ML20040D294

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Forwards IE Info Notice 82-01, Auxiliary Feedwater Pump Lockout Resulting from Westinghouse W-2 Switch Circuit Mod, Providing Early Notification of Event That May Have Safety Significance.Review Requested
ML20040D294
Person / Time
Site: Wolf Creek, Cooper, Arkansas Nuclear, River Bend, Waterford, South Texas, Comanche Peak, Fort Calhoun, 05000000, Fort Saint Vrain
Issue date: 01/25/1982
From: Jay Collins
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
ARKANSAS POWER & LIGHT CO., GULF STATES UTILITIES CO., HOUSTON LIGHTING & POWER CO., KANSAS GAS & ELECTRIC CO., LOUISIANA POWER & LIGHT CO., NEBRASKA PUBLIC POWER DISTRICT, OMAHA PUBLIC POWER DISTRICT, PUBLIC SERVICE CO. OF COLORADO, TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
References
NUDOCS 8202010152
Download: ML20040D294 (2)
v • d • e


Text

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4IE INFORMATION NOTICE 82-01:

AUXILIARY FEEDWATER PUMP LOCK 0UT RESULTING FROM WESTINGHOUSE W-2 SWITCH CIRCUI' MODIFICATIONS Licensee Facility / Docket Number Arkansas Power and 1.19ht Conpany Arkansas Nuclear One, Unit 1 & 2 Little Rock, Arkansas 50-313; 50-368 Nebraska Public Power District Cooper Nuclear Station Columbus, Nebraska 50-298 Omaha Public Power District Fort Calhoun Station Omaha, Nebraska 50-285

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Public Service Company of Colorado Fort St. Vrain Generating Station Denver, Colorado 50-267 Gulf States Utilities River Bend Beaumont, Texas 50-458; 50-459 c

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Houston Lighting & Power Company South Texas Proje

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g Texas Utilities Generating Company Comanche Peak Steam Electric Station Dallas, Texas 50-445; 50-446 l

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REGION IV 8

611 RYAN PLAZA DRIVE. SUITE 1000 ARLINGTON, TEXAS 70011 January 25, 1982 Gentlemen:

The enclosed IE Information Notice provides early notification of an event that may have safety significance.

It is expected that recipients will review the IE Information Notice for possible applicability to their facilities.

If you have any questions regarding this matter, please contact this office.

Sincerely, John T. Collins Regional Administrator

Enclosures:

l 1.

IE Information Notice No. 82-01 2.

List of Recently Issued Information Notices

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SSINS No.:

6835 Accession No.:

8107230043 IN 82-01 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.

20555 January 22, 1982 IE INFORMATION NOTICE NO. 82-01:

AUXILIARY FEEDWATER PUMP LOCK 0UT RESULTING FROM WESTINGHOUSE W-2 SWITCH CIRCUIT MODIFICATION Description of Circumstances:

On September 14, 1981, Commonwealth Edison's Zion Unit 2 was conducting a normal plant cooldown to begin a refueling outage.

The reactor coolant system was operating at 350 psig and 250 F.

Both residual heat removal (RHR) systems were operating to remove decay heat and control reactor coolant system temperature.

Steam generator water levels dropped below the 10% low level auxiliary feedwater (AFW) pump auto-start setpoint, and the motor-driven AFW pumps activated as designed.

The operator placed the control switches in the pull-to-lock-out position to stop the AFW pumps.

Later, to control the rate of plant cooldown, the operator tried to increase the cooldown rate by feeding water to the steam generators.

The AFW pumps would not restart on command.

The power supply circuit breaker for one of the pumps was momentarily racked out to the disconnect position and then racked back in for service.

As a result of this procedure, the AFW pump restarted.

No further problems were encountered during the plant cooldown operation.

Investigation into the problem revealed that the licensee's modification to the Westinghouse W-2 control switch used with the AFW pumps differed from that recommended in IE Bulletin 80-20 (IEB).

IEB 80-20, entitled " Failures of Westinghouse Type W-2 Spring Return to Neutral Control Switches," recommended using only the existing green status light to provide early detection of an open circuit caused by a neutral position (auto-start) contact failure of the control switch.

However, in this application, the licensee's modification included both the red and green status lights.

This resulted in a sneak circuit path which prevented AFW pump restart under certain circumstances.

Following an auto-start of the AFW pump and the subsequent securing of that pump by placing the control switch in the pull-to-lock-out position, the licensee found that a live continuous circuit existed between the red light and the anti pump coil.

This sneak current path prevented deenergization of the anti pump coil (circuit reset) that is necessary for pump restart.

IN 82-01 January 22, 1982 Page 2 of 2 The licensee reports that, following the initial circuit modification, the sneak path was noted to cause the red indicating light to glow only dimly when

'the control switch was placed in the pull-to-lock-out or trip positions (see Figures 1 through 3 and Table 1).

However, the sneak path was not fully analyzed at that time, and no detailed function testing of the modified circuit was performed.

Note that when the red light is used to indicate " pump on," as in this application, the light should not go on when the control switch has been placed in either the pull-to-lock-out or trip positions.

Circuit modifications may have been made at various plants in response to information in IEB 80-20.

These modifications, where different from IEB 80-20 recommendations, may have caused sneak paths with various degrees of impact that may not have been detected by previous engineering analysis or post-installation testing.

This information notice is provided as an early notification of a potentially significant matter.

It is expected that recipients will review the information for applicability to their facilities.

No specific action or response is required at this time.

If you have any questions regarding this matter, please contact the Regional Administrator of the appropriate NRC Regional Office.

Attachment:

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i IE Information Notice No. 82-01 January 25, 1982 l

LISTING OF RECENTLY ISSUED l

IE INFORMATION NOTICES Information Subject Date Issued To Notice No.

Issued 81-32 Transfer and/or Disposal of 10/23/81 All medical licensees Spent Generators 81-33 Locking Devices Inadequately 11/9/81 All power reactor facilities Installed on Main Steam with an Operating License Isolation Valves (OL) or Construction Permit (CP) 81-34 Accidental Actuation of Prompt 11/16/81 All power reactor facilities Public Notification System with an Operating License (OL) or Construction Permit (CP) 81-35 Check Valve Failures 12/2/81 All power reactor facilities with an Operating License (0L) or Construction Permit (CP) 81-36 Replacement Diaphragms for 12/3/81 All power reactor facilities Robertshaw Valve (Model with an Operating License No. VC-210)

(0L) or Construction Permit (CP) 81-37 Unnecessary Radiation 12/15/81 All byproduct material Exposure to Public &

licensees Workers during Events Involving Thickness &

Level Measuring Devices 81-38 Potentially Significant 12/17/81 All power reactor fac,lities Equipment Failures with an Operating License Resulting from Contam-(0L) or Construction Permit ination of (CP)

Air-Operated Systems 81-39 EPA Crosscheck Program -

12/23/81 All power reactor facilities Low Level Radioiodine in with an Operating License Water Test Program (0L) or Construction Permit (CP), and Priority I material licensees Enclosure

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