ML17263A225

LER 93-001-00:on 930312,both Source Range Detectors Found Inoperable During Energization.Caused by Center Electrode Degradation Due to Gamma Corrosion.Failed Detectors Replaced W/Qualified spares.W/930412 Ltr

ML17263A225
Person / Time
Site:	Ginna
Issue date:	04/12/1993
From:	Backus W, Mecredy R ROCHESTER GAS & ELECTRIC CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-93-001, LER-93-1, NUDOCS 9304160043
Download: ML17263A225 (26)

Text

ACCEI.E ED DOCUMENT DIS OBVTION SYSTEM REGULA ORY INFORMATION DISTRIBUT 8 SYSTEM (RIDS)

ACCESSION NBR:9304160043 DOC.DATE: 93/04/12 NOTARIZED: NO DOCKET FACIL:50-244 Robert Emmet Ginna Nuclear Plant, Unit 1, Rochester G 05000244 AUTH. NAME AUTHOR AFFILIATION BACKUSgW HE Rochester Gas & Electric Corp.

MECREDY,R.C. Rochester Gas & Electric Corp.

RECIP.NAME RECIPIENT AFFILIATION S UBJECT: LER 93-001-00:on 930312,both source range detectors found inoperable during energization.Caused by center electrode degradation due to gamma corrosion. Failed detectors replaced w/qualified spares.W/930412 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:

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

NOTES:License Exp date in accordance with 10CFR2,2.109(9/19/72). 05000244 RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD1-3 LA 1 1 PD1-3 PD 1 1 JOHNSONiA 1 1 INTERNAL: ACNW 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DE/EELB 1 1 NRR/DE/EMEB 1 1 NRR/DORS/OEAB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRIL/RPEB 1 1 NRR/DRSS/PRPB 2 2 RR7'DSSA/ PLB 1 1 NRR/DSSA/SRXB 1 1 G FILE 02 1 1 RES/DSIR/EIB 1 1 RGN E 01 1 1 EXTERNAL'G&G BRYCE g J ~ H 2 2 L ST LOBBY WARD 1 1 NRC PDR 1 1 NS IC MURPHY, G. A 1 1 NSIC POOREiW. 1 1 NUDOCS FULL TXT 1 1 f'23 7 4 pQg c 5 NOTE TO ALL"RIDS" RECIPIENTS:

$ 0- t DESK, PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL ROOM PI-37 (EXT. 504-2065) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 30 ENCL 30

J Jr r'~

ROCHESTER GAS AND ELECTRIC CORPORATION 4 t~j 89 EAST AVENUE, ROCHESTER N.K 14649-0001 tE

'rOarr St Jlf ROBERT C. h1ECREDY TELEPHONE Vice President AREA CODE 7 i 6 546 2700 CrnnJ NucteJr Production April 12, 1993 U.S. Nuclear Regulatory Commission Document Control Desk Nashington, DC 20555

Subject:

LER 93-001, Loss of Source Range Detector Indication During Energization, Due to Faulty Detectors, Causes a Condition Prohibited by Plant Technical Specifica-tions.

R.E. Ginna Nuclear Power Plant Docket No. 50-244 In accordance with 10 CFR 50.73, Licensee Event Report System, item (a)(2)(i)(B), which requires a report of, "any operation prohibited by the plant's Technical Specifications",

the attached Licensee Event Report LER 93-001 is hereby submitted.

This event has in no way affected the public's health and safety.

Very truly yours, Robert C. Me redy XCJ U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 Ginna USNRC Senior Resident Inspector

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'9304160043 930412 PDR ADOCK 05000244 If S 'PDR

NAC FORM 300 US. NUCLEAR REGULATORY COMMISSI (Se)9) APPAOVED OMB NO. 3)500(OC EXP IRF5: C/30/92 ESTIMATED BURDEN PER RFSPONSE TO COMPLY WTH THIS INFORMATIOAI COLLKCTION AEOUESTI 50.0 HAS. FORWARD LICENSEE EVENT REPORT (LER) COMMENTS REGARDING BUADEN ESTIMATE TO THE RECORDS AND RFPORTS MANAGEMENT BRANCH (F030). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON. DC 20555, AND TO THE PAPEAWORK ABDUCTION PROiECT (31500'IOe). OFFICE OF MANAGEMENTAND BUDGET. WASHINGTON, DC 20503.

FACILITY NAME (1) PA 4ioFll DOCKET NUMBER (2)

R. E. Ginna Nuclear Power Plant o 5 o o o 24 '

TITLE (e)

Loss of Source Range Detector Indication During Energization, Due to Faulty Detectors Causes a Condition Prohibited v Technical Snecifica io ~

y CC ~ 'VENT DATE (Sl LEA NUMBER (0)

SEQUENTIAL REVISION MONTH REPORT DATE (7 OTHER FACILITIES INVOLVED (0)

MONTH OAY YEAR YEAR Ig@ OAY YEAR FACILITYNAMES DOCKET NUMBFRISI NUMSER 0 5 0 0 0 0 312 93 93 001 0 0 0 4 1 2 9 3

~ ~

0 5 0 0 0 THIS REPORT IS SUBMITTED PURSUANT T 0 THE REDUIREMENTS OF 10 CFR (): (Check onr or more of the fo//owindi (11)

OPERATING MODE (0)

N 20.I02(0) 20.e05( ~ ) 50,7 3 le I (2) I Ir) 73.71(III POWER 20.e00( ~) IIIIII BOM(c) (I) 50.73(el(2) 4l 73.71(c)

LEVEL p p p 20A05(e l(1 ) (9) 50.30(cl(2) 50.73(e)(2) lrQ) OTHER ISptcify cn Atjttrect Orrow rot/ ln yrrt, /j/RC Form 20.005(e) ll 1(ill) 50.73(e I (2 I I II 50.73(e)(2)(rljj) (A) 300AI 20A05 4) ll)Grl 50.73(e) (2) IIII 50.73(el(2)(r(QI( ~ )

20.405( ~ Ill)4) 50.734)(2)(III) 50.73(e) (2) (el LICENSFE CONTACT FOA THIS LER (12)

NAME TELEPHONE NUMBER Wes1ey H. Backus AREA CODE Technical Assistant to the Ooerations Mana er 31 552 4-4 44 6 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE OKSCRIBED IN THIS REPORT ll3) C MANUFAC. REPORTABLE MANUFAC. EPOATABLE (c CAUSE SYSTEM COMPONENT TURER TO NPADS j~jPN~QQ cAUsE SYSTEM COMPONENT TURKR TO NPRDS Qt MY. 'NU wY, I G D T W 1 2 p kklk)MI.

QjtKi PyX~(

SUPPLEMKNTAL REPORl'XPECTED (IC) MONTH OAY YEAR EXPECTED SUBMISSION DATK (15)

YES IIIyrt, complrtt EXPECTED St/der/SSION DATEI NO ABSTRACT ILlmlt to Irdd tpecrt, I,r., rppror/mrtrfy Iiftten rindle.eptcr typrwrittrn /inrd I10)

On March 12, 1993, at 1425 EST, vith the reactor subcritical during planned shutdown, both source range detectors vere found a

inoperable with the reactor trip breakers closed.

The Control Room operators immediately entered and performed the applicable actions of equipment restoration procedure ER-NZSe1 (SR Malfunction). The reactor trip breakers vere opened vithin five (5) minutes of the event.

The most likely cause of the source range detector failures was center electrode degradation due to gamma corrosion of the bare tungsten center ~ e"trode (center wire). (This event is NUREG--

1022 (B) cause code).

Corrective action was to replace the failed detectors vith qualified spares. Corrective action to prevent recurrence is outlined in section V(B).

NRC Form 300 (509)

NRC FORM 3SSA US, NUCLEAR REGULATORY COMMISSION (649) APPROVED OMB NO,3150010S EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY IYTH THIS LlCENSEE EVENT REPORT (LER) INFORMATION COLLECTION REOUEST: 500 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATlON AND REPORTS MANAGEMENT BRANCH (F430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO SHE PAPERWORK REDUCTION PROJECT (31500)04), OFFICE OF MANAGEMENTAND BUDGET,WASHINGTON. DC 20503.

FACILITYNAME (1) DOCKET NUMBER (2) LER NUMBER (8) PAGE (3)

YEAR  ??o SEOUCNTIAL >5~ REVrdr0N

?.'/1/ NUMddA SP/r) NUM EA R.E. Glnna Nuclear Power Plant o s o o o 24 493 0 0 1 0 0 02 oF l 1 TEXT ///more d/rdee /d //r/rer/ ude/(r)roe/ir//IC Form 3//S42/(12)

PRE- PMNT CONDIT ONS A plant shutdown was in progress per operating procedure 0-2.1 (Normal Shutdown to Hot Shutdown) for the annual refueling and maintenance outage. The turbine generator had gust. been taken off the line and Control Room operators

'were in the process of shutting the reactor down and inserting all control and shutdown rods.

DESCRIPTION OF EVENT DATES AND APPROXIMATE TIMES OF MAZOR OCCURRENCES o March 12, 1993, 1425 EST: Event date and time o March 12, 1993, 1425, EST: Event discovery date and time o March 12, 1993, 1430 EST: Control Room operators complete inserting all control and shutdown rods and open the reactor trip breakers.

o March 12, 1993, 1435 EST: Plant stabilized at hot shutdown.

o March 12, 1993, 1501 EST: Source Range NIS N-31 and NIS N-32 declared inoperable.

o March 12, 1993, 1730 EST: Source Range NIS N-32 declared operable using the installed spare source range detector.

o March 16, 1993, 1747 EST: Source Range NIS N-31 declared operable.

o March 17, 1993, 2040 EST: Source Range NIS N-32 declared operable, using its normal source range detector.

NRC Penn 388A (589)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (689) APPROVED OM 6 NO. 31500106 EXPIRES: 6/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) LNFORMATION COLLECTION REGUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE To THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT SRANCH (PJ)30). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT (3)500106), OFFICE OF MANAGEMENTANO BUDGET, WASHINGTON. DC 20503.

FACILITYNAME (I) DOCKET NUMBER (2) LER NUMBER (6) I'AGE I3)

YEAR O~>: SSOUSNTIAI v~4'EVISION NVM66R '&- NUMFSA R.E. Ginna Nuclear Paver Plant 0 s 0 0 02 ~ ~93 p 01 0 0 0 3 DF 1 1 TEXT lllmoto tptcoitttquia/, utt At//oont/P/RC%%dmt36SA't/(IT)

B. EVENT-On March 12, 1993 at approximately 1425 EST with the reactor subcritical during a planned shutdown, source range (SR) Nuclear Instrumentation System (NIS)

Channel N-31 and Channel N-32 automatically energized at the normal setpoint of </= 5E-11 amps on the two intermediate range (IR) NIS channels. The Control

.Room operators were closely monitoring the decay of the intermediate range currents, and were anticipating the 'reset level for the .source ranges. At the time of automatic energization of the source range detec-tors, there was no count rate indication on Channel N-31 or Channel N-32. Seeing no indication of count rate, the Control Room operators, in accordance with plant procedures and training guidance, immediately attempted to manually energize the source range detectors using the P-6 defeat pushbuttons. The source range detectors still did not indicate counts.

The Control Room operators continued to expeditiously insert control and shutdown rods per 0-2.1 and at approximately 1430 EST the reactor trip breakers were opened. The plant,was subsequently stabilized in hot shutdown at approximately 1435 EST.

NRC Form 366A (649)

NRC FORM 366A US. NUCLEAR REGULATORY COMMISSION (64)9) APPROVED OMB NO.3ISOOI04 EXPIRESI 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REOUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P4)30), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31504)104). OFFICE OF MANAGEMFNTAND BUDGET, WASHINGTON,OC 20503.

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

YEAR SEOUENZIAL,Oi)i AEVISION NUMB%4 NUMO64 R.E. Glnna Nuclear Power Plant o s o o o 24 49 3 001 00 0 40F TEXT ///mom 4/>>oo JF

~os, uoo d/d/ooo/ NRC FomI 35549/ ()7)

~ Subsequently the Control Room operators notified higher supervision and the Instrument & Control (I&C)

Department of the event and at approximately 1501 EST declared source range NIS N-31 and N-32 inoperable.

The Plant Operation Review Committee (PORC) was convened to review the actions taken, conformance to Technical Specifications, event classification and reportability. PORC directed that access to the Containment Building (CNMT) be prohibited until one source range channel was restored to operable status.

In addition PORC confirmed that actions were taken to ensure plant cooldown would not occur, and that dilution of boron concentration would not occur. The Control Room operators entered and performed the applicable actions of equipment, restoration procedure ER-NIS.1 (SR Malfunction) including continued boration to greater than 54 shutdown margin .and sampling the Reactor Coolant System (RCS). for boron concentration on a periodic basis during the boration.

C. INOPERABLE STRUCTUEUKSF COMPONENTS, OR SYSTEMS THAT CONTRIBUTED TO THE 15TENT:

None.

D. OTE&R SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:

None.

E METHOD OP DISCOVERY The event was immediately apparent due to indications in the Control Room.

NRC FoIm 366A (64)9)

NRC FORM 366A US. NUCLEAR REGULATORY COMMISSION (689) ~ APPROVED OMB NO, 31500106 5 XP IR ES: 6/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFOAMATION COLLECTION REQUEST: 500 HRS. FORWARD COMMENTS REGARDING BUAOEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON. DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31500106). OFFICE OF MANAGEMENTAND BUDGET. WASHINGTON, OC 20503.

FACILITY NAME n) DOCKET NUMBER (2) LER NUMBER (6) PAGE D))

SEQUENTIAI. REVISION YEAR LPNL I+I: NUMEER 4.'UM

+WC:

ER R.E. Ginna Nuclear PoT6er Plant o s o o o 24 493 0 1 0 0 0 5 OF JEXT ///6NKE Epecr is>>6U9od. u>> >>M/6'one/N/IC Form 35569) nl)

P OPERATOR ACTION The Control Room operators, after recognizing that there were no indicated count rates on either of the source range detectors, immediately attempted to manually energize the- source range detectors using the P-6 defeat pushbuttons. The operators entered ER-NIS.1 and performed the applicable actions, including pulling the fuses for Instrument Power, in another attempt to reinstate, the source'anges.

Subsequently, the Control Room operators notified higher supervision 'and the I&C Department and declared source range NIS N-31 and N-32 inoperable.

G. SAFETY SYSTEM RESPONSES None.

III. CAUSE OF OSTENT A. IMMEDIATE CAUSE The cause of the failure of source range detectors N-31 and N-32 to indicate counts was detector failure due to center electrode degradation. Specific measurements indicate that the center electrode to shield had become short circuited on source range detector N-31, most, likely due to the electrode breaking at the bottom of the detector. Source range detector N-32 was found to be open circuited, possibly due to the electrode breaking at the top of the detector.

NAC Form 366A (689)

NRC FORM 366A US. NUCLEAR REGULATORY COMMISSION ISS9) APPROVED OMS NO. 31600104 EXPIRES: E/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REOUESTI 603) HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH IF@30), U,S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20655, AND TO 1HE PAPERWORK REDUCTION PROJECT 131600)04), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20603.

FACILITY NAME 11) DOCKET NUMBER 12) LER NUMBER IS) PAGE 13)

YEAR X6% SEOUENTIAI. REVISION NUMBER NUMSER R.E. Gonna Nuclear Power Plant o s o o o 24 493 0 0 1 00 06 OF TEXT illmoro EPoco lr rorlrr/rod, Irw oddldorM/ll/IC Forrrr 366AS/)17)

B ROOT CAUSE:

After consulting with Westinghouse Electric Corporation (the manufacturer and vendor for these detectors), it was concluded that the underlying cause of the center electrode degradation of source range detectors N-31 and N-32 is most likely due to gamma corrosion of the bare tungsten center electrode (center wire). This effect occurs whenever the source range detector is energized.

ANALYSIS Op EVENT The event is reportable in accordance with 10 CFR 50.73, Licensee Event Report System, item (a)(2)(i)(B), which requires a report of, "any operation prohibited by the plant's Technical Specification", in that the failure of source range detectors N-31 and N-32 to indicate counts at

</= 1E-10 amps on the two intermediate range NIS channels was an operation prohibited by the plant Technical Specifications as follows:

o Specification 3.5.1.1 states, "The Protection System Instrumentation shown on Table 3.5-1 shall be operable whenever the conditions specified in Column 6 are exceeded". For the source range instruments, column 6 refers to Note 2, which states, "Channels should be operable at all modes below the bypass condition with the reactor trip system breakers in the closed position and control rod drive system capable of rod withdrawal". Contrary to the above, source range channels N-31 and N-32 were inoperable below the bypass condition of </= 1E-10 on both IR NIS channels with the reactor trip breakers closed and the control rod drive system capable of rod withdrawal. This condition existed for approximately five (5) minutes until the reactor trip breakers were opened. While an Action Statement exists for one source detector inoperable, there is no stated action requirement for two, detectors inoperable with the Reactor Trip breakers closed. Therefore, a condition prohibited by the plant's Technical Specifications existed.

NRC Form 366A )689)

NRC FORM 366A 2~ U.S. NUCLEAR REGULATORY COMMISSION (669) APPROVED OMB NO. 3(600104 EXPIRES: A/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REOUESTI 500 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE To THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND To 1HE PAPERWORK REDUCTION PROJECT (3150010I), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (11 DOCKET NUMBER (2) PAGE (3)

LER NUMBER (6)

<~~ REVISION YEAR ~rA SEOUENTIAL NUMSER ..IH: NUM ER R.E. Ginna Nuclear Power Plant 0 s 0 0 0 244 93 0 0 1 0 0 070F1 1 TEXT /I/mom H>>ce /t >>I)r/irer/ Ir>> pr/r//I/orN/HRC Form 366AB/ (17)

Once the trip breakers are open, the minimum operable channels required reduces to one (1) instead of two (2) and the action statement states in part as follows:

With the number of operable channels one less than the minimum operable channels requirement, suspend all operations involving positive reactivity changes.

An assessment was performed considering both the safety consequences and implications of this event with the following results and conclusions:

The safety significance of the failure of both source range channels is the loss of detection of subcritical neutron flux in the core and the function those channels provide for both automatic actuation of the reactor protection system and the prompting of operator action to protect shutdown margin. However, this significance is minimized in this instance for the following reasons:

0 The failure occurred completely within the sequence of shutting down the-reactor in accordance with plant procedure 0-2.1 in that the operators were closely monitoring the decay of the intermediate range currents and were anticipating the reset level for the source ranges.

ln accordance with 0-2.1 the operators were ex-peditiously inserting the control and shutdown rods to five steps prior to manually opening the reactor trip breakers. This sequence, simultaneous with injecting boric acid to achieve the required RCS cold shutdown boron concentration insured that shutdown margin was maintained greater than the requirements of Technical Specifications, and that shutdown margin did not decrease during this event.

NRC Form 366A (BJ)9)

J NRC FORM 355A U.S. NUCLEAR REGULATORY COMMISSION (689) APPROVED OMB NO. 31600104 EXPIRES: 4/30JS2 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EYENT REPORT ILER) INFORMATION COLLECTION REQUESTI 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT (31504104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, OC 20503.

FACILITY NAME (1) DOCKET NUMBER (21 LER NUMBER (5) PAGE (3)

YEAR(PSEQUENTIALS)I(REVISION M3 NUMSEA 'P..: NUMBER R.E. Ginna Nuclear Power Plant s o2 44 93 00 0 0 0 8Oi TEXT FIT mo>> ~ JJ>>ookod, u>> aktJNeal HRC Ann 35543) (IT) o o o 1 o After immediately recognizing that the source range channels did not indicate counts at the intermediate range reset point, the operators took appropriate actions in attempting- to reinstate source range -

detectors. They continued to expeditiously insert control and shutdown rods, and within five minutes, opened the reactor trip breakers. The operator continued boration to the cold shutdown, xenon free concentration required by procedure for RCS cooldown below 500 degrees. There was no decrease in shutdown margin, from the time'of failure of both source range channels until the time the spare source range detector was used to declare Channel N-32 operable.

All operations involving positive reactivity changes were suspenders until after the spare source range detector was declared operable.

Based on the above, it health and safety was assured at all times.

can be concluded that the public's V CORRECTIVE ACTION A ACTION TAKEN TO RETURN AFFECTED SYST1963 TO PRE-EVENT NORMAL STATUS:

0, The detector installed in source range channel N-32 was disconnected and the previously installed spare source range detector was connected to source range channel N-32. NIS N-32 high voltage setting and the pulse height discriminator (PHD) bias setting were ad)usted to conform to the data for the spare detector. At approxi-mately 1730 EST on March 12, 1993, source range Channel N-32 was declared operable.

NRC Form 365A (SSS)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (669) APPROVED 0MB NO. 31500)04 EXPIRES: 6/30)92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REQUEST: 500 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P630), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555, AND TO 1'HE PAPERWORK REDUCTION PROJECT (31500106), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503, FACILITY NAME (I) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR S~y SEQVSNTIAL REVISION

~ 2 NUMSSII NUM SA R.E. Gonna Nuclear Power Plant 2 44 3 001 0 0 0 9 oF 11 TEXT Nmon JIMce ls ~, VJP ~HRC Form 35663) (IT) p p p p p The detector installed in source range channel N-31 was replaced with a detector withdrawn from stock. Subsequently, for source range channel N-31 the high voltage power supply was replaced.

The detector anode voltage curve (also referred to as the plateau curve). was obtained, and the PHD bias setting was adjusted. At approximately 1747 EST on March 16, 1993, source range Channel N-31 was declared operable.

o The detector installed in source range channel N-32 was replaced with a detector withdrawn from stock. For this newly installed detector, the plateau curve was obtained and the PHD bias setting was adjusted. The installed spare source range detector was then disconnected from source range channel N-32 and this newly installed source range detector was connected to source range channel N-32. .The channel operability test was completed, and at approximately 2040 EST on March 17, 1993 source range Channel N-32 was declared operable, using its normal source range detector.

B ACTION TAKEN OR PLANN19) TO NUGENT REC&tRENCE:

To minimize future source range detector failures, the following actions are being planned:

0 A periodic replacement interval for BF~ filled source range detectors will be established, based upon time in service or number of ener-gizations of the detectors.

NRC Form 366A (689)

NRC FORM 366A UE. NUCLEAR REGULATORY COMMISSION APPROVED OM 8 NO. 31600104 (689)

E XP I R ES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT tLER) INFORMATION COLLECTION REQUEST: 50/) HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P830), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31500104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (8) PAGE (3)

YEAR P444 SEQUENTIAL .Ay REVISION NUMSSR NUMSER R.E. Gonna Nuclear Power Plane TEXT /// mare S>>ce JI re/Ir/red, Iree edd/dar>>/N/IC %%drm 38642/ ((7) ps ppp24 493 0 0 1 00 10 OF o A new Westinghouse design for these BF3 filled source range detectors incorporates low voltage source range detectors with gold-plated tungsten center wire conductor material. Detectors of this new design will be procured. When detectors of this new design are installed, as part of a planned detector upgrade schedule, as replace-ments for existing detectors, the periodic replacement interval will be re-evaluated.

0 Existing calibration procedures will be revised,

" or new procedures developed, to include steps to perform time domain reflectometry (TDR) measure-ments on N-31, N-32 and spare detector, prior to scheduled refueling outages. (TDR measurements can determine wire is broken, if the shorted detector out or center electrode if it has high or low resistance) .

0 A trending program to detect potential degradation of source range detectors will be established, for the following data:

1) Detector plateau curve data will be trended.

As the BF3 gas in the detector dissociates over time, the high voltage will be adjusted higher each time until set on the plateau.

it can no longer be

2) PHD bias curves will be trended.

RMAT ON A PAXLED COMPONENTS:

The faulty detectors were BF3 filled, source range detector proportional counters, Part No. WL-24182 manufactured by Westinghouse Electric Corporation.

NRC Form 388A (889)

NRC FORM 366A (SJ)9) t LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION US. NUCLEAR REGULATORY COMMISSION APPROVEO OMB NO, 31500104 EXPIRES: EI30(92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 500 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (F430). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON. OC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT (31500104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1I DOCKET NUMBER (2) LER NUMBER (SI I'AGE (3)

YEAR SEQUENTIAL REVISION NVMSER NVMSER R.E. Ginna Nuclear Power Plant o s o o o 2 449 3 001 0 0 1 1 OF RJOOOOPooo (ssoSs(INL goo oddlooIMI HRC %%dmI 36643) (17)

B. PREVXOUS LERs ON SIMILAR KGFNTS.

A similar LER event historical search was conducted with the following results: LER 90-003 (Higher Than Normal Count Rate on Source Range NIS, Due to a Faulty Detector, Causes a Reactor Trip During Source Range Re-energization) was a similar event with the same root cause. The corrective action to prevent recur-rence, of the event described in LER 90-003, was to initiate a evaluation which will ultimately result in procurement and installation of detectors, of a new Westinghouse design. It should be noted that even if the evaluation had been completed, and detectors of a new design had been procured and were in stock, these detectors would not have been installed prior to the 1993 outage.

C SPECIAL COMMENTS None.

NRC FoIm 366A (SJ)9)