Information Notice 1986-52, Conductor Insulation Degradation on Foxboro Model E Controllers

Conductor Insulation Degradation on Foxboro Model E Controllers

ML031220692
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, 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, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Skagit, Marble Hill
Issue date:	06/26/1986
From:	Jordan E NRC/IE
To:
References
IN-86-052, NUDOCS 8606230384
Download: ML031220692 (4)

SSINS NO.: 6835 IN 86-52 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 June 26, 1986 IE INFORMATION NOTICE NO. 86-52: CONDUCTOR INSULATION DEGRADATION

ON FOXBORO MODEL E CONTROLLERS

Addressees

All nuclear power reactors holding an operating license or a construction permit.

Purpose

This rotice is to alert recipients to a potentially generic problem with conductor

insulation degradation on 15 conductor/24 gage interconnection coil-cord cable

sets (cable sets) supplied by the Foxboro Company (TFC) for use with Foxboro

model E electronic controllers. Degradation of the insulation could result in

a common mode failure in that wiring of the same age in various controllers

may fail in certain circumstances, such as a seismic event. Recipients are ex- pected to review the information for applicability to their facilities and consider

actions, if appropriate, to preclude a similar problem from occurring at their

facilities. However, suggestions contained in this information notice do not

constitute NRC requirements; therefore, no specific action or written response

is required.

Description of Circumstances

While performing routine surveillance on the reactor protection system (RPS)

instrumentation at the Haddam Neck Nuclear Plant in October 1984, Connecticut

Yankee Atomic Power Company (CY) found that the conductor insulation on a

cable set for a Foxboro model E electronic controller in the control room RPS

logic cabinet was in a degraded condition after more than 10 years of service.

The degradation consisted of embrittlement of the insulation on the conductors

within the cable set. CY determined that handling could cause the wire insu- lation to disintegrate with the potential for unanalyzed short circuits occurring.

Further inspections determined that 21 similar Foxboro cable sets in the RPS

exhibited the same degradation. Normal CY maintenance activities did not require

access to the terminal block portion of the cable set, so it is not clear how

long this condition may have existed. CY issued a licensee event report

(LER 50-213/84-017 dated 11/01/84) in which it stated that the cause of the

degradation was aging and that the insulation had poor stability.

8606230384

IN 86-52 June 26, 1986 TFC has been aware of this problem since the fall of 1978, and after concluded in a

about 15

1979 internal report that the failures seemed to be occurring the report

years in the field and were due to oxidation aging. Additionally, individual wires will

stated that sometime after 10 years the insulation of the

deteriorate and wires may contact each other and that all model E controllers

10 years or older should be examined for insulation deterioration at least

annually. Due to inadequacies in TFC's Part 21 evaluation and reporting

or the

procedure, TFC failed to make notification to either their customers 99900225/85-01).

NRC (reference violation 85-01-01 in VPB inspection report

Discussion:

An NRC inspection at the Foxboro Company (reference VPB inspection report

manufacturers have determined

99900225/85-01) and discussions with the cable

that:

model E

1. The Foxboro Company recommends that all cable sets for Foxboro

controllers should be examined for insulation degradation cable sets annu- at least

may

ally, regardless of when they were purchased since these several years.

have been in stock at The Foxboro Company warehouse for

Foxboro has disposed of all of the remaining coil-cord cable sets in

2.' condition.

stock to prevent recurrence of the insulation degradation

3. The cable manufacturers typically had a 1-year warranty for the coil-cord

cable sets. The life expectancy of the cable sets under mild service

conditions and environment is under 10 years.

In addition, the Institute of Materials Science (IMS) of the University of

cable sets for CY.

Connecticut performed an analysis of two of the defective of some production

The IMS analysis concluded that the insulation degradation

batches was due to poor stability of the insulation material.

Foxboro model E electronic controller numbers 61, 62, and 67 have been identi- sets. A subsequent Foxboro

fied as utilizing the coil-cord type of cable H, 62 H, and 67 H but

electronic controller model line has similar numbers 61 which nuclear facilities have

they are not affected. Foxboro cannot determine systems. Foxboro

installed model E electronic controllers in safety-related

components.

issued a letter on October 18, 1985 which discussed "end of life" end users of the

However, this letter may not have been effective at notifying

letter to all nuclear power plants

problem. Therefore, Foxboro issued a second electronic control- on June 4, 1986. Foxboro stopped manufacturing the mod'eFE

support in 1984. Coil-cord cable

lers in 1970 and withdrew model E product line 1984. However, the cable

sets were available for replacement from Foxboro until

old. In the June 4, 1986 sets that Foxboro had in stock were several years system needs.

letter, TFC committed to supporting nuclear power plant control

IN 86-52 June 26, 1986 notice is required.

No specific action or written response to this informationcontact this office or

If you have any questions regarding this matter, please

the appropriate Regional Administrator.

an, Director

Divisi pnof Emergency Preparedness

and Edgineering Response

Office of Inspection and Enforcement

J. J. Petrosino

(301) 492-4513 Attachment:

List uf Recently Issued IE Information Notices

Attachment 1 IN 86-52 June 26, 1986 LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information Date of

Notice No. Subject Issue Issued to

86-51 Excessive Pneumatic Leakage 6/18/86 All BWR facilities

In The Automatic Depressuriza- holding an OL or CP

tion System

86-50 Inadequate Testing To Detect 6/18/86 All power reactor

Failures Of Safety-Related facilities holding

Pneumatic Components Or an OL or CP

Systems

86-49 Age/Environment Induced 6/16/86 All power reactor

Electrical Cable Failues facilities holding

an OL or CP

86-48 Inadequate Testing Of Boron 6/13/86 All BWR facilities

Solution Concentration In The holding an OL or CP

Standby Liquid Control System

86-47 Feedwater Transient With 6/9/86 All BWRs and PWRs

Partial Failure Of The facilities holding

Reactor Scram System an OL or CP

86-46 Improper Cleaning And Decon- 6/12/86 All power reactor

tamination Of Respiratory facilities holding

Protection Equipment an OL or CP and

fuel fabrication

facilities

86-45 Potential Falsification Of 6/10/86 All power reactor

Test Reports On Flanges facilities holding

Manufactured By Golden Gate an OL or CP and

Forge And Flange, Inc. research and test

facilities

86-44 Failure To Follow Procedures 6/10/86 All power reactor

When Working In High Radiation facilities holding

Areas an OL or CP and

research and test

reactors

OL = Operating License

CP = Construction Permit