Information Notice 1995-33, Switchgear Fire and Partial Loss of Offsite Power at Waterford Generating Station, Unit 3

Switchgear Fire and Partial Loss of Offsite Power at Waterford Generating Station, Unit 3

ML031060305
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	08/23/1995
From:	Crutchfield D Office of Nuclear Reactor Regulation
To:
References
IN-95-033, NUDOCS 9508180092
Download: ML031060305 (7)

K>UNITED STATES NUCLEAR REGULATORY

COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 August 23, 1995 NRC INFORMATION

NOTICE 95-33: SWITCHGEAR

FIRE AND PARTIAL LOSS OF OFFSITE POWER AT WATERFORD

GENERATING

STATION, UNIT 3

Addressees

All holders of operating

licenses or construction

permits for nuclear power reactors.PurDose The U.S. Nuclear Regulatory

Commission (NRC) is issuing this information

notice (IN) to alert addressees

to a switchgear

fire and subsequent

partial loss of offsite power at Waterford

Generating

Station, Unit 3. It is expected that recipients

will review the information

for applicability

to their facilities

and consider actions, as appropriate, to avoid similar problems.However, suggestions

contained

in this information

notice are not NRC requirements;

therefore, no specific action or written response is required.Description

of Circumstances

On June 10, 1995, Waterford

3 was operating

at 100 percent power with an operations

staff consisting

of a shift supervisor (SS), a control room supervisor (CRS), and two reactor operators.

At 8:58 a.m. a generator

trip occurred in response to failure of a lightning

arrester on a remote offsite substation

transformer.

The generator

trip resulted in a fast transfer activation.

All 6.9 kV and 4.16 kV buses transferred

as designed except the 4.16 kV A2 bus. A fire and electrical

fault on the 4.16 kV A2 bus normal power supply breaker caused a voltage and frequency

perturbation

on the 6.9 kV Al bus, which caused an underspeed

condition

on rector coolant pumps IA and 2A. This circumstance

resulted in a reactor trip and a loss of offsite power to the 4.16 kV nonsafety-related

A2 bus and the associated

4.16 kV safety-related A3 bus. Emergency

Diesel Generator

A started and loaded to power the A3 bus. At 9:06 a.m., an auxiliary

operator informed the control room of heavy smoke within the turbine generator

building.

At that time, the SS did not activate the plant fire alarm or dispatch the fire brigade, but directed two auxiliary

operators

to don protective

gear and investigate

whether a fire existed. At 9:35 a.m., the operators

reported seeing flames above the A2 switchgear

and the SS activated

the fire brigade. Operators

requested assistance

from the local offsite fire department

and declared an Unusual Event in accordance

with emergency

response procedures.

The fire brigade was unable to suppress the fire using portable fire extinguishers.

The offsite fire department

arrived on the scene at 9:58 a.m. and extinguished

the fire with water at 10:22 a.m., after the A2 bus was deenergized.

During the cooldown transition

from Mode 4 to Mode 5, operators

discovered

that the isolation

valves for both trains of shutdown cooling did not operate properly.9508180092 PDR It 9S-.o33 9,s5T3 tJ <J IN 95-33 August 23, 1995 The plant cooldown to Mode 5 was delayed approximately

38 hours4.398148e-4 days <br />0.0106 hours <br />6.283069e-5 weeks <br />1.4459e-5 months <br /> while these valves were repaired.Discussion

During the period of June 13-16, 1995, the NRC conducted

an augmented inspection

team (AIT) inspection

to determine

the causes, conditions, and circumstances

relevant to this event. The results of this AIT inspection

are documented

in NRC Inspection

Report 50-382/92-15, dated July 7, 1995. The AIT identified

three primary issues: fire protection, fast bus transfer design, and shutdown cooling valve inoperabilit).

These three issues are discussed

in greater detail in the following

sections.Fire Protection

Several recent events at U.S. nuclear power plants have included a fire concurrent

with a plant transient.

The fire at Waterford

3 highlights

the importance

of (1) training for timely and effective

response to initial indications

of a plant fire, (2) ensuring personnel

are not assigned potentially

conflicting

duties, and (3) plant staffing.An auxiliary

operator (a trained fire brigade member) noticed heavy smoke in the turbine generator

building and notified the control room. The auxiliary operator was asked if there was a fire in the room and responded

that he did not see flames because of the presence of heavy smoke. The CRS did not declare a fire until 29 minutes after receiving

the report of heavy smoke.Activating

the fire brigade required the SS to assume the responsibilities

of the CRS (the designated

fire brigade leader), who was directing

plant personnel

responding

to the event. Following

the event, operators

stated that the loss of the CRS from the control room did not adversely

affect their ability to respond to this event and noted that a fire scenario, which requires that the CRS leave the control room, is routinely

used during requalification

training.Before the local offsite fire department

was allowed to extinguish

the fire with water, the fire brigade attempted

to extinguish

the fire using portable carbon dioxide (CO ), halon, and dry chemical fire extinguishers.

The use of portable extinguishers

was not effective

in extinguishing

the fire. When the fire department

arrived, it recommended

the use of water to extinguish

the fire. The fire brigade leader did not allow the use of water until about 20 minutes later. The fire was finally extinguished

by the offsite fire department

within 4 minutes of using water. The use of water is consistent

with documented

NRC staff positions.

The AIT determined

that the operators were reluctant

to apply water to an electrical

fire based on previous training that had emphasized

the use of water as a last resort on electrical

fires.Although the appropriate

fire alarms had activated

in the control room, the control room crew was not aware of the alarms because of (1) other auditory alarms caused by the event and (2) the lack of a visual fire alarm signal on a front panel of the control room. Control room operators

did not refer to the fire alarm panel when the auxiliary

operator reported seeing heavy smoke. In this instance, the ineffectiveness

of the fire alarms did not directly affect

KJ-J IN 95-33 August 23, 1995 the response to the fire because an auxiliary

operator alerted the control room to heavy smoke in the turbine building.

Nevertheless, fire alarms that are inaudible

under actual operational

conditions

and lack redundant

visual signals can inhibit prompt identification

of, and response to, plant fires.Also, it is important

for operators

to refer to the fire alarm panel upon any verbal report of a potential

fire, in order to ensure that the fire is not wider spread than visually reported.

NRC fire protection

requirements

and guidelines

specify that fire drills include an assessment

of fire alarm effectiveness.

IN 91-77 'shift staffing at Nuclear Power Plants', reminded licensees

that Section 50.54(m) of Title 10 of the Code of Federal Regulations

(10 CFR 50.54 (m)) addresses

minimum staffing levels for licensed personnel.

It does not address availability

of personnel

for performing

all actions specified

in the licensee's

administrative

procedures

required during an event. NRC fire protection

requirements

and guidelines

provide flexibility

in assigning

personnel

to a fire brigade (e.g., the brigade leader may possess either an operator's

license or an equivalent

knowledge

of plant safety-related systems).

The potential

exists for personnel

to be assigned duties that, during certain events, may present concurrent

and conflicting

demands.Such conditions

could significantly

delay or degrade the response of those individuals.

Fast Bus Transfer Design The Waterford

3 fast bus transfer design consists of an automatic

transfer of safety and nonsafety-related

station auxiliary

loads from the normal power supply (from the main generator

through the unit auxiliary

transformer)

to the alternate

power supply (from the offsite transmission

network through the startup transformer).

All supply breakers are General Electric, Magne-Blast

type. During a fast bus transfer, the normal supply breakers are designed to open in five cycles and the alternate

supply breakers are designed to close in seven cycles, resulting

in a two-cycle

deadband on the respective

buses. To prevent simultaneous

closing of both the supply breakers, some other fast bus transfer designs include mechanical

or electrical

interlocks.

The Waterford

3 design does not include interlocks.

During this event, when the fast bus transfer was initiated, the A2 bus normal supply breaker did not open in five cycles but the alternate

supply breaker closed within seven cycles. As a result, (1) the A2 bus was connected

to both the offsite transmission

network and the main generator, (2) both supply breakers to the A2 bus received overcurrent

trip signals, (3) while the A2 bus alternate

supply breaker adequately

isolated the offsite transmission

network, the A2 bus normal supply breaker did not isolate the main generator, (4) the A2 switchgear

cubicle for the normal supply breaker caught fire, and (5) the cable bus for the normal supply breaker also caught fire.Shutdown Cooling Valves During the plant cooldown to Mode 5, the shutdown cooling isolation

valves failed to operate properly when operators

attempted

to align low-temperature

overpressure

protection

relief valves in preparation

for placing shutdown

IN 95-33 August 23, 1995 cooling into service. The Loop 1 shutdown cooling suction header isolation valve (SI-405B)

failed to fully open and automatically

closed after approximately

15 minutes. The Loop 2 shutdown cooling suction header isolation

valve (SI-405A)

fully opened; however, several hours later, the valve hydraulic

pump was observed to be running continuously

instead of cycling as designed.

These two valves isolate low-pressure

portions of the shutdown cooling system from the reactor coolant system and must be opened in order to complete plant cooldown below 200 OF (Mode 5). Troubleshooting

revealed that both valves contained

inadequate

hydraulic

oil levels in the valve actuator reservoirs.

The cause of the low levels was inadequate

instructions

for a periodic maintenance

task for the valves.Related Generic Communications

BUL 75-04, wCable Fire at Browns Ferry Nuclear Power Station," dated March 24, 1975.BUL 75-04A, "Cable Fire at Browns Ferry Nuclear Power Station," dated April 3, 1975 BUL 75-04B, "Cable Fire at Browns Ferry Nuclear Power Station," dated November 3, 1975.IN 85-80, "Timely Declaration

of an Emergency

Class, Implementation

of an Emergency

Plan, and Emergency

Notifications," dated October 15, 1985.IN 91-57, "Operational

Experience

on Bus Transfers," dated September

19, 1991.IN 91-77, "Shift Staffing at Nuclear Power Plants," dated November 26, 1991.IN 93-44, "Operational

Challenges

During a Dual-Unit

Transient," dated June 15, 1993.IN 93-81, "Implementation

of Engineering

Expertise

on Shift," dated October 12, 1993.This information

notice requires no specific or written response.

If you have any questions

about the information

in this notice, please contact the technical

contact listed below or the appropriate

Office of Nuclear Reactor Regulation (NRR) project manager.DennvsWM.

CrutchfieldP

Director Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical

contact: Eric J. Benner, NRR (301) 415-1171 Attachment:

List of Recently Issued NRC Information

Notices@-gL~5~ 44yAGgQ

K>Kreachment

IN 95-33 August 23, 1995 LIST OF RECENTLY ISSUED NRC INFORMATION

NOTICES Information

Date of Notice No. Subject Issuance Issued to 95-10, Supp. 2 95-32 95-31 95-30 94-66, Supp. 1 95-29 95-28 95-27 Potential

for Loss of Automatic

Engineered

Safety Features Actuation Thermo-Lag

330-1 Flame Spread Test Results Motor-Operated

Valve Failure Caused by Stem Protector

Pipe Inter-ference Susceptibility

of Low-Pressure Coolant Injection and Core Spray Injection Valves to Pressure Locking Overspeed

of Turbine-Driven Pumps Caused by Binding in Stems of Governor Valves Oversight

of Design and Fabrication

Activities

for Metal Components

Used in Spent Fuel Dry Storage Systems Emplacement

of Support Pads for Spent Fuel Dry Storage Installations

at Reactor Sites NRC Review of Nuclear Energy Institute,"Thermo-Lag

330-1 Combustibility

Evaluation

Methodology

Plant Screening Guide" 08/11/95 08/10/95 08/09/95 08/03/95 06/16/95 06/07/95 06/05/95 05/31/95 All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power plants.OL -Operating

License CP = Construction

Permit

-11 IN 95-XX August xx, 1995 order to complete plant cooldown below 200 *F (Mode 5). Troubleshooting

revealed that both valves contained

inadequate

hydraulic

oil levels in the valve actuator reservoirs.

The cause of the low levels was inadequate

instructions

for a periodic maintenance

task for the valves.Related Generic Communications

BUL 75-04, "Cable Fire at Browns Ferry Nuclear Power Station," dated March 24, 1975.BUL 75-04A, "Cable Fire at Browns Ferry Nuclear Power Station," dated April 3, 1975 BUL 75-04B, "Cable Fire at Browns Ferry Nuclear Power Station," dated November 3, 1975.IN 85-80, "Timely Declaration

of an Emergency

Class, Implementation

of an Emergency

Plan, and Emergency

Notifications," dated October 15, 1985.IN 91-57, "Operational

Experience

on Bus Transfers," dated September

19, 1991.IN 91-77, -Shift Staffing at Nuclear Power Plants," dated November 26, 1991.IN 93-44, "Operational

Challenges

During a Dual-Unit

Transient," dated June 15, 1993.IN 93-81, "Implementation

of Engineering

Expertise

on Shift," dated October 12, 1993.This information

notice requires no specific or written response.

If you have any questions

about the information

in this notice, please contact one of the technical

contacts listed below or the appropriate

Office of Nuclear Reactor Regulation (NRR) project manager.Dennis M. Crutchfield, Director Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical

contacts:

Eric J. Benner, NRR (301) 415-1171 Attachments:

1. List of Recently Issued NRC Information

Notices DOCUMENT NAME: G:\IN\WATERFOR.INR

• See Previous Concurrence

To receive a copy of this document, Indicate In the box: 'C' = Copy without attachment/enclosure

'E' = Copy with attachment/enclosure

'N" = No copy---------I OFFICE PECB:DRPM

ADM:PUB C/PECB:DRPM

C/SPLB:DSSA

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I NAME EBenner* Tech Editor* EGoodwin*

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DATE 8/1/95 8/2/95 /95 /95 95 jOFFICE D/DRPM NAME DCrutchfield

DATE / /95 OFFICIAL RECORD COPY

IN 95-XX'__ _ July xx, 1995 Related Generic Communications

BUL 75-04, "Cable Fire at Browns Ferry Nuclear Power Station," dated March 24, 1995 BUL 75-04B, "Cable Fire at Browns Ferry Nuclear Power Station," dated November 3, 1995 BUL 75-04A, "Cable Fire at Browns Ferry Nuclear Power Station," dated April 3, 1995 IN 85-80, "Timely Declaration

of an Emergency

Class, Implementation

of an Emergency

Plan, and Emergency

Notifications, " dated October 15, 1985 IN 91-57, "Operational

Experience

on Bus Transfers," dated September

19, 1991 IN 91-77, "Shift Staffing at Nuclear Power Plants," dated November 26, 1991 IN 93-44, "Operational

Challenges

During a Dual Unit Transient," dated June 15, 1993 IN 93-81, Implementation

of Engineering

Expertise

on Shift," dated October 12, 1993 This information

notice requires no specific or written response.

If you have any questions

about the information

in this notice, please contact one of the technical

contacts below or the appropriate

Office of Nuclear Reactor Regulation (NRR) project manager.Dennis M. Crutchfield, Director Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical

contacts: Forrest R. Huey, RIV (510) 975-0342 Eric J. Benner, NRR (301) 415-1171 Amarjit Singh, NRR (301) 415-1237 David (301)R. Desaulniers, NRR 415-1043 Sikhindra

K. Mitra, NRR (301) 415-2783 Thomas A. Bergman, NRR (301) 415-1021 Attachments:

A.1. List of Recently Issued NRC Information

Notices If- M DOCUMENT NAME: G:\IN\WATERFOR.IN

To rocalva a ca at ofis docunm Indicatae

I Oem box: ' -COY wilthout atachment/enrcbsum

T a Cov with Irtthnt/encosure

W -No copy*. 4tD SW07teV1_F OFFICE PECB:DRPM

ADM:PUB SC/PECB:DRPM

I C/SWA C/EELB:DE NAME EBenner _ Tech Editors EGoodwin I McC__;_____

JCavo /_T-DATE 07/21/95 '/-r//95 /I&2J95 'I / 3795 "A 12/27 /95 l"a'OFFICE /"ff:DRCgL

D/DRCH C/TQMB:DOTS

RIV PECB:DRPM NAME h [BBoger SBlack RHueyQ! A k~ RKiessel DATE I /95 / 95 /95 J 1/-> /95 I / /95 OFFICE PECB:DRPM

D/DRPM NAME AChaffee DCrutchfield

_DATE / /95 R D/95 O OFF ICIA L RECORD COPY