ML18033A865

Responds to K Rogers Question on Potential Problem Re Electrical Cable Installation,Per 890719 Meeting.In Event That Cable Damaged During Installation,Damage Would Be Readily Apparent Since Cable Visible Along Route in Tray

ML18033A865
Person / Time
Site:	Browns Ferry
Issue date:	08/04/1989
From:	Kingsley O TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 8908100171
Download: ML18033A865 (10)

Text

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Ik ACCESSION NBR:8908100171 DOC.DATE: 89/08/04 NOTARIZED: NO DOCKET FACIL:50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee 05000260 AUTH.NAME AUTHOR AFFILIATION KINGSLEY,O.D.

Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Responds to K Rogers question on electrical cable installation,per 890719 meeting.

DISTRIBUTION CODE:

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p TENNESSEE VALLEYAUTHORITY CHATTANOOGA. TENNESSEE 3'7401 6N 38A Lookout Place August 4, 1989 U.S. Nuclear Regulatory Commission ATTN:

Document Control Desk

%1ashington, D.C.

20555 Gentlemen:

In the Matter of Tennessee Valley Authority Docket No. 50-260 BROWNS FERRX NUCLEAR PLANT (BFN) RESPONSE TO NRC COMMISSIONER K.

ROGERS QUESTION ON ELECTRICAL CABLE INSTALLATION In a meeting with NRC Commissioners on July 19, 1989, TVA presented the scope and status of corrective action programs related to the planned restart of BFN Unit 2.

During, the discussions on electrical issues, Commissioner K. Rogers questioned if TVA had considered and assessed the potential problem of cable installation damage being obscured by fire retardant coatings.

The enclosure to this letter provides TVA's response to that question.

C Please refer any questions you may have to me at (615) 751-4770.

Very truly yours, TENN E VALLEY AUTHORITY 0.

D Kings Senior Vic sxd nt,,

Nuclea ower Enclosure cc:

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PDC An Equal Opportunity Employer

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U.S. Huclear Regulatory Commission August 4, 1989 cc (Enclosure)x Hs.

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C. Black, Assistant Director for Projects TVA Projects Division U.S. Huclear Regulatory Commission One Mhite Flint, Horth 11555 Rockville Pike Rockville, Haryland 20852 Hr. B. A. Milson, Assistant Director for Inspection Programs TVA Projects Division U.S. Huclear Regulatory Commission Region II 101 Harietta Street, HW, Suite 2900 Atlanta, Georgia 30323 HRC Resident Inspector Browns Ferry Hucleax; Plant Route 12, Box 637

Athens, Alabama 35609-2000

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ENCLOSURE NRC Comment During discussions on electrical issues, Commissioner K. Rogers questioned if TVA had considered and assessed the potential problem of cable installation damage being obscured by fire retardant coatings.

TVA Res onse The electrical cables in trays at BFN were and are being installed using industry accepted installation practices.

Typically, the installation method is to pull cable over temporarily installed rollers or sheaves located along the length of the tray.

The cable is then hand laid into it's final position in the tray.

Small diameter cables are sometimes entirely hand laid in the tray.

If the route of a particular cable is in both conduit and tray, the tray portion is normally installed first and the remaining section is then pulled in the conduit from the tray to the end device.

These installation practices are regarded as non-stressful to the cables due to the absence of confining enclosures (i.e. conduit and conduit fittings), which present a

potential for cable degradation caused by pullby or jamming.

In addition, the use of rollers and sheaves to reduce friction result in reduced pull tension and sidewall pressure, and the physical size of the cable tray generally eliminates bend radius concerns.

Therefore, cables in trays typically do not have to endure the rigors of installation normally associated with cable installed in conduit.

Consequently, they have not been extensively evaluated for potential installation damage.

In the unlikely event that a cable had been damaged during installation, the damage would be readily apparent since the cable is visible along its entire route in the tray.

Additionally, the damage could have been identified during subsequent cable installation activities or during.appL'ication of the fire retardant coating.

It should be noted that the majority of BFN's cables were installed and operational before fire retardant coatings were applied.

Therefore, a significant time period existed during which damage could have been observed.

Cable installation concerns were identified at BFN as a result of generic reviews of condition adverse to quality reports issued at Sequoyah.

The scope of activities undertaken to resolve these concerns'ere directed towards cables installed in conduit.

However, the test data accumulated in this effort and the conclusions reached are pertinent to this assessment since many of the cables reviewed are routed in both tray and conduit.

The results of our evaluations are contained in the "Cable Installation Concerns Summary Report" (Reference

1) and the "Cable Issues Supplemental Report" (Reference 2) in which we concluded that the integrity of the electrical cable at BFN has been maintained.

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Iq addition, TVA has committed to perform high-potential DC testing on a number of medium voltage class IE cables which represent worst-case vertical drop and bend radius conditions (Reference 3).

As discussed in Reference 1,

these types of cable are the most sensitive to damage.

Results to date, on a number of cables which are routed in conduits and trays, indicate no cable degradation.

In summary, flame retardant coatings are applied to cable in cable trays, not in conduit.

Cable in cable trays is not subject to the installation damage as sometimes experienced in conduit as a result of high sidewall pressure.

References:

1.

TVA letter to NRC on June 19,

1989, "ELECTRICAL CABLE INSTALLATION-REVISEDWALKDOWN AND

SUMMARY

REPORTS (TAC No. 62260)"

2.

TVA letter to NRC on September 29,

1988, "RESOLUTION OF CABLE INSTALLATION ISSUES CABLE TESTING" 3.

TVA letter to NRC on December 9,

1988, "RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON ELECTRICAL ISSUES (TAC 62260)"

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