ML19347D047
| ML19347D047 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 03/05/1981 |
| From: | Oprea G HOUSTON LIGHTING & POWER CO. |
| To: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, ST-HL-AE-632, NUDOCS 8103100610 | |
| Download: ML19347D047 (5) | |
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Mr. Karl Seyfrit Director, Region IV
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Nuclear Regulatory Commission Y
611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76012
Dear Mr. Seyfrit:
South Texas Project Units 1&2 Docket Nos. STN 50-498, STN 50-499 Final Report Concerning Stud Welds on Concrete Embedments On July 31, 1930, Houston Lighting & Power Company, in accordance with 10CFR50.55(e), notified your office of an item concerning studs welded to concrete enbedded plates. Our final report is attached.
A safety analysis perfomed with respect to this condition has deter-mined that no safety hazard would exist if the condition were left uncorrected.
If there are any questions, please contact Mr. Michael E. Powell at (713) 675-8592.
l Very truly yours,
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E ec ive Vice President ol RRH/ par S
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Nmion Ughting & Power Compam March 5, 1981 ST-HL-AE-632 cc:
J. H. Goldberg SFN: V-0540 D. G. Barker Page 2 Howard Pyle R. L. Waldrop H. R. Dean D. R. Beeth J. D. Parsons G. B. Painter L. K. English J. W. Briskin R. A. Frazar H. S. Phillips (NRC)
J. O.
Read (Read-Poland,Inc.)
M. D. Schwarz (Baker &.Botts)
R. Gordon Gooch (Baker & Botts)
J. R. Newman (Lower. stein, Newnan, Reis & Axelrad)
Director, Office of Inspection & Enforcement Nuclear Regulatory Commission Washington, D. C.
20555 M. L. Borchelt Charles Bechoefer, Esquire Executive Vice President Chairman, Atomic Safety & Licensing Board Central Power & Light Company U. 5. 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 Dr. Dnmeth A. Luebke Director of Electrical Utilities Atomic Safety & Licensing Commission City of Austin U. S. Nuclear Regulatory Commission P. O. Box 1088 Washington, D. C.
20555 Austin, Texas 78767 T. H. Muehlenbeck Citizens for Equitable Utilities City of Austin c/o Ms. Peggy Buchorn P. O. Box 1088 Route 1, Box 1684 Austin, Texas 78767 Brazoria, Texas 77422 J. B. Poston Pat Coy Asst. General Manager of Operations
' Citizens Concerned About Nuclear Power City Public Service Board 5106 Casa Oro P. O. Box 1771 San Antonio, Texas 77422 San Antonio, Texas 78296 A. vonRosenberg Betty Wheeler City Public Service Board Hoffman, Steeg & Wheeler
'P. O. Box 1771 1008 S. Madison San Antonio, Texas 78296 Amarillo, Texas Brian E. Berwick Bernard M. Bordenick Asst. Attorncy for the State of Texas Hearing Attorney P. O. Box-12548 Office of the Executive Legal Director Capitol Station U. S. Nuclear Regulatory Commission Austin, Texas 78711 Washington, D. C.
20555
FINAL REPORT CONCERNING STUD WELDS ON C0f' CRETE EMBEDMENTS MARCH B, 1981 1.
SUMMARY
During an unscheduled inspection of the Category 1 embed plate site storace area at the South Texas Project, it was observed that portions of the ceranic ferrules were attached to the fillet welds of some studs on the embedded plates. The presence of the ceramic ferrules established that a portion of the stud welds had not received a 1007, visual inspection as required by AWS D1.1 (1975) and.the South Texas Project Specification " Miscellaneous Steel for Category 1 Structures". On July 31, 1980, Houston. Lighting &
Power Company, in accordance with 10CFR50.55(e), notified the Nuclear Regulatory Commission of this item of nonconformance.
In order to identify the extent of this nonconformance a rein-spection of all embedded plate in the field was immediately
. initiated. Over 3'96,000 stud welds were reinspected. A total of
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162 stud welds were rejected and an additional 49 studs were fourid to be missing.
Additionally, a safety analysis has been performed which concludes.
that this item if left uncorrected would not result in a safety hazard.
II. DESCRIPTION OF THE INCIDENT Steel embeds for Category 1 applications at the South Texas Project, Units 1 & 2, have been fabricated offsite by structural steel suppliers and onsite by Brown & Root. These embed plates should have been fabricat ej in accordance with a South Texas Project Specification, " Miscellaneous Steel for Category 1 Structures". The. inspection of the stud welds was required to be performed in accordance with AWS DI.1 (1975) which requires that
'the stud weld be inspected 100% visually.
During an unscheduled inspection of _the Category I embed plate storage area at the South Texas Project it was observed that portions of the embed _ stud plate welds were covered by portions of the ceraaic ferrules. The ceramic ferrule is useo in the actual welding of the stud to the steel plate but it must be removed in
. order to provide 100% visual inspection of the completed weld.
4 III. CORRECTIVE ACTION Upon identification of the nonconforming condition, a stud weld reinspection program was initiated at the South Texas Project.
This program was applied to both vendor fabricated and field fabricated embed plates. This program has resulted in rein-spection of over 396,000 stud welds. Of this number, 2,371 studs were found to have incomplete welds. Consistent with AWS code:
requirements, the. studs with incomplete welds were subjected to a hammerbend test and _162 were found to be rejectable. Addition-ally, 49 studs were found t-o be missing..These nonconforning conditions were -limited to vendor fabricated embed plates..
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During this investigation plates found with nonconforming conditions have been appropriately ider;tified and segregatec: from acceptable plates. Rejectable welds are being repaired and the missing studs replaced to bring the specific embed into compl iance. All welding carried out in the repair of the embed is being performed consistent with our AWS welding program require-ments.
In order to prevent a recurrence of the noted conditions, Project Vendor Surveillance personnel have been reinstrected in AWS D1.1 acceptance standards. Additionally, Vendor Surveillance personnel are now required to verify that 100% visual inspection of all stud welds has been performed prior to shipment of embed plates. No final inspection waivers prior to shipment are authorized.
Consistent with previous practice,100% visual inspection of stud welds on field fabricated embed plates will continue.
IV.
SAFETY ANALYSIS A safety analysis has been performed regarding the nonconforming embed plate conditions. This analysis assumed the application of the full' design load at-the site of 'a missing or defective stud.
In some cases it was found that stresses may exceed the design allevable for the embed plate, however, in no case would the ultimate strength capacity be exceeded and failure would not occur. Therefore,-ic has been determindd that no significant safety hazard would exist -if the nonconforming conditions were
.left uncorrected.
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