ML20058F479
| ML20058F479 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 10/30/1990 |
| From: | Sailer W GILBERT/COMMONWEALTH, INC. (FORMERLY GILBERT ASSOCIAT |
| To: | Murley T Office of Nuclear Reactor Regulation |
| References | |
| REF-PT21-90 NUDOCS 9011080309 | |
| Download: ML20058F479 (2) | |
Text
s Gilbert / Commonwealth, Inc. enenmi ano consunants V
P.0 Box 1498 Reading. PA 1960314981 Telephone 215-775 2600. Cable Gitasoc/ Telex 836 431 W F SAILER, P E Senor vice Presnient October 30,1990 United States Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington,D.C. 20555 Attention: Mr T.E.Murley, Director Re: Reportable Event, V. C. Summer Nuclear Station Chilkd Water System
Dear Mr. Murley:
Tnis letter documents my report by telephone under the provisions of 10CFR21 on October 26,1990 at approximately 10:45 a.m. to Ron Loyd of the NRC.
Individual Who Renorted:
Mr W. F. Sailer, Senior Vice President, Gilbert / Commonwealth, Inc.
Facility Involved:
V, C. Summer Nuclear Station (Docket 50-395) operated by South Carolina Electrie & Gas Company.
Activity involvei Design of chilled water system.
Nature of Defect:
The V. C. Summer Chilled Water System consists of (2) redundant, closed cooling loops, each of which provides safety related chilled water to cooling coils in several safety related and several non saf ety related components. Water flow to all non safety related cooling coils is stopped by automatic isolation valves actuated by a Safety injection Signal or a low-low level signal (8" tank level) from the expansion tank in each chilled water train. T!4 xpansion tanks are located at a low level ( centerline elev. 423') relative to the high point of the system (centerline elev. 499'.10"), and rely on a pressurized air pocket to keep the Chilled Water System full of water. In the event of a postulated selsmic occurrence, non safety, non-seismic piping, equipment, and supports may become over stressed, collapse and/or rupture. Although the expansion tank is initially pressurized so as to maintain the system filled to its high point (499' elev.), the tank must depressurize as level drops, before the level switch will actuate. For a rupture of the lowest non-safety piping at elevation 426', the chilled water system may drain down to this elevation, without actuating the level switch b the expansion tank (elev. 422'-8"). Cooling water flow to most of the safety related air handling units, which are above this elevation, could be lost. Depletion of water inventory may prevent the system from providing the necessary cooling water flow to the charging pump, component cooling pumps, and safety related air handling units. Loss of these safety functions could result in the inability to achieve safe shutdown conditions.
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- '.'Silbert/C:mmdwealth e'aem.. wconsaum GlNaf /COMWomwl At1M. INC. P0 Sca le98 neadme PA HEQUfei tt5 r4M00ltatne Gdasociteesi 450 Mr. T.E. Murley*, Director United States Nuclear Regulatory Commission October 30,1990 Page 2 Date Information Obtained; This event was determined to be reportable on October 26,1990.
Other Nuclear Facilitics:
L This situation is currently being tr.newed for the other nuclear power plants for which G/C was the A/E of record. We will advisc you of 1.c results of this review by November NJ,1990..
6 Corrective Action:
V. C. Summer Nuclear Station has been placed in a safe condition by manually isolating the non-safety piping in the chilled water system.
Permanent modifications are being evaluated and pursued by SCE&G.
t G/C will issue an internal design bulletin to alert all engineers to this situation.
If you require any further information, please call nie at (215) 775 2600, extension 7543.
Very truly yours, a
William F. Sailer Senior Vice President MGC:mge.
cc:
T.E. Murley (NRC) (3)-
Document Management Branch (NRC)
.R.J. Wasclus (SCE&G)
' A. R. Koon (SCE&G) k L
L L
.