ML19339A172

Interim Deficiency Rept Re Cracks in Insulation of Certain Feed Through Conductors of Entrance or Exit of Epoxy Module Portion of Penetration.Rework Procedure Has Not Been Formally Submitted.Supplemental Rept Expected by 810101

ML19339A172
Person / Time
Site:	LaSalle
Issue date:	10/02/1980
From:	Delgeorge L COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19339A170	List: ML19339A172
References
NUDOCS 8011030190
Download: ML19339A172 (3)

Text

- __ _______________

- 't

'/S Commonwealth Edison

() '

one First National Pista Chicago. Ilknois

-~ ~ M Address Reply to Post Office Box 767 e ,

Chicago, Illinois 60690 l

t October 2, 1980 Mr. James G. Keppler, Director Directorate of Inspection and Enforcement - Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137

Subject:

LaSalle County Station Unit 2 Electrical Penetration - 10 CFR 50.55(e)

Interim Report NRC Docket No. 50-374

Dear Mr. Keppler:

Commonwealth Edison notified your office on September 3, 1980 of a possible deficiency on the LaSalle County Unit 2 electrical penetrations. Cracks were discovered in the insulation of certain feed through conductors as they enter or exit the epoxy module portion of the penetration. This report provides the current status of the review of this issue. A subsequent report will be submitted by January 1, 1981.

I. Problem Definition A. Cracked insulation, exposing bare copper, was identified on certain conductors as these enter / exit the epoxy module portion of the penetration.

B. The cracks occurred approximately 1/4" from the face of the overmold portion of the epoxy modules.

C. The penetrations involved had modules which contained a high density of small diameter (approximately #14) conductors.

,0. The penetrations were manufactured by Bunker Ramo Corporation, Connector Division Sams Operation.

E. Site initiated NRC #156.

8 01103o110 OCT 6 980

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3 k .

II. Potential Cause A. For LaSalle penetrations, a single layer of heat shrink tubing or regular conductor insulation (no jack'eting) was used to insulate the cables as they enter / exit the module portion :af the penetration.

B. Phone conversation with Mr. M. Aaron, manufactor's Project Engineer, indicated the problem to be stress point in the insulation / heat shrink tubing caused by a mechanical bond between the potting compond (used to form the over-mold portion of the module) and the insulation / heat shrink tubing.

C. No report / analysis has been received from Bunker Ramo in writing.

III. Corrective Action Taken to Date  ;

i A. Bunker Ramo Corporation telecopied a rework procedure No. l SK-MA-ll70 Rev. I to Commonwealth Edison Station Nuclear ,

Engineering Department (SNED) for comments on September 8, j 1980. l B. On 9/22/80, SNED received a telecopy requesting return of four penetrations and two ; '.gtail assemblies for rework to SK-MA-ll70. 1 C. A rework procedure has not been formally submitted at this time.

D. Several concerns remain unanswered at this time:

1. The rework procedure issued for comnent addresses only.

the penetrations in which the heat shrink tubing was used.

2. The site feels very strongly that the acceptability of penetrations in which the regulary conductor insulation was used should be investigated.

3. The site questions the feasibility of the proposed

. rework procedure.

4 Discussions with SNED indicate a question on how the proposed rework will affect the seismic qualifications of the penetration.

E. On 9/26/80, SNED telecopied a letter to Bunker Ramo requesting a prompt response to a list of questions which when answered is expected to resolve the concerns identified above.

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l t l As has been stated, a supplemental report will be submitted on or before January 1, 1983. It is worth noting at this point that the electrical penetrations on LaSalle County Unit 1, Byron Unit 1 and 2, and Braidwood Unit 1 and 2 have also been assessed. The problem discussed herein is inapplicable to LaSalle County Unit 1, Byron Unit 1 and Braidwood Unit 1 because the electrical penetrations on those units were supplied by a different manufacturer (Conax). The Byron Unit 2 and Braidwood Unit 2 penetrations were produced by the same manufacturer as is tne case for LaSalle County Unit 2. However, the Byron /Braidwood design is different from that used on LaSalle County Unit 2. Furthermore, a sample inspection at Byron /Braidwood has not identified a similar problem. Upon completion of the failure mechanism assessment for the LaSalle penetrations the Byron /Braidwood Unit 2 design will be assessed to assure no design deficiency exists.

If you have any questions in this regard, please direct them to this office.

Very truly yours, L. O. De1 George Nuclear Licensing Administrator cc: Mr. R. Walker (NRC-RIII)

Resident Inspector - LSCS 7117A

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