ML20245C761

Safety Evaluation Concluding That Splices within Containment Annulus Consistent W/Industry Practice & Therefore Acceptable

ML20245C761
Person / Time
Site:	Sequoyah
Issue date:	10/30/1987
From:	NRC OFFICE OF SPECIAL PROJECTS
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ML20245C752	List: ML20245C749 ML20245C761
References
NUDOCS 8711030523
Download: ML20245C761 (2)

Text

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g l'- i UNITE D STATES h a NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C 20555

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SAFETY EVALUATION BY THE OFFICE OF SPECIAL PROJECTS

" JUSTIFICATION OF SPLICES IN ANNULUS TRAYS" TENNESSEE VALLEY AUTHORITY, SEQUOYAH NUCLEAR POWER PLANT, UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328

1.0 INTRODUCTION

Cable splicing is generally not recommended in cable trays in order to minimize adjacent cable trays.the potential for overheating and fire to circuits within a ca a fire stop for the splices in annulus cable trays.At Sequoyah, a special enc inspectors raised a question regarding cable splices in the annulus traysDurin and requested the enclosure the Tennessee configuration used.Valley Authority (TVA) provide justification for By letter dated April 30, 1987, TVA provided justification for cable splices in the annulus trays.

TVA stated that these and therefore, are suitable for use in Sequoyah Nuclear Plant 2.0 EVALUATION We have reviewed TVA's letter of justification dated April 30, 1987, and requested additional information (RAI) by letter dated August 3,1987, regardirig1,the September qualification of the electrical splices. By letter dated 1987 contained an error, TVA responded to the RAI stating that its earlier submittal regarding the number of splices involved. The splices in ends at each penetration assembly. question are located within the last 5 This is to allow splicing of the vendor ',

penetrations containment liner.pigtails to the field cables on the outboard side of the steel

• of containment electrical penetration for low voltage power cable I

cables and instrumentation cables, which feed a variety of equipment. TVA has also stated that the splices are performed in accordance with vendor-recom-mended splicing procedures and fully meet the environmental qualification requirement for this area of the plant. ,

separation requirements of the single failure criterion of IEEECable routing also me i 279-1971. TVA '

frequencies in accordance with Sequoyah Technical Spe i outage with complete inspection and maintenance every 5 yea l

design is based on full scale mockup tests. TVA's enclosure NUREG-0011 Supplement No. 1 Section 9, dated Febru TVA has also made a commitment to revise FSAR Section 8.3.1.2.3 in the next annual update to include a description of the splice enclosure used in the annulus trays.

8711030523 871030 DR ADOCK 050 7

i The NRC staff evaluation of cable splices in the annulus trays at Sequoyah is based on two criteria. The first is that a postulated fire is contained within the affected cable tray and the second is the electrical separation of redundant Class 1E cables. As stated above, NUREG-0011 Supplement 1 states that NRC has evaluated the Sequoyah electrical penetration fire stops for cable and cable trays and has concluded that the design is acceptable with respect to fire resistibility and consistent with the guidance of Appendix A to BTP ASB 9.5-1.

With regard to cable separation, FSAR Section 8.3.1.4.2 states that the Sequoyah design has ensured cable separation such that no single event, such as a fire, is capable of disabling sufficient equipment to prevent safe shutdown of the reactor, removal of decay heat from the core, or isolation of the primary containment. Therefore, the approved design and the separation of Class 1E cables ensures sufficient equipment will not be disabled from any single event, such as a fire, as discussed above.

3.0 CONCLUSION

Based on our review of the information provided, we conclude that the splices within the containment annulus are consistent with industry practice and in the unlikely event of a fire in a splice area, the fire is contained within the affected tray and therefore, cannot propagate to adjacent trays or electrical equipment and hence are acceptable.

Principal Contrbutor: H. Garg, T. Rotella Dated:

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