ML19296A392
| ML19296A392 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 02/16/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Goodwin C PORTLAND GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 7903190515 | |
| Download: ML19296A392 (1) | |
Text
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%s,O UNITED STATES c
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,S NUCLEAR REGULATORY COMM!sslON h h./l.,
REGION V
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SUITC 202. VIALNUT C REEK PL AZ A
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1990 N. C ALIFORT41 A DOULEV AR D
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WALNUT CREEK, C ALIFORNI A 94536 February 16, 1979 Docket ilo. 50-344 Portland General Electric Company 121 S. W. Salmon Street Portland, Oregon 97204 Attention: Mr. Charles Goodwin, Jr.
Assistant Vice President 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.
flo specific action or response is requested at this time.
If further flRC evaluations so indicatc, an IE Circular, Bulletin or liRR Generic Letter will be issued to recom.end or request specific licensee actions.
If you have questions regarding the natter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, h qck W R. H. Engelken Director
Enclosures:
1.
IE Information flotice No. 79-04 2.
List of IE Information Notices Issued in 1979 cc w/encls:
B. Withers, PGE F. C. Gaidos, PGE 7903190 5/5
.O' UNITED STATES t'UCLEAR REGULATORY COMMISSION OFFICE OF INSPECTI0tl AND E!.70RCE*>.ENT WASHINGT0il, D.C.
20555 February 16, 1979 IE Information tiotice tio. 79-04 DEGRADATI0t1 0F EliGINEERED SAFETY FEATURES Summary On September 15, 1978, an unusual sequence of events occurred at Arkansas fluclear One, Units 1 anc 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 At;0 site electrical systen that orovides offsite power to Units 1 and 2 did not fully meet the Cornission's Regula-tions, 10 CFR 50, Appendix A, General Design Criterion 17, because in certain circumstances a loss of one cf the two offsite power circuits would also result in a loss of.the other such circuit.
(3) Deficiencies existed in the operation of the t' nit 2 inverters that convert DC to AC power for the uninterruotable 120 volt vital AC buses.
Description of Circumstances Initially Unit I was operating at 100 percent cower; Unit 2 was in hot standby perferning hot functional testing in preparation for initial criticality and power operation (l) Unit 1 auxiliary electrical loads were being supplied from the Unit 1 main generator via the unit auxiliary transformer. Unit 2 auxiliary electrical leads were being fed from the offsite grid through Startup Transforner No. 3.
The nornal 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 Dr.it 1 Reactor Protection Systen 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.
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