ML18037A213

Forwards IE Bulletin 79-27, Loss of Non-Class IE Instrumentation & Control Power Sys Bus During Operation. Written Response Required

ML18037A213
Person / Time
Site:	Nine Mile Point
Issue date:	11/30/1979
From:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:	Schneider R NIAGARA MOHAWK POWER CORP.
References
CON-IIT07-450-91, CON-IIT7-450-91 NUREG-1455, NUDOCS 7912190044
Download: ML18037A213 (10)

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NUCLEAR REGULATORY COMMISSION REGION I 631 PARK AVENUE KING OF PRUSSIA, PENNSYLVANIA19406 November 30, 1979 Docket No. 50-220 Niagara Mohawk Power Corporation ATTN:

Nr.

R.

R. Schneider Vice President Electric Operations 300 Erie Boulevard West

Syracuse, New York 13202 Gentlemen:

The enclosed IE Bulletin No. 79-27 is forwarded for action.

A written response is required.

If you desire additional information regarding this

matter, please contact this office.

Sincerely, Boyce H. Grier Director

Enclosures:

l.

IE Bulletin No. 79-27 2.

List of Recently Issued IE Bulletins CONTACT:

D. L. Caphton (215-337-5308) cc w/encl:

T. E.

Lempges, General Superintendent, Nuclear Generation T. J. Perkins, Station Superintendent R. Abbott, Operations Supervisor E.

B. Thomas, Jr.,

Esquire

I t

ENCLOSURE 1 UNITED. STATES SSINS No.:

6820 NUCLEAR REGULATORY COMMISSION Accession No.:

'OFFICE OF INSPECTION AND ENFORCEMENT 7910250499 WASHINGTON, D.C.

20555 IE Bulletin No. 79-27 Date:

November 30, 1979 Page 1 of 3 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 resulted 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., with 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 ren'dered 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 TMI LER 78-021-03L whereby the RCS depressurized and Safety Injection occured on loss of-a vital bus due to inverter failure.

0 Enclosure 1

Actions to Be Taken bv Licensees IE Bulletin No. 79-27 Date:

November 30,'979 Page 2 of 3 For all power reactor facilities with an operating license and for those nearing completion of construction (North Anna 2, Diablo Canyon,

McGuire, Salem 2, Sequoyah, and Zimmer):

1.

Review the class-1-E and non-class 1-E buses supplying power to safety and non-safety related instrumentation and control systems which could affect the ability to achieve a cold shutdown condition using existing procedures or procedures developed under item 2 below.

For each bus:

a) identify and review the alarm and/or indication provided in the control room to alert the operator to the loss of power to the bus.

b) identify the instrument and control system loads connected to the bus and evaluate the effects of loss of power to these loads including the ability to achieve a cold shutdown condition.

c) describe any proposed design modifications resulting from these reviews and evaluations, and your proposed schedule for implementing those modifications.

2; Prepare emergency procedures or review existing ones that will be used by control room operators, including procedures required to achieve a cold shutdown condition, upon loss of power to each class 1-E and non-class 1-E bus supplying power to safety and non-safety related instrument and control systems.

The emergency procedures should include:

a) the diagnostics/alarms/indicators/symptom resulting from the review and evaluation conducted per item 1 above.

b) the use of alternate indication and/or control circuits which may be powered from other non-class 1-E or class 1-E instrumentation and control buses.

c) methods for restoring power to the bus.

Describe any proposed design modification or administrative controls to be implemented resulting from these procedures, and your proposed schedule for implementing the changes.

3.

Re-review IE Circular No, 79-02, Failure of 120 Volt Vital AC Power Suppli'es, dated January ll, 1979, to include both class 1-E and non-class 1-E safety related power supply inverters.

Based on a review of operating experience and your re-review of IE Circular No. 79-02, describe any proposed design modifications or administrative controls to be implemented as a result of the re-review,

0

Enclosure 1

IE Bulletin No. 79-27 Date:

November 30, 1979 Page 3 of 3 4.

Within 90 days of the date of this Bulletin, complete the review and evaluation required by this Bulletin and provide a written response describing your reviews and actions. taken in response to each item.

Reports should be submitted to the Director of the appropriate NRC Regional Office and a copy should be forwarded to the NRC Office of Inspection and Enforcement, Division of Reactor Operations Inspection, Washington, D.C.

20555.

If you desire additional information regarding this matter, please contact the IE Regional Office.

Approved by GAO B180225 (R0072); clearance expires 7/31/80.

Approval was gi'ven under a blanket clearance specifically for identified generic problems.

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Bulletin No.

Subject ENCLOSURE 2 RECENTLY ISSUED IE BULLETINS Date Issued IE Bulletin No. 79-27 Date:

November 30, 1979 Page 1 of 1 Issued To 79-22 79-14 (Supplement No. 2) 79-23 79-24 Possible Leakage of Tubes of Tritium Gas Used in Timepieces for Luminosity Same as Title 79-14 Potential Failure of Emergency Diesel Gen-erator Field Exciter Transformer frozen Lines 9/5/79 9/7/79 9/12/79 9/27/79 Each Licensee who Receive Tubes of Tritium Gas in Time-pieces for Luminosity Same as 79-14 All Power Reactor Facilities with an OL or CP All Power Reactor Facilities which have either OLs or CPs and are in late stage of con-struction 79" 13 (Rev. 2) 79-17 (Rev.

1) 79-25 79-02 (Rev. 2)

Cracking in Feedwater 10/17/79 System Piping Pipe Cracks in Stagnant 10/29/79 Borated Water Systems at PWR Plants Failures of Westinghouse ll/2/79 BFD Relays in Safety-Related Systems Pipe Base Plate Designs ll/8/79 Using Concrete Expansion Bolts All PWRs with an OL and Designated Ap-plicants (for Action),,

All Other Power Reactor Facilities with an OL or CP (for Information)

All PWRs with an OL (for Action).

All other Power Reactor Facilities with an OL or CP (for Information)

All Power Reactor Facilities with an OL or CP (for Action)

All Power Reactor Facilities with an OL or CP 79-26 Boron Loss From BWR Control Blades 11/20/79 All BWR Power Reactor Facilities with an OL

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