ML20043F034
| ML20043F034 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 05/07/1990 |
| From: | Chrzanowski R COMMONWEALTH EDISON CO. |
| To: | Murley T Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9006140110 | |
| Download: ML20043F034 (3) | |
Text
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Commonwealth Edison g Ge,n,ye g g,9,n Zion lilinois 600e9 Telephone 708 / 746-2084 -
May 7, 1990 Dr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555-Subjec't:
Zion Station Units 1 & 2 Evaluation of Safety Equipment Outages for Significance at Zion NRC Docket Nos 50-295/304
Reference:
"05000295/LER-1990-001-02, :on 900103,RCS Leak of Approx 20 Gpm Developed. on 900104,leak Source Determined to Be Packing Failure on RHR Pump RCS Suction Isolation Valve [[SSC" contains a listed "[" character as part of the property label and has therefore been classified as invalid..Caused by Failure to Center Valve Stem.Valve Repacked|January 31, 1990, letter]] from T.M. Novak to T.P. Joyce concerning TR Report No AEOD/T925
Dear Dr. Hurley:
The referenced report evaluates conditional core damage probability for Zion Station Event Notifications (EN's)-reporting equipment outages on-November 22 -.23, 1989. Commonwealth Edison has reviewed this report and has determined that incorrect information on the operation of Zion Station was used that resulted in a core damage probability that was significantly higher than actual.
-The most significant error made was the assumption that the 2B Essential Service Water (ESH) Pump was powered from the 2B Diesel Generator.(DG).
In fact, the 2B ESH Pump is powered from the 2A DG and the 2C ESH Pump is powered from the 2B DG.
With this correction alone, the 2B DG and 2C ESH pump would be available.to-provide AC power to other components.
The net result would be service water available to both units, the turbine driven auxiliary feedwater pumps (which are independent of AC power) available to both units, DC power available to the instruments necessary to monitor the auxiliary feedwater removal function on both' units and various other AC powered equipment available from the essential bus powered from the 2B DG.
Also, not included in the analysis is the fact that a diesel driven fire pump, which can,be run independent of AC power, was available to provide a backup source of cooling water to the available DG's in the event a ESH pump was unavailable.
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- The above items were discussed wlth Mr. Fred Manning of AE00 by Dr. Terrance-L Rieck, Technical Superintendentlof Zion Station (708-746-2084 x2214).
Please-contact Dr. Rieck if you have any further questions.
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Commonwealth Edison would appreciate the use of this new information to reevaluate the conclusions of the report.
Very-truly yours
@Wh R.A. Chrzanowski Nuclear Licensing Administrator RAC:jma(7) cc:- Zion Resident Inspector Office of Nuclear Reactor Safety IDNS T.H. Novak - AEOD C. Patel - NRR Region III Office I
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