ML17342A935

LER 87-018-01:on 870711,operation in Excess of 24 H W/ Greater than 2% Calculated Quadrant Power Tilt Ratio W/O Running Flux Map or Reducing Overpressure,Overtemp Occurred. Caused by Personnel Error.Procedure updated.W/870925 Ltr

ML17342A935
Person / Time
Site:	Turkey Point
Issue date:	08/11/1987
From:	Wager V, Woody C FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
L-87-393, LER-87-018, LER-87-18, NUDOCS 8710050147
Download: ML17342A935 (5)

Text

REGULATORY . FORMATION DISTRIBUTION S rM (RIDS)

ACCESSION NBR: 8710050147 DOC. DATE: 87/08/11 NOTARIZED: NO DOCKET FACIL: 50-251 Turkey Point Plantc Unit 4i Florida Power and Light C 05000251 AUTH. NAME AUTHOR AFFILIATION WAGER'. Florida Power ~% Light Co.

WOODY> C. O. Florida Power h Light Co.

RECIP. NAME RECIPIENT AFFILIATION

SUBJECT:

LER 67-018-01: on 87071ii operation in excess o8 24 h w/

greater than 2/ calculated quadrant power tilt ratio w/o running 8'lux map or reducing overpressurei overtemp occurred.

Caused bg personnel error. Procedure updated. W/870925 ltr.

DISTRIBUTION CODE: IE22D COPIES RECEIVED: LTR ENCL SIZE:

TITLE: 50. 73 Licensee Event Report (LER) Incident Rpti etc.

NOTES:

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Unit 4 was increasing power after being returned to service on July 1987. Power Range detector N-41 vas replaced 9, thus the channel required recalibration. Until the during the outage and, completed the Upper and Lover section deviation alarms were calibration vas to be out of service and a manual calculation of Quadrant declared Ratio (QPTR) was performed each shift At 0023-on July Pover Tilt increase was stopped at 92Z due to a calculated 2.84Z 11, the power QPTR. Due to operating difficulties unrelated to QPTR, reactor pover was reduced to 75Z. Prior to increasing pover from 75Z a map vas run and it verified Hot Channel Factors to be acceptable flux and QPTR to be less than 2Z.

The manual calcuation QPTR performed of 2.36Z. Pover was conservatively limitedvith a tilt concurrently the flux map showed to 95Z until nev detector currents to use in the manual calculations could The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> time 'limit for Technical be issued.

exceeded. The Overpressure/Overtemperature Specification 3.2.6.i.l had been Delta Temperature setpoints were not reduced as required by Technical because Pover Range detector N-44 was out of Specification 3.2.6.i.2, Logic vill not allov tvo channels to be out of service service . Pover Range vithout generating a reactor trip. The applicable procedure at the same time to address the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> time limit of Technical will be revised Specifications 3.2.6.i.l.

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~ uCEN$ FE EVEI ~ REPORT (LER) TEXT CONTINUATlo~

U,E. NVCLEAh IIEOVLATONT COMMISSION APPhoTEGCME NQ.3150~10A EXPIEESI 41311a PACIUTT NAPIE (11 COCKET HLSNEh 131 LEh NUEIEEh IE) PAGE 131 YEAN eIQVENTIAL IItVItIQ II IIUM 9 A IIVM tll

~ ~~ Point Unit 251 87 Turke 4 o 5 o o o 0 8 ill 0 OF 0 0 N ~'el I IW PVPEPAPINPC AIIIII eveer Prior to Unit 4 startup on July 8, 1987, during the latest outage, Power Range Detector N-41 was replaced. Replacement of N-41 requires recalibration of the channel. Until the calibration was completed the Upper and Lower section deviation alarms were declared out of service (OOS) and a manual calculation of the Quadrant Power Tilt Ratio (QPTR) was performed on each shift. A decision was made that reactor power would be limited by the most conservative calculation of QPTR. On July 9, 1987, with the unit at 50X power, a series of Flux Maps were performed to develop new interim numbers to be used in the manual calculation of QPTR and the QPTR calibration of N-41. The 50 percent Flux Map showed acceptable Hot Channel Factors, and manual calculations of QPTR showed less than 2 percent tilt. During the subsequent power increase, the manual calculation of QPTR on July 11, 1987 at 0023, showed a tilt planned, reactor power was limited to 94.32 percent. Subsequent QPTR calculations of 2 '4 percent. As showed an additional increase in tilt to approximately 5.0 percent and power was further limited to 90 percent. There was a perception that the calculated power tilt was erroneous, based on the results of the flux map run on July 9, 1987.

Technical Specification 3.2.6'i requires that with a QPTR greater than 2 percent, the Hot Channel Factors must be verified or the Overpressure/Overtemperature Delta Temperature (OP/OT DT) setpoint shall be reduced. Additional calculation of QPTR showed some improvement in QPTR but due to other operational difficulties unrelated to QPTR, reactor power was reduced to approximately 75 percent.

(Unit 4 experienced a Turbine runback refer to LER 251,87-19.) Prior to increasing power a second flux map was performed on July 12, 1987 at 1930. The flux map verified Hot Channel Factors acceptable and QPTR to be less than 2 percent.

The manual calculation of QPTR performed concurrently with the flux map showed a tilt of 2.36 percent. The maximum allowed power was still based on the most conservative calculation and power was therefore limited to 95 percent. To correct the difference in the QPTR calculation, a second set of interim calibration numbers was developed to be used in the manual calculation of QPTR.

With new numbers the manual QPTR calculation showed less than 2 percent tilt, which was similar to the results of the second Flux Map. As the unacceptable flux tilt calculation was initially discovered at 0023 on July 11, Technical Specification 3.2.6.i.2 required reduction of the OP/OT DT setpoint by 0023, July 12. Contrary to this the OP/OT DT setpoints were not reduced because Power Range detector I N-44 was out of service to replace a faulty power supply.

Power Range Logic will not allow 2 Power Range Channels out of service at the same time without generating a reactor trip. Hot Channel Factors were not determined because of the power limits that were placed on the unit of 94.32 percent and subsequently 90 percent. Hot Channel Factors were determined at 75 percent power and found acceptable . This exceeded the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> time limit of Technical Specification 3.2.6.i.l by 19 hours2.199074e-4 days <br />0.00528 hours <br />3.141534e-5 weeks <br />7.2295e-6 months <br /> and 07 minutes.

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~ wap A AapMaE m ~ Nhc pena ~ 'pl Ilzl o s 0 o o 2 5 1 1 0 3 OF 0 ChlJSE OF EVENT The perception that the calculated power tilt of the flux map run on July 9 1987", resulted in the delay of running a second was erroneous, based on the results

~

flux map The perception was s t reng thened by the problems that were known to

~

exist with the power range detector currents at the time of the event ~

The cause of exceeding the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> limit of the Technical Specification, Limiting Condition of Operation was personnel error mainly due to insufficient emphasis on the Technical Specification requirement in procedure ONOP-12308 '

'NALYSIS OP EVEHT The power level was limited to 94 '2 percent and subsequently to 90 percent for a QPTR of 2 '4 percent and 5 percent respectfully. The results of the second flux map that was run at 1930, July 12, 1987, verified the Hot Channel Factors to be acceptable and the QPTR was less than 2- percents Based on the above the health and safety of the public was not affected.

CORRECTIVE ACTION

1) A second Flux Map was performed to verify Hot Channel Factors and QPTR to be level was limited, based on the most conservative calculation of QPTR.

acceptable')

Power

3) Procedure ONOP-12308.2, Power Range Nuclear Instrumentation Verification of Upper, Lower and Channel Deviation Alarms, will be updated to address the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> time limit for determining Hot Channel Factors and reducing the OP/OT DT setpoints ~

4)This event will be addressed in the Licensed Operator Requalification classes.

ADDITIONAL DETAILS5 Manufacturer: Power Range Detector, Electro Stardard Labs, Model WL 24154 ~ High Voltage Power Supply, Westinghouse, Model UPMD-X54W.

Similar occurrences: none aac poAM SeeA ~ II 5 OPO I9&S 0 &tea&& ~ SS t94S I

P. O. Bo 00, JUNO BEACH, PL 33408 0420 SEPTEMBER 2 5 $ 98i L-87-393 IO CFR 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Des'k Washington, D. C. 20555 Gen t'lemen:

Re: Turkey Point Unit 4 Docket No. 50-25 I Reportable Event: 87-IS-Ol Date of Event: July I 2, I 987 Operation in Excess of 24 Hours With Greater Than 2 Percent Calculated Quadrant Power Tilt Ratio Without Runnin Flux Ma or Reducin Over ressure Overtem erature Set pints I

The attached Licensee Event Report revision is being submitted to include the Special Report requirement of Technical Specification 6.9.3.6. No changes to the abstract or text of Revision 0 have been made.

Very truly yours, C. O.~

~ dy ~

Group ice President Nuclear Energy COW/TCG/gp Attachmen t cc: Dr. J. Nelson Grace, Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, Turkey Point Plant SDF I /063/ I an FPL Group company