ML20084L840

Ao:On 740611,during Refueling,Reactor Pressure Switch PS-2-263-53C Found to Operate High.Caused by Lack of Precycling Prior to Installation.Switch Will Be Removed & Sent to Factory for Precycling

ML20084L840
Person / Time
Site:	Dresden
Issue date:	06/19/1974
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084L843	List: ML20084L840 ML20084L845 ML20084L849
References
442-72, NUDOCS 8305240018
Download: ML20084L840 (2)

Text

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@ One Forst( Addrrss Riply to: Post Othee Box 767 Chicago, Ilknois 60690 -

BBS Ltr.d442-74 Dresden Nuclear Power Station R. R. #1 Morris, Illinois 60450 , _

June 19, 1974

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.i Mr. J. F. O' Leary, Director 50-237 N 57S74e.

Directorate of Licensing U. S. Atomic Energy Commission \gp. . ,

Washington, D. C. 20545 2 '/

SUBJECT:

LICENSE DPR-19, DRESDEN NUCLEAR POWER STATION, UNIT 42, REPOR "

OF ABNORMAL OCCURRENCE PER SECTION 6.6.B. l.a OF THE TEGINICAL SPECIFICATIONS.

_ SUSTAINED REACTOR HIGH PRESSURE SWITOI DRIFT.

References:

1) Notification of Region III of AEC Regulatory Operations Telephone: Mr. F. Maura,1330 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.06065e-4 months <br /> on 6/12/74 Telegram: Mr. J. Keppler,1338 hours0.0155 days <br />0.372 hours <br />0.00221 weeks <br />5.09109e-4 months <br /> on 6/12/74

2) Dwgs: P & ID M-26 S & L 12E2506 T:-r Mr. 0*i_er ry:

This letter is to report a condition relating to the operation of the unit at about 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br /> on June 11, 1974. At this time, one of the four sustained high reactor pressure switches was found with a trip point of 1075 psi. This taalfunction is contrary to Table 3.2.2 of the Technical Specifications which requires that the switchcA be set at

_f,1070 psig.

IROBLEM At the time of the occurrence, Unit 2 was in the refuel mode.

Routine surveillance was in progress. During the calibration check of pressure switches PS-2-263-53A, B, C and D, switch C was found to operate at 1075 psi f . This is 5 psi above the 1070 psig limit set by the Technical Specifications. The switch was immediately reset to 1054 psi.

The function of PS-2-263 A through D is to initiate the isolation condenser if reactor pressure is sustained at 1070 psi for 15 seconds.

INVESTICATION The switch in question is a Heletron Model 372 which utilizes a bourdon tube actuator.- This switch was previously checked on May 12, 1974 At that time, it was set at 1059 pai. -

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Mr. J. F. O'Le ry Juna 19, 1974 All Meletron bourdon tube pressure switches are subject to setpoint drif t in both the increasing and decreasing direction. The problem has been identified by Barksdale Corporation, who presently manufactures Heletron switches, to be a lack of pre-cycling prior to installation. A program is presently underway to remove bourdon tube switches from service and send them to the factory for pre-cycling. This program is approximately 30% complete at this time.

CORRECTIVE ACTION The corrective action to resolve the drif t problem associated with PS-2-263-53C will be to remove the switch and send it to the factory for pre-cycling.

EVALUATION PS-2-263-53A is one of four switches that initiate the isolation condenser. The switches are connected in a "one out of two twice" logic configuration. The settings of the remaining three switches were such that in the event of a sustained high reactor pressure condition, the isolation condenser wculd have been initiated at 1068 pai. This is within the limits of the Technical Specification, and it is therefore concluded that the safety of the plant personnel or the general public was not jeopardized as a; result

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of thie ww w...u ..

i The cumulative experience with these switches does not indicate

, that more frequent calibration of them would be of any help.

The cumulative experience of pressure switch drif t is inconclusive at this time because of lack of history, however, the vendor indicates that lack of pre-cycling is the cause of the persistent drift problem at Dresden

Station.

i Sincerely, ,

lf' ,' D ?] E K B. B. Stephenson Superintendent BBS:WEH:do l

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