ML19291C009
| ML19291C009 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/05/1979 |
| From: | Carroll D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Wright G ILLINOIS, STATE OF |
| References | |
| NUDOCS 7912190503 | |
| Download: ML19291C009 (2) | |
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NUCLEAR REGULATORY COMMISSION 3.,q/'
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GLEN ELLYN.1LLINOIS 60137 DE.c 51979 State of Illinois Department of Public Health ATTN:
Mr. Gary N. Wright, Chief Division of Nuclear Safety 535 West Jefferson Street Springfield, IL 62761 Gentlemen:
The enclosed IE Bulletin No. 79-27 titled " Loss Of Non-Class-1-E Instrumen-tation And Control Power System Bus During Operation" was sent to the following licensees on November 30, 1979, for action and information:
ACTION American Electric Power Service Corporation Indiana and Michigan Power Company D. C. Cook 1, 2 (50-315, 50-316)
Cincinnati Gas and Electric Company Zimmer (50-358)
Commonwealth Edison Company Dresden 1, 2, 3 (50-10, 50-237, 50-249)
Quad-Cities 1, 2 (50-254, 50-265)
Zion 1, 2 (50-295, 50-304)
Consumers Power Company Big Rock Point (50-155)
Palis.ed-s (50-255)
Dairyland Power Cooperative LACBWR (50-409)
Iowa Electric Light and Power Company Duane Arnold (50-331)
Northern States Power Company Monticello (50-263)
Prairie Island 1, 2 (50-282, 50-306)
Toledo Edison Company Davis-Besse 1 (50-346)
Wisconsin Electric Power Company Point Beach 1, 2 (50-266, 50-301)
Wisconsin Public Service Corporation Kewaunee(50-305) 1790 329 7012190
DEC 51979 State of Illinois INFORMATION Cleveland Electric Illuminating Company Perry 1, 2 (50-440, 50-441)
Commonwealth Edison Company Braidwood 1, 2 (50-456, 50-457)
Byron 1, 2 (50-454, 50-455)
La Salle 1, 2 (50-373, 50-374)
Consumers Power Company Midland 1, 2 (50-329, 50-330)
Detroit Edison Company Fermi 2 (50-341)
Illinois Power Company Clinton 1, 2 (50-461, 50-462)
Northern Indiana Public Service Company Bailly (50-367)
Ohio Edison Company Erie 1, 2 (50-580, 50-581)
Public Service of Indiana Marble Hill 1, 2 (50-546, 50-547)
Union Electric Company Callaway 1, 2 (50-483, 50-486)
Sincerely,
/
D rothy E.
arroll, Acting Chief Administrative Branch
Enclosure:
IE Bulletin Nc. 79-27 cc w/ encl:
Mr. D. W. Kane, Sargent & Lundy Central Files Reproduction Unit NRC 20b Local PDR NSIC TIC 1790 330
4 UNITED STATES SSINS No.:
6820 NUCLEAR REGULATORY COMMISSION Accession No.-
0FFICE OF INSPECTION AND ENFORCEMENT 7910250499 WASHINGTON, D.C.
20555 November 30, 1979 IE Bulletin No. 79-27 LOSS OF NON-CLASS-1-E INSTRUMENTATION AND CONTROL POWER SYSTEM BUS DURING OPERATION Description of Circumstances:
On November 10, 1979, an event occurred at the Oconee Power Station, Unit 3, that resultei in loss of power to a non-class-1-E 120 Vac single phase power panel that supplied power to the Integrated Control System (ICS) and the Non-Nuclear Instrumentation (NNI) System. This loss of power resulted in control system malfunctions and significant loss of information to the control room operator.
Specifically, at 3:16 p.m., wi'th Unit 3 at 100 percent power, the main condensate pumps tripped, apparently as a result of a technician performing maintenance on the hotwell level control system. This led to reduced feedwater flow to the steam generators, which resulted in a reactor trip due to high coolant system pressure and simultaneous turbine trip at 3:16:57 p.m.
At 3:17:15 p.m., the non-class-1-E inverter power supply feeding all power to the integrated control system (which provides proper coordination of the reactor, steam generator feedwater control, and turbine) and to one NNI channel tripped and failed to automatically transfer its loads from the DC power source to the regulated AC power source.
The inverter tripped due to blown fuses.
Loss of power to the NNI rendered control room indicators and recorders for the reactor coolant system (except for one wide-range RCS pressure recorder) and most of the secondary plant systems inoperable, causing loss of indication for systems used for decay heat removal and water addition to the reactor vessel and steam generators. Upon loss of power, all valves controlled by the ICS assumed their respective failure positions. The loss of power existed for approximately three minutes, until an operator could reach the equipment room and manually switch the inverter to the regulated AC source.
The above event was discussed in IE Information Notice No. 79-29, issued November 16, 1979.
NUREG 0600 " Investigation into the March 28, 1979 TMI Accident" also discusses THI LER 78-021-03L whereby the RCS depressurized and Safety Injection occured on loss of a vital bus due to inverter failure.
Actions to Be Taken by Licensees For all power reactor facilities with DUPLICATE DOCUMENT completion of construction (North Anna Sequoyah, and Zimmer):
Entire document pr eviously entered into system under:
L790 331 nNo 79/gggWP No. of pages: