ML19224D505
| ML19224D505 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 06/21/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Short T OMAHA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 7907120375 | |
| Download: ML19224D505 (1) | |
Text
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/ i NUCLEAR REGULATORY COMMISSION
.p ai REGION IV
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June 21, 1979 Docket No.
50-285 Omaha Public Power District ATTN:
T. E. Short, Assistant General Manager 1623 Harney Street Ocaha, Nebraska 63102 Gentlemen:
Enclosed is IE Bulletin No. 79-02, Revision No. 1, which requires action by you with regard to your paver reactor facility with an operating license or a construction pernit.
Should you have any questions regarding this Bulletin or the actions required by you, please contact this of fice.
Sincerely, s.
o M
l Y t.h,i Earl V. Seyfrit,
Director
Enclosures:
1.
IE Bulletin No. 79-02 Revision No. 1 2.
List of IE Bulletins Issued in Last Twelve Months cc:
R. L. Andrews, !!anager Fort Calhoun Station Post Of fice Box 98 Fort Calhoun, Nebraska 6S102 3 2 J 2 '" -
79071203 7 5
UNITED STATES NUCLEAR REGULATORY C0!!!!ISSION 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 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 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-Ap:11 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(c), 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 anchoc 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 nver 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 enployed for the use of concrete expansion anchors. The current trends in the industry are toward more rigorous controls and verification of the in-+al-lation of the bolts.
The data available on dynamic testing of the concrete expansion anchors show fatigue failures can occur at loads subN i?lM belnwthe. bolt sta,';ic.capa-s cities due to material imperfections or~
X j
'u su also show low cycle dynamic failures at DUPLICATE DOCUMENT ti due to joint slippage.
, ;l Entire document previously entered 6h A Lines indicate changes to previous ed into system under:
79<0 G 0M1 ANO 5q No. of pages:
k 321 256 6
.