ML20066H919
| ML20066H919 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 01/23/1991 |
| From: | Carier P TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9101290372 | |
| Download: ML20066H919 (3) | |
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TENNESSEE. VALLEYlAUTHORITY.
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P. O. Box 2000 Decatur, AlabamaL35609-JAN-23199F LJ
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.U.S.. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C..
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Gentlemen:
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In the Matter of
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Docket No.;^50-260 i
Tennessee Valley Authority-
- )t BROWNS FERRY NUCLEAR' PLANT (BFN) - UNIT 2/-: BRAND-REX CABLE'
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Reference:
. TVA's letter to NRC dated October 4,.1990, ". Resolution of Cable Installation Issues Supplemental: Report - Corrective Actions" The purpose of this~. letter 1s to inform NRC.that BFN has completed'an.
engineering evaluation for cable's. installed in'10 CFR 50.49: circuits that!were:
manufactured by Brand-Rex under contract 180K6-825419.- This=evaluationc concludes that the cables are capable of performing their.-intended safety.
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functions for at~1 east one cycle ~.
LACKGROUND During:high voltage de testing at BFN.to. resolve cable' installation. concerns, one Brand Rex cable failed. This is. discussed in the referenced letter.
Subsequent to the BFN testing, cables from the same contract.at Watts Bar Nuclear Plant experienced similar' failures. TVA ' contracted the University of Connecticut's Electrical Insulation Research Center:(EIRC) to perform 1 tests on these failed. cables to determine..the cause.of'the hi-pot testing. anomalies'.
-The testing performed at EIRC indicated that the anomalies ~were due to atypically large inorganic particles'within the insulation system. In order to assess the operability of the Brand Rex cables in' question,~BFN performed an engineering evaluation.
-L ENGINEERING EVALUATION RESULTS The engineering evaluation concluded that the cables are capable of: performing -
their intended safety function for at least=one cycle This conclusion is based on the following four major factors:.
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- 1.. Breakdown of. the cable insulation occurred at 2500-4900V,dc during.hi-pot-testing. The maximum applied system voltage for the c' abler: installed at BFN is 120V ac.
These breakdown voltages are approximately-an order of magnitude above-the normal system operation' voltages.
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U.S. Nuclear Regulatory Commission JAM 231991 2.
The particles that were identified during testing at EIRC are normal components of the insulation system or manufacturing process and since they are inorganic, they are more thermally stable than the base polymer. Therefore, the presence of the inhomogeneities is not expected to alter the rate at which the insulation ages.
3.
The subject cables are rated for 600V ac at 90 degrees C.
The maximum applied system voltage for the cables installed at BFN is 120V ac and a maximum current of 1 ampere. The maximum normal ambient temperature for the cables is 52 degrees C.
Since there is negligible ohmic heating associated with the these loads, the cables will remain at ambient, well below their rated temperature and will be in an "as-new" condition (having experienced insignificant degradation) at the onset of any harsh environment event.
4.
The combined normal and accident radiation dose in the areas where this cable is installed is approximately eight percent of the value for which the cables have been qualified. The worst accident temperature peaks at 116 degrees C but drops to 54 degrees C after six minutes and 40 seconds. Therefore, the environmental conditions of a 10 CPR 50.49 event will have no adverse effect on these cables.
The environmental qualification of this cable is based upon generic IEEE 383 1974 parameters. TVA is performing */litional tests to verify the qualification of the Brand Rex cable for life of plant. Environmental parameters have been chosen to bound the BFN applications for these cables.
In summary, based on the engineering evaluation results, the ability of the cables to perform their intended safety function for at least one cycle is unaffected by the anomalies identified. The complete evaluation is availabic on site for review. This closes the remaining open issue for cable installation at SFN.
If you have any questions, please telephone me at BFN, Site Licensing, (205) 729-3566.
Very truly yours, TENNESSEE VALLEY AUTHORITY
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$bOtff ( dNYG Patrick P. Carier, Manager of Site Licensing cc:
See page 3
-3 U.S4 Nuclear Regulatory Commission JAN 23 't991 cc:
Ms. S. C. Black, Deputy Director Project Directorate II-4 U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike, Rockville, Maryland 20852 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637 Athens, Alabama 35609-2000 Mr. Thierty M. Ross, Project Manager U. S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Mr. B. A. Wilson, Project Chief U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 i