ML19224D506
| ML19224D506 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 06/21/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Millen C PUBLIC SERVICE CO. OF COLORADO |
| References | |
| NUDOCS 7907120377 | |
| Download: ML19224D506 (1) | |
Text
CEilTRAL FILES f" "' '%
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NUCLEAR REGULATORY COMMISSION
....i a., M-%gg hh. s REGION IV fl$1C k@d 0, fi/2,.E / [
611 RYArJ PLAZA DRIVE, SUITE 1000 h, \\/ [
AR Lt.'iG TON, T E X AS 7F,012
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June 21, 1979 Docket No.
50-267 Public Service Company of Colorado ATTIi:
fir. C. K, blillen Senior Vice President P. O. Box 840 Denver, Colorado 80201 Gentlecen:
Enclosed is IE Bulletin No. 79-02, Revision No. 1, which requires action by you with regard to your power Icactor facility with an operating license or a construction permit.
Should you have any questions regarding this Bulletin or the actions required by you, please contact this office.
Sincerely, O-
[ '. /-
-fpf l
,lV ')
Aarl V. Seyfrit' Director
Enclosures:
1.
IE Bulletin No. 79-02 Revision No. 1 2.
List of IE Bulletins Issued in Last Twelve Months D. W. Uarcebourg, Nuclear Produc'; ion cc:
11anager Fort St. Vrain Nuclear Station P. O. Box 368 Platteville, Colorado 80631 L. Brey, Manager, Quality Assurance 321 255 907120377 4
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT 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 March 8,1979, IE inspection experience and many inquiries from licensees indicate that additional inforn,a-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 s.tpersedes the text of Bulletin 79-02.
Changes from the original 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 March-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 of loads on some anchor bolts.
Initial investigation indicated that nearly fifty percent of the base plates could not be assumed to behave as rigid plates.
In addition, licensee inspection of anchor bolt installations at Shoreham has shown over fifty percent of the bolt installations to be deficient.
Vendor Inspection Audits by NRC at Architect Engineering firms 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 substantially below the bolt static capa-cities due to material imperfecticas or ~+ ^ + m "
~
i also show low cycle dynamic failures a r
due to joint slippage.
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