05000280/LER-1985-001, :on 850101,safe Signal Placed in Loop B Channel 2 of Overtemp Delta T W/O Cognizance of Operations or Instrumentation Staff.Caused by Lack of Administrative Controls.Event Will Be Reviewed

:on 850101,safe Signal Placed in Loop B Channel 2 of Overtemp Delta T W/O Cognizance of Operations or Instrumentation Staff.Caused by Lack of Administrative Controls.Event Will Be Reviewed

ML20101U009
Person / Time
Site:	Surry
Issue date:	01/28/1985
From:	Saunders R VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF ADMINISTRATION (ADM)
References
85-001, 85-1, LER-85-001, LER-85-1, NUDOCS 8502060513
Download: ML20101U009 (4)

LER-1985-001, on 850101,safe Signal Placed in Loop B Channel 2 of Overtemp Delta T W/O Cognizance of Operations or Instrumentation Staff.Caused by Lack of Administrative Controls.Event Will Be Reviewed

Event date:
Report date:
2801985001R00 - NRC Website

text

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On January 1,1985 with the unit at 34% power, at 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />, it was disco,ered that a safe signal was in place in "B" loop channel 2 of overtemperature delta T (0 PAT) without the cognizance of the Operations or Instrumentation staff.

Safe signals are permitted by Technical Specifications for short periods of time during testing, however, this does imply cognizance of the signal.

With the activity associated with the trip on 12-31-84 and the subsequent investigations to determine the trip cause, Admin. Control of the safe signal was not maintained in the turnover from day shif t to swing shif t.

A procedure was written that will be used when a safe signal is required.

Details of the event will be reviewed by licensed personnel. The NI's were rescaled,the "B" loop AT channel was placed in trip and the safe sign 61 removed.

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Description of the Event On January 1,1985 with the unit at 34% power, at 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />, it was discovered that a safe signal was in place in "B" loop channel 2 of over-temperature delta T (0 PAT) without the cognizance of the Operations or Instrumentation staff. Safe signals are permitted by Technical Specifications for short periods of time during testing, however, this does imply cognizance of the signal.

This event began on 12-29-84 when the (OTAT) channel 2.bistables for "B" loop were placed in trip due to a failed RTD. On 12-31-84 at 1147 hours0.0133 days <br />0.319 hours <br />0.0019 weeks <br />4.364335e-4 months <br />, a safe signal was injected, with the permission of the Shif t supervisor, into the "B" loop AT instrumentation channel to allow performance of Periodic Test 8.1 (Reactor Protection Logic) 'and to rescale the excore nuclear detectors (NI's).

During this test, a reactor trip occurred at 1324 hours0.0153 days <br />0.368 hours <br />0.00219 weeks <br />5.03782e-4 months <br /> (See Unit 1 LER-84-026-00). The test was terminateo, but the safe signal remained in for rescaling the NI's.

This informatic s was not passed on to the subsequent _shif ts and was not detected by pre-criticality checklists.

2.

Probable Consequences The OTAT logic is designed to protect the core against departure from nucicate boiling (DNB). Sufficient margin to DNB is maintained with the unit at full power. A very large margin to DNB was maintained from the reactor trip until the safe signal was discovered because reactor power remained below 35%.

The total time the safe signal was in place was 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> 13 minutes, however, the time that plant personnel were unaware of it was 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> 30 minutes. Also, the 2 redundant OTAT channels remained operable throughout this event, therefore an unreviewed safety question was not created and the health and safety of the public were unaffected.

3.

Cause

With the activity associated with the trip on 12-31-84 and the subsequent investigations to determine the trip cause, Admin. Control of the safe signal was not maintained in the turnover from day shift to swing shift. This information was available in the Control Room Operator's log.

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4.

Immediate Corrective Action

When the safe signal was discovered, administrative control was reestablished, and since it was still needed for rescaling the NI's, no immediate corrective actions were taken.

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Additional Corrective Actions

The NI's were rescaled, and the "B" loop AT channel was placed in trip and the safe signal removed.

6.

Action Taken to Prevent Recurrence A procedure was written that will be used when a safe signal is required.

Details of the event will be reviewed by licensed personnel.

7.

Generic Implications None.

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f VIRGINIA ELECTRIC AND POWER COMPANY Surry Power Statim P. O. Box 315 Surry, Virginia 23883 Serial No:

85-001 January 28, 1985 Docket No:

50-280 License No: DPR-32 U. S. Nuclear Regulatory Commission Document Control Desk 016 Phillips Building Washington, D.C. 20555 Gentlemen:

Pursuant to Surry Power Station Technical Specifications, the Virginia Electric

' and Power Company 1.ereby submits the following Licensee Event Report for Surry Unit 1.

REPORT NUMBER 85-001-00

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This report has been reviewed by the Station Nuclear Safety and Operating Committee and will be reviewed by Safety Evaluation and Control.

Very truly yours, R. F. Saunders Station Manager Enclosure cc: Mr. James P. O'Reilly Regional Administrator Suite 2900 101 Marietta Street, NW Atlanta, Georgia 30323 i

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