ML20093A487

Second Interim Deficiency Rept 84-03 Re Butt Splices in Electrical Conductors.Acceptance Criteria Utilized for Reinsp of Both Covered & Uncovered Butt Splices & Evaluation of Data Encl.Next Rept Will Be Submitted by 840710

ML20093A487
Person / Time
Site:	Byron
Issue date:	07/02/1984
From:	Tramm T COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
84-03, 84-3, 8899N, NUDOCS 8407100559
Download: ML20093A487 (7)

Text

_

, Commonwealth Edison

/ on) First National Plf za. Chic':go, Ilknois 7 Address Reply to: Post Office Box 767 Chicago, I!!inois 60690 July 2, 1984 Mr. James G. Keppler, Regional Administrator United States Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137

Subject:

Byron Generating Station Units 1 and 2 Electrical Conductor Butt Splices N_RC Docket Nos. 50-454 and 50-455 References (a): May 17, 1984 letter from D. L. Farrar to J. G. Keppler.

(b): May 25, 1984 letter from R. L. Spessard to Cordell Reed.

(c): June 6, 1984 letter from R. L. Spessard to Cordell Reed.

(01: June 12, 1984 letter from T. R. Tramm to J. G. Keppler.

Dear Mr. Keppler:

ibis letter provides the second interim report of a deficiency potentially reportable pursuant to 10 CFR 50.55(e) regarding butt splices in electrical conductors at Byron station. A final report is expected to be available by July 10, 1984. For tracking purposes, this deficiency is numbered 84-03.

As indicated in the first interim report submitted in reference (d), a reinspection program was undertaken in May, 1984 to verify the acceptability of crimped butt splices in electrical conductors. This letter presents an overall summary of the data accumulated during this reinspection program. Attachment A to this lists contains the acceptance criteria utilized for the reinspection of both uncovered and covered butt splices. It identifies by unit the quantity of deficiencies identified for each criterion. Attachment B to this letter presents our evaluation of the reinspection data.

During this reinspection, 1,311 butt splices were identified on conductors of safety-related cables on Byron 1 and 2. 747 of these installed butt splices were found uncovered (i.e., without a tape and cement or heat shrink covering). Documented visual inspections were performed on all 747 splices. The remaining 564 installed butt splices b ib 8407100559 840702 PDR ADOCK 05000454 S PDR $

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J. G. Keppler July 2, 1984

'identified were found covered with heat shrink material or nuclear cement and tape. Their installation location'was documented by identifying the cable number on which they were installed, the specific conductors of the cable, and the-equipment number of the component in which they were located.- Of the 564 covered butt splice installations identified, 92 were determined to be associated with redundant cables. These 92 butt splices were cut out and had the covering material removed. Documented visual inspections were performed on all 92 splices.

A total'of 839 butt splices were visually inspected. 65 of these splices are considered unacceptable for various reasons as described in Attachment A. The reject rate is 7.7%, well below the 10%

threshhold. established in. reference (a) for expansion of the reinspection program. The visual inspection work has therefore been terminated.

In general, it appears that the butt splice installation discrepancies observed are relatively minor. The spliced conductor would

- probably have' performed satisfactorily for the life of the plant. The potential safety significance of all defects will, however, be determined. This work is now in progress and the results will be reported in the final report on this discrepancy.

This is still considered to be a discrepancy which is potentially reportable pursuant to 50.55(e). The final determination of reportability cannot be made until the engineering evaluations have been made to determine if_these butt splice deficiencies could have adversely af fected the safety of plant. operations if they had not been detected.

As. identified in reference (b), the implementation of this reinspection program has been under constant surveillance at Byron by Region III electrical inspectors.

Very truly yours, f 0.fA&W T. R. Tramm

. Nuclear Licensing Administrator 1m

- Attachment 8899N'

ATTACHMENT A Deficiencies Identified in Electrical Butt Splices There was a total of 747 uncovered butt splices identified during the program which were visually inspected. Of these, 653 on Unit'l and 31 on Unit 2 were determined to be acceptable. All 747 butt splices were inspected per the criteria in Table A-1 below. This table

-identifies by criterion-the quantity of deficiencies identified on each unit during the reinspection program for uncovered butt splica installations.

TABLE A-1 Acceptance Criteria For Installed Butt Splices UNCOVERED Deficiencies Unit Unit Criterion 1 2

1. The butt splice installed appearsoto have been crimped with the proper tool. 2 0  ;

I2. The butt splice installed is the proper size for the size of cable it is installed on. 0 0  :

3. The conductor crimp is approxiately centered on the wire barrel. 11 0

4. The end of the conductor is visible beyond the point of crimp. 47 4

5. The conductor insulation is approximately flush with or under the insulating sleeve of the butt splice.. 0 0 Total Deficiencies Identified: 60 4 Note: 1 butt splice was deficient for both criteria 3 & 4, so there were 64 deficiencies on 63 splices.

I Attachment A There was a total of 92 covered butt splices identified during the program which required the removal of the covering material so that a visual inspection could be performed. Of these, 90 were determined to be

-acceptable. All 92 of these butt splices were associated with Unit 1

. cables, and they were all inspected per the criteria in Table A-2 below.

This table identifies by criterion the quantity of deficiencies identified on each unit during the reinspection program for covered butt splice installations.

TABLE A-2 Acceptance Criteria For Installed Butt Splices COVERED Deficiencies t Unit Unit Criterion 1 2

1. The butt splice installed appears to have been crimped with the proper tool. 0 0

2. The butt splice installed is the proper size for the size of cable it is installed on. 0 0

3. The conductor crimp is approximately centered on -

the wire barrel. 2 0

4. The end of the conductor is visible beyond the 1.

c point of crimp. 0 0 [

2 0 t

Note: The covering on these splices made it unnecessary I to impose any acceptance criterion on the conductor t insulation, as was done for uncovered splices.

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ATTACHMENT B Evaluation of Butt Splice Reinspection Data l

PROGRAM The butt splice reinspection program consisted of the inspection Ond documentation of previously installed butt splices on conductors of safety-related control and instrumentation cables located in safety-related panels, switchgear, motor control centers and both sides of electrical penetrations. The four basic phases of this reinspection program were:

1. Inspect the butt splices which were found to be uncovered and document the results of these inspections.

2. Document the installation location (i.e. equipment, cable and l cable conductors) of butt splices found which were covered with heat shrink material or nuclear cement and tape. I

3. For any redundant cables identified in item 2 above, remove the butt splice (s) installed on one of the cables, remove the covering material and document the inspection concerning the condition of the butt splice as it was found to be installed.

4. Accumulate the results of items 1 and 2 above and determine the overall inspection rate for installed butt splices. If the rejection rate for the overall program was greater than 10%,

then all remaining butt splices identified in item 2 above wou]d be required to be reinspected or replaced.

The inspection activities associated with this reinspection program identified 1,311 butt splices installed on approximately 454 safety related cables associated with Byron Units 1 and 2. For this reinspection effort, 7,246 safety-related cable ends ware documented as having been inspected. The inspection documents and the butt splices which were removed and dissected are all on file.

n a Attachment B RESULTS-The tabulation of the results of this butt splice inspection as it? relates to these four phases of'the program are:

31. . Uncovered-Butt Splices

-The total quantity of. uncovered butt splices identified and reinspected was 747;

'a) Quantity rejected by the initial inspector 275 b) Quantity.found acceptable by 2nd inspector aft.r dissection 16

- c )- Quantity found acceptable based on manufacturer's documented test data 196

? Total Acceptable.After Dissection 212 d) Quantity rejected for inspection criterion (1) 2 e) Quantity rejected for inspection crtierion (3) 10 f)'. Quantity rejected 1for inspection criterion (4) 51

_. Total Rejected After Dissection 63 Total ~ Dissected Butt Splices 775 The accumulated results for uncovered-butt splices inspected, therefore,

- ields 63 rejectable . butt. splices identified out of a total of 747.

L{nspected gin reference to--item 1.(a)-above, the butt splices which were

' initially; inspected.in'the-plant and found rejected, were cut out and

-tagged to identify the cable and the conductors on which they were found. These butt splices were then brought into the office and dissected-and-reinspected by a second QC inspector. This inspection was documented.and attached to the original inspector's inspection report

[see item 1.(b)]. This was done because the conditions surrounding

. installed: butt splices did not always allow easy. accessibility for

reinspection.-

, ~ 2. Covered Butt ~ Splices A total quantity of 564 covered butt splices have been identified and

, their installation-location has-been documented.

3. ' Redundant Butt Splice Installations Of the 564. covered butt-splices identified in item 2 above, 92 butt splice installations'were identified as being redundant and required

inspection. _These butt splices were all cut out and dissected in the

construction > office with the following results

o , .

Attachment B a) Quantity of covered butt splices removed and 92 dissected b) Quantity found to be acceptable after inspection 16 c) Quantity found to be acceptable based on manufacturer's documented test data 74 Total Acceptable After Dissection 90 d) Quantity rejected for criterion (3) 2 Total rejected after dissection 2 Total covered butt splices dissected and inspected 92

4. Accumulated Results There'was a total of 1,311 installed butt splices identified in this program. 747 were found uncovered and were inspected. 564 were found covered with heat shrink material or nuclear cement and tape, and were inspected.

a) Total quantity of uncovered butt splices inspected 747 b) Total quantity of covered butt splices dissected and inspected 92 c) Total quantity of butt splices installations inspected in the program 839 d) Total quantity of uncovered butt splices found rejected 63 e) Total quantity of covered butt splices dissected and found rejected 2 f) Total quantity of butt splice installations inspected and found rejected during the program 65 The rejection rate for the overall program (item f divided by item c) is calculated to be 7.7%.

BASIS FOR ACCEPTANCE With reference to items 1.(c) and 3.(c) above, during this butt splice inspection program, installed butt splices (size #16-14) were identified which appeared to be crimped with a #22-18 crimping tool rather than the size #16-14 tool. While this tool is not the correct tool for crimping a #16-14 size butt splice / wire, it is, an acceptable

(" proper") crimping tool for butt splice installation. Tests on such splices by the manufacturer and at Byron station indicate that the #22-18 tool makes crimps in #16-14 butt splices which are in all respects acceptable and in some respects superior to those produced with the size

1. 16-14 tool. After evaluation of these test results, previously installed butt splices which were identified to have been crimped with the #22-18 crimping tool were considered to be acceptable and items of this nature previously reported were removed from the deficiency population.

8899N u