solenoid valves were replaced by special order solenoid valves from ASCO which were assembled without using any break-in lubrication. It was believed that using valves assembled without any break-in lubricant would eliminate the source of residue that contributed to these failures. The valves involved in LER 260/95008 were replaced in April 1994.

In addition to the replacement of these two valves, the other 22 solenoid valves were replaced. Additionally, the periodicity of alternating fans was increased from monthly to weekly (this resulted in cycling the dampers); therefore, these valves have been exercised successfully on a weekly basis. TVA believed the corrective actions taken for LER 296/92003 would have precluded the 260/95008 event.

c. Current Status of Znvesti ation Results:

Chemical analysis was performed on two of the three failed valves by TVA's Central Lab Facilities. Results showed deposits of silicon (assumed to be lubrication grease), copper, and zinc.

Ol NRC FORH 366A U.S. NUCLEAR REGULATORY COHHISSION APPROVED BY OHB NO. 3150 0104 (5.92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE TO COHPLY MITH THIS INFORHATIOH COLLECTION REQUEST: 50.0 HRS. FORMARD COHHEHTS REGARDING BURDEN EST IHATE TO TIIE INFORHAT I OH AND RECORDS HANAGEHENI'RANCH (HNBB 7714), U.S. NUCLEAR REGULATORY COHHISSIOH, LZCENSEE EVENT REPORT, MASNINGTON, DC .0555-0001, AND TO 'IHE PAPERIQRK REDUCTI OH TEXT CONTINUATION PROJECT;3150. 0104), OFF ICE OF HANAGEHEHT AND Ble GET,

'WASHINGTON DC 20503 FACILITY NAHE (1) DOCKET NUMBER (2) LER NUHBER ( ) PAGE ( )

YEAR SEQUEN'IIAL REVISION NUHBER NUHBER Browns Ferry Unit 2 05000260 7of7 TEXT If sere s ce is r ired use additional co ies of NRC Fore 3 66A (17)

Samples of residue on the core/plugnut were too small for analyses using equipment at this laboratory. As a result, the results of TVA's analyses were sent to ASCO as preliminary information to aid in identifying the residue at ASCO's lab facility.

VZZ. COhICZTMENTS None.

Energy Industry Identification System (EIIS) system and component codes are identified in the text with brackets (e.g., [XX].

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