ML20098D895
| ML20098D895 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 09/10/1984 |
| From: | Jens W DETROIT EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 134, EF2-69705, NUDOCS 8409280021 | |
| Download: ML20098D895 (2) | |
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$4ff) fjo*Th Cme H ghway I S O n a u % cso Newf0ft f/ichgfin 40166 September 10, 1984 EF2-6 9705 Mr. James G. Keppler Regional Administrator Region III U.
S.
Nuclear Regulatory Commission 7 99 Roosevelt Road Glen Ellyn, Illinois 60137
Dear Mr. Keppler:
Reference:
(1)
Fermi 2 NRC Docket No. 50-341 (2)
Letter W.
H.
Jens to J.
G.
Keppler April 20, 1984, EF2-67809
Subject:
Report of 10CFR50.55 (e) Item 134
" Design Deficiency in Use of Bent Conduit" On August 9, 1984, De troit Ed iso n's Mr. Lewis P.
Bre g ni, telephoned Mr. J.
McCormick - Barger of the NRC Region III to report that the design for some conduit supports in Standard ED of Specification 3071-128 did not include considerations for bent conduit.
This discrepancy was discovered during a review of conduit supports. relating to 10CFR50.55 ( e) Item 119, Reference (2).
Description of Deficiency 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 co nd ui t.
Giffels Associates, Inc. prepared these standards for Edison aoproval via Design Change Notice DCN-10513; however, the use of bent rigid conduit was not considered during the development of the standards.
This deficiency was discovered by Detroit Edison's Field E ngi neering personnel during a review for the structural acceptance of a particular conduit span of length in excess 'g the allowable as required by Specification 3071-128-ED.
8409280021 840910 PDR ADOCK 05000341 S
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.o v'W Mr. James G. Keppler September 10, 1984 EF2-69705 Page 2-This span has a bent rigid conduit section and a flexible conduit section.
Field Engineering personnel' 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.
It was subsequently discovered that no prior research had been done to quantify a unistrut clamp's resistance to torsional slip, or to otherwise review the bent rigid with flexible conduit span case.
Standard ED-2-3-4. 2 diagram shows a straight line representing the rigid part of a combined rigid / flexible conduit span.
This line was interpreted by field design and inspection staf f as representing either a bent or straight rigid conduit sections.
Analysis of Safety Implications The structural integrity of conduit systems containing combined bent rigid / flexible conduit spans which contain safety related cables cannot be assured for design seismic event conditions.
Corrective Action The Detroit Edison Engineering Research Department (ERD) has been requested to test clamped conduit samples of sizes used on site so that the torsional resistance of clamped connections to conduit twist can be determined.
Gif fels Associates Incorporated has been requested to qualify combined bent rigid / flexible conduit spans based on the ERD data for worst case conditions.
Another report on this item, either interim or final, will be sent when further information is available.
If you have questions concerning this matter, please contact Mr. Le vis P.
Br eg ni, (313) 586-5083.
Sincerely, cc:
Mr.
P.
M. Byron Mr.
R.
C.
DeYoung Mr.
R.
C. K nop
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