Information Notice 1996-62, Potential Failure of the Instantaneous Trip Function of General Electric RMS-9 Programmers

Potential Failure of the Instantaneous Trip Function of General Electric RMS-9 Programmers

ML031050511
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:	11/20/1996
From:	Martin T Office of Nuclear Reactor Regulation
To:
References
IN-96-062, NUDOCS 9611040290
Download: ML031050511 (6)

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UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555-0001 Noverhiber 20, 1996 NRC INFORMATION NOTICE 96-62: POTENTIAL FAILURE OF THE INSTANTANEOUS

TRIP FUNCTION OF GENERAL ELECTRIC RMS-9 PROGRAMMERS

Addressees

All holders of operating licenses and construction permits for nuclear power plants.

Purnose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert

addressees to the potential that the instantaneous trip function of some General Electric

RMS-9 overcurrent trip device programmers may fail to trip the associated 480-V ac circuit

breaker at the desired current setting. 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.

Descrintion of Circumstances

General Electric Nuclear Energy (GE NE) sent the results of an evaluation of some reported

failures of the instantaneous trip function of GE Type RMS-9 Overcurrent Trip Device

Programmers to all affected customers and the NRC in a letter dated August 30, 1996.

These devices were provided as spare parts, or as components of either refurbished GE

Type AK 480-V ac circuit breakers or new AFt7/AKR-7 circuit breakers for overcurrent

protection. The affected programmers may trip at an instantaneous current value below

the selected setting.

The devices were manufactured by GE Electrical Distribution and Control and supplied by

GE NE as safety-related components for balance-of-plant and unspecified applications.

Since the specific applications and associated safety functions of the RMS-9 programmers

are not known to GE NE, the company notified affected licensees in accordance with

10 CFR 21.21(b). However, because some licensees may have purchased these devices

as commercial-grade items or from a dedicating entity other than GE NE, the NRC is issuing

this information notice to ensure that all potentially affected licensees are notified.

9611040290

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IN 96-62 November 20, 1996 Discussion

The cause of the failure of the instantaneous trip function was determined to be a

polyester epoxy film on the internal switch contacts. The film acts as an insulator, so that

if the instantaneous switch setting is changed from its initial setting, the contacts do not

make and the programmer automatically fails to its lowest instantaneous pickup setting

(1.5X). The film is the result of insufficient curing of the conformal coating (polyester

epoxy) applied to the RMS-9 programmer during final assembly. Testing by GE showed

that some of the coating ran under the switch during application and the coating was not

properly cured because it was masked by the switch during the ultraviolet curing process.

Over time, the external switch contacts acted as wicks and drew some of the uncured

coating into the switch where it formed a thin film on the internal switch contacts.

Testing by GE also showed that the film did not form between the movable contacts and

the stationary contacts in the switch. Therefore, if the instantaneous trip function is

operating properly and the switch has not been moved from its initial position, it should

continue to operate properly.

An RMS-9 programmer that trips at a value lower than the selected value could cause a

motor to fail to start because the starting current could be higher than the setpoint in the

programmer. If a programmer trips at higher than expected value, it is possible that the

breaker may not trip soon enough under fault conditions and other breakers upstream may

have to trip to clear the fault, resulting in the loss of more of the power system than

anticipated. However, no reported failures of the type discussed herein have resulted in a

breaker tripping at a current higher than the desired setting.

Related Generic Communications

NRC Information Notice 93-75, "Spurious Tripping of Low-Voltage Power Circuit Breakers

With GE RMS-9 Digital Trip Units," was issued on September 17, 1993, to alert licensees

to the potential for the RMS-9 programmers to cause spurious circuit breaker trips when

exposed to short duration (100 microseconds) current spikes (high-frequency electrical

noise). Although the same component is involved in both instances, the two problems are

unrelated.

IN 96-62 November 20, 1996 This information notice requires no specific action 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.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Stephen D. Alexander, NRR

(301) 415-2995 E-mail: sda@nrc.gov

David L. Skeen, NRR

(301) 415-1174 E-mail: dls@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

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Attachment

IN 96-62 November 20, 1996 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

96-61 Failure of a Main Steam 11/20/96 All holders of OLs or

Safety Valve to Reseat CPs for nuclear power

Caused by an Improperly reactors

Installed Release Nut

96-60 Potential Common-Mode 11/14/96 All holders of OLs or

Post-Accident Failure CPs for nuclear power

of Residual Heat Removal reactors

Heat Exchangers

96-59 Potential Degradation of 10/30/96 All holders of OLs or

Post Loss-of-Coolant CPs for nuclear power

Recirculation Capability reactors

as a Result of Debris

96-58 RCP Seal Replacement with 10/30/96 All holders of OLs or

Pump on Backseat CPs for pressurized-water

reactors

96-57 Incident-Reporting Require- 10/29/96 All U.S. Nuclear

merits Involving Intakes, Regulatory Commission

During a 24-Hour Period licensees

That May Cause a Total

Effective Dose Equivalent

in Excess of 0.05 Sv

(5 rems)

OL = Operating License

CP = Construction Permit

IN 96-62 November 20, 1996 This information notice requires no specific action 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.

original signed by

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Stephen D. Alexander, NRR

(301) 415-2995 E-mail: sda@nrc.gov

David L. Skeen, NRR

(301) 415-1174 E-mail: dls@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

• See previous concurrence

Tech Editor has reviewed and concurred on 10/17/96 DOCUMENT NAME: 96-63.IN

To receive a copy of thisdocument. hIdicate In the box: 'C' - Copy w/o

attachmentlenclosure 'E' - Copy w/attachment/lnclosure 'N' - No copy

OFFICE TECH CONTS l C/PECB:DRPM LD/DR ILI

NAME SAlexander* AChaffee* TM Utin

lf DSkeen*

DATE 10/28/96 11/08/96 11/to/96 OFFICIAL RECORD) COPY

IN 96-XX

November xx, 1996 This information notice requires no specific action 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.

Thomas T. Martin, Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contacts: Stephen D. Alexander, NRR

(301) 415-2995 E-mail: sda@nrc.gov

David L. Skeen, NRR

(301) 415-1174 E-mail: dls@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

• See previous concurrence

OFC PECB:DRPM PSIB:DISP C/PSIB:DISP C/PECB:DRPM

NAM DL S e rider) AEC

DATE 101496[1 0I 196 10__6 __ 1496

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OFC DIDRPM

NAM TTMartin

DATE 10/ /96 LFICIAL KRECORU COPYJ

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DOCUMENT NAME: G:\DLS\IN96-XXR.MS9