ML19282A928
| ML19282A928 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 02/16/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Hines E DETROIT EDISON CO. |
| References | |
| NUDOCS 7903080339 | |
| Download: ML19282A928 (1) | |
Text
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'4 NUCLEAR REGULATORY COMMISSION f,I Il[
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799 ROOSEVELT Ro AD 9
. ? N I sLYN, ILLINOIS 60137 FEB 16 J9 Docket No. 50-341 The Detroit Edison Company ATTN:
Mr. Edward Hines, Assistant Vice President and Manager Quality Assurance 2000 Second Avenue Detroit, MI 48226 Gentlemen:
This Information Notice is provided as an early notification of a possibly significant matter. It is expected that recipients will review the information for possible applicability to their facilities.
No specific action or response is requested at this time.
If further NRC evaluations so indicate, an IE Circular, Bulletin or ERR Generic Letter will be issued to recommend or request specific licensee actions.
If you have qucstions regarding the matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, M.$p h b--
(/ James G. KeNer Director
Enclosures:
1.
IE Information Notice No. 79-04 2.
List of IE Information Notice Issued in 1979 e
ccN/encls:
Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Ronald Callen, Michigan Public Service Commission Eugene B. Thomas, Jr.,
Attorney 7903080334
U.S. NUCLEAP. REGULATORY CCMMISSION OFFICE OF INSPECTION AND ENFORCEMENT REGION III February 16, 1979 IE Information Notice No. 79-n4 DEGRADATION OF ENGINEERED SAFETY FEA"URES Su= mary On September 16, 1978, an unusual sequence of events occurred at Arkansas Nuclear One, Units 1 and 2.
The events involved the electrical power sources and culminated in the spurious activation and degraded operation of Unit 2 Engineered Safety Features (ESF). Analysis of the course of the incident has identified three safety concerns in the electrical distribution system operation and design.
(1) The offsite power supply for ANO Unit 1 Engineered Safety Feature loads was deficient in that degraded voltage could have resulted in the unavailability of ESF equipment, if it were to be needed.
(2) The design of the ANO site electrical system that provides offsite power to Units 1 and 2 did not fully meet the Co= mission's Regula-tions, 10 CFR 50, Appendix A, General Design Criterion 17, because in certain circumstances a loss of one of the two offsite power circuits would also result in a loss of the other such circuit.
(3) Deficiencies existed in the operation of the Unit 2 inverters that convert DC to AC power for the uninterruptable 120 volt vital AC buses.
Description of Circumstances Initially Unit I was operating at 100 percent power; Unit 2 was in hot standby performing hot functicnal testing in preparation for initial criticality and power operation.1 Unit 1 auxiliary electrical loads were being supplied from the Unit 1 main generator via the unit auxiliary transformer. Unit 2 auxiliary electrical loads were being fed from the offsite grid through Startup Transformer No. 3.
The normal operating status was interrupted by the failure of the Unit 1 Loop "A" Main Steam Line Isolation Valve (MSIV) air operator solenoid causing the MSIV to close as designed.
The U-it 1 Reactor Protection System sensed conditions requiring reactar 2hutdown and tripped the reactor. The 1 The Unit 2 Operating License did not permit criticality or power operation at the time of the incident.
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