ML19261E265
| ML19261E265 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 06/21/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Eric Turner HOUSTON LIGHTING & POWER CO. |
| References | |
| NUDOCS 7907050485 | |
| Download: ML19261E265 (1) | |
Text
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",h NUCLEAR REGULATORY COMMISSION
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REGION IV O
8 611 RYAN PLAZA DRIVE, SUITE 1000 s
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ARLINGTON, TEX AS 76012 June 21, 1979 In Reply Refer To:
RIV Docket Nos. 50-498/IE Bulletin No. 79-02 (RI) 50-499/IE Bulletin No. 79-02 (Rl) llouston Lighting & Power Company ATTN:
Mr. E. A. Turner, Vice President Power Plant Construction and Technical Services Post Office Box 1700 Houston, Texas 77001 Gentlemen:
Enclosed is IE Bulletin No. 79-02, Revision No. 1, which requires action by you with regard to your power reactor facilities with an operating license or a construction permit.
Should you have any questions regarding this Bulletin or the actions required by you, please con. tact t_his office.
Sincerely, 7
3.
N&
KarlV.Seyfri[!
Director
Enclosures:
1.
IE Bulletin No. 79-02 Revision No. 1 2.
List of IE Bulletins Issued in Last Twelve Months 9
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3 790705045'6
UNITED STATES NUCLEAR REGULATORY C0tNISSION OFFICE OF INSPECTION AND ENFORCEBIENT WASHINGTON, D.C.
20555 IE Bulletin No. 79-02 (Revision No. 1)
Date:
June 21, 1979 Page 1 of 6 PIPE SUPPORT BASE PLATE DESIGNS USING CONCRETE EXPANSION ANCHOR BOLTS Description of Circumstances:
Since the issuance of IE Bulletin 79-02 on Flarch 8,1979, IE inspection experience and many inquiries from licensees indicate that additional informa-tion and clarification is needed. This revision is intended to serve that purpose.
None of the requirements of the original Bulletin have been deleted, and the due date for completion of the requested actions (July 6, 1979) has not been changed.
The following text supersedes the text of Bulletin 79-02.
Changes from the c riginal text are identified by lines in the margin. The purpose of this revision is to identify acceptable ways of satisfying the Bulletin requirements.
While performing inservice inspections during a tiarch-April 1978 refueling outage at Millstone Unit 1, structural failures of piping supports for safety equipment were observed by the licensee.
Subsequent licensee inspections of undamaged supports showed a large percentage of the concrete anchor bolts were not tightened properly.
Deficiency reports, in accordance with 10 CFR 50.55(e), filed by Long Island Lighting Company on Shoreham Unit 1, indicate that design of base plates using rigid plate assumptions has resulted in underestimation or loads on some anchor bolts.
Initial investigation indicated that nearly fif ty percent of the base plate; could not be assumed to behave as rigid plates.
In addition, licensee inspection of anchor bolt installations at Shoreham has shown ovec fifty percent of the bolt installations to be deficient.
Vendor Inspection Audits by NRC at Architect Engineering Zirms have shown a wide range of design practices and installation procedures which have been employed for the use of concrete expansion anchors.
The current trends in the industry are toward more rigorous controls and verification of the instal-lation of the bolts.
The data available on dynamic testing of the concrete expansion anchors show fatigue failures can occur at loads ssG m
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cities due to material imperfections
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also show low cycle dynamic failures DUPLICATE DOCUMENT due to joint slippage.
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