ML18038B572

LER 95-006-00:on 951030,scram Discharge Instrument Vol Vent & Drain Valves Failed to Close After Reactor Mode Switch Was Placed in Shutdown Position.Caused by Dogged Open SDIV Vent & Drain Valves.Valves undogged.W/951121 Ltr

ML18038B572
Person / Time
Site:	Browns Ferry
Issue date:	11/21/1995
From:	Hsieh C, Machon R TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-95-006-03, LER-95-6-3, NUDOCS 9512150145
Download: ML18038B572 (16)

Text

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REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR: 9512150145 DOC. DATE: 95/11/21 NOTARIZED: DOCKET N Browns Ferry Nuclear Power Station, Unit 3, Tennessee NO'ACIL:50-296 05000296 AUTH. NAME AUTHOR'FFILIATION HSIEH,C.S. Tennessee Valley Authority Authority

'ECIPIENTValley MACHON,R.D. Tennessee RECIP.NAME AFFILIATION

SUBJECT:

LER 95-006-00:on 951030,scram discharge instrument vol vent

& drain valves failed to close after reactor mode switch was placed in shutdown position. Caused by dogged open SDIV vent

& drain valves. Valves undogged.W/951121 ltr.

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

I ENCL I SIZE:

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-3-PD 1, 1 WILLIAMS,J. 1 1 INTERNAL: ACRS 1 1 AEOD/SPD/RAB 2 2 AEOD/SPD/RRAB 1 1 CENTER~ 'ZTB.

1 1 NRR/DE/ECGB 1 1 7 DE/EEL 1 1 NRR/DE/EMEB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 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 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 iiOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE iVKSTE! CONTACI'THE DOCL'iIEYTCONTROL DES~K. ROOM PI -37 (EAT. SN-2083 ) TO EL I XIIiATE 5'OL'R AMLz PRON!

DISTRIBUTION. LISTS I:OR DOCL'iIEiTS YOL'Oi "I'EI:.D!

i FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF 'COPIES REQUIRED: LTTR 26 ENCL 26

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Tennessee vatey Atrtnority. post offce Box 2000, Decatur. A'aoa~ 35509 2000 R. D. (Rick) Machon Vice President, Browns Ferry Hudear Ptant November 21, 1995 U.S. Nuclear Regulatory Commission 10 CFR 50.73 ATTN: Document Control Desk Washington, D.C. 20555

Dear Sir:

BROWNS'ERRY NUCLEAR PLANT '(BFN) -,UNZTS 1q 2~ AND 3 DOCKET

'NOS' 50-259'0-260'ND,50-296 PACZLZTY OPERATZNG LZCENSE DPR-33'2'ND 68. LZCENSEE EVENT REPORT (LER) 50-296/95006 The enclosed LER .provides details concerning an event where the scram discharge instrument volume vent and drain valves failed to .close after the reactor mode switch was the shutdown mode. This report is submitted in, accordance placed'n with 10 CFR '50.73(a) (2) (i)(B), 10 CFR 50.73(a) (2)'(y) (C), and 10 CFR'0.73(a)(2)(vii)'(C).

Sincerely.,

R.. D. Machon Enclosure cc: See page 2 r

g J eg 9512150145 951121 PDR ADOCK 0500029b 8 PDR

k U.S. Nuclear Regulatory 'Commission

,Page .2 November 21, 1995 Enclosure cc (Enclosure):

INPO Records Center Suite 1500'100'ircle 75 Parkway Atlanta, Georgia 30339 Paul Krippner American Nuclear Insurers Town Center, Suite 300S 29 South 'Mai.n 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 101 II 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

4l 0 NRC FORK (5-92) 366 U.S WCLEAR REGULATQIY CQNIISS ION APPROVED BY le5/31/95 EXPIRES NO. 3150-0104 EST I HATED BURDEN PER RESPONSE TO COKPLY UI TH

'LICENSEE EVENT REPORT (LER) THIS IHFORHATIOH COLLECTION REQUEST: 50.0 HRS.

FORMARD COKKEHTS REGARDING BURDEN ESTIKATE TO THE INFORHATION AND RECORDS KAMAGEKEMT BRANCH (HNBB '7714), U.S. NUCLEAR REGULATORY COKKISSIOH, (See reverse for required nunber of digits/characters for each block) llASHINGTOH, DC 20555-0001 AMD TO THE PAPERUORK REDUCTION PROJECT (3140-0104), OFFICE OF KAMAGEKEMT AND BUDGET MASHIMGTON DC 20503.

FACILITY KQK (1) DOCKET IRKKR (2) PAGE (3)

Browns Ferr Nuclear Plant BFN Unit 3 05000296 1 OF 5 TITLE (4) Scram discharge instrument volume vent and -drain valves failed to close after the reactor mode switch was placed in shutdown position EVENT DATE 5 LER NKBER 6 REPORT DATE 7 OTHER FACILITIES INVOLVED 0 SEQUENTIAL FACILITY MAHE DOCKET NUMBER HOHTH DAY 'EAR NUMBER REVI SIGH NUMBER MONTH DAY Y~ NA 10 FACILITY NAKE DOCKET NUMBER 30 95 95 006 00 11 21 95 NA lPERAT ING N

THIS REPORT IS SlRNITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR: Check one or more 11 INN)E (9) 20.402(b) 20.405(c) 50.73(a)(2)(iv) 73.71 (b) 20.405(a)(1)(i) 50.36(c) (1) 50.73(a)(2)(v)(C) 73.71 (c)

LEVEL (10) 0 20.'405 (a) (1) ( I I ) 50.36(c)(2) 50 '3(a)(2)(vii)(C) OTHER 20.405 (a) (1) ( i I i ) X 50.73(a)(2)(i)(B) 50 '3(a)(2)(viii)(A) (Specify in 20 '05(a)(1)(iv) 50.73(a)(2)(ii) 50.73(a)(2)(viii)(B) Abstract below and in Tex't,

'0.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x) MRC Form 366A LICENSEE CQITACT FQI THIS LER 12 NAKE TELEPHONE NUHBER (Include Area Code)

Clare S. Hsieh, Compliance Licensing Engineer (205) 729-2635 CQIPLETE ONE LINE FQI EACH CQ%%HENT FAILURE DESCRIBED LN THIS REPORT 13 REPORTABLE REPORTABLE CAUSE SYSTEK CQlPONENT HANUFACTURER CAUSE SYSTEH COHPOHENT HAMUFACTURER TO NPRDS TO HPRDS QPPLEHENTAL REPORT EXPECTED 14 EXPECTED MONTH DAY YEAR

'If YES yes, complete EXPECTED SUBMISSION DATE).

X No SIHNISS ION DATE (15)

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

On October 30, 1995 at 0902 hours0.0104 days <br />0.251 hours <br />0.00149 weeks <br />3.43211e-4 months <br />, the Unit 3 scram di.scharge instrument volume (SDIV) vent and drain valves failed to close after placing the Unit 3 reactor mode switch in the Shutdown positi.on as a pre-requisite for containment integrated leak rate testi.ng. The SDIV vent and drain valves were found to be mechanically blocked or "dogged" open, which prevented the valves from closing. After the valves were unblocked or "undogged," the valves operated as desi.gned. TVA has not i.dentified any work or testing activity that required the Unit 3 SDIV vent and drain valves to be in the "dogged" position and has not determined why the valves were "dogged" open. However, to alert personnel to the uni.que design of the SDIV valves, tags have been attached to the valve handwheels, and operator aids have been placed on the valves. This event is reportable i.n accordance with 10 CFR 50.73(a)(2)(v)(C), 50.73(a)(2)(vi.i)(C), and 50.73(a)(2)(i.)(B).

NRC FORK 366 (5-92)

41 0 NRC F(MN 36AL U.S. INCLEAR REGULATORY CQIIISSIQI APPROVED BY QHI NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COKPLY llITH THIS INFORMATION COLLECT IOH REQUEST: 50.0 HRS. FORIIARD COKKENTS REGARDING BURDEN EST IKATE TO THE INFORMATION AMD RECORDS KANAGEKENT LICENSEE EVENT REPORT BRANCH (KNBB 7714), U.S. NUCLEAR REGULATORY COKKISSIOM, MASHIMGTOH, DC 20555-0001 ~ AND TO THE PAPERIJORK REDUCTION TEXT CONTINUATION PROJECT (3150-0104); OFFICE OF KANAGEKENT AHD BlRGET, UASHINGTOM DC 20503 FACILITY NAlE (1) DOCKET NMSER (2) LER IRHBER (6) PAGE (3)

'EAR SEQUENTIAL REVISION NUMBER NUKBER Browns Ferry Unit 3 05000296 95 006 00 2 of 5 TEXT If more s ce is r ired use additional co ies of HRC Form 366A (1/)

I ~ . PLANT CONDZTZONS Unit 3 was in cold shutdown and in the refueling mode. Unit 2 was at approximately 100 percent power. Unit 1 was shutdown and defueled.

DESCRIPTION OF EVENT Events On October 30, 1995 at 0902 hours0.0104 days <br />0.251 hours <br />0.00149 weeks <br />3.43211e-4 months <br /> Central Standard Time (CST),

the Scram Discharge Instrument Volume (SDZV) vent and drain valves [V] [BD] failed to close after the Unit 3 reactor mode switch was placed in the Shutdown position as a pre-requisite for containment integrated leak rate testing.

With the switch in the Shutdown mode, the Unit 3 reactor scrammed as expected. However, all eight Unit 3 SDZV vent and drain valves failed to close as designed. The vent and drain valves were found to be mechanically blocked or "dogged" open, which prevented the valves from closing.'fter the valves were unblocked or "undogged," they operated as designed.

TVA formed an Incident Investigation (II) team to investigate this event. The team reviewed completed work and testing documents, researched computer data printouts, and interviewed plant personnel to identify any activity that may have recJuired or resulted in the SDZV valves to be in the "dogged".position or impacted the position of the valves. However, no procedures or work documents were found which would have positioned these valves.

This event is reportable in accordance with 10 CFR 50.73 (a)(2)(v)(C) and (a)(2)(vii)(C) as a condition that prevented the fulfillment of the function of a safety system or two independent channels in a single system to control the release of radioactive material. The above condition is also reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by the plant's Technical Specifications.

The SDZV vent and drain valves have handwheels, which are mechanical stops or "dogs." The "dogged" open position is in the counterclockwise direction, and the "undogged" position is in the clockwise direction., The vent and drain valve handwheels were found in the fully counterclockwise position, which blocked the normally'open valves in the open position rendering the valves incapable of closing as designed.

41 0 NRC RRN 366A U.S IN)CLEAR REGULATNIY C<<BBIISSI(NI APPROVED SY QNI NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY MITH THIS INFORMATION COLLECTIOM REOUESTs 50.0 HRS. FORMARD COMMENTS REGARD IMG BURDEN ESTIMATE TO THE INFORMATION AMD RECORDS MANAGEMENT LICENSEE EVENT REPORT

'BRANCH (NMBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, MASHINGTON, DC 20555-0001, AND TO THE PAPERMORK REDUCTION TEXT CONTZNUATZON PROJECT (3150-0104) ~ OFFICE OF MANAGEMENT AMD BIB)GET, MASHIMGTON DC 20503 FACILITY ISA (1) DOCKET IRBSBER (2) LER IRBSBER (6) . PAGE (3)

YEAR SEOUENT IAL REVISION NIIIBER NQIBER Browns Ferry Unit 3 05000296 95 006 00 3 of 5 TEXT If more s ce is r ired use sdditionoi co ies of NRC Form 366A <<17)

B. Zno erable Structures Com nents or 8 stems that Contributed to the Events None.

C~ Dates and A roximate Times of Ma or Occurrences:

October 30, 1995 at 0902 CST The reactor. scrammed when the mode switch was placed in the Shutdown position. The SDIV vent and drain valves failed to close.

at 1209 CST A four-hour nonemergency notification was made to NRC in accordance with 10 CFR 50.72 (b)(2)(iii).

Do Other S stems or Seconda Functions Affecteds None.

E~ Method of Discove This condition was discovered when indications in the control room showed that the SDIV vent and drain valves did not close after a scram init'iation.

Fo erator Actionss After discovering the vent and drain valves were mechanically "dogged" open, an Assistant Shift Operation Supervisor (ASOS)

[utility, licensed] "undogged" the valves to restore them to normal operating condition.

G, Safet S stem Res nsess II'ith CAUSE'F the exception of the SDZV vent and drain valves, safety systems responded as designed when the Unit 3 reactor mode switch was placed in the Shutdown mode.

THE EVENT A'. Immediate Cause:

The "dogged" open SDIV vent and drain, valves caused the valves to be incapable of closing upon a scram.

4i t NRC F(RN U S. NJCLEAR REGULAT(NIY C(NB(I SS ION APPROVED BY (NBI NO 3150-0104 3'5-92)

EXPIRES 5/31/95 ESTIMATED BURDEM PER RESPONSE TO COMPLY MITH THIS ION REQUEST: 50.0 HRS.

INFORMATION'OLLECT FORMARD COMMENTS REGARD IMG BURDEN ESTIMATE TO THE INFORMATION AND RECORDS 'IIAMAGEMEHT LICENSEE EVENT REPORT BRANCH (NHBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, MASHIMGTOH~ DC 20555-0001, AMD TO THE PAPERUDRK REDUCTIOH TEXT CONTINUATZON PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BISGET, NASHINGTOH DC 20503 FACILITY NAIF (1) DOCKET IRNIBER (2) LER IRNIBER (6) PAGE (3)

YEAR SEQUEHT IAL REVISION NUMBER NUMBER Browns Ferry Unit 3 05000296 95 006 00 4 of 5 TEXT If more s ce is r ired use addi Ionsl es of NRC Form 366A (17)

B, ~ot Causet TVA has not determined why the SDIV vent and drain valves were "dogged" open. The ZZ team's extensive review of work and testing documentation and interview of plant personnel did not identify any work or testing activity that required all eight of the SDIV vent and drain valves to be positioned in the "dogged" open position.

TVA beli.eves the valves were not repositioned through willful misconduct, but rat'her by not understanding how the valves worked due to the uniqueness of the valve design.

ZVo ANALYSIS OF THE EVENT The purpose of the SDIV vent and drain valves is to limit inventory loss from the reactor vessel through the control rod drive seals after a scram. In the cold shutdown condition, no significant i.nventory loss occurred since the vessel was not pressurized. Plant 'safety was not compromised during the event. This event did not result i.n. any adverse condition that could have affected the health and safety of plant personnel or the public.

Vo CORRECTIVE ACTIONS Ao Immediate Corrective ActionsI An ASOS dispatched from the control room di.scovered the "dogged" vent and drai.n valves. The valves were "undogged" and veri. fied to operate as designed.

Bo Corrective Actions to Prevent Recurrances The desi.gn of the SDIV vent and drain valves is uni.que. With the valve handwheel turned in a fully, counterclockwi.se direction, the handwheel blocks the normally open valves in the open position preventing the valves from achieve their designed fail safe position of closing upon a scram.

To alert plant personnel to this un'ique operati.ng characteristic, TVA has attached tags to the valve handwheels and placed operator aids on the valves. As an enhancement, TVA has identified and li.sted other valves with unusual operating characteristics.

i NRC FORM 366A U.S INCLEAR REGLRATORY CQHIISSIQI APPROVED SY QNI HO 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO CQ(PLY MITH THIS IMFORNATIOM COLLECTIOH REOUEST: 50.0 HRS ~ FORMARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORNATI ON AND RECORDS HAMAGEMEHT LICENSEE EVENT REPORT BRANCH (HNBB'714), U.S ~ NUCLEAR REGULATORY CQNISSIONg MASH INGTOH, DC 20555-0001, AMD TO THE PAPERINRK REDUCTION TEXT CONTZNUATZON PROJECT (3150-0104) ~ OFFICE OF MANAGEMENT AND BISGET, MASH IMGTOH DC 20503 FACILITY NHK C1) DOCKET IRNIBER C2) LER IRMBER C6) PAGE C3)

TEAR SEQUENTIAL REVI SION NiiBER NNIBER Browns Ferry, Unit 3 05000296 95 006 00 5 of 5 TEXT tf more s ce is r ired use addi iona( c les of N C Form 366A (17)

TVA will revise this determined.s LER if the root cause of the event is VIo ADDITIONAL INFORMATION A. Failed Cpm nentsi None.

BE Previous LERs on Similar Eventsl LER 260/94004 was issued for a valve mispositioning event. The personnel involved in the event deviated from an approved work order by closing the outlet valve of the standby pressure regulator on the Scram Pilot Air Header. Contributing to the event was a discrepancy between the control diagram and the flow di.agram utilized by the personnel. The outlet valve did not have any unusual operating characteristi.cs that would have resulted in mispositioni.ng the valve.

VII+ CONNITNENTS None.

Energy Industry Identifi.cation'ystem (EIIS) system and component codes are identified in .the text with brackets (e.g., [XX]).

Thi.s i.s not a regulatory commitment.

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