ML20236H115

Safety Evaluation Supporting Util long-term Proposal for Support of Cable in Vertical Cable Trays Through Use of Stainless Steel Cable Ties

ML20236H115
Person / Time
Site:	Vogtle
Issue date:	07/30/1987
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20236H101	List: ML20236H099 ML20236H115
References
NUDOCS 8708050064
Download: ML20236H115 (1)

Text

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O l Enclosure Safety Evaluation Vogtle Units 1 and 2 Support of Cables in Vertical Cable Trays In SSER 4, the staff identified an open item regarding the seismic adequacy of plastic cable ties used to support seismic Class IE cables in vertical cable trays. The issues involved the load capacity of the plastic cable ties and the effects of aging, embrittlement, plastic creep, etc. on the structural behavior 3 of the ties over the life of the facility. By letter dated December 22, 1986, j the applicant (now licensee) provided justification for the use of plastic  ;

cable ties during the first fuel cycle and committed to address the long-term effects of plastic cable ties by June 1, 1987. The staff partially resolved this issue in SSER 5 by concluding, based on the licensee's December 22, 1986, submittal, that the use of plastic cable ties to support Class IE cables in

_ vertical raceways was acceptable for the first fuel cycle. However, the  !

adequacy of the plastic cable ties for the period beyond the first fuel cycle  !

was considered confirmatory pending staff review of the program to address  ;

long-tenn effects of the plastic ties.

l By letter dated May 27, 1987, the licensee provided a response to the remaining issue regarding long-term effects. In its May 27, 1987, response, the licensee comitted to use stainless steel cable ties to support cables in vertical cable trays. The stainless steel ties to be used at Vogtle Units 1 and 2 are fabricated from AISI Type 302/304 steel which has superior corrosion resistance and mechanical properties at elevated temperatures. This material will not

, experience plastic creep, embrittlement, or reduction in structural strength I

due to aging or environmental conditions as might the plastic ties. The .

licensee has conducted static pull tests on the stainless steel ties to {

establish the load capacity of the tie. The test method used to establish the load capacity of cable ties for various configurations of cable bundles was previously reviewed and accepted by the staff in SSER 5. The data from these .

tests, together with seismic and dead loads for the cables, and cable tie i spacings were used to maintain a minimum safety factor of 1.3. The safety  !

factor of 1.3 was accepted by the staff in SSER 5. l Based on the licensee's May 27, 1987, submittal, the staff concludes that with j the use of stainless steel cable ties to support seismic Class IE cables in l vertical cable trays the integrity of the cables will be assured over the life  :

of the facility. The staff further concludes that the requirements of General  !

l Design Criterion 2 of Appendix A to 10 CFR 50 is satisfied by the use of the j stainless steel tie wraps. These ties will be installed in Unit I before restart after the first refueling outage and will be installed in Unit 2 before fuel l load. Therefore, open item 22 is fully resolved for both units.

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