ML20153C886

Amend 2 to 870311 Part 21 Rept Re Problem W/Static Exiter Voltage Regulator Reset Design Provided as Part of Dsr/Dsrv Standby Diesel Generator.Recommends That Sevr Control Circuits Be Modified to Energize Serv on Start Signal

ML20153C886
Person / Time
Site:	Comanche Peak
Issue date:	08/17/1988
From:	Guntrum B IMO DELAVAL, INC.
To:	NRC
References
REF-PT21-88-093-000 PT21-88-093-000, PT21-88-93, NUDOCS 8809010341
Download: ML20153C886 (3)

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415 577 7410 August 17, 1988 Director, Office of Inspection and Enforcement US Nuclear Regulatory Commisalon Mail Station F1-137 Washington, DC 20553 Report #138 Amendment 2

Dear Sir,

This letter la intended to amend our March li, 1987 report to you relative to a potential problem with the static exciter voltage regulator reset design provided as a part of a DSR and DSRV standby diesel generator.

Our original report discussed a design feature of the SEVR whe-redn it will de-energize upon receipt of a notaal shutdown eignal and reset when the engine speed falle below 20o RPM. If an emer-gency start signal le received before the engine coasts below this recet speed, the engine will accelerate to its normal oper-ating speed of 450 RPM. The exciter would not have been ener-giaed, however, any output voltage.

thereby preventing the generator from providing In fact, this problem will exist in any installation where there le an SEVR reset circuit based on engine speed. A review of our files reveale one (1) other installation, not previously reported, where the voltage regulator reset point is 425 rpm, engine speed. While the engine will slow the 425 rpm in less than 5 seconde, there exists the possibility of the above stated ece-nario within this timeframe.

The installation referenced above is as follows:

UTILITY SITE SERIAL NO. MODEh Texas Utilities Comanche Peak 76001-04 DSRV-16-4 IMO Delaval recommende that the SEVR control circuite be modified to energine the SEVR upon receipt of an emergency start signal; this is consistent with the recommended action in our original report.

Since action by othere le required, we cannot estimate when corrective action will be completed.

8809010341 080017 PDR

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Page 2 August 17, 1988 US Nuclear Regulatory Commission our evaluation of this matter was concluded on August 15, 1988.

A copy of this letter will be sent to the affected sites as indicated by the cc list.

Sincerely,

\

/

Bruce ntrum Manager. Quality Aesurance BCG/dfa cc: Carolina Power & Light Co.

Shearon Harris Nuclear Plants P.O. Box 101 New Hill, North Carolina 27562 t

Attn: Mr. B.A. Watson, Vice President Mr. L.I. Loflin, Mgr.

Harrie Plant Engineering Mr. George Forehand Director, QA/QC Tennessee Valley Authority - Bellefonte W7C126, 400 West Summit Hill Drive Knoxville, Tennessee 37902 Attn: Mr. I.L. Belts Sacramento Municipal Utility District 14440 Twin Cities Road Herald, CA 95638 Attn: Mr. Cranston Nuclear Engineering Dept., M.S. 208 J.R. Beal Purchasing Dept., M.S. 50

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Page 3 August 17, 1988 US Nuclear Regulatory Commission cc: Continued

,, Washington Public Power Supply System Post Office Box 460 Richland, WA 99352 Attn: Mr. G.K. Dyekman Acting Asst. Program Director Georgia Power Company Plant Vogtle P.O. Box 1600 Waynesboro, Georgia 30830 Attn: Mr. George Bockhold, Jr.

Plant Manager Texas Utilities Skyway Tower 400 North Oliver Street L.B. 81 Dallas, Texas 75201 Attn: Mr. W.G. Counsil Jr.

Executive Vice President