ML19338D003

AO 50-10/1975-9:on 750528,instrument Mechanics Routinely Calibr Reactor Pressure to Core Spray Header Pressure Permissive Switch dPS-CS126B,switch Failed to Operate.Caused by Component Failure.Bellows Seal Ruptured.Switch Replaced

ML19338D003
Person / Time
Site:	Dresden
Issue date:	06/05/1975
From:	Stephenson B COMMONWEALTH EDISON CO.
To:
References
342-75, NUDOCS 8009150586
Download: ML19338D003 (2)

Text

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Di'** den Nuclear Power Station R. R. #1 Morris, Illinois 60450 June 5,1975 Mr. James G. Keppler, Regional Director Directorate of Licensing U. S. Nuclear Regulatory Comunission wa=hington, D. C.

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SUBJECT:

REPORT OF AItiORMAL OCCURRENCE PER SEL' TION 6,6.A OP THE TEL'HNICAL SPECIFICATINS CORE SPRAY-REACTOR PRESSURE PERMISSIVE SWITCH FAILURE

References:

1) Regulatory Guide 1.16 Rev. 1 Appendix A

2) Notification of Region III of U. S. Nuclear Regulatory Coennission Telephone P. Johnson, 1?50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> on May 29, 1975 Telegram:

J. Keppler, ?412 hours0.00477 days <br />0.114 hours <br />6.812169e-4 weeks <br />1.56766e-4 months <br /> on May 29, 1975 Report Number: 50-10/1975-9 Report Dates: June 5, 1975 Occurrence Date: May 28, 1975 Pacility: Dresden Nuclear Power Station, Morris, Illinois IDE2frIFICATIN OF OCCURRENCE The reactor pressure to core spray permissive switch (dPS-CS126B) failed to operate.

CONDITIONS PRIOR TO OCCURRENCE At the ti.ne of the occurrence Unit-1 was in a steady-state condition at 573 MWt and 180 MWe, There were no other surveillance tests in progress at that time.

DESCRIPTION OP OCCURPlNCE i

At 1400 hours0.0162 days <br />0.389 hours <br />0.00231 weeks <br />5.327e-4 months <br /> on May 28, 1975 as the Instrument Mechanics were routinely calibrating tne reactor pressure to core spray header pressure pe missive sn tch (dPS-CSi26EO, the ac tch fai'.ed T.:

cperate. After t.ne operat.nr 8 0091,50 Nd g

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w-Mr. Jame] G. Keppler

- June 5, 1975 k.3 engineer was notified, the switch was jumpered closed to render the system operable.

DESIGNATl'N OF APPARENP CAUSE OF OCCURRENCE (Component Failure)

The cause of the occurrence was component failure. The bellows seal of the switch had ruptured.

ANALYSIS OF OCCURRENCE The failure of dPS-CS126B negated only one side of a parallel-wired subsystem on reactor protection system channel "B".

The health and safety of plant personnel and the public were not jeopardized by this incident since channel "B" renained operable through the parallel switch.

After jumpering the switch closed, channel "B" was positively operable, ensuring core spray system capability even in the event of a similar failure of the parallel switch.

CORRECTIVE ACTION The inmiediate corrective action was to jumper the contacts closed. The switch was replaced at 1900 hours0.022 days <br />0.528 hours <br />0.00314 weeks <br />7.2295e-4 months <br /> on June 3, 1975

_ FAILURE DATA There has been no previous failure of this type of component. The switch is

.a Barton 288-A switch.

C_ B. B. Stephenson Superintendent BBS sup Pile /NRC

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