ML20106E224

Final Deficiency Rept,Item 134 Re Design Defect in Use of Bent Conduit.Initially Reported on 840809.Item Not Reportable Under 10CFR50.55(e)

ML20106E224
Person / Time
Site:	Fermi
Issue date:	10/08/1984
From:	Jens W DETROIT EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
134, EF2-70026, NUDOCS 8410290090
Download: ML20106E224 (2)

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- Nuclear Operatois' >

6 North Dixie Highway N)isNY[

October 8, 1984 EF2-70026

,Mr. James G.?Keppler.'

Regional Administrator

-Region III i

U. S. Nuclear Regulatory Commission 799' Roosevelt Road Glen Ellyn, Illinois 60137'

Reference:

(1)

Fermi 2 l

NRC Docket No. 50-341' (2)

Letter, W.-H. Jens to J. G. Keppler, September 10, 1984, EF2-63703

Subject:

Final Evaluttion of 10CFR50.55(e) Item 134

" Design Deficiency in Use of Bent Conduit" Detroit Edison has completed its investigation of Item 134,

" Design Deficiency in Use of Bent Conduit" and has deter-mined it is not reportable under 10CFR50.55(e). Item 134 was I

originally reported as a potential deficiency on August 9, 1984, and was subsequently documented in Reference (2).

l Specification 3071-128, Standards ED-1-1-8.26 and ED-2-3-4.2 specify criteria for the allowable length of spans contain-ing combinations of rigid and flexible electrical conduit.

Giffels Associates, Inc. prepared these standards for Edison approval via Design Change Notice DCN-10513; however, the use of bent rigid conduit was not considered during the developement of the standards.

This deficiency was discovered by Edison Field Engineering during a review of the structural acceptance of a parti-cular conduit spe'l of length in e.: cess of the allowable permitted by Specification 3071-128.

This span had a bent rigid conduit section and a flexible conduit section.

Field Engineering determined that the unistrut clamp at the rigid conduit must resist torsional slip caused by twisting of the conduit at the clamp if the conduit is to be considered seismically acceptable.

The unistrut clamp's resistance to torsional slip was not documented when the specification was developed.

8410290090 841008 OCT 15 E84 PDR ADOCK 05000341 d

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ji Mr. James G.

Keppler October 8' 198 4 EF2-7 0026 Page 2

.131e Detroit Edison Engineering Research Department tested three conduit strap assembly samples for each of the ten conduit sizes in use at Fermi'2.

The torque _value at which torsional slip of the conduit through the strap occurred -was determined.

Giffels Associates Inc. used this data to review spans of combined Lbent rigid and flexible conduit as allowed by Specification 3071-128.

Detroit-Edison. determined from this evaluation that no revision to the specification or re-work of installed conduit is required.

Therefore, Item 134 is not reportable under-10CFR50. 55(e).

This is Detroit Edison's final report of Item 134.

If you have questions concerning this matter, please contact Mr. Lewis Bregni, (313) 586-5083.

Sincerely, h

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cc:

Mr.

P.

M.

Byron Mr.

R. C.

DeYoung Mr.

R.

C. Knop s

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