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Rcbert A. FenechVice P'e anent senxry:5n N.gry P;ani

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tFebruary 4, 1994

U.S. Nuclear Regulatory Commission ,'

ATTN: Document Control DeskWashington, D.C. 20555

Gentlemen:

TENNESSEE VALLEY AUTIl0RITY - SEQUOYAH NUCLEAR PLANT UNIT 2 - DOCKETNO. 50-328 - FACILITY OPERATING LICENSE DPR-79 - LICENSEE EVENT REPORT(LER) 50-328/94001

The enclosed LER provides details concerning entry into Technical ;Specification Limiting Condition for Operation 3.0.3 as the result of two !inoperable rain steam isolation valves. This event is being reported inaccordance with 10 CFR 50.73(a)(2)(1)(B) as an operation prohibited bytechnical specifications.

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_Sincerely,

/ |h^'

Robert A. Fenech

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Enclosure- cc: See page 2

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.9402150103 940204 3 L lPDR ADOCK 05000328 O! IS PDR M

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U.S. Nuclear Regulatory CommissionPage 2February 4, 1994

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cc (Enclosure):INPO Records CenterInstitute of Nuclear Power Operations700 Galleria ParkwayAtlanta, Georgia 30339-5957

Mr. D. E. LaBarge, Project Manager.

U.S. Nuclear Regulatory CommissionOne White Flint, North11555 Rockville PikeRockville, Maryland 20852-2739

NRC Resident Inspector ,Sequoyah Nuclear Plant -

2600 Igou Ferry RoadSoddy-Daisy, Tennessee 37379-3624 ,

Regional AdministratorU.S. Nuclear Regulatory Commission ;Region II !

101 Marietta Street, NW, Suite 2900Atlanta, Georgia 30323-2711

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_- . . .-- - - - - - ~ . = . - - - . . . - -_

*,

NRC form 366 U.S. NUCLEAR REGULATORY COMMISSION Approved OMB No. 3150-0104

.(5-92) Expires 5/31/95*

LICENSEE EVENT REPORT (LER).

FACILITY NAME (1) |DOCKETNUMBER(2) |_PAQL{3)_

._sewnatweentalauttsonL_ unit 2 .10151aininuJULill0LL9LSTITLE (4) Two Inoperable Main Steam Isolation Valves (MSIVs) Caused Entry Into Technical Specification (TS)jlmLt10g_ Condition _ f or_Qperaupn10. 3__.EYLNL A11hL_L LIR_t4UUaELifzL j _ REPORT DATEJJL1 OTHER fA( RI D E$_[NVQLYED_10.)

| | | | | SEQUENTIAL | | REVISION | | | | FACILITY NAMES |DOCKETNUMBER(S)

nQuiuLRAYJnAtittaLLJ_munsts LLwtiettir10NTHLDALlYEAll_ 1Rj510]D10]J_LI I I LI l _. I I I I I i

_aLijJLLaL2L413L4LJJL10 i LLLJLLLLOL2LoliL9141 121510J010LLLOPERATING | |THISREPORTISSUBMITTEDPURSUANTTOTHEREQUIREMENTSOF10CFR$:

MODE | |_Jfheci one_pr_mgre_pLtheJqllowingHillt(9) | 3L_120.402(b) L|20.405(c) L|50.73(a)(2)(iv) |._I73.71(b)

POWER | |_.|20.405(a)(1)(1) |__l50.36(c)(1) |_|50.73(a)(2)(v) L|73.71(c)LEVEL | |_l20.405(a)(1)(ii) L]50.36(c)(2) |_|50.73(a)(2)(vii) L|0THER (Specify in

__1]ALlLlL lLL|20.405(a H 1 H ii i) |Ul50.73(a)(2)(1) |_|50.73(a)(2)(viii)(A) | Abstract below and in|_|20.405(a)(1)(lv) |_|50.73(a)(2)(li) |_|50.73(a)(2)(viii)(B) | Text, NRC form 366A)El20dQ1(a)(1)(v) | 150,73(a1(21[111]_j _ l50 2 LaJ12)(x) I

LI_CEU$ELCONTACT FOR THIS LLRd121NAME | TELEPHONE NUMBER

|AREACODE|1_1mHeademComnLiancLLLcentina I LL1J_LLaJ_4_L31 - ! 71116 I ra_

COMPLETE ONE LINLfDR EACH CQUPONENT FAILURE DISCRjaLD IN THI$_BEPORT (13)

| | | | REPORTABLE | | | | | | REPORTABLE |

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|_ | SUBMISSION | | |__LYEid1LJe3mcmpleitex1rritD_SUDMIS$JON DATE) IJLLNO I DATE (15L1 I I I I I

ABSTRACT (Limit to 1400 spaces, i.e., approximately fif teen single-space typewritten lines) (16)

On January 8, 1994, with Unit 2 in Mode 3 with the reactor coolant system at 547 degreesFahrenheit (F) and 2,235 pounds per square inch gauge, a shutdown of Unit 2 was beingperformed as the result of a problem with the 2B-B charging pump. As the result ofgeneric concerns from an incident that had occurred approximately two weeks previouslyat the McGuire Nuclear Station, a decision was made that the MSIVs would be tested. TheSQN testing of the MSIVs was performed at 547 degrees F. As the result of the testing,two of the four MSIVs failed the TS surveillance test. Once the unit was in Mode 4, all .

of the MSIVs were inspected, and the necessary adjustments were performed. The valveswere retested at 547 degrees F, and all four MSIVs had stroke times within TSrequirements. The root cause of this condition was a lack of guidance from the MSIVmanufacturer on the required clearance adjustments necessary to compensate for thermalexpansion. Testing of the MSIVs will be performed at approximately 547 degrees F untilan adjustment method that is not temperature dependent can be developed.

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NRC form 366(6-89)

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m . . _ __

.-,

NRC Form 366A U.S. NUCLEAR REGULATORY COMMISSION Approved OMB No. 3150-0104

(5-92) * Expires 5/31/95 |LICENSEE EVENT REPORT (LER)-.

TEXT CONTINUATION

FACILITY NAME (1) |DOCKETNUMBER(2)1 LERl4RtjaW_L6)_] } PAGL( 31__,

| | | | SEQUENTIAL | |REVISIONj | | |-|Sequoyah Nuclear Plant (SQN), Unit 2 | jYEARl | NVMER___l_j_MLMQLL| | | | | |

loJslolololLitlaA14 l I O I .o 1 11-101 0 13L210f13DL ITEXT (If more space is required, use additional NRC Form 366A's) (17) |

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I. PLANT CONDITIONS

Unit 2 was in Mode 3 with the reactor coolant system at 547 degrees Fahrenheit (F)' and 2,235 pounds per square inch gauge. ;

II. DESCRIPTION OF EVENT

A. Event,

On January 8, 1994, a shutdown of Unit 2 was being performed as the result of aproblem with the 2B-B charging pump. As the result of generic concerns from an'incident that had occurred approximately two weeks previously at the McGuireNuclear Station, a decision was made that the main steam isolation valves

i- (MSIVs) would be tested once the unit entered Mode 3. At McGuire, an MSIV didnot fully close at operating temperature as the result of valve binding. The

; binding occurred as the result of thermal expansion in the valve bonnet. The

: MSIVs are normally tested at a temperature significantly less than normaloperating temperature. Therefore, the MSIVs are not tested under full thermal

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expansion conditions.

The SQN testing of the MSIVs was performed at 547 degrees F. As the result ofthe testing, two of the four MSIVs failed the technical specification (TS)surveillance test. One of the valves failed to meet the required MSIV stroketime. The MSIV is required to fully close within 5.0 seconds. The Loop 4 MSIVclosed in 5.2 seconds. The Loop 1 MSIV failed to fully close as the result ofthermal binding. It is estimated that the valve was approximately 0.25 inchesfrom the full closed position. The full stroke of the MSIV is 14 inches. BothMSIVs were declared inoperable and TS Limiting Condition for Operation(LCO) 3.0.3 was entered. The unit was already being shut down to Mode 4conditions as the result of the subject charging pump problem.

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Once in Mode 4, all of the MSIVs were inspected and the necessary adjustmentswere performed. The valves were retested and all four MSIVs had stroke timessubstantially less than at operating temperature and well within TSrequirements. On January 11, 1994, Unit 2 was restarted from the subjectoutage. At 547 degrees F, the MSIVs were retested again. All four MSIVs metthe TS required stroke time.

B. InaparablRJirntiMreL_Comnonenis_,_oI_Sy1tema_IbAtlantribute11_tp the Event

None.

C. nates _and_ Approximate Times _of_Majnr occurrences

December 27, 1993 An MSIV did not fully close at the McGuire NuclearStation during a unit transient. A failure analysis idetermined that the MSIV failed as the result of thermalbindig.

NRC Form 366(6-09)

NRC Form 366A U.S. NUCLEAR REGULATORY COMMISSION Approved OMB Ho. 3150-0104

(5-92) Expires 5/31/95'

LICENSEE EVENT REPORT (LER).

TEXT CONTINUATION

FACILITY NAME (1) |DOCKETNUMBER(2) | L.LR_NitMBER (G) ! l PAGC_13)

| | | |SEQUEN11AL| | REVISION | | | | |Sequoyah Nuclear Plant ($QN), Unit 2 | j YLAR_|_l_.31VMBER I |_flVWIR_1 | | | |

10J5]QjpjDjLjl |81914 l-l 0101 1 j-l 0 l 0_j_QJ_3}Qfj_QJ_5_TEXT (If more space is required, use additional NRC Form 366A's) (17)

January 8, 1994 Unit 2 was being shut down as the result of charging pwnpproblems. The main steam system engineer determined thatSQN would be prudent to test the MSIVs as the McGuirecondition could be generic to SQN. The subject test '

resulted in two of the four MSIVs being declaredinoperable.

January 9, 1994 Inspections and the necessary adjustments to all fourMSIVs were performed. A retest of the MSIVs atapproximately 325 degrees F resulted in acceptableperformance.

January 11, 1994 Unit 2 was restarted from the charging pump outage. TheMSIVs were retested at operating temperature (547 degreesF). All four MSIVs successfully passed the TS requiredtest.

D. 01he r_ Systems _or_Se conda ry_Eunclions_.Miected

None. ;

E. Mathod_qLD_isnavery

As the result of generic concerns from the McGuire event, testing of the MSIVswas performed at the first available outage. This testing determined thatthermal binding of the MSIVs also existed at SQN.

Op_etalor_As11ons

Operations personnel performed the subject MSIV testing. The appropriate TS !LCOs were entered for failure of the subject valves. !

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C. SafetLSys1.emlereellne i!

No safety system responses were required.

III. CAUSE OF EVENT

A. Lmmediate Cante

The immediate cause of this condition was thermal expansion of the valvebonnet. This caused the valve travel time to increase and, in one case, jprevented an MSIV from fully closing.

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NRC form 366(6-89)

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. m . _. . . _ - .

J

NRC Form 366A U.S. NUCLEAR REGULA10R'( COMMISSION Approved OMB No. 3150-0104

(5-92) ' Expires 5/31/95LICENSEE EVENT REPORT (LER) fe

TEXT CONTINUATION |-

FACILITY NAME (1) |DOCKETNUMBER(2)j L ULMLMRIR_L(t)_| L_fAGli3)| | | | SEQUENTIAL | | REVISION | | | | |

Sequoyah Nuclear Plant (SQN), Unit 2 | }YEARl I NUMBER | | NUMBERJ | | | | .lQl3]fjDlDj3 12 18 19 14 l-l 0 1 0 1 1 1-101 010141Dfl015

TEXT (If more space is required, use additional NRC form 366A's) (17)

B. Ro.ol_.Cause

The root cause of this condition was a lack of guidance from the MSIVmanufacturer on the required clearance adjustments necessary to compensate forthermal expansion.

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IV. ANALYSIS OF EVENT

The MSIVs provide the isolation function for each of the four main steam lines.This isolation function is required for several design basis accidents. The mostlimiting accident for this event is the steam generator tube rupture. Exact MSIVfast closure times are not required for this event. The MSIVs are only required toclose.

The subject MSIVs are normally assisted in their closure by steam flow. The testcenditions under which the subject MSIVs failed did not include flow assistance. ,

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it has been concluded that had the MSIVs been flow assisted, all the valves would

have fully closed as required. Further, the failure of an MSIV to fully close ,during a steam generator tube rupture accident is covered in the emergencyprocedures. The emergency procedures require the secondary side of the plant to be ;

'closed in order to prevent any leakage to the outside atmosphere. These actionswould maintain the plant within the 10 CFR 100 limits. !

Therefore, there was no danger to the health and safety of the public as.a resultof this condition. i

V. CORRECTIVE ACTION

A. Immediate Corrective Action iv

The Unit 2 MSIVs were tested at the first available outage. Adjustments to theMSIVs were performed. The MSIVs successfully passed their surveillance test atnormal operating temperature.

B. Corrective Action to Prevent Returience *

The appropriate maintenance instructions will be revised to ensure that thermalexpansion is accounted for when performing valve adjustments.

Testing of the MSIVs will be performed at approximately 547 degrees F until anadjustment method that is not temperature dependent can be developed.

VI. ADDITIONAL INFORMATION

A. Eail.ed_C.omponeEtts

The Loop 1 MSIV failed to fully close at normal operating temperature.

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INRC form 366(6-89)

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*. ,

NRC form 366A U.S. NUCtEAR REGULATORY COMMISSION Approved OMB No. 3150-0104(5-92) ' Expires 5/31/95* tICENSEE EVENT REPORT (LER)

1 EXT CONTINUATION

FACILITY NAME (1) |DOCKETNUMBER(2)J LG_NU!1BIR_1hL_| | PArg__(3 )| | | | SEQUENTIAL | | REVISION | | | | |

Sequoyah Nuclear Plant (SQN), Unit 2 | J11AILL_j_HUMER___[__|_!NtIO.fS_1 | | | |In151ala1213_lLla_l1_lL1_-101011 1-I O 1 0 I OLS10LLtLL

TEXT (If more space is required, use additional NRC Form 366A's) (17)

B. freylons_Similar Events

A review of previous similar reportable events did not identify any similarevents.

VII. COMMID1ENTS

1. The appropriate maintenance instructions will be revised by June 1, 1994, toensure that thermal expansion is accounted for when performing valveadjustments.

2. Testing of the MSIVs will be performed at approximately 547 degrees F until anadjustment method that is not temperature dependent can be developed.

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NRC Fonn 366(6-89) -

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