ML20106E226

Amended Final Deficiency Rept,Item 105 Re Electrical Conduit & Steam Pipe Thermal Separation Criteria violations.Case-by- Case Evaluation Resulted in Identification of One Violation in Main Steam Tunnel & 336 Violations in Drywell

ML20106E226
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
105, EF2-69718, NUDOCS 8410290095
Download: ML20106E226 (3)

Text

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. Vice Presxtent -

Nuclear Operatens Ferrnt-2 '

6400 North Duie Rghway

$3N Y" October 8,-1984 EF2-69718-Mr. James G. Keppler l Regional-Administrator

-Region III U.

S.. Nuclear Regulatory Commission

.799 Roosevelt Road

' Glen-Ellyn, Illinois 60137

Reference:

(1) Fermi 2 NRC Docket No. 50-341 (2) Letter, D. A. Wells to J. G. Keppler, December: 5, 1983, EF2-66482-(3) Letter, W. H. Jens to J. G. Keppler, August' 21, 1984, EF2-69695

Subject:

Amended Report of 10CFR50.55(e) Item 105

" Thermal Separation Criteria Violations" This letter amends Reference (3), Detroit Edison's final report of 10CFR50.55(e), Item 105, " Thermal Separation Criteria Violations."

The additional 'information requested by NRC Region III has been incorporated into this amended final report..

Description of Deficiency Edison Specification:3071-33 requires a minimum separation I

of 12 inches for conduits and traya crossing a single.insu-lated process steam pipe.-

Crossing multiple insulated steam pipes or running parallel to a single insulated steam pipe is to be avoided whenever possible; however, if not avoid-able a four foot separation is required.

Contrary to speci-fication requirements, the required separation was not main-tained in some cases.

This was discovered by Quality control during an electrical' inspection in the-steam tunnel.

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Mr. James G. Keppler October 8, 1984 EF2-69718 Page 2 Analysis of Safety Implications In situations where steam pipes are too close to electrical conduits and trays, localized high temperatures can result in the cable.

These high temperatures can affect the electrical characteristics of the cable and may result in premature degradation of cable insulation.

Corrective Action To disposition riiolations in the main steam tunnel of the cable thermal separation criteria in Specification 3071-33, the Detroit Edison Engineering Research Department developed methods to permit the evaluation of each violation on a case by case basis.

This method consisted of calculating curves showing the temperature rise of a cable as a function of:

pipe surface temperature, the separation between the pipe surface and conduit or tray surface, and the amount and type of pipe insulation.

Using these curves along with the specific pipe surface temperature and the allowable temp-erature rise of the cable,the minimum required separation was determined for each identified violation of the specification.

In the inspection of the main steam tunnel, 129 violations of the thermal separation section of specification 3071-33 were identified and evaluated in DDR E-12051.

Using the methods described above, all but one case were found to be acceptable.

The single unacceptable conduit was rerouted.

Based on the results of the inspection of the main steam tunnel, Ediscn determined that the potential for similar deficiencies existed in the Drywell.

Edison initiated a walkdown of the Drywell using special procedure, Number 7.39, " Inspection Requirements for Drywell Thermal Separa-tion Between Electrical Components and Hot Mechanical Components."

This inspection used DCN 10060 to Specifi-cation 3071-33 as the acceptance criteria.

This DCN contained a table that provided minimum separation as a function of the system pipe diameter.

This DCN permitted the acceptance of cable separations that were more restrictive than the separation which would be permitted by the calculational method, similar to that described above, but less restrictive than the single value specified in the original specification.

2.*'

Mr. James G. Keppler r.

-October 8, 1984 EF2-69718 Page 3 In the drywell, 855 violations of the criteria in DCN 10060 were identified and evaluated in DDR's E-13079, E-13080 and E-13083.

Individual determinations using-similar methods used for the steam tunnel violations were performed to evaluate each of these violations of DCN 10060.

As a result, 106 cases required that conduit be rerouted; 230 cases were dispositioned by the addition of thermal shielding;and 519 cases were found to be acceptable.

Specific descriptions of each violation and its disposition are available for inspection at the Fermi 2 site.

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

Sincerely, cc:

P.

M. Byron j(h R. C. DeYoung R. C. Knop V