05000354/LER-1997-007, :on 970407,Struthers-Dunn 219NR Series Relay Failed Due to Thermal Degradation of Magnetic Vinyl Plastic Bearing Pad Matl.Replaced Degraded Relays Before End of Seventh Refueling Outage,Per 10CFR21

:on 970407,Struthers-Dunn 219NR Series Relay Failed Due to Thermal Degradation of Magnetic Vinyl Plastic Bearing Pad Matl.Replaced Degraded Relays Before End of Seventh Refueling Outage,Per 10CFR21

ML20141A676
Person / Time
Site:	Hope Creek
Issue date:	05/07/1997
From:	Duke P Public Service Enterprise Group
To:
Shared Package
ML20141A644	List: 05000354/LER-1997-007, :on 970407,Struthers-Dunn 219NR Series Relay Failed Due to Thermal Degradation of Magnetic Vinyl Plastic Bearing Pad Matl.Replaced Degraded Relays Before End of Seventh Refueling Outage,Per 10CFR21
References
REF-PT21-97 LER-97-007, LER-97-7, NUDOCS 9705140420
Download: ML20141A676 (6)

LER-1997-007, on 970407,Struthers-Dunn 219NR Series Relay Failed Due to Thermal Degradation of Magnetic Vinyl Plastic Bearing Pad Matl.Replaced Degraded Relays Before End of Seventh Refueling Outage,Per 10CFR21

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(viii) 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
3541997007R00 - NRC Website

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NRJ FORJ 366 U.S. NUCLEAR REGULATORY COM_lSSION APPROVED CY t.M8 NO. 3150-0104 (4-96)

EXPIRES 04130X8 lfaNav 'Oi"R.Jo"N "!a07eno.PJ8 tin M n't LICENSEE EVENT REPORT (LER)

"ETJM Aislin Mo^"M8 #c'x 7s "NM'# 7MwRs

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20603.

FACluTY MAISE (1) 00CMET NUM8ER (2)

P AGE (3)

Hope Creek Generating Station 05000354 1OF6 i

TITLE (4)

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Struthers-Dunn 219NE Series Relay Failures Due to Thermal Degradation of Magnetic Vinyl Pirtic Bearing Pad Material EVENT DATE (5)

LER NUMBER (6)

REPORT DATE (7)

OTHER FACILITIES INVOLVCD (8)

MONTH DAY YEAR YEAR SEQU AL R V Si N MONTH DAY YEAR 04 07 97 97 - 007 - 00 05 07 97

' ' * " " " ^ " '

05000 OPERATING j

ml8 REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR $: (Check one or more) (11)

MODE (9) 20.2201(b) 20.2203(a)(2)(v) 50.73(a)(2)(i)(B) 50.73(a)(2)(viii)

POWER 100 20.2203(a)(1) 20.2203(a)(3)(i) 50.73(a)(2)(ii) 50.73(a)(2)(x)

LEVEL (10) 20.2203(a)(2)(i) 20.2203(a)(3)pi) 50.73(a)(2)(iii) 73.71 20.2203(a)(2)(ii) 20.2203(a)(4) 50.73(a)(2)(iv)

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20.2203(a)(2)(iii) 50.36(c)(1)

X 50.73(a)(2)(v) gg6gbetrage

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20.2203(a)(2)(iv) 50.36(c)(2) 50.73(a)(2)(vii)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NVedER (include Area Code)

Paul Duke, Sr. Staff Engineer (609) 339-1466 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTA E

CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTAR E O pp p

i B

El RLY S440 Y

s S

3 4

i SUPPLEMENTAL REPORT EXPECTED (14)

EXPECTED MONTH DAY YEAR YES NO SUBMISSION

{If yes, complete EXPECTED SUBMISSION DATE).

X DATE (15)

ABSTRACT (Limit to 1400 spaces,i.e., approximately 15 single-spaced typewritten lines) (16)

On April 7, 1997, Public Service Electric & Gas Co. (PSE&G) completed its evaluation of an increase in the failure rate of Struthers-Dunn 219NE I

series relays with 120 VAC and 24 VAC coils and concluded that the failures were due to the use of magnetic vinyl plastic for the bearing pad material in normally energized relays.

Based upon the extent of the condition, PSE&G concluded that, if undiscovered, it could have caused one or more safety systems to fail to perform their intended function.

A four hour

~

notification was made to the NRC at 1848 on April 7, 1997, pursuant to 10CFR50.72 (b) (2) (iii).

This LER is being submitted pursuant to 10 CFR 50.73 (a) (2) (v) and 10 CFR 21.

The apparent cause of the high failure rate was thermal degradation of the magnetic vinyl plastic bearing pad material in Struthers-Dunn 219NE series 24 VAC and 120 VAC relays.

Panels containing the degraded relays are being inspected weekly to assure J

continued operability until the relays are replaced.

The degraded relays will be replaced before the end of Hope Creek's seventh refueling outage.

i There were no actual safety consequences associated with this condition.

There was no impact on public health and safety.

9705140420 970507 PDR ADOCK 0500 4

S

NRC FORJ 386A U.S. MUCLEAR REAULATORY COM_f SION (46)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUMBER (2)

LER NUMBER C6)

PAGE (3)

YEAR SEQU AL u

N Hope Creek Generating Station 05000354 97 - 007 -- 00 2

OF 6 TEXT (if more space is required, use additional copies of NRC Form 366A) (17)

PIANT AND SYSTEM IDENTIFICATION, General Electric - Boiling Water Reactor (BWR/4)

)

Station Service Water System - EIIS Identifier {BI)

Intake Structure HVAC System - EIIS Identifier {UA}

Remote Shutdown Panel - EIIS Identifier {JL}

IDENTIFICATION OF OCCURRENCE u

Discovery date: 04/07/97 Problem Report: 970306444 CONDITIONS PRIOR TO OCCURRENCE The plant was in OPERATIONAL CONDITION 1 (POWER OPERATION) at 100% of rated thermal power. There were no other structures, systems, or components that were inoperable at the beginning of the event that contributed to the event.

DESCRIPTION OF OCCURRENCE On April 7, 1997, PSE&G completed its evaluation of an increase in the i

failure rate of Struthers-Dunn 219NE series relays with 120 VAC and 24 VAC coils and concluded that the failures were due to the use of magnetic vinyl plastic for the bearing pad material in normally energized relays.

A walkdown of the Class 1E panels containing 219NE series relays identified 170 relays with magnetic vinyl plastic bearing pads.

Forty eight (48) of these relays had degraded bearing pads.

Based upon the extent of the condition, PSE&G concluded that, if undiscovered, it could have caused one or more safety systems to fail to perform their intended function.

A four hour notification was made to the NRC at 1848 on April 7, 1997, pursuant to 10CFR50.72 (b) (2) (iii).

The bearing pad functions as a silencer at the pivot point of the hinged armature plate.

It is mounted on a metal frame with the relay coil and the armature.

Failure of the bearing pad affects the alignment between the armature and the AC relay coil and causes rapid oscillatory motion of the relay armature and contacts.

The rapid motion is observable as a loud buzzing or chattering from the relay.

Relay failure eventually results.

The length of time from the onset of rapid oscillatory motion and eventual failure cannot be precisely quantified.

However, it is on the order of weeks based on experience with relays observed to be buzzing.

NRC TORM 366A (4-96)

\\

t SU.S. NUCLEAR REiULATORY COM.itSION (4 96)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUMBER (2)

LEit NUMBER [6) l PAGE (3)

NNeYk EE Hope Creek Generating Station 05000354 97 - 007 _ 00 l 3 OF 6 TEXT (if more space is required, use additional copies of NRC Form 366A) (17)PSE&G conducted a walkdown of the fifty one Class 1E panels containing 219NE series relays.

A total of forty eight (48) relays with degraded bearing pads were identified in the following applications:

- Forty four (44) relays in the Remote Shutdown Panel (RSP);

- Three (3) relays in the Station Service Water System (SSWS) vacuum breaker controls; and

- One (1) relay in the Traveling Screen Motor Room Ventilation System controls.

One of the relays with degraded bearing pads in the RSP was observed to be buzzing and was replaced.

Degraded bearing pads were observed only in AC relays with magnetic vinyl plastic bearing pad material.

The walkdown also j

identified a total of 122 relays that have magneti.c vinyl plastic bearing pads that are not degraded and two (2) relays were found to have been assembled with no bearing pad.

None of these re?ays were observed to be chattering or buzzing.

With the exception of the relays in the SSWS vacuum breaker controls, all of the degraded relays are located in mild EQ environments.

The SSWS j

vacuum breaker control relays are located in a harsh envj;onment, but they were not included in the Hope Creek Equipment Qualification (EQ) program.

The qualified life for these relays is calculated to be 11.6 years (expires November 24, 1997).

Continued operability of the affected systems is assured by performing panel walkdowns weekly to identify relays that have begun buzzing (an indicator of degradation to the point that rapid armature motion is occurring) and taking immediate action if any buzzing is detected.

The relay manufacturer, Struthers-Dunn, stated that magnetic vinyl plastic was used in 219NE series relays until April, 1983.

The design was changed to use silicone rubber after that time.

However, PSE&G has identified one relay with magnetic vinyl plastic bearing pad material that was manufactured in 1985.

The bearing pad material can be identified by color:

magnetic vinyl plastic is brown; silicon rubber is red; and Teflon is white.

NRC FOTW 36M (4-95)

_ =.

NRJ FORM 888A U.S. NUCLEAR REIULATORY CO_._1.SiON (44s)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION q

FACILITY NAME (1)

DOCKET NUMBER (2)

LER NUMBER 48)

PAGE (8)

'WJ.TP =

=

Hope Creek Generating Station 05000354 97 _ 007 _ 00 4

OF 6 TEXT (if more space is required, use additional copies of NRC Form 366A) (17)

,]

)

This event is being reported pursuant to 10CFR50.73 (a) (2) (iii) as a

)

condition that could have prevented the fulfillment of a safety function.

Th'_s report is also being submitted in accordance with 10 CFR 21 as a defect which could result in a loss of safety function necessary to mitigate the consequences of an accident.

The affected relays are Struthers-Dunn series 219NE 120 VAC (model number 219BBX222NE) and 24 VAC (model number 219BBX232NE) relays with magnetic vinyl plastic bearing pad material.

The relays were supplied to PSE&G by Comsip, the vendor for many of the Hope Creek plant panels.

1 APPARENT CAUSE OF OCCURRENCE The apparent cause of the high failure rate was thermal degradation of the magnetic vinyl plastic bearing pad material in Struthers-Dunn 219NE series j

(

relays with AC coils.

The thermal degradation is due to exposure to high 1

temperatures when the relay coils are energized.

Thermal degradation causes the bearing pad to disintegrate and become dislodged from the relay frame.

NRC FORM 386A (4-95)

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l NRC FORA 366A U.S. NUCLEAR REGULATORY COM_18.lON (pH) '

{

LICENSEE EVEkT REPORT (LER)

TEXT CONTQUATION FACILITY NAME (1)

DOCl ET NUMBER (2)

LER NUMBER [6)

PAGE (3)

I "niW 313

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Hope Creek Generating Station 05000354 97 - 007 - 00 5

OF 6 TEXT (if more space is required, use additional copies of NRC Form 366A) (17) 4

ASSESSMENT OF SAFETY CONSEQUENCES

Three (3) of the four (4) relays controlling the Station Service Water System (SSWS) vacuum breakers were found to have degraded magnetic vinyl plastic bearing pads.

The SSWS is designed to operate during normal plant operation and during a design basis accident, including a LOCA, loss of offsite power (LOP), and a LOCA with LOP conditions.

Normally closed solenoid operated valves, two per loop for redundancy, are located at the hichest point of each SACS heat exchanger discharge pipe. Following a LOP, the.se valves fail cpen to admit air and close after a preset time delay following restoration of power.

This arrangement reduces the pressure surge caused by the subsequent restart of all station service water pumps to within design limits.

Multiple failures of the degraded relays could prevent the vacuum breakers from remaining open for the preset time delay following restoration of power after a LOP.

This could potentially increase pipe support loads beyond the current analyzed levels and result in failure of the pressure

)

4 boundary.

This could result in the loss of a SSWS loop.

Quarterly testing of the SSWS vacuum breakers per the Hope Creek Inservice Testing (IST) program minimized the potential for undetected failures of the degraded relays.

Forty four (44) relays with degraded magnetic vinyl plastic bearing pads j

were found in the Remote Shutdown Panel (RSP).

Of these, twenty seven relays supply indicators or alarms required by plant Technical Specifications.

The Remote Shutdown System (RSS) provides the means for achieving and maintaining safe shutdown conditions from outside the main control room in the unlikely event the main control room becomes uninhabitable.

The primary control station for the RSS is the remote shutdown panel (RSP).

Multiple failures of the degraded relays could render the RSP inoperable.

However, in the event of a failure at the RSP, sufficient redundant safety grade instrumentation and controls are available apart from both the main control room and the RSP to ensure that safe shutdown of the reactor can be achieved.

One (1) relay with a degraded magnetic vinyl plastic bearing pad was found in the damper controls for one train of the Traveling Screen Motor Room Ventilation System.

The traveling screen room is provided with two 100 percent capacity supply fans, each with motorized outside air intake and return air dampers and one common exhaust opening with backdraft damper.

Failure of the degraded relay would not affect the redundant train and would not prevent the system from performing its function.

NRC FORM 306A (4 95)

j NR J FjDR.) 346A U.S. NUCLEAR REGULATORY COM_18 lON g-es)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUMBER (2)

LER NUMBER C6)

PAGE (8)

'WJNP Ma

=

Hope Creek Generating Ste.t;on 05000354 97 - 007 - 00 6 OF 6 TEXT (if more space is requirerf, use additional copies of NRC Form 366A) (17)There were no actual safety consequences associated with this condition.

There was no impact on public health and safety.

Therefore, the safety consequences associated with this event were negligible.

PREVIOUS OCCURRENCES

No previous occurrences similar to this condition were identified in a review of Hope Creek LERs.

CORRECTIVE ACTIONS, l

1. As of May 1, 1997, six (6) of the Struthers-Dunn 219NE series relays with degraded magnetic vinyl plastic bearing pad material have been replaced.

2. Panels containing Struthers-Dunn 219NE series relays with degraded magnetic vinyl plastic bearing pad material are being inspected weekly to ensure continued operability until the relays are replaced.

3. Struthers-Dunn 219NE series relays with degraded magnetic vinyl plastic bearing pad material will.be replaced as soon as possible within the Hope Creek work week schedule.

Replacement will be complete before the end of Hope Creek's seventh refueling outage.

4. Normally energized Struthers-Dunn 219NE series 120 VAC (model number j

219BBX222NE) and 24 VAC (model number 219BBX232NE) relays with no bearing pad or with non-degraded magnetic vinyl plastic bearing pad material will be inspected to verify no degradation.

The results of this inspection will be assessed to determine the need for additional inspections until the relays are replaced.

This activity will be completed by August 29, 1997.

5. The SSWS vacuum breaker relays that were omitted from the EQ Program have been added to the program and will be replaced before the end of their qualified life (November 24, 1997).

l

6. Normally energized Struthers-Dunn 219NE series 120 VAC (model number 219BBX222NE) and 24 VAC (model number 219BBX232NE) relays with no i

bearing pad or with non-degraded magnetic vinyl plastic bearing pad material will be replaced before the end of their calculated service j

life (April 15, 1998).

NRC FORM 306A (4-95) l l

l