ML20098A070

RO-369/82-66 Re Failures of Ventilation Unit Condensate Drain Tank Flow Totalizer.Caused by Inadequate Rosemount Transmitter.Mod to Replace Transmitter W/Vortex Meter Under Evaluation

ML20098A070
Person / Time
Site:	McGuire
Issue date:	08/28/1984
From:	Tucker H DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
RO-369-82-66, NUDOCS 8409240255
Download: ML20098A070 (2)

Text

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O DUKE POWER COMPANY P.O. BO K 33180 oHA3LOTTE, N.O. 28242 HAL H. TUCHER TELEMME

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. _ _... - - - 34 SEP 10 tiWg4s2 f8 1984 Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission-Region II Suite 2900 101 Marietta Street, hv Atlanta, Georgia 30323

Subject:

McGuire Nuclear Station Unit 1 Docket No. 50-369 LER/RO-369/82-66

Dear Mr. O'Reilly:

The following is additional information relating to Reportable Occurrence Report R0-369/82-66 which was submitted by my letter dated September 10, 1982 and sub-sequently amended by my letter of October 28, 1982.

R0-369/82-66 reported failures of the Ventilation Unit Condensate Drain Tank (VUCDT) Flow Totalizer in which the totalizer either failed to count during a VUCDT to Condenser Circulating Water (RC) release, or continued to count slowly after termination of a release. Two additional failures were reported in the October 28, 1982 addendum.

The totalizer has experienced a series of malfunctions beginning in 1981, with many of the causes undetermined. In some cases, the totalizer continues to register after the isolation valves have been closed, and in other cases the totalizer fails to register when the isolation valves are open and tank dis-charge is in progress. Numerous attempts have been made to correct these pro-blems; however, to date no definitive corrective action has been accomplished.

Periodic test frequency has been increased to every three months with additional-preventative maintenance performed every eighteen months.

In August of 1981, a Barton transmitter was replaced with a Rosemont transmitter (to increase stability) after a vacuum in the waste liquid (WL) system allowed a continuous differential pressure across the bellows to exist causing the total-Izer to continue to count. Pump head curves, which are conservative, are presently used to calculate releases. ,

l An evaluation of the problems which have., occurred over the years indicate that the l presently installed equipment is inadequate for the application. A Modification that will replace the Rosemont transmitter with a vortex meter is presently being evaluated. The vortex meter has an in line probe attach'ed to the totalizer which terminates flow totals when flow is isolated. The absence of the bellows should eliminate dry or partially filled reference legs thus preventing vacuums and dif-ferential pressures. l l

I 8409240255 840828 PDR ADOCK 05000369 8 PDR OFFICIAL cod. d.

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N A final report will be submitted following the completion of this modification and will detail the e*ffects of its operation.

Very truly yours, b /gg.

Hal B. Tucker PBN:glb I

cc: Document Control Desk U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Records Center Institute of Nuclear Power Operations 1100 circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 M&M Nuclear Consultants 1221 Avenue of the Americas New York, New York 10020 Mr. W. T. Orders NRC Resident Inspector McGuire Nuclear Station American Nuclear Insurers c/o Dottie Sherman, ANI Library <

The Exchange, Suite 245 270 Farmington Avenue Farmington, CT 06032

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