Information Notice 1992-01, Cable Damage Caused by Inadequate Cable Installation Procedures and Controls

Cable Damage Caused by Inadequate Cable Installation Procedures and Controls

ML031200776
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:	01/03/1992
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-92-001, NUDOCS 9112270125
Download: ML031200776 (7)

UNITED STATES

- NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 January 3, 1992 NRC INFORMATION NOTICE 92-01: CABLE DAMAGE CAUSED BY INADEQUATE CABLE

INSTALLATION PROCEDURES AND CONTROLS

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

The U.S. Nuclear Regulatory Commission is issuing this information notice to

alert addressees to the possibility that inadequate cable installation

procedures and quality control could cause safety-related cables to fail. It

is expected that the 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

In June 1989, the Tennessee Valley Authority (TVA) removed the cables from

a conduit in the reactor protection system of,the Watts Bar Nuclear Plant, Unit

2, to inspect for damage. TVA selected this conduit in response to an

employee's concern that a welding arc that struck the conduit during

construction may have damaged cables in the conduit. When the cables were

removed, TVA found significant damage in the insulation of some cables. This

damage was not attributed to heat generated by the alleged welding arc. The

damage was principally attributed to the pulling stresses exerted during the

initial installation of the cables. Some of the cables had insulation removed

down to the conductors. To assess the extent of cable damage and determine the

scope of its investigation, TVA removed more cables from conduits that

constituted the most difficult pulls (worst case) and found varying degrees of

damage that it attributed to pulling stresses.

To fill a conduit at Watts Bar, personnel used pull cords to pull more cables

through the conduits over the top of existing cables. This practice is called

"pull-by." This practice can cause damage to the existing cables from the

71,-Ile

IN 92-01 January 3, 1992 sawing action of the pull cords and the friction of cables as they are pulled

over existing cables. The University of Connecticut, under contract for TVA,

evaluated damaged cables and determined the cause of damage to have been cable

pull-bys. Usually such damage would be minimized by using the proper and

adequate amounts of lubricants, controlling pulling tension, choosing appro- priate pull cords, limiting the distance between pull points, and minimizing

the number and angle of bends allowed in the conduit. Industry standards

provide no specific guidance for performing multiple pulls of cables in

conduits.

TVA instituted programs to assess the adequacy of cable installation at all its

nuclear facilities and take appropriate corrective actions. At Watts Bar, TVA

replaced cables in conduits which exceeded a calculated threshold value of side

wall bearing pressure (SWBP) and performed high-potential (hi-pot) tests on a

number of other cables in conduits with SWBP below the calculated threshold

value. The hi-pot test voltage was 240 Vdc per mil of insulation thickness

(based on the minimum qualified thickness) not to exceed 80 percent of the

factory's test voltage. Before conducting the testing, TVA flooded the segments

of conduits with the highest SWBP values with water to establish a continuous

electrical ground at the external surface of the cable. TVA did not flood

conduits with shielded cables because the shield provided adequate ground.

At the Sequoyah and Browns Ferry Nuclear Plants, TVA performed hi-pot tests on

cables in a smaller sample of conduits with high SWBP values. TVA did not

replace, but included in the test sample, cables at these plants that exceeded

the threshold SWBP values of Watts Bar because it had not used the very abrasive

nylon cord (parachute cord) at these plants that was extensively used at Watts

Bar. This cord was used as pull cord and seemed to have caused the more severe

damage to cables. Though TVA observed some failures during the hi-pot testing, it attributed none of the failures to the effects of cable pull-bys.

Discussion of Safety Significance

The damage identified in the reactor protection system cables at Watts Bar

demonstrates that the safety function of safety systems could be lost if

damaged cables are located in harsh environments. Such cable damage can be

caused by the pulling stresses exerted during cable installation. If moisture

enters the affected conduits, it can cause cables to short, which could cause

the common mode loss of safety function of systems whose performance is

required to mitigate the consequences of an accident.

IN 92-01 January 3, 1992 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate Office of Nuclear Reactor

Regulation (NRR) project manager.

h/aresE. ssi* or'

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contact: H. Garg, NRR

(301) 504-2929 Attachment: List of Recently Issued NRC Information Notices

Attachment

IN 92-01 January 3, 1992 LIST OF RECENTLY ISSUED

KRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

91-87 Hydrogen Embrittlement of 12/27/91 All holders of OLs or CPs

Raychem Cryofit Couplings for nuclear power reactors.

91-86 New Reporting Requirements 12/27/91 All licensees authorized

for Contamination Events at to use byproduct materials

Medical Facilities for human use.

(10 CFR 30.50)

91-85 Potential Failures of 12/26/91 All holders of OLs or CPs

Thermostatic Control Valves for nuclear power reactors.

for Diesel Generator Jacket

Cooling Water

91-84 Problems with Criticality 12/26/91 All Nuclear Regulatory

Alarm Components/Systems Commission (NRC) fuel

cycle licensees, interim

spent fuel storage licens- ees, and critical mass

licensees.

91-83 Solenoid-Operated Valve 12/20/91 All holders of OLs or CPs

Failures Resulted in for nuclear power reactors.

Turbine Overspeed

91-18, High-Energy Piping Failures 12/18/91 All holders of OLs or CPs

Supp. 1 Caused by Wall Thinning for nuclear power reactors.

91-82 Problems with Diaphragms 12/18/91 All holders of OLs or CPs

in Safety-Related Tanks for nuclear power reactors.

91-81 Switchyard Problems that 12/16/91 All holders of OLs or CPs

Contribute to Loss of for nuclear power reactors.

Offsite Power

91-80 Failure of Anchor 12/11/91 All holders of OLs or CPs

Head Threads on Post- for nuclear power reactors.

Tensioning System During

Surveillance Inspection

OL = Operating License

CP = Construction Permit

IN 92-01 January 3, 1992 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate Office of Nuclear Reactor

Regulation (NRR) project manager.

Origfnal Signed by

Charles E. Rossi

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contact: H. Garg, NRR

(301) 504-2929 Attachment: List of Recently Issued NRC Information Notices

• SEE PREVIOUS CONCURRENCE

OFC :SICB :SICB :SELB:DST :SICB:DST :PDD-4DPR :DST :OGCB

_ _ 4 . _. .__ _ _ .__ . _

NAME :*HGarg:bp  :*EMarinos  :*FRosa  :*SNewberry  :*FHebdon  :*AThadani  :*CBerlinger

• * *4 . .

DATE :6/19/91 :6/19/91 :11/12/91 :11/06/91 :11/14/91 :12/10/91 :12/16/91 OFC :NRR:DOEA :RPB:ADM  :  :  :

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NAME CIes$I-j7) :*Tech Ed .  :  :

DATE :124 791 :12/17/91  :  :  :

OFFICIAL RECORD COPY

Document Name: IN 92-01

IN 91-XX -Line 4 December XX, 1991 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate Nuclear Reactor Regulation

(NRR) project manager.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contact: H Garg 1RR

(301) S6 4-2929 Attachment: List of Recently Issued NRC Information Notices

• SEE PREVIOUS CONCURRENCE

OFC :SICB :SICB :SELB:DST :SICB:DST :PDD-4DPR :DST :OGC XI1 NAME :*HGarg:bp  :*EMarinos  :*FRosa  :*SNewberry  :*FHebdon  :*AThadani :CBerlinger

DATE :6/19/91 :6/19/91 :11/12/91 :11/06/91 :11/14/91 :12/10/91 :12/4/91 OFC :NRR:DOEA :0 P4 :

rp---------.-,---:--------- ------------ ------------

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NAME :CRossi F 3>

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DATE :12/ . /91 9117/ 91.

I I

OFFICIAL RECORD COPY

Document Name: GARG/INFORMATION NOTICE 91XX

IN 91-XX A4 e 4 June XX/i991 Page? of 3 This information notice requires no specific action or writt response. If

you have any questions about the information in this notice, please contact

the Technical contact listed below or the appropriate pro ct manager.

Charles E. Rossi Director

Division of Op ational Events Assessment

Office of Nuc ar Reactor Regulation

Technical Contact:

H. Garg (NRR)

(301) 492-0929 Attachment: List of NRC Information Notices

, *SEE PREVI[OUS CONCURRENCE

OFC MSICB :SICB :SELB:DSLT_ :SICB:DST :PDDI*4DPR :DST . 4J :NRR:UUEA

• EMarinos :FRosa v :SNeferry :FHe.don :AThadani V "CRo55i i

NAME :*HGarg:bp

DATE :6/19/91 :6/19/91 :11/i2/91 :11/6 /91 :11/04/91 :12./ 10/91 :11/ /91 OFFICIAL RECORD COPY

Document Name: GARG/INFORMATION NOTICE 91XX

IN 91 XX -Line 4 June XX, 1991 tage 3 of 3

.,

This information notice requires no specific action or kitten response. If

you have any questions about the information in this notice, please contact

the Technical contact listed below or the appropri project manager.

Ot

Charles E.J ossi, Director

Division A Operational Events Assessment

Office Nuclear Reactor Regulation

Technical Contact:

H. Garg (NRR) of

(301) 492-09g

Attachment: List of Recently^Issued NRC Information Notices

riv

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OFC :SICB ut S :SICB:DST :NRR:DOEA  :  :  :

NAME :HGarg:bp :EMarinos :SNewberry :CRossi  :

DATE :6/Ie/71 :6/1(/91 :6/ /91 :6/ /91  :  :

OFFICIAL RECORD COPY

Document Name: GARG/INFORMATION NOTICE 91XX