ML19329E442
| ML19329E442 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 04/29/1977 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Howell S CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| NUDOCS 8006160246 | |
| Download: ML19329E442 (1) | |
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I APR 2 9197T Dochet No. 50-329 Docket No. 50-330 Conoumero Power Ceepany ATTU:
Mr. Stephen 11. l'ouell Vico Prcoident 1945 Ucst Parnall noad Jachcon, MI 49201 6
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Centlenen:
Enclosed is I" Bulletin No. 77-01 which requirca action by you with regard to your pouer reactor fac111 tics with an operating licence or a construction porrit.
Should you havo questions regarding thin Ett11etin or the actions required of you, please conteet this offico.
Sincerely, Ja=co C. Kcppler Director
Enclosure:
IE Dulletin No. 77-01
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IHIS DOCUMENT CONTAINS central riles Reproduction t' nit URC 20b E00RQUAUTYPAGES 3 PDR Local PDR L
Ronald Callen, Itichigan Public Sorvice Cor=iscion l
Dr. Wayne E. North lyron it. Cherty, Chicago NSIC TIC No A c4
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NRC FORM 388 (W76) NRCM 0240 W u. a. aovanwuawr en.wri e orrica. nore-eae.es4
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April 29,1977 IE Eulletin No. 77-01 PNEUl!ATIC TIME DELAY RELAY SETPOINT DRIFT DESCRIPTION OF CIRCUMSTANCES:
Mi11 stone Unit 2 and North Anna Unit 1 facilities experienced repeated diesel-generator starting failures several of which investigation revealed were caused by setpoint drift on the pneumatic time delay relays used in the control circuitry for the diesel-generator. The relays involved are identified as ITE Imperial, Catalog Nos. J20T3/J13P20 and J20T3/J13P30. The affected diesel-generators are Fairbanks Morse Units by Colt Industries.
These types of time delay relays are used in several different applications in the control circuitry for the diesel-generator.
One of these relays is used to bypass the normal icw oil pressure shutdown functions during diesel-generator startup. At Millstone Unit 2 the relay had drifted approximately 10 seconds from the required 20 secc:'.d delay which allowed the low oil pressure trip circuit to shut down the diesel-generator before the oil pressure had time to build up.
At North Anna Unit 1, excessive drift of similar ITE time delay relays was also observed during preopera-tional testing of the diesel-generators.
ITE Imperial has identified the time delay relays involved at Millstone Unit 2 as coming from the 1972 and 1973 production runs.
The catalog specification for this vintage of relays requires a
. trip-point setting repeat accuracy of i 15 percent. Units manu-factured in 1974.or later have demonstrated a repeat accuracy of 3 to 4 percent, well within the catalog specification of + 15 percent.
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IE Bulletin No. 77-01 April 29, 1977 Month and year of production for the time delay relays in question-can be determined.lur the six or seven digit bold white number on the timer head. The first two or three digits indicate the month and year or production.
(The last four digits provide other coded information.) For exampic:
124056 indicates a production date of January 1972; 1234056 indicates a production date of December 1973.
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According to the time delay relay manufacturers, the potential for setpoint drift is a common characteristic of most pneumatic relays, irrespective of manufacturer. The magnitude of setpoint drif t is related to the repeat accuracy specified for the device and the mode in which it will operate, that is, energized or de-energized.
In most cases energized units tend to be susceptible to greater devia-tions from setpoint because of the temperature effects on the internal parts of the unit.
ACTION TO BE TAKEN BY LICENSEES AND PERMIT HOLDERS:
For all power reactor facilities with an operating license or con-struction permit:
1.
If you have been notified of the potential problem, describe the actions taken regarding corrective measures to identify and resolve any setpoint drift problems with the ITE time delay relays.
2.
In addition to Item 1 above, pneumatic time delay relays intended for use in safety related systems and specifying a repeat accuracy range of + 15 percent or greater should be demonstrated to provide satisfactory operation. Yau are requested to provide your basis for concluding that existing pneumatic time delay relays are functioning as required, or provide your plans to assure satisfactory operation.
Reports for fac111 tics with operating licences should be submitted within 30 days after receipt of this Bulletin, and reports for facilities with construction permits should be submitted within 60 days after receipt of this Bulletin.
Your report should include the date when the above actions were or will be completed.
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4 3-April 29, 1977 IE Bulletin No. 77-01 Reports should be submitted to the Director of the NRC Regional Office and a copy should be forwarded to the NRC Office of Inspection and Enforcement, Division of Reactor Inspection Programs, Washington, D. C.
20555.
Approval of NRC requirements for reports corscrning possible generic probicms has been obtained under 44 U.S.C 3152 from the U. S. General Accounting Office.
(GA0 Approval B-18025i (R0072), expires 7/31/77) e f
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