ML20137M562

Part 21 & Deficiency Rept Re Cooper-Bessemer Diesel Generators.Erroneous RPM Readings Discovered on 840926 & 850706 for Diesel Generators 1B & 2A,respectively.Dc to Dc Converter Will Replace Dc to Dc Regulator

ML20137M562
Person / Time
Site:	Byron
Issue date:	09/06/1985
From:	Miosi A COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
REF-PT21-85, REF-PT21-85-382-000 2077R, PT21-85-382, PT21-85-382-000, NUDOCS 8509130273
Download: ML20137M562 (2)

Text

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) One First N tion:1 PL:za. Chiergo. Ilknois 7 Address Reply to: Post Othee Box 767

/ ChtCago, Illinois 60690 September 6, 1985 Mr. James G. Keppler Regional Administrator U.S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137

Subject:

Byron Station, Unit 1 Part 21 Notification Degradation of Diesel Generator (s),

Faulty RPM Reading NRC Docket'No. 50-454

Dear Mr. Keppler:

This letter follows our conversation with Mr. Robert'Lerch of your staff yesterday, during which a matter reportable under 10CFR21 was addressed. The specific Part 21 concern brought to your attention was a matter involving the Cooper-Bessemer Diesel Generators at Byron Station, where erroneous RPM readings were discovered first on September 26, 1984, for DG 1B, and second, on July 6, 1985, for DG 2A. The 2A DG is considered, in our current mode of operation at Byron Station, to be administratively necessary for Unit 1 operation.

Byron Station personnel, in both cases, discovered that the speed sensing tachometer, supplied by Airpax Electronics, was erroneously showing an RPM reading, while the engine was in the standby mode. A series of alarms was also found annunciated, with the " Starting System Malfunction Alarm", being the most critical. As a result, " essential safety-related equipment", required to safely shutdown the reactor, was affected.

The problem in each case was thought to be a faulty power supply (manufactured by Panalarm), located in the DG local control panel annunciator package, which caused " noise" to reach the speed sensing tachometer. At greater than 280 RPM, the starting air solenoid valves become de-energized. Therefore the diesels could not start in this alarm 3 mode due to design circuitry. After replacement of the faulty power fsupply, the noise signal at the-speed sensing tachometer was no longer initially present, implying that the problem was corrected. Currently, hourly surveillances are being conducted to monitor the tachometer. The tJ hourly surveillance is in addition to an alarm, " Local DG Panel Trouble" p which would annunciate in the main control room to alert shift personnel n of any problem for the local controls.

o 3" Further investigation by Corporate and Station personnel gfm e determined rather than athat DC Airpax recommendations to DC regulator, suggestina place which is currently DC tosoDC converter, that the positive signals.

and negative leads are isolated frc, the input and output As suppplied by Entronics, a Division'of Cooper-Bessemer SEP 10 585 (Energy), a DC to DC regulator was installed instead, which does not provfde isolation of the positive and negative leads. The necessary converters have been ordered by Byron Technical Staff personnel. Also, Ccoper-Bessemer'sEntronicControlsDivision(MountVernon, been notified of our intent to contact your office in this matter. Ohio),have.gg[dI

,o

tro e In addition to the above, our plans are to test the DC to DC converters on the 2B DG, where a simulated noise signal will verify if the converter eliminates the noise problem. Airpax expects to expedite our order within three weeks to augment Station modification paperwork new in progress. Retrofit and the possibility of changing to a new vorsion power supply (under current review) will begin immediately after receipt of the parts and completion of the modification packages.

The manufacturers involved and their addresses follow:

Airpax Electronics Cooper Energy Services Controls Division Entronic Controls Div.

6801 W. Sunrise Blvd. North Sandusky St.

Fort Lauderdale, FL 33313 Mount Vernon, OH 43050 Panalarm Div. of Riley Co.

7401 N. Hammily Skokie, IL 60076 Since this matter is generic to other stations with this type Cooper-Bessemer Diesel, the Braidwood Project Engineering Staff will be requested to initiate a 50.55e report for the necessary retrofit, as well as the pursuit of this matter to completion under Station Nuclear Engineering procedures for Commonwealth Edison's other Nuclear Stations.

Very truly yours,

. . t I A.D. Miosi l

Nuclear Licensing Administrator SGM/ji 2077R*

cc: Director, Office of Inspection and Enforcement - 3 copies NRC Resident Inspector - Byron L. Olst.an - NRR I