ML17265A666

LER 99-009-00:on 990503,instrumentation Declared Inoperable in Multiple Channels Resulted in Condition Prohibited by Ts. Caused by Unanticipated High Frequency AC Voltage Ripple. Entered TS LCO 3.0.3.With 990602 Ltr

ML17265A666
Person / Time
Site:	Ginna
Issue date:	06/02/1999
From:	Mecredy R, St Martin J ROCHESTER GAS & ELECTRIC CORP.
To:	Vissing G NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-99-009, LER-99-9, NUDOCS 9906080307
Download: ML17265A666 (13)

Text

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RXDS)A CCESSZON NBR:9906080307 DOC.DATE: 99/06/02 NOTARIZED:

NO DOCKET I PACZL:50-244 Robert Emmet Ginna Nuclear Plant, Unit 1, Rochester G ter G 05000244 AUTH.NAME AUTHOR AFFILIATION ST MARTIN,J.T.

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

~Rochester Gas&.Electric Corp.RECIP.NAME

,RECIPIENT AFFILIATION VISSXNG,G.S.

SUBJECT:

LER 99-009-00:on 990503,instrumentation declared inoperable in multiple channels resulted in condition prohibited by TS.Caused by unanticipated high frequency AC voltage ripp e.Entered TS LCO 3.0.3.With 990602 ltr.DISTRIBUTION CODE XE22T COPIES RECEIVED e LTR g ENCL (S I ZE a TITLE: 50.73/50.9 Licensee Event Report (LER), Xncident Rpt, etc.NOTES:License Exp date in accordance with 10CPR2,2.109(9/19/72)

.G 05000244 0 RECIPIENT ZD CODE/NAME LPD1-1 PD INTERNAL: AEOD/SPD/RRAB NRR/DZPM/IOLB NRR/DRIP/REXB RES/DET/EIB EXTERNAL: L ST LOBBY WARD NOAC POORE,W.NRC PDR COPIES LTTR ENCL 1 1 1 1 1'1 1 1 1 1 1 1.1 1 1 RECIPIENT XD CODE/NAME VZSSXNG,G.

FILE CENTER R/DXPM/XQMB NRR/DSSA/SPLB RGN1 PILE 01 LMXTCO MARSHALL NOAC QUEENER,DS NUDOCS FULL TXT COPIES LTTR ENCL 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE.TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION LISTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION<

CONTACT THE DOCUMENT CONTROL DESK (DCD)ON EXTENSION 41S-2083 FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 16 ENCL 16 4HD ROCHESTfR GAS AND E'ELECTRIC CORFORATION

~89EASTAVENUE, ROCHfSTER, N, Y I46d9.000I AREA CODE216 586-27M RosERT c.MEcREDY Vice Presislenl t4uc!eor Operosions June 2, 1999 U.S.Nuclear Regulatory Commission Document Control Desk Attn: Guy S.Vissing Project Directorate I-1 Washington, D.C.20555

Subject:

.LER 1999-009, Instrumentation Declared Inoperable in Multiple Channels Results in Condition Prohibited by Technical Specifications R.E.Ginna Nuclear Power Plant Docket No.50-244

Dear Mr.Vissing:

The attached Licensee Event Report LER 1999-009 is submitted in accordance with 10 CFR 50.73, Licensee Event Report System, item (a)(2)(i)(B),"Any operation or condition prohibited by the plant's Technical Specifications".

Very ruly yours, XC: Mr.Guy S.Vissing (Mail Stop 8C2)Project Directorate I-1 Division of Reactor Projects-I/II Office of Nuclear Reactor Regulation U.S.Nuclear Regulatory Commission Washington, D.C.20555 Regional Administrator, Region I U.S.Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 U.S.NRC Ginna Senior Resident Inspector+t 990b080307

'll's!0602 PDR ADQCK 05000244 S PDR NRC FORM 866 IB I%BI U.S.NUCLEAR REGULATORY COMMISSION LICENSEE EYENT REPORT (LER)fSoe reverse for required number of'digitslcharacters for each b(ockl M5QIk rN p NIIsp@e igA'P%88Sy'nformation coBoctP)a rortuost: 50 hrs.Reported lessons learned are ncorporated krto the Bcenskrg process and fod back to hdustry.Forward comments regarding burden estimate to the Records Msnagernont Branch p4 F33), U.S.Nudear Regulatory Commfssbn, Wasfsngton, DC 205554001~and to the Paperwork Reduction Project (31500104), Ofree of Management and Budget, WasNngton, DC 20503.If an information coeect'on does not display a currendy vs M OMB, control number, the NRC may not conduct or sponsor.and a FACILITY NAME I 11 R.E.Ginna Nuc(ear Power Plant I DOCKET NUMBER I2)05000244 PAGE I3)1 OF 7 TITLE te)Instrumentation Declared Inoperable in Multiple Channels Results in Condition Prohibited by Technical Specifications 05 03 1999, EVENT DATE (5)OAY LER NUMBER (6)SEOUFNTIAL RENSION NUMBER NUMBER 1999", 009-00 MONTH ON 06 02 1999 REPORT DATE (7)DOCKET NUMSER 05000 OOCKETNUMSER 05000 FACfLITY NAME FACILrTY NAME OTHER FACILITIES INVOLVED (6)OPERATING MODE (9)POWER LEVEL (10)090 URSUANT TO THE REQUIREMEN THIS REPORT IS SUBMITTFD P 20.2203(a)(2)(v) 20.2203(a)

(3)(i)20.2201(b) 20.2203(a)(1) 20.2203(a)(3)(ii)20.2203(a)

(2)(i)20.2203(a}(4) 50.36(cl(1) 20.2203(a)(2)(ii) 20.2203(a)

(2)(iii}50.36(c)(2) 20.2203(a)(2)(iv)

LICENSEE CONTACT FOR THIS LER (12)TS OF 10 CFR B: (Check one or more)(11)50.73(a)(2)(viii)50.73(a}(2}(x)

X 50.73(a)(2)(i)(B) 50.73(a)(2)(ii)73.71 50.73(a}(2l(iii)

OTHER 50.73(a)(2wiv) 50.73(a)(2)(v)

Specify m Abstract below or in NRC Form 355A 50.73(a)(2)(vii)

TELEPMONE NUMSER (Inrrude Ares Code)John T.St.Martin-Technical Assistant (716)771-3641 CAUSE SYSTEM COMPONOIT MANUFACTURER REPORTABLE TO EPOS CAUSE SYS'fEM MANUFACTURER REPORTABLE TO EPIX SUPPLEMENTAL REPORT EXPECTED (l4)YES (If yes, complete EXPECTED SUBMISSION DATE).NO X EXPECTED SUBMISSION DATE R5)IlONTH OAY ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single.spaced typewritten lines}(16)On May 3, 1999, the plant was in Mode 1 at approximately 90%steady state reactor power.It had previously been determined that Overtemperature Delta T and Overpower Delta T bistable trip setpoints were potentially non-conservative on three out of four reactor protection system channels, and an evaluation was in progress.At approximately 2330 EDST, instrumentation for these three channels was declared inoperable.

Immediate corrective action was to entei Technical Specification Limiting Condition for Operation 3.0.3, and take actions to restore the channels to operable status.Following replacement of the affected bistables with bistab(es of a different design, the bistable trip setpoints were recalibrated and three of four channels were declared operable.The plant exited Limiting Condition for Operation 3.0.3.The underlying cause of the event was an unanticipated high frequency AC voltage ripple on the Delta T signals that adversely affected the trip setpoints for the bistables.

Corrective action to prevent recurrence is outlined in Section V.B.

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NRC FORM 366A$1999)LICENSEE EVENT REPORT (LER)TEXT CONTINUATION U.S.NUCLEAR REGULATORY COMMISSION FACILITY NAME (1)DOCKET (2)LER NUMBER (6)PAGE(3)..R.E.Ginna Nuclear Power Plant 05000244 SEOUEMTIA(8EVSIOII IIUMBN ImMBN 1999-009-00 3 OF 7 TEXT Iif more spaceis required, use additional copies of NRC Form 366'17)The Plant Operations Review Committee (PORC)was convened at approximately 1900 EDST to review this situation.

PORC concurred that reducing power to 90%was a prudent measure.Channel 2 bistables, in service for more than 18 months, were not affected by this condition.

Channel 2 was proven fully operable and channel 1 was currently in the tripped mode.Thus, continued plant operation was permissible, while bistable operability was assessed by NES personnel.

Preliminary calculations were subsequently performed by NES staff.These calculations indicated that RPS channel 1 bistable trip setpoints were within design limits.The margin for OT DT and OP DT were low, but the bistables were considered operable.II.DESCRIPTION OF EVENT: A.DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES'ay 3, 1999, 0820 EDST: RPS channel 1 is removed from service and declared inoperable to perform troubleshooting

((per CPI-TRIP-TEST-5.10)).

May 3, 1999, dayshift: AC ripple is discovered in RPS channel 1.Later, AC ripple is discovered in RPS channels 3 and 4.May 3, 1999, 2330 EDST: Event Date and Time and Discovery Date and Time.May 3, 1999, 2347 EDST: Plant shutdown initiated.

May 4, 1999, 0136 EDST: RPS channel 1 is declared operable.May 4, 1999, 0428 EDST: RPS channel 3 is declared operable.May 4, 1999, 0428 EDST: ITS LCO 3.0.3 is exited.Plant shutdown is stopped at 21%power.May 4, 1999, 2121 EDST: RPS channel 4 is declared operable.EVENT: On May 3, 1999, the plant was in Mode 1 at approximately 90%steady state reactor power after the power decrease from full power, which was started at approximately 1840 EDST and completed at approximately 2000 EDST.NES personnel completed the calculations, which now indicated that RPS channel 1 bistables were not operable.The Shift Supervisor and plant management were immediately notified.At approximately 2330 EDST, based on the revised calculational data, it was determined that three affected channels of RPS (channels 1, 3 and 4)be declared inoperable.

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'I NRC FORM 366A (CISSS)LlCENSEE EVENT REPORT (LER)TEXT CONTINUATION U.S.NUCLEAR REGULATORY COMMISSION

~FACILITY NAME I1)R.E.Ginna Nuclear Power Plant DOCKET I2)05000244 LER NUMBER Ie)YEAR SEQUENTIAL REYISION NUMSER NUMSER 1999-009-00 PAGE I3)6 OF 7 TEXT (If more spaceis required, use additional copies of itiRC Form 366AJ I17)IV.ANALYSIS OF EVENT: This event is reportable in accordance with 10 CFR 50.73, Licensee Event Report System, item (a)(2)(i)(B),"Any operation or condition prohibited by the plant's Technical Specifications"~The entry into ITS LCO 3.0.3 as a result of declaring more than one Function in ITS Table 3.3.1-1 inoperable is considered to be a condition prohibited by Technical Specifications.

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

There were no operational or safety consequences attributed to three RPS channels for OT DT and OP DT being inoperable.

A more detailed post-event review was performed.

It has subsequently been determined that only one trip function (RPS channel 3 OP DT)was actually inoperable.

This determination is based on the as-found data and a more rigorous analysis of the associated instrument uncertainties.

All four OT DT channels were found to be within accident analysis assumptions, after accounting for the as-found margin to trip setpoint and incorporating the appropriate instrument uncertainties.

Hence, the only function that would not have actuated within the bounds of the Ginna Station accident analysis was one channel of OP DT.With three operable channels available and a 2 out of 4 logic to provide the required trip function, there is adequate assurance that the reactor protection system would have performed within its required envelope as assumed in the accident analysis.Based on the above, it can be concluded that the public's health and safety was assured at all times.V.CORRECTIVE ACTION: A.ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL STATUS: Following replacement of bistables and calibration of the bistables in RPS channels 1 and 3, three channels (channels 1 and 3 and previously unaffected channel 2)were declared operable.ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

NUS indicated that they will be updating the parts list to remove the incorrectly sized component.

NES personnel designed a modification to the math modules to eliminate the effects of AC ripple on the OP DT and OT DT bistable trip setpoints.

This modification has been implemented.

NRC FORM 366A g IBBBI LICENSEE EVENT REPORT (LER)TEXT CONTINUATION U.S.NUCLEAR REGULATORY COMMISSION

~FACILITY NAME I1)R.E.Ginna Nuclear Power Plant DOCKET I2)05000244 LER NUMBER I6)SB)UalTIAl RSNSIOH IIUMBIA IIUMBBI 1999-003-00 PAGE I3)7 OF 7 TEXT llf more spaceis required, use additional copies of NRC Form 866AJ I17)o This event is being reviewed for any potential lessons to be learned and applied to the appropriate parts of the Ginna modification process: design, procurement, installation, testing.The industry will be notified of this event via an entry in the Nuclear NETWORK system.VI~ADDITIONAL INFORMATION:

A.FAILED COMPONENTS:

None B.PREVIOUS LERs ON SIMILAR EVENTS: A similar LER event historical search was conducted with the following results: No documentation of similar LER events with the same root cause at Ginna Nuclear Power Plant could be identified.

C.SPECIAL COMMENTS: None