ML20196J451

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Forwards Addl Info Re ATWS Mitigation Sys Actuation Circuitry Output Isolators Qualification Testing to Complete Review of AMSAC Design for Plant
ML20196J451
Person / Time
Site: Beaver Valley
Issue date: 03/03/1988
From: Sieber J
DUQUESNE LIGHT CO.
To:
NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
TAC-62943, NUDOCS 8803140332
Download: ML20196J451 (2)


Text

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""#""*"*' March 3, 1988 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

Reference:

Beaver Valley Power Station, Unit No. 1 and No. 2 BV-1 Docket No. 50-334, License No. DPR-66 BV-2 Docket No. 50-412, License No. NPF-73 10 CFR 50.62, ATWS Rule Implementation Gentlemen:

Attached is additional information on our ATWS Mitigation System Actuation Circuitry (AMSAC) output isolators qualification testing.

This information was requested by members of your staff to complete your review of our AMSAC design for Beaver Valley Unit No. 1 and No.

2. The information provided supplements discussion on these isolators in our previous submittal on this subject dated December 2, 1987.

If you have any additional questions on our AMSAC design, please contact my office.

Very truly yours,

$.hD. SSieber n

s jVicePresident, Nuclear Attachment ,

cc: Mr. J. Beall, Sr. Resident Inspector Mr. W. T. Russell, NRC Region I Administrator Mr. P. Tam, Project Manager Director, Safety Evaluation & Control (VEPCO) gc5 6 ih 8803140332 880303 PDR ADOCK 05000334 P DCD

, ATTACHMENT BEAVER VALLEY UNITS 1 AND 2 Supplemental Testing Information for AMSAC Output Isolators Refer to previous Duquesne Light Company submittal on AMSAC dated December 2, 1987 and the attached Figure 1 to that document.

I. Pass / Fail Acceptance Criteria Following each of the three fault tests, the fault voltages were applied between the terminals and the mounting plate to verify no current flow and dielectric (high potential) tests were done between the inputs and mounting plate, inputs and outputs and the outputs and mounting plate to verify no insulation breakdown (< 2 milliamps).

II. Test Requirements and Sequence A. Dielectric (high potential) test each relay - 1800 VAC for one minute. Breakdown shall not occur in excess of 2 milliamperes.

B. Continuity check the contact of the relays.

C. Megger test the relays -

500 VDC. Insulation resistance shall be 1 mogohm or greater.

D. Conduct isolation fault tests per attached Figure 1 (Input Test, AC Output Test and DC Output Test). After each test sequence a dielectric (high potential) test was performed to check for insulation breakdown.

III. Test Results A. Input Test - Upon application of the fault to the input, the relay contacts closed for approximately 23 seconds and then opened. A leakage current of 19.07 micro amps was measured ,

when the 600 VAC was applied between the input terminals and the mounting plate. Dielectric strength results after testing was < 2 milliamperes. <

B. AC Output Test - A leakage current of 19.23 micro amps was 1 measured when the 600 VAC was applied octween the output terminals and the metal mounting plate. Dielectric strength l results after testing was < 2 milliamperes.

C. DC Output Test - No current flow was measured when the 150 VDC was applied between the output terminals and the metal mounting plate. Dielectric strength results after testing was < 2 milliamperes. l IV. Conclusions The small leakage currents measured after the fault tests of less l than 20 micro amps is acceptable. The dielectric tests indicated I no insulation breakdown. The test demonstrated the isolation devices ability to survive destructive electrical faults and continue to provide isolation of non lE circuits to lE circuits.