ML20084L761

AO 50-237/1974-30:on 740724,during Monthly Surveillance, Setpoint on HPCI Turbine Trip Pressure Switch Found High. Caused by Lack of Precycling of Switch Prior to Installation.Switch Reset

ML20084L761
Person / Time
Site:	Dresden
Issue date:	08/02/1974
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
References
553-74, NUDOCS 8305230698
Download: ML20084L761 (2)

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up Ccmm*^ adth Edison g4 of.e r rsi l.cnal P ara. Ch Cago. f!!vnoit ,

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i{gy Address He,p!y to- Poet Ofhce Box 767 Ch:cago. lihnois 60690 ,

BBS Ltr.d553-74 Dresden Nuclear Power Station R. R. #1 '

Morris, Illinois 60450 - 6 '

• August 2, 1974 x S

{ l Mr. J. F. O' Leary, Director  : __

W 4.eg..,o a(2 4 Directorate of Licensing (T, k;

\ C'fUhDI U. S. Atomic Energy Co:nission ,

id$ft, /M Washington, D. C. 20545 -- s.v' "

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SUBJECT:

REPORT OF ABNORMAL OCCURRENCE PER SECTION 6.6.B OF ' DIE TECHNICAL '

SPECIFICATIONS.

SETPOINT DRIFT OF IIPCI LOW PRESSURE TURBINE TRIP PRESSURE SWITCH.

References:

1) Regulatory Guide 1.16 Rev.1 Appendix A

2) Notification of Region III of AEC Regulatory Operations Telephone: lir. F. I' aura,1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br /> on July 26, 1974 Telegram: Mr. J. Keppler, 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br /> on July 26, 1974

3) Draving Numbers: P&ID H-51 & S&L 12E2528 Report Number: 50-237/1974-30 Report Date: August 2., 1974 Occurrence Date: July 24, 1974 Facility: Dresden Nucicar Power Station,.Horris, Illinois IDENTIFICATION OF OCCURRENCE'

- Setpoint drif t of high pressure coolant injection turbine trip prescuro switch.

CONDITION PRIOR TO OCCURRENCE l Dresden Unit 2 was operating in the "run" mode with a steady load of 720 MWe. }!onthly instrument surveillance vaa in progress.

DESCRIPTION OF OCCURRENCE At 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br /> on July 24, 1974, during routine calibration curveil-lance of pressure evitch PS2389B, the setpoint was found to be 96,. psi increaaing pressure. Tha Technical Specification limit is 90 psi. , 'p '

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COPY SENT REGIO 2 ,

Nr. J. F. O' Leary -2a August 2,1974 DESICNATION OF APPARENT C/.USE OF OCCURRENCE l The cause of the occurrence is due to a lack of pre-cycling of the switch prior to installation. The pre-cycling deficiency has been identified by the manufacturer and a program is presently underway to I -remove all Barksdale pressure switches and return them to the factory for pre-cycling.

ANALYSIS OF OCCURRENCE Switch PS 2389B is one of four switches that trip the HPCI turbine.

. The switches are connected in a "one of two twice" logic configuration.

This arrangement allows for one of the two switches to be out of calibration or inoperable with no effect on the' system. Analysis of the setpoints of the remaining switches indicates that the HPCI turbine would have been operable at 87 psi reactor pressure, which is below the 90 psi limit described in the Technical Specifications.

CORRECTIVE ACTION The switch was immediately reset to 83 psi. In addition, the switch will be pre-cycled as soon as practicable.

FAILURE DATA The switch is a Barksdale Model B2T-A12SS, with a range of 50-120 psi. It has previously been found with a high setpoint on January 25, 1973. "

Sincerely,

, /hE.B.Stephenson B

Superintendent BBS:WEH:do l

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