ML20082G275
| ML20082G275 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 08/12/1991 |
| From: | William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-PT21-91 CP-86-051, CP-86-51, IEIN-86-094, IEIN-86-94, TXX-91282, NUDOCS 9108160284 | |
| Download: ML20082G275 (2) | |
Text
O
- Y Log # TXX-91282
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File # 10110 227 22 903.9 Ref. # 10CFR50.55(e) 7UELECTRIC August 12, 1991 Wimam J. Cahill. Jr.
Enecwn Vke Presidreu U.S. Nuclear Regulatory Commission Attn:
Document Control Desk Washington, D.C. 20555
Subject:
COMANCHE PEAK STEAH ELECTRIC STATION (CPSES)-UNIT 2 DOCKET NO. 50-446 ANCHOR BOLTS SUPPLIED BY HILTI l
SDAR:
CP-86-051 (SUPPLEHENTAL REPORT)
Ref: TV Electric letter from William J. Cahill Jr.
to NRC dated April 5, 1989, logged TXX-89176 Gentlemen:
On July 17, 1986. TU Electric orally notified the NRC of a deficiency involving anchor bolts supplied by Hilti.
Information Notice 86-94 documented a condition found at another utility whereby the Hilti Kwik Bolts (HKB) did not meet the average tensile loads for certain sizes as published by the supplier.
Ililti's evaluation of this issue limited the problem to one-half inch diameter HKBs with design embedments of 3 1/2 inches and deeper.
CPSES site specific tensile strength testing of HKBs resulted in reduced tensile capacities for one-half and three-quarter inch diameter HKBs with embedments greater than 4 1/2 and 7 inches, respectively.
In the reference above, TV Electric committed to assess the applicability of these Unit 1 and Common evaluations to-Unit 2 to determine if any Unit 2 corrective actions are required. This letter addresses the Unit 2 corrective actions to resolve this issue.
For Unit 1, 594 one-half inch and three-quarter inch diameter HKBs with deep embedments were evaluated by Engineering.
Appropriate anchor bolt capacity reductions were calculated and compared to the dasiar loads. The evaluation results indicated a high level of confidence that concretc embedments performed to the current design criteria.
It shiuld be noted that the design and installation of Seismic Category I and 11 cor crete embedmects in both Units 1 and 2 were performed based on the same criteria.
To ascure that the corrfidence level obtained f rom Unit 1 is maintained for Unit 2, additional sampling surfaces in Unit 2 will be evaluated.
Deep embedment installations with one-half and three-quarter inch diameter HKBs will be selectei from l
Unit 2 surfaces for further engineering evaluation.
Similar to Uni' 1. these l
evaluations will include appropriate HKB tensile capacity reductions and a comparison with the design loads.
If the additional Unit 2 evaluations disclose the need for further corrective actions, a supplement to this report will be submitted describing those actions.
91081602f34 910812 PDR ADOCK 05000446 400 North Olive Street L B. 81 Dallas. lexas 75201
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.s TXX 91282 Page 2 of 2 To preclude recurrence, the applicable Design Basis Document (DBD) was revised to incorporate the reduction in the ultimate tensile capacity for the affected sizes of HKBs.
Additionally, the related Unit 2 installation specification provides instructions in installing affected HKBs with deep embedments.
The evaluation of the subject deep embedment installations will be completed prior to Unit 2 fuel load.
Sincerely,
,4 W. J. Cahill Jr.
CLW/RJB/rjb cc: Mr. R. D. Martin, Region IV Resident inspectors, CPSES (2)
Mr. M. Fields, NRR L
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