ML19309H811

Forwards IE Info Notice 80-20, Loss of Decay Heat Removal Capability at Davis-Besse Unit 1 While in Refueling Mode. No Response Required

ML19309H811
Person / Time
Site:	Point Beach
Issue date:	05/08/1980
From:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:	Burstein S WISCONSIN ELECTRIC POWER CO.
References
TAC-42114, TAC-42115, NUDOCS 8005190747
Download: ML19309H811 (1)

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8005190'"7p7 iliG0 AT0!!Y10METF1C0pY CENTRAL FILES MAY R mRO Docket No. 50-266 Docket No. 50-301 Wisconsin Electric Power Company ATTN:

Mr. Sol Burstein Executive Vice President Power Plants 231 West Michigan Milwaukee, WI 53201 Gentlemen:

The enclosed Information Notice provides early notification of an event that may have safety significance. Accordingly, you should review the Information Notice for possible applicability to your facility.

No specific action or response is requested at this time; however, con-tingent upon the results of further staff evaluation, a Bulletin or Circular recommending or requesting specific licensee actions may be issued.

If you have questions regarding this matter, please contact me.

Sincerely, James G. Keppler Director

Enclosure:

IE Information Notice No. 80-20 cc w/ enc 1:

Mr. G. A. Reed, Plant Manager Central Files Director, NRR/DPM Director, NRR/ DOR C. M. Trammell, ORB /NRR PDR Local PDR NSIC TIC Sandra A. Bast, Lakeshore Citizens for Safe Energy Mr. John J. Duffy, Chief Boiler Inspector, Department of Industry, Labor and Human Relations I

RIII RIII Hei an/jp K pler 5/8/80

SSINS No.:

6370 UNITED STATES Accession No.:

NUCLEAR REGULATORY COMMISSION 8002280671 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C. 20555 l

May 8, 1980 IE Information Notice 80-20 LOSS OF DECAY HEAT REMOVAL CAPABILITY AT DAVIS-BESSE UNIT 1 WHILE IN A REFUELING MODE Description of Circumstances:

1 On April 19, 1980, decay heat removal capability was lost at Davis-Besse Unit 1 for approximately two and one-half hours.

At the time of the event, the unit was in a refueling mode (e.g., RCS temperature was 90F; decay heat was being removed by Decay Heat Loop No. 2; the vessel head was detensioned with bolts in place; the reactor coolant level was slightly below the vessel head flanges; and the manway covers on top of the once through steam generators were removed).

(See Enclosure A, Status of Davis-Besse 1 Prior to Loss of Power to Busses E-2 and F-2 for additional details regarding this event.)

Since the plant was in a refueling mode, many systems or components were out of service for maintenance or testing purposes.

In addition, other systems and components were deactivated to preclude their inadvertent actuation while in a refueling mode.

Systems and components that were not in service or deactivated included:

Containment Spray System; High Pressure Injection System; Source Range Channel 2; Decay Heat Loop No. 1:

Station Battery IP and 1N; Emergency Diesel-Geierator No. 1; 4.16 KV Essential Switchgear Bus C1; and 13.8 KV Switchgear Bus A (this bus was energized but not aligned).

In brief, the event was due to the tripping of a non-safeguards feeder breaker in 13.8 KV Switchgear Bus B. Because of the extensive maintenance and testing i

activities being conducted at the time, Channels 1 and 3 of the Reactor Protec-tion System (RPS) and Safety Features Actuation System (SFAS) were being ener-gized from only one source, the source emanating from the tripped breaker.

Since the SFAS logic used at Davis-Besse is a two-out of-four input scheme in which the loss (or actuation) of any two input signals results in the actuation of all four output channels (i.e., Channels 1 and and loss of power to Channels 1 and 3 Channels 2 and 4.

The actuation o Decay Heat Loop No. 2, the operati DUPMCATE DOCUMENT Since the initiating event was a lo were actuated (i.e., Level 1 - High Entire document reviously tion; Level 3 - Low Pressure Inject entered into sy ANO bb 7

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