Information Notice 1998-36, Inadequate or Poorly Controlled, Non-Safety-Related Maintenance Activities Unnecessarily Challenged Safety Systems

Inadequate or Poorly Controlled, Non-Safety-Related Maintenance Activities Unnecessarily Challenged Safety Systems

ML031040558
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:	09/18/1998
From:	Roe J Office of Nuclear Reactor Regulation
To:
References
IN-98-036, NUDOCS 9809210079
Download: ML031040558 (7)

~0- f 9 Acre UNITED STATES NUCLEAR REGULATORY

COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555-0001 September

18, 1998 NRC INFORMATION

NOTICE 98-36: INADEQUATE

OR POORLY CONTROLLED, NON-SAFETY-RELATED

MAINTENANCE

ACTIVITIES

UNNECESSARILY

CHALLENGED

SAFETY SYSTEMS Addressee All holders of operating

licenses for nuclear power reactors.purpose The U.S. Nuclear Regulatory

Commission (NRC) is issuing this information

notice (IN) to alert addressees

to several recent events in which inadequate

or poorly controlled, non-safety- related maintenance

activities

resulted in unnecessary

challenges

to safety systems. It is expected that recipients

will review the information

for applicability

to their facilities

and consider action, 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

BRAIDWOOD

UNIT 2 On January 18, 1996, with Braidwood

Unit 2 operating

at full power, .offsite power was lost.Inadequately

secured roofing repair materials

located on the roof of the adjacent service building were blown off the roof during a rain storm, causing a phase-to-ground

arc on one of two station auxiliary

transformers (SATs). As designed, the second SAT tripped when the first SAT failed. Both emergency

diesel generators (EDGs) automatically

started and all safe-shutdown loads automatically

sequenced

on to the engineered

safety feature (ESF) buses. All automatic

bus transfers

occurred as designed, maintaining

power to non-ESF buses from the unit auxiliary

transformers (UATs). The reactor remained stable at full power throughout

the event. To restore offsite power to Unit 2, the licensee cross-tied

both Unit 2 ESF buses to the respective

ESF buses of Unit 1, which also remained at full power throughout

the event.Inspection

of the faulted SAT revealed damage to (1) the Phase B and C bushings and (2) a gas detector relay on top of the transformer

where heavy arcing occurred.

The licensee determined

that the Initiating

event was a Phase C arc-to-ground, followed by a Phase B to vNOrT g NO -98T- goz 98 0e 8<9809 td n

f IN 98-36 September

18, 1998 Phase C arc. A 345-kilovolt

switchyard

breaker, Which connected

the SAT to the switchyard

ring bus, was also damaged. Approximately

one square foot of the Phase B bushing was blown out.BYRON UNIT I On May 23, 1996, with the Unit 1 reactor shut down In excess of a month for a refueling

outage, offsite power was lost when one of the two Unit I SATs Isolated because of a Phase A to Phase B current differential

relay operation.

The second SAT tripped as designed when the first SAT failed. Both EDGs automatically

started and all safe-shutdown

loads automatically

sequenced

on to the ESF buses. Because the reactor was shut down, power to non-ESF buses was lost and two service water pumps and a station air compressor

common to both Byron units tripped. Without the service water pumps, Unit 2, which was operating

at full power, had no cooling water to many loads, including

the main generator

auxiliaries, station air compressors, condensate

pumps, and condensate

booster pumps. Subsequently, Unit 2 was manually tripped.The licensee determined

that the SAT that initially

tripped underwent

a phase-to-ground

fault on a Phase B insulator.

The failed insulator

was located outdoors, about halfway between the SAT and the auxiliary

building.

After Initiating, the arc continued

down the bus bar, Increasing

in width until It involved the other two phases. Air and water present in the bus bar duct was heated by the arc and resulted in pressurization

of the duct.Chronic water leakage through inadequately

caulked Insulator

mounting holes and through an improperly

compressed

gasket caused degradation

of the insulator

metal inserts and Insulator material between these inserts. Eventually, the bus flashed to ground through the degraded insulator

and initiated

the transient.

PERRY On June 5, 1997, Perry was operating

at full power when an automatic reactor scram occurred following

a three-phase

fault in one of two high-voltage

secondary

winding termination

compartments

of the UAT. The fault resulted in the actuation

of the auxiliary

transformer

phase differential

relay, a main generator

lockout, a main turbine trip, and fast closure of the turbine control valves.At the time of the transient, safety-related

electrical

loads were being supplied by the in-service

startup transformer.

The non-safety-related

electrical

loads supplied by the transformer

automatically

transferred

to the startup transformer

except for the bus that was faulted.Operators

stabilized

the plant without major complication.

The licensee determined

that the fault had developed

as a result of an accumulation

of moisture and dust that had entered the termination

compartment

housing where a 2-Inch-long

piece of gasket material was missing from the compartment

housing-to-transformer

sealing surface.The missing piece of gasket material may have been lost during work performed

when

K>1 IN 98-36 September

18, 1998 replacing

the auxiliary

transformer

following

failure of the transformer

on May 30, 1996. The cause of that failure was attributed

to Inadequate

original design or poor assembly practices

or both.POINT BEACH UNIT I During a severe storm on January 8, 1998, a ground In the low-voltage-side

bus duct caused the failure of the Unit I SAT. This failure and a failure of the 13.8-kilovolt

automatic

bus transfer to the Unit 2 SAT resulted in the loss of normal power to the Unit I safeguards

buses. The EDGs subsequently

started and restored power to the buses. Unit I remained at 98 percent power throughout

the transient.

Unit 2 was in cold shutdown.The licensee attributed

the failure of the transformer

to the buildup of condensation

internal to the buses and long-term

insulation

degradation

In the bus duct on the low-voltage

side of the transformer.

Before the transformer

failed, the circuit breaker for a heater designed to keep the bus duct dry would not remain closed. Consequently, in August 1996, the licensee left the circuit breaker open and wrote a work order for its repair. However, work schedulers

did not recognize

that the bus duct heater was inoperable

with the circuit breaker open, and the work order was erroneously

classified

as "minor maintenance" and given low priority.

At the time the transformer

failed, the work order was in the "backlog'

of maintenance

Items. In addition to the inoperable

heater, the:licensee

determined

that the lack of a routine inspection

program for the bus ducts may have contributed

to the event. Inspection

of the bus ducts after the transformer

failed revealed insulation

breakdown

that would likely have been Identified

through a periodic Inspection

program.Discussion

These events illustrate

the potentially

significant

consequences

of inadequate

or poorly performed

maintenance

activities

on non-safety-related

plant components.

Unnecessary

challenges

to plant safety systems or control room operators

or both could result from inadequate

control or inattention

to detail during non-safety-related

maintenance

activities.

The potential

impact on safety systems of such activities

as the re-roofing

of nuclear power plant support buildings, the Installation

of gaskets, or the caulking of outdoor components, could easily be overlooked.

In addition, several of the events discussed

here highlight

the need for licensees

to have better control over the maintenance

activities

of contractor

and non-station

utility employees, and the need for thorough periodic walkdowns

or preventive

maintenance

on auxiliary

transformers

and the associated

outdoor bus ducts.

IN 98-36 September

18, 1998 This information

notice requires no specific action or written response.

However, recipients

are reminded that they are required to consider Industry-wide

operating

experience (including

NRC INs) where practical, when setting goals and performing

periodic evaluations

under Section 50.65, "Requirements

for Monitoring

the Effectiveness

of Maintenance

at Nuclear Power Plants," of Part 50 of Title 10 of the Code of Federal Regulations.

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.eJack , Acting Director Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical

contacts:

Mike Kunowski, Region IlIl John Neisler, Region IlIl 630-829-9816

630429-9718 E-mail: mak3@nrc.gov

E-mail: jhn@nrc.gov

Attachment:

List of Recently Issued NRC Information

Notices

A,(ttachment

1 IN 98-36 September

18, 1998 LIST OF RECENTLY ISSUED NRC INFORMATION

NOTICES Information

Notice No.Date of Issuance Subject 98-35 Threat Assessments

and Consideration

of Heightened

Physical Protection

Measures 914/98 Issued to All U.S. NRC fuel cycle facilities

power and non-power

reactor licensees (Safeguard

issues, not for public disclosure.)

98-34 98-33 98-32 98-31 NRC Configuration

Control Errors NRC Regulations

Prohibit Agreements

that restrict or Discourage

an Employee from Participating

In Protected

Activities

Problems Associated

with Post-Fire Safe-Shutdown

Circuit Analyses 8/28/98 8128198 8126198 All holders of Operating

licenses for nuclear power reactors, except for those who have ceased operations

and have certified

that fuel has been permanently

removed from the reactor vessel All holders of a U.S. Nuclear Regulatory

Commission (NRC)license.All holders of operating

licenses for nuclear power reactors, except those who have permanently

ceased operations

and have certified

that fuel has been permanently

removed form the reactor All holders of operating

licences for nuclear power reactors, except those licensees

that have permanently

ceased operations

and have certified

that fuel has been permanently

removed from the reactor vessel.Fire Protection

System Design 8/26/98 Deficiencies

and Common-Mode

Flooding of Emergency

Core Cooling System Rooms at Washington

Nuclear Project Unit 2 OL = Operating

License CP = Construction

Permit

-IN 98-36 September

18, 1998 This information

notice requires no specific action or written response.

However, recipients

are reminded that they are required to consider industry-wide

operating

experience (including

NRC INs) where practical, when setting goals and performing

periodic evaluations

under Section 50.65, "Requirements

for Monitoring

the Effectiveness

of Maintenance

at Nuclear Power Plants," of Part 50 of Title 10 of the Code of Federal Regulations.

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.Jack W. Roe, Acting Director Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical

contacts:

Mike Kunowski, Region IlIl 630-829-9816 E-mail: mak3@nrc.gov

John Neisler, Region IlIl 630-829-9718 E-mail: jhn@nrc.gov

Attachment:

List of Recently Issued NRC Information

Notices*See previous concurrence

C,,tt & e.**E-mail concurrence

c<f()DOCUMENT NAME: G:\NICK\REGION.IN

To receive a copy of this document, indicate in the box C=Copy wlo attachment/enclosure

E=Copy with attachmentlenclosure

N = No copy OFFICE PECB I Tech Ed I Reg III Reg [ il I PECB I C:PECB l_ji D M NAME NFields* RSanders*

MKunowski**

JNeisler**

RDennig* JStolz* JRo DATE 09/03/98 08/26/98 09/03/98 Ii09/03/98

09/14/98 J 09/14/98 \/98 OFFICIAL RECORD COPY

IN 98-xx September

xx, 1998 This information

notice requires no specific action or written response.

However, recipie are reminded that they are required to consider industry-wide

operating

experience (includ g NRC INs) where practical, when setting goals and performing

periodic evaluations

under ection 50.65, "Requirements

for Monitoring

the Effectiveness

of Maintenance

at Nuclea ower Plants," of Part 50 of Title 10 of the Code of Federal Regulations.

If you have ny questions about the information

in this notice, please contact one of the technical

con cts listed below or the appropriate

Office of Nuclear Reactor Regulation (NRR) project man er.Jack W. Roe, Acting irector Division of Reactor rogram Management

Office of Nuclea eactor Regulation

Technical

contacts:

Mike Kunowski, Region IlIl Joh eisler, Region IlIl 630-829-9816

63 -829-9718 E-mail: mak3@nrc.gov -mail: jhn@nrc.gov

Attachment:

List of Recently Issued NRC Info tion Notices DOCUMENT NAME: G:\NICK\REGION.IN

To receive a copy of this document, Indicate in the box C=Copy wlo attachmentenclosure

E=Copy with attachmentlenclosure

N = No copy OFFICE PECB. I _ Tech Ed I _ Reg I _I lI Reg 11 l 1/E "ECB (A)D:DRPM

lNAME NFiells' { RSanders MKu owsk Jeisler ennig l l JRoel DATE /3/98 1SW98 17/3/98 15/3198 lH/ 48 q/l98 l I /98 OFFICIAL RECORD COPY I