ML19330B747

Final Interim Deficiency Rept Re RHR Heat Exchanger Lateral Support provisions.Non-standard Embed Plates Selected for re-insp.Addl Instructions Provided to Appropriate Const Supervisory & QC Insp Personnel.Insp Criteria Stressed

ML19330B747
Person / Time
Site:	Clinton
Issue date:	07/28/1980
From:	Koch L ILLINOIS POWER CO.
To:
References
U-0162, U-162, NUDOCS 8008050446
Download: ML19330B747 (3)

Text

'*O g

U-0162 ILL/ND/S POWER COMPANY y 3; Ll4-80(07-28)-9 j 500 SOUTH 27TH STREET DECATUR. ILLINOIS 62525 July 28, 1980 Mr. James G. Keppler Director, Region III Office of Inspection and Enforcement U.S. Nuclear Regulatory' Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137

References:

(1) Illinois Power Company letter U-0148, 6/13/80, L. J. Koch to J. G. Keppler, NRC Region III;

" Extension of Time for .10CFR50. 55(e) Final Report" (2) Telephone communication on 7/1/80, G. E. Wuller (IP) ahd H. M. Wescott, URC Region III;

" Additional Extension Request for Final Report" Clinton Power Station Unit 1 Docket No. 50-461 Construction Permit No. CPPR-137 Illinois Power Company has determined that the referenced potential reportable deficiency is reportable as per 10CFR50.55(e) (iii). We have conducted an investigation in this matter and herewith submit our final report concerning the RHR heat exchanger lateral support provisions.

Investigation of Incorrect Embed Plates for RHR Heat Exchanger Lateral Support

1. Statement of Reportable Deficiency Eight carbon steel plate embeds cast in the concrete structure surrounding the RHR heat exchangers were discovered to have plate thicknesses less than that indicated-on the drawings and required by the design. Two of these embeds were also mislocated.

2. Investigation Results During installation of the lateral supports for the RHR heat exchangers located in the Auxiliary Building, it was discovered that two of the eight embed plates had been mislocated in elevation by half of a plate width (top edge of the plate had been set at the desired elevation instead of the center line of plate). Nonconformance Report (NCR) 2959 was written for 80080506 % fI$ l o bi

U-0162 Ll4-80(07-28)-9 James G. Keppler July 28, 1980 Page 2 ,

thase mislocated embeds, cast into the 110 line wall, when connection of the lateral support steel could not be made.

Disposition'of NCR 2959 required that the concrete above the two plates be chipped down to a depth of one inch. New one-inch thick plates were to be bolted to the concrete wall and welded flush to the edge of the existing cislocated embed plates.

During the chipping operation, it was discovered thac the exist-ing plates were only one-half inch thick, not one inch thick as expected. At this point, it was realized that these two and the other six embed plates were of the wrong size. NCR 3207 was written documenting this nonconformance.

Subsequent study of the drawings revealed that a moment resist-ing connection had been designed for the lateral support structural steel members rather than the customary framed beam connection (simple support) . It had been assumed by both the contractor's personnel performing the take-off and installing the plates, and the QA instructors checking the installation prior to the concrete pours, that standard framed beam connections were to be used at these eight locations. Both failed to notice the note on the design drawing calling for non-s tandard embeds.

The QC inspectors also missed the details called out on the applicable inspection checklists.

3. Corrective Action The General Electric Company was contacted to determine what the effect would be to have a less rigid lateral support system than specified for the RHR heat exchangers. According to General Electric Company, considerable time would be required to determine the significance of this error. Therefore, as a practical matter, we assume the deficiency to be significant enough to be reportable, rather than stand the cost of a detailed and time-consuming engineering analysis.

Illinois Power Company has directed that the rework restore the RHR lateral support system to the stiffness specified by the General Electric Company's established criteria. Subsequently,

, the repairs were made.

To provide assurance that this embed installation / inspection

-error was an isolated occurrence, a population of non-standard i embed plates was selected for reinspection. Inspection  !

results have confirmed that this was an isolated instance.

To avoid recurrences of a similar nature,' additional instruction

[ _has been provided to appropriate construction supervisory and I

-s l l

mi

U-0162 Ll4-80(07-28)-9 James G. Keppler July;28, 1980 Page 3 QC inspection personnel. The requirements for accuracy in adhering.co design details and inspection criteria have been stressed.

We trust that the information provided in this final report is sufficient for your analysis and evaluation of the deficiency and the corrective. action.

Sincerely, L. J. Koch Vice President di cc: Director, Office of I&E, NRC, Washington, D.C.

H. H. Livermore, NRC Resident Inspector f