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)

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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 normal6.9 kV

power supply breaker caused a voltage and frequency perturbation on the

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- the

related A3 bus. Emergency Diesel Generator A started and loaded to power

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

The plant cooldown to Mode 5 was delayed approximately

valves were repaired.

Discussion

an augmented

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

causes, conditions, and

inspection team (AIT) inspection to determine the of this AIT inspection are

circumstances relevant to this event. The resultsdated July 7, 1995. The AIT

documented in NRC Inspection Report 50-382/92-15, fast bus transfer design, identified three primary issues: fire protection, issues are discussed in

and shutdown cooling valve inoperabilit). These three

greater detail in the following sections.

Fire Protection

have included a fire

Several recent events at U.S. nuclear power plants Waterford 3 highlights the

concurrent with a plant transient. The fire at

response to initial

importance of (1) training for timely and effective are not assigned

indications of a plant fire, (2) ensuring personnel

potentially conflicting duties, and (3) plant staffing.

noticed heavy smoke in

An auxiliary operator (a trained fire brigade member) room. The auxiliary

the turbine generator building and notified the control and responded that he did

operator was asked if there was a fire in the room

The CRS did not

not see flames because of the presence of heavy smoke. report of heavy smoke.

declare a fire until 29 minutes after receiving the

SS to assume the responsibilities of

Activating the fire brigade required the was directing plant

the CRS (the designated fire brigade leader), who event, operators stated that

personnel responding to the event. Following the

adversely affect their

the loss of the CRS from the control room did not fire scenario, which

ability to respond to this event and noted that a used during

requires that the CRS leave the control room, is routinely

requalification training.

to extinguish the fire

Before the local offsite fire department was allowed the fire using portable

with water, the fire brigade attempted to extinguish extinguishers. The use of

carbon dioxide (CO ), halon, and dry chemical fire the fire. When the

portable extinguishers was not effective in extinguishing

water to extinguish the

fire department arrived, it recommended the use of of water until about

fire. The fire brigade leader did not allow the use by the offsite fire

20 minutes later. The fire was finally extinguished of water is consistent

department within 4 minutes of using water. The use that the operators

with documented NRC staff positions. The AIT determined based on previous training

were reluctant to apply water to an electrical fire on electrical fires.

that had emphasized the use of water as a last resort

in the control room, the

Although the appropriate fire alarms had activated of (1) other auditory

control room crew was not aware of the alarms because fire alarm signal on a

alarms caused by the event and (2) the lack of a visual did not refer to the

front panel of the control room. Control room operators seeing heavy smoke. In

fire alarm panel when the auxiliary operator reported did not directly affect

this instance, the ineffectiveness of the fire alarms

KJ-J IN 95-33 August 23, 1995 the control

the response to the fire because an auxiliary operator alerted fire alarms that

room to heavy smoke in the turbine building. Nevertheless, redundant visual

are inaudible under actual operational conditions and lack to, plant fires.

signals can inhibit prompt identification of, and responsealarm panel upon any

Also, it is important for operators to refer to the fire the fire is not

verbal report of a potential fire, in order to ensure that requirements and

wider spread than visually reported. NRC fire protection of fire alarm

guidelines specify that fire drills include an assessment

effectiveness.

licensees that

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

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

licensed personnel.

(10 CFR 50.54 (m)) addresses minimum staffing levels for all actions

It does not address availability of personnel for performing

required during an

specified in the licensee's administrative procedures provide flexibility in

event. NRC fire protection requirements and guidelines leader may possess

assigning personnel to a fire brigade (e.g., the brigade

plant safety- either an operator's license or an equivalent knowledge ofbe assigned duties

related systems). The potential exists for personnel to

demands.

that, during certain events, may present concurrent and conflictingof those

the response

Such conditions could significantly delay or degrade

individuals.

Fast Bus Transfer Design

transfer of

The Waterford 3 fast bus transfer design consists of an automatic

the normal power

safety and nonsafety-related station auxiliary loads from

unit auxiliary transformer) to the

supply (from the main generator through the through the

alternate power supply (from the offsite transmission network

Magne-Blast

startup transformer). All supply breakers are General Electric, are designed to

type. During a fast bus transfer, the normal supply breakers

breakers are designed to close in

open in five cycles and the alternate supply buses. To

seven cycles, resulting in a two-cycle deadband on the respective

supply breakers, some other fast bus

prevent simultaneous closing of both the The Waterford 3 transfer designs include mechanical or electrical interlocks.

design does not include interlocks.

the A2 bus normal

During this event, when the fast bus transfer was initiated, supply breaker

supply breaker did not open in five cycles but the alternate

was connected to both

closed within seven cycles. As a result, (1) the A2 bus (2) both supply

the offsite transmission network and the main generator, (3) while the A2 bus

breakers to the A2 bus received overcurrent trip signals, transmission network, alternate supply breaker adequately isolated the offsite generator, (4) the

the A2 bus normal supply breaker did not isolate the main fire, and (5) the

A2 switchgear cubicle for the normal supply breaker caught

cable bus for the normal supply breaker also caught fire.

Shutdown Cooling Valves

isolation valves

During the plant cooldown to Mode 5, the shutdown cooling low-temperature

failed to operate properly when operators attempted to align

for placing shutdown

overpressure protection relief valves in preparation

IN 95-33 August 23, 1995 suction header isolation

cooling into service. The Loop 1 shutdown cooling closed after

valve (SI-405B) failed to fully open and automatically suction header

approximately 15 minutes. The Loop 2 shutdown cooling

several hours later, the

isolation valve (SI-405A) fully opened; however, continuously instead of

valve hydraulic pump was observed to be running portions of the

cycling as designed. These two valves isolate low-pressure and must be opened in

shutdown cooling system from the reactor coolant system5). Troubleshooting

order to complete plant cooldown below 200 OF (Mode oil levels in the

revealed that both valves contained inadequate hydraulic

was inadequate

valve actuator reservoirs. The cause of the low levels valves.

instructions for a periodic maintenance task for the

Related Generic Communications

Station," dated March 24, BUL 75-04, wCable Fire at Browns Ferry Nuclear Power

1975.

Station," dated April 3, BUL 75-04A, "Cable Fire at Browns Ferry Nuclear Power

1975 Station," dated

BUL 75-04B, "Cable Fire at Browns Ferry Nuclear Power

November 3, 1975.

of an

IN 85-80, "Timely Declaration of an Emergency Class, Implementation

15, 1985.

October

Emergency Plan, and Emergency Notifications," dated

dated September 19, 1991.

IN 91-57, "Operational Experience on Bus Transfers,"

dated November 26, 1991.

IN 91-77, "Shift Staffing at Nuclear Power Plants,"

Transient," dated

IN 93-44, "Operational Challenges During a Dual-Unit

June 15, 1993.

Shift," dated

IN 93-81, "Implementation of Engineering Expertise on

October 12, 1993.

response. If you have

This information notice requires no specific or writtenplease contact the

any questions about the information in this notice, Office of Nuclear Reactor

technical contact listed below or the appropriate

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

Potential for Loss of 08/11/95 All holders of OLs or CPs

95-10, for nuclear power reactors.

Supp. 2 Automatic Engineered

Safety Features Actuation

Thermo-Lag 330-1 Flame 08/10/95 All holders of OLs or CPs

95-32 Spread Test Results for nuclear power reactors.

Motor-Operated Valve 08/09/95 All holders of OLs or CPs

95-31 for nuclear power reactors.

Failure Caused by Stem

Protector Pipe Inter- ference

Susceptibility of Low- 08/03/95 All holders of OLs or CPs

95-30 for nuclear power reactors.

Pressure Coolant Injection

and Core Spray Injection

Valves to Pressure Locking

Overspeed of Turbine- 06/16/95 All holders of OLs or CPs

94-66, for nuclear power reactors.

Supp. 1 Driven Pumps Caused by

Binding in Stems of

Governor Valves

Oversight of Design and 06/07/95 All holders of OLs or CPs

95-29 for nuclear power reactors.

Fabrication Activities

for Metal Components Used

in Spent Fuel Dry Storage

Systems

Emplacement of Support 06/05/95 All holders of OLs or CPs

95-28 for nuclear power reactors.

Pads for Spent Fuel Dry

Storage Installations at

Reactor Sites

NRC Review of Nuclear 05/31/95 All holders of OLs or CPs

95-27 for nuclear power plants.

Energy Institute,

"Thermo-Lag 330-1 Combustibility Evaluation

Methodology Plant Screening

Guide"

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 'N" = No copy

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

---

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OFFICE PECB:DRPM ADM:PUB C/PECB:DRPM C/SPLB:DSSA C/EELB:DE I

NAME EBenner* Tech Editor* EGoodwin* CMcCracken* JCalvo*

DATE 07/21/95 7/24/95 8/2/95 7/25/95 7/27/95 OFFICE C/HHFB:DRCH RI D/DSSA I1> PECB:DRPM J A C/0&.DRPM l

NAME CThomas* RHuey* Wb! Riiessel M1AC~affee AGHolahan

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 Eric J. Benner, NRR

(510) 975-0342 (301) 415-1171 Amarjit Singh, NRR David R. Desaulniers, NRR

(301) 415-1237 (301) 415-1043 Sikhindra K. Mitra, NRR Thomas A. Bergman, NRR

(301) 415-2783 (301) 415-1021 Attachments: A. *. 4tD

1. List of Recently Issued NRC Information Notices If-MSW07teV1 DOCUMENT NAME: G:\IN\WATERFOR.IN

To rocalva a ca at

ofis docunm Indicatae I Oembox: ' - COY wilthout atachment/enrcbsum T a Cov with Irtthnt/encosure W - No copy _F

OFFICE PECB:DRPM ADM:PUB SC/PECB:DRPM I C/SWA C/EELB:DE

NAME EBenner _ Tech Editors EGoodwin IMcC__;_____ 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