ML19224D308
| ML19224D308 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 05/07/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Nichols T SOUTH CAROLINA ELECTRIC & GAS CO. |
| References | |
| NUDOCS 7907110333 | |
| Download: ML19224D308 (1) | |
Text
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'.i UNITED ST ATE 3 t>* "8 009 y*
NUCLEAR REGULATORY COMMISSION R EGloN 11 b
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MAY 7 1979
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In Reply Refer To:
RII:JPO South Carolina Electric and Gas Company Attn:
Mr. T. C. Nichols, Jr.
Vice President and Group Executive Power Production and System Operations P. O. Box 764 Columbia, South Carolina 29218 Gentlemen:
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This Information Notice is provided as an early notification of a possibly significant matter. It is expected that recipients vill review the inforcation for possible applicability to their facilities.
To specific action or response is requested at this time.
If further URC evaluations so indicate, an IE Circular or Bulletin will be issued to recommend or request specific licensee actiont..
If you have ques-tions regarding this matter, please contact the Director of the appro-riate NRC Regional Office.
Sincerely, a
R b
Director
Enclosure:
1.
IE Info nation Fotice No. 79-11 2.
Draft Transmittal Letter i
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UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCDIENT WASHINGTON, D.C.
20555 May 7, 1979 12 Information Notice No. 79-11 LOWER EACTOR VESSEL HEAD INSU1J SUPPORT PROBLEM Virginia Electric and Pover Company, North Anna Power Staticn No. I reported on Noveaber 8, 1978, a field modification pertaining to the lower vessel hen / insu~ ation support system which was not seistically analyzed at the ice of codification. A subsequent stress analysis the ASMI Code allowable stress and the yield stress for indicated that the operating base earthquake (OBE) on roce of the instrument guide tubes were exceeded.
1 field codification, the lower vessel head For the North Anna No.
insulation was supported by angle brackets that are clamped onto the gridwork to about 20 of the 53 instrument guide tubes. This additional load on the guide tubes was not considered in the original stress analysis.
The maximum stress occurs in the socket welds between the Thichle guide tubes and the Instrumentation nozzles that penetrate the vessel.
The maximum stress was about 70 percent of the ultimate and, therefore, violation of the pressure boundary would not be expected.
VEPCO plans to modify the supporting arrange =snt by building a fracework underneath the insulation, which will take the leading of f the guide tubes.
All holders of operating licenses and/or construct. ion permits should be aware of the potential problem of exceeding the allowable stress and the yield stress for OBE.
This Information Not2ce is provided as an early notification of a It la expected that recipients will review possibly significant estter.
No the information for possible applicability to their facilities.
this time. If further NRC specific action or response is requested at evaluations so indicate, an IE Circular or Bulletin will be issued to specific licensee actions.
If you have questions reco==end or request regarding the catter, please contact the Director of the appropriate NRC Regional Office.
No written response to this information notice is required. '
t 7906060158
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Enc *'sure IE Information Notice No. 79-11 Page 1 of I May 7, 1979 LISTING OF IE INFORMATION NOTICES ISSLTED IN 1979 Date Issued To Information Subject Issued Notice No.
79-01 Bergen-Paterson Hydraulic 2/2/79 All power reactor facilities with an Shock and Sway Arrestor OL or a CP 79-02 Attempted Extortion -
2/2/79 All Fuel Facilities Low Enriched Uranium 79-03 Limitorque Valve Geared 2/9/79 All power reactor facilities with an Linit Switch Lubriem,
OL or a CP 79-04 Degradation of 2/16/79 All power reactor facilities with an Engineered OL or a CP Safety Features 79-05 Use of Improper Materials 3/21/79 All power reactor facilities with an in Safety-Related Cocponents OL or CP 79-06 Stress Analysis of
'3/23/79 All Holders of Reactor OL or CP Safety-Related Piping 79-07 Rupture of Radwaste Tanks 3/26/79 All power reactor fscilities with an OL or CP 79-08 Interconnection of 3/28/79 All pnwer reactor facilities with an Contaminated Systems with OL and Pu Processing Service Air Systems Used fuel facilities As the Source of Breathing Air 79-09 Spill of Radioactively 3/30/79 All power reactor facilities with an Contaminated Resin OL 79-10 Nonconforcing Pipe 4/16/79 All power reactor facilities with a Support Struts i'
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