ML17252A187

Report of Abnormal Occurrence Per Section 6.6.A of the Technical Specifications Reactor High Pressure Instrument Setpoint Drift

ML17252A187
Person / Time
Site:	Dresden
Issue date:	09/04/1975
From:	Stephenson B Commonwealth Edison Co
To:	James Keppler NRC/RGN-III
References
BBS Ltr. #578-75 50-249/75-37
Download: ML17252A187 (3)

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CommAAth Edison One First~ Plaza, Chicago, Illinois Addr_.ess 'Reply to: Post Office Box 767 Chicago, Illinois 60690

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BBS Ltr. #578-75 Dresden Nuclear Power Station Mr. James G. Keppler, Regional Director Directorate of Regulatory Ope.ration-Region III

u. s. Nuclear Regulatory Commission 799 Roosevelt Road.

Glen Ellyn, Illinois 6cn 37 R. R. #1 Morris, Illinois September 4, 1975 SUBJmr:

REPORT OF ABNORMAL OCCURRmCE PER SEx::TION 6.6,A OF THE TmHNICAL SPEX:IFICA'l'IONS REACTOR HIGH PRF.SSURE INSTRUMENT

• SETPOIN'l' DRIFl'

References:

1 ) Regulatory Guide 1'.1\\. 16 Rev*~ 1 Appendix. A

2) Notification of Regien Ill of u. S, Nuo~ear Regulatory Commission

'l'elepbone: R. Knop, 1710 hours0.0198 days <br />0.475 hours <br />0.00283 weeks <br />6.50655e-4 months <br /> on August 26, 1975 Telegram: J, Keppler, 1347 hours0.0156 days <br />0.374 hours <br />0.00223 weeks <br />5.125335e-4 months <br /> on.August 27, 1975

3) Drawing Number 12E2506 Report Number:

50-2.49/75-37 Report Date: September ~4, 1975 Occurrence Date: August 26, 1975 Facility: Dresden Nuciear Power Station, Morris, Illinois IDENTIFICATION OF OCCURRENCE*

On August 26, 1975, during routine instrument surveillance, pressure switches PS}-263-53A, -53B, and -530 were folm.d with setpoints above the Technical Specification limit *"'1070 psig),

CONDITIONS PRIOR TO OCCURRENCE Unit-3 was in the shutdown mode during a iletueling outage, DESCRIPl'ION OF OCCURRENCE Pressure switches 263-53A, -53B, and -530 were discovered with setpoints of 108o psi, 1077 psi, and 1112 psi respectively. Pressure switches 263-53A-D initiate operation of the isolation condenser in response to sustained high reactor vessel

pressure,

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• James G. Keppl,_

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September 4, 1975 DESIGNATION OF APPARENT CAUSE OF OCCURRmCE (Unusual Servic~ Conditions).

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The recent trend of similar instrument setpoint drifting suggests that extended periods.at zero pressure allow minor setpoint deviations(which are fuutinely

• oorre.cted during plant operation) to significantly accumulate.* The length of.

the current refueling_ outage undoubtedly contributed to excessive setpoint variations on many types of pressure-sensitive instrumentation..The cause of discrete, r

incremental setpoint drifts 'i'S; unknown *

.ANALYSIS OF OCCURRENCE Th~* last surveillance of these switches had been performed on April 7, 1975, nine days pefore the beginning of ~e refueling outage. *All four switches (263-53.A-D) had been found within limits. The switches have proven to be reliable when checked roµtinely, and ~t1~;iS* considered improbable that any.$1signifioant

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setpoint dri(t occurred during reactor operation.

• Had setpoint drifting of this magnitude occurred during reactor operation, the two-channel. aogic of.this system would have ensured system avaiiabl.il.i01;y at a reactor pressure no greater than 1080 psi. This occurrence did not Jeopardize.

the_ safety of plant personnel or the public *. *

,~ORREx::'l'IVE ACTION The switches' *s~points were immediately reset to within the Dresden "band" of 1055 +/-t~~* Further corrective action will be ~en when specific drift causes*

are identified.. -

FAILURE DATA Pressure switches 263-53A-D are Meletr<>n.Model 372 Bolirdon ~be i;)ressure sensors

• • with a range of 28-1400 psi. Meletron Model 372 pressure sensors have ha

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SPL030 WAD037.C0949><2-008125D240-00l>PD 08/28/75 0901 ICS IPMWAWF WSH SUSPECTED DUPLICATE: 2~00772SE240 WAD 026 !CS IPMBNGZ CSP.

8159424449 TDBN MORRIS IL 206 08-28.0830A CDT PMS.~ERNARD C RUSCHE. DIRECTOR DIRECTORATE OF LICENSING WUX

.. US NUCLEAR REGULATORY COMMISSION WASH ING TON DC 20555

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SUBJECT:

DPR-25. DRESDE~ NUCLEAR POWER. STATION. UNIT 3 *. TkIS WILL

'CONFIRM A CONVERSATION WITH MR R KNOP OF YOUR OFFICE AT 1710 HOURS 8-26-75 CONCERNING INSTRUMENT *DRIFT OF 1* ISOLATION CONDENSOR SUSTAINED HIGH REACTOR PRESSURE SWITCMES PS3-263-53A.B&C TO ABOVE THE TECH~ SPEC~ LIMIT OF LESS T~AN OR EQUAL TO 1070 PSIG* PS3-263-53A WAS F'OUND AT 1090PSIJ 538 AT 1087PSIJ 53C AT 1J22PSI. SWITCHES ARE MELETRON TYPE AND DRIFT IS BELIEVED.CAUSED

.BY INACTIVITY CAUSED BY CURRENT REFUEL OUTAGE.

~* ADDITIONALLY. REACTOR PRESSURE ECCS INITIATION SWITCHES PS1-263-52A-t AND

~2A-i WERE ALSO FOUND ABOVE TECH* SPEC LIMiTS OF_

300PSIG LESS THAN OR EQUAL TO P LESS THAN OR EQUAL TO 350PSIG. THE.

MELETRON SWITCHES WERE FOUND.AT 365PSI CA-1> AND 366PSI CA-2>. THESE DRIFTS ALSO ARE BELIEVED TO BE CAUSED BY INACTIVITY.

3* MAIN STEAM LINE DRAIN ISOLATION VALVE MOj-220-1* DURING*

MAINTENANCE. WAS FOUND WITH A FAILED OVERLOAD RELAY WHICH CAUSED MALOPERATION OF THE VALVE DURING TESTING. PRIMARY CONTAINMENT lNTE~RITY MAY HAVE BEEN AFFECTED IN THE SINGLE-FAILURE MODE WOULD HAVE AN ISOLATION DURING OPERATION OCCURRED* ADDITIONAL INFORMATION WILL FOLLOW IN A TEN DAY REPORT*

B B STEPHENSON SUPERINTENDENT DRESDEN NUCLEAR POWER STATION COM~ONWEALTH EDISON CO RR.1 MORRIS ILL.INOIS 60450

. l 04,6 EST NRC-BHDA

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