ML20005A906
| ML20005A906 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 06/10/1981 |
| From: | Oprea G HOUSTON LIGHTING & POWER CO. |
| To: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| REF-PT21-81-459-000 PT21-81-459, PT21-81-459-000, ST-HL-AE-682, NUDOCS 8107020389 | |
| Download: ML20005A906 (4) | |
Text
The Light Company nooston tighting & Power P.O. Box 1700 Houston. Texas 77001 (713)228-9211 I
June 10, 1981 ST-HL-AE-682
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I Mr. Karl Seyfrit l
Director, Region IV
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l Nuclear Regulatory Commission S
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Dear Mr. Seyfrit:
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South Texas Project M
n-Units 1 & 2 Docket Nos. STN 50-498, STN 50-499 Third Interin Report Concerning HILTI Kwik - flolt l
Exoansion Anchors l
l On December 12, 1980, pursuant to 10CFR50.55(e), Houston Lighting & Power Company (HL&P), notified your office of an item involving a 10CFR21 notifica-tion by HILTI Inc. concerning the average ultimate tensile loads of their 1 inch concrete expansion anchors. Subsequently, on May 12, 1981, HL&P notified your j
office of preliminary results for an on-site testing program to confirm the average ultimate tensile load capacities, for concrete expansion anchors. The preliminary results identi,ied potential concerns with respect to several dia7eters of concrete expansion anchors manufactured by HILTI Inc. Please find attached our third interim report regarding this item. The next interim report will be submitted to your office by September 4,1981.
If you have any questions concerning this matter, please contact Mr.
Michael E. Powell at (713) 676-8592.
Very truly yours, h
L.
G. W. Oprea, Jr.
Executive Vice President MEP/fij Attachment
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J. H. Goldberg June 10, 1981 D. G. Barker ST-HL-AE-682 C. G. Robertson SFN: V-0530
-Howard. Pyle Page 2 R. L. Waldrop H. R. Dean D. R. Beeth J. D. Parsons J. W. Williams J. W. Briskin R. A. Frazar STP RMS H. S. Phillips (NRC)
J. O. Read (Read-Poland,Inc.)
M. D. Schwarz (Baker & Botts)
R. Gordon Gooch (Baker & Botts)
J. R. Newman (Lowenstein, Newman, Reis, & Axelrad)
Director, Office of Inspection & Enforcement Nuclear Regulatory Comission Washington, D. C. 20555 M. L. Borchelt Charles Bechhoefer, Esquire President Chairman, Atomic Safety & Licensing Board Central Power & Light Company U. S. Nuclear Regulatory Commission P. O. Box 2121 Washington, D. C.
20555 Corpus Christi, Texas 78403 R. L. Range Dr. James C. Lamb, III Central Power & Light 313 Woodhaven Road P. O. Box 2121 Chapel Hill, North Carolina 27514 Corpus Christi, Texas 78403 R. L. Hancock Mr. Ernest E. Hill Director of Electrical Utilities Lawrence Livermore Laborat*ory City of Austin University of California P. O. Box 1088 P. O. Box 808, L-123 Austin, Texas 78767 Livermore, California 194550 f
T. H. Muehlenbeck William S. Jordan, III
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City of Austin Harmon & Weiss P. O. Box 1088 1725 I Street, N. W.
Austin, Texas 78767 Suite 506 l
Washington, D. C.
20006 Lanny Sinkin J. B. Poston Assistant General Manager of Operations Citizens Concerned About Nuclear Power l
City Public Service Board 5106 Casa Oro P. O. Box 1771 San Antonio, Texas 78233 San Antonio, Texas 78296 r
A. vonRosenberg Citizens for Equitable Utilities, Inc.
l City Public Service Board c/o Ms. Peggy Buchorn P. O. Box 1771 Route 1, Box 1684 i
San Antonio, Texas 78296 Brazoria, Texas 77422 i
Brian E. Berwick, Esquire Jay Gutierrez, Esquire Assistant Attornay for the State of Texas Hearing Attorney P. O. Box 12548 Office of the Executive Legal Director Capitol Station U. S. Nuclear Regulatory Commission pusti,ng,eyas, M711,,,,,
T Wphington, D. C,,
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Third Interim Report Concerning HILTI Kwik-Bolt Concrete Expansion Anchors As previously identified in the Second Interim Report concerning l
this item, Houston Lighting & Power has conducted an on-site testing program to confirm the average ultimate tensile load capacity values for HILTI Kwik-Bolts. The results of the test are being evaluated by i
Engineering, however, preliminary findings are:
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a.
Generally, expansion anchors installed in concrete supplied to l
STP develop the capacity to carry loads equal to or greater than the capacities as published in the supplier's design manual.
b.
Expansion anchors tested at less than 28 days concrete age show a lower load carrying capacity than those tested at 28 days or more.
c.
In grout, a significant number of test results fell below the vendor's published values of the ultimate capacity of expansion anchors in concrete. There are, however, no ultimate load values for expansion anchors used specifically in grout.
d.
Non-perpendicularity of the expansion anchor in concrete or grout does not appear to affect the ultimate c3pacities when held within 6 degrees of normal.
e.
Torque relaxation amounts to about 25 percent of installation torque within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with 50 percent of that amount occurring in the first hour.
f.
Expansion anchors installed at the minimum embedment of 4.5 times the diameter and tested in tension generally caused a concrete shear cone type failure while embedments of 6 times the diameter and greater caused wedge slippage type failure.
i The 1/4 and 1/2 inch sizes of expansion anchors had the g.
greatest number of failures in tension, while the 1/4, 3/8, and 1/2 inch sizes had the largest number of shear failures.
Although a relatively large number of bolts have been used at STP, only a small percentage have been permanently installed in safety-l related applications. These safety-related applications include pipe supports and restraints, cable tray supports, and HVAC hanger supports.
As an immediate response to this concern the supplier has been informally advised of the preliminary test results which indicate ultimate values. Final test results as presented in the testing agency's report are being evaluated for safety significance and need for corrective action. Recurrence control will be provided through revisions, as necessary, to design criteria documents and appropriate l
construction procedures. The testing agency's report will provide the 1
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. bases for revisions to these documents. Designs will then be reviewed and revised as required relative
- to any revision of the design criteria documents.
A determination of the safety significance of this concern is pending review and evaluation of the data and information presented in the testing agency's report.
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