ML19281A208
| ML19281A208 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 02/16/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Cavanaugh W ARKANSAS POWER & LIGHT CO. |
| References | |
| NUDOCS 7903080415 | |
| Download: ML19281A208 (1) | |
Text
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UNITE D STATES p
o NUCLEAR REGULATORY COMMISSION G11 RYAN PL ZA DPt /E, SUITE 1000 t
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AR LINGTON, TEXAS 76011 IISIC o*/
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February 16, 1979 Docket Mos. 50-368 50-313 Arkansas Power and Light Company ATTN: Mr. William Cavanaugh III Executive Director of Generation and Construction Post Office Box 551 Little Rock, Arkansas 72203 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 NRR Generic Letter will be issued to recommend or request specific licensee action.
If you have questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely,
, ?.
'{'!);,f't?
- G:
- q Karl V. Seyfrit
'/
Director
Enclosures:
1.
IE Infonnation Notice No. 79-04 2.
List of IE Information Notices Issued in 1979 79030804(f
UtlITED STATES tlUCLEAR REGULATORY COMMISSI0tt OFFICE OF IrlSPECTI0tl AtlD EilFORCEMErlT WASHIflGT0tl, D.C.
20555 IE Information flotice flo. 79-04 Date:
February 16, 1979 Page 1 of 5 DEGRADATI0tl 0F EtlGIflEERED SAFETY FEATURES Summary:
On September 16, 1978, fluclea'r One, Units 1 and 2.an unusual sequence of events occurred at Arkansas The events involved the electrical power sources and culminated in the spurious activation and degraded operation of Unit 2 E 4gineered Safety Features (ESF).
Analysis of the course of the incider t has identified three safety concerns in the electrical distributi,n system operation and design.
(1)
Tb; offsite power supply for At10 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 Atl0 site electrical system that provides offsite power to Units 1 and 2 did not fully meet the Commission'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 1 was operating at 100 percent power; Unit 2 was in hot standby performing hot functional testing in prepat ation for initial criticality and power operation ]/.
Unit 1 auxiliary electrical loads were being supplied from the Unit 1 main generator via tle unit auxil.ary transformer.
from the offsite grid through Startup Transformer flo. 3. Unit 2 auxiliary e 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 Unit 1 Reactor Protection System sensed conditions requiring reactor shutdown and tripped the reactor.
The 1/ -The Unit 2 Operating License did not permit criticality of power operation at the time of the incident.
DUPE 7903020383