ML19319C060

Responds to NRC 770114 Question Re Cable Tray Fill Exceeding Tray Side Rails,As Allowed in Fsar,Section 8.3.1.2.20. Clarifies Impact on Separation Criteria & on 60% Fill Limitation for Essential Sys Control Cable Trays

ML19319C060
Person / Time
Site:	Davis Besse
Issue date:	01/26/1977
From:	Roe L TOLEDO EDISON CO.
To:	Stolz J Office of Nuclear Reactor Regulation
References
NUDOCS 8001310439
Download: ML19319C060 (3)

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EDISON Docket No. 50-346 .-t M, -5

• LOWELL E. RCE 49 Seria1 No. 195 \0 &' k T';[,*E",',,,,,,,,,,

January 26, 1977 So

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// 1 Director of Nuclear Reactor Regulation  %

el i e Attn: Mr. John F. Stolz, Chief Light Water Reactors Branch No. 1 k eldflyg

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• United States Nuclear Regulatory Commission

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Washington, D. C. 20555

Dear Mr. Stolz:

This letter presents our response to a clarification requested orally by staff member Mr. Andy Szukiewicz at our meeting in Bethesda on January 14, 1977, re-garding the Davis-Besse Nuclear Power Station Unit No. 1 Mr. Szukiewicz asked for clarification of the impact upon separation criteria by :able tray fill exceeding tray side rails as allowed in section 8.3.1.2.20 of che FSAR (page 8-21d), and the impact of such fill practices upon the 60%

fill limitation for control cable trays related to essential systems. This item also relates to SER Outstanding Review Item 15.

We have the following responses to Mr. Szukiewicz's requests:

1) Where the intent of vertical cable tray separation criteria would be negated by cable exceeding the tray rail heights, the inclusion of thermal insulating material provides the required separation in accordance with the criteria of the last paragraph of FSAR section 8.3.1.2.20.

2) The cable cross-sectional area above the tray side rails is included with the cable cross-sectional area within the side rails in deter-mining tray fill percentage.

3) The minimum cross-sectional area of the cable tray cross fittings used is 90% of the combined cross-sectional area of the two (2) intersecting trays, and therefore, in veder to maintain the 60% fill limitation within the cross fitting, limits the fill to 54% (90% of 60%) in the entering and exiting legs of the cross. We have verified that in no instance is there any essential system tray cross fitting with entering or exiting legs having a cable fill in excess of 54%. The identified 54% fill limitation will be maintained for tray cross fittings' legs on essential system trays.

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THE TCLEDO ECISCN CCMPANY EDISCN PLAZA 300 MADISCN AVENUE TCLECO, CHIO 43652 l

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Mr.. John'F. Stolz January 26, 1977

4) By not exceeding the 60% fill limit on each leg, recognizing that cables cannot terminate within a Tee, the exceeding of the 60% fill of the Tee is prevented.

The above information should allow the conclusion of Mr. Szukiewicz's review of this matter.

Yours truly, CCs 1

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