ML20023C384

Final Significant Deficiency Rept SD 413-414/82-23 Re Violation of Const Procedures for Mixing & Placing Sikatop 122 During Drill Hole Repair.Initially Reported on 821208.Test Program Concluded Sikatop 122 Acceptable

ML20023C384
Person / Time
Site:	Catawba
Issue date:	05/06/1983
From:	Tucker H DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
10CFR-050.55E, 10CFR-50.55E, SD-413-414-82-2, NUDOCS 8305170292
Download: ML20023C384 (3)

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DUKE POWER GOMPANY P.O. HOX 33180 GilAHLOTTE, N.G. 28242 IIALH. TUCKER TELEPHONE WM E PRESfDENT 904)3 M 531 WELLE4B Ph4pCCTION May 6, 1983 Mr. James P. O'Reilly, Regional Administrator $

U. S. Nuclear Regulatory Commission 3::

Region II Q , ,

101 Marietta Street, NW, Suite 2900 -

" Qg Atlanta, Georgia 30303 .>J ,

lb cy n Re: Catawba Nuclear Station c.o (n _O Units 1 and 2 - 00 Docket Nos. 50-413 and 50-414 -

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Dear Mr. O'Reilly:

Pursuant to 10 CFR 50.55e, please find attached a final response to Significant Deficiency Report SD 413-414/82-23.

Very truly yours, hM Hal B. Tucker I

~p RWO/php Attachment cc: Director Mr. Robert Guild, Esq.

Office of Inspection & Enforcement Attorney-at-Law U. S. Nuclear Regulatory Commission P.O. Box 12097 Washington, D. C. 20555 Charleston, South Carolina 29412 Mr. P. K. Van Doorn Palmetto Alliance NRC Resident Inspector 2135 Devine Street Catawba Nuclear Station Columbia, South Carolina 29205 l

INPO Records Center Suite 1500 l

1100 Circle 75 Parkway Atlanta, Georgia 30339

. . c;1C Yz ,c,OTb 8305170292 3 PDR ADOCK 0 PDR t'

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Duke Power Company Catawba Nuclear Station Report Number: SD 413-414/82-23 Initial Report Date: December 8, 1982 Final Report Date: May 6, 1983 Corrective Action:

Test programs were initiated to determine the quality of a typical repair made with SikaTop 122 at a dry pack consistency. Several holes 5/8 inch, 1 inch, and 2 inches in diameter were drilled into a test slab and dry packed with SikaTop 122. Repairs were performed on October 28, 1982, and left to air cure.

On November 5, one inch and 5/8 inch diameter holes were drilled at locations varying from completely within a repair to tangent to a repair. During drilling of these holes, the repair material did not ravel and the drill did not drift.

Expansion anchors were then installed into the holes drilled into the larger repairs and axially loaded to failure. In each case, failure resulted in a conical fracture extending from the base of the anchor through the repair material and into the concrete. The anchor capacities achieved correlated well with the capacities anticipated in sound concrete. The repaired areas were therefore found to have negligible effect on the capacity of the anchors.

A test program was also initiated to define the strength characteristics of SikaTop 122. Two inch cube specimens were cast for testing at 3, 7, 14, 28, 56 and 90 days. Specimens were cast with material mixed to a dry pack consistency and with material mixed with the total quantity of liquid component to a workable consistency. The placing and tamping of the dry pack specimens simulated actual field conditions. The specimens cast with material at the workable consistency were molded in accordance with ASTM C109-80. All specimens were cured with wet burlap for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and then stored in air in the laboratory until the time of test. Half of the specimens were removed from their molds after casting while the other half remained in their molds until immediately before testing.

l Typically, the average strength of the dry pack specimens was greater than the I

average strength of the ASTM C109 molded specimens at all stages of testing.

The 90-day compressive strengths of the dry pack specimens and the ASTM C109 molded specimens averaged 10750 psi and 10400 psi, respectively. Test results i indicate that the SikaTop 122 material will have acceptable strength when mixed and placed as both a dry pack and a workable mortar.

A test program was also initiated to determine the influence that an improperly made repair might have on installed expansion anchors. A list of hangers whose

! anchors were likely installed in or near repairs made with SikaTop 122 was compiled by reviewing the documentation forms for abandoned drill holes repaired during the months of May 1982 through September 1982. Each of these hangers l

was assigned a number. A statistical sampling approach was then used to determine within a 95% confidence level that less than 5% of the anchors installed could be adversely affected by an improperly made repair. The Random Numbers Table from CRC Standard Math Tables, 24th Edition was used tt generate random numbers.

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Hangers corresponding to the random numbers selected comprised the random sample population. Test procedures required that at least one anchor on a minimum of 74 hangers be tested. If a hanger was inaccessible, it was eliminated from the sample population and the next hanger on the sample list was tested. Anchors were tested by a calibrated center-hole hydraulic jack, pressurized by a hand actuated pump. Anchors were loaded to 125% of their design capacity and held for 60 seconds before unloading. A total of 119 anchors on 74 hangers were tested and found to hold the imposed load verify-ing a 95% confidence level; less than 5% of the anchors installed could be affected by improperly made repairs.

Based on our tests and investigations, it can be concluded that SikaTop 122 is acceptable for use at a dry pack consistency. Repairs properly made with SikaTop 122 at this consistency will have adequate strength and will not adversely affect the capacity of anchors located in or near the repairs. The faulty repair which initiated the concerns resulted from peor workmanship or the use of incompletely mixed and drying material. The tests on in-place anchors indicate, however, that the possibility of other repairs being made improperly and having detrimental effect on anchor capabities is negligible. To ensure that SikaTop materials are properly mixed and placed, craf t personnel have been retrained in the proper methods for mixing and placing. Construction Procedure 447, " Proprietary Material for Concrete Repair", will also be revised to provide the following additional guidance: 1) SikaTop materials shall be mixed until the components are thoroughly combined. Mixing time shall be 3 to 5 minutes;

2) Combined SikaTop material shall be placed within 15 minutes after mixing.

After this time unused material shall be discarded and 3) Reduction of the powder "B" component into smaller units shall be accomplished in a manner similar to Method A - Mechanical Splitter of ASTM C702-80. These requirements will ensure that the material is properly mixed and is used before it dries significantly.

The investigation indicates that SikaTop 122 was not used as a dry pack at McGuire or Oconee Nuclear Stations and that similar problems have not been experienced at these stations. Construction procedures at these plants nevertheless will be revised in a similar manner to Catawba's to provide better guidance in the mixing and placing of SikaTop materials.

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