ML19224D307
| ML19224D307 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 05/07/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Mary Johnson SOUTH CAROLINA ELECTRIC & GAS CO. |
| References | |
| NUDOCS 7907110332 | |
| Download: ML19224D307 (2) | |
Text
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NUCLEAP AEGULATOPY COMMISSION
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fA 7g In Reply Refer To:
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South Carolina Electric and Gas Company Atcn:
Mr. M. C. Johnson, Vice President and Group Executive - Special Services and Purchasing P. O. Box 764 Columbia, South Carolina 29218 Gentlemen:
This Information Notise is provided as an early notification of a possibly significant matter.
It is expected that recipients vill review the information for possible applicability to their facilities.
No specific action or response is requested at this time.
If further NRC evaluations so indicate, an IE Circular or Bulletin will be issued to recccrend or request specific licensee actions.
If you have ques-tions regarding this catter, please contact the Director of the appro-riate NRC Regional Office.
Sincer'ely, b
Director
Enclosure:
1.
IE Information Notice No. 79-11 2.
Draft Transnittal Letter i
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lanY 7 1979 South Carolina Electric
~2-and Gas Cocpany cc w/ encl:
T. B. Conners, Jr.
Conners, Moore and Corber 1747 Pennsylvania Avenue, N.W.
Vashington, D.C.
20006 A. A. Scith Quality Assurance Post Office Box 8 Jenkinsville, South Carolina 29065 O. S. Bradham, Manager Nuclear Operations Post Office box 8 Jenkinsville, South Carolina 29065 O
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UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCDENT WASHINGTON, D.C.
20555 May 7, 1979 IE Information Notice No. 79-11 1NER REACTOR VESSEL HEAD INSULATION SUPPORT PROBLEM I
Virginia Electric and Power Company, North Anna Power Station No.
reported on Nove=ber 8, 1978, a field modification pertaining to the lower vessel head insulation support system which was not seistically analyzed at the tice of modificatior.. A st - 'uent stress analysis indicated that the ASMI Code allowable stres. and the yield stress for the operating base earthquake (OBE) on some of the instrument guide tubes were exceeded.
1 field modification, the lower vessel head For the North Anna No.
insulation was supported by angle brackets that are clamped onto the grideork to about 20 of the 53 instru=ent guide tubes. This additional load on the guide tubes was not considered in the original stress analysis.
The maximum stress occurs in the socket velds between the Thichle guide The tubes and the Instrumentation nozzles that penetrate the vessel.
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 arrangement by building a framework underneath the insulation, which vill take the loading off the guide tubes.
All holders of operating licenses and/or construction permite should be aware of the potential problem of exceeding the allowable stress and the yield stress for OBE.
This Information Notice is provided as an early notification of a It is expected that recipients vill review possibly significant catter.
No the information for possible applicability to their facilities.
If further NRC specific action or response is requested at this time.
evaluations so indicate, an IE Circular or Bulletin vill be issued to specific licensee e-tions.
If you have questions reco==end or request regarding the matter, please contact the Director of the appropriate NRC Regional Office.
No written response to this inforcation notice is required.
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Enclosure IE Information Notice No. 79-11 Page 1 of 1 May 7, 1979 LISTING OF IE INFORMATION NOTICES ISSUED IN 1979 Date Issued To Infor=ation 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 Atte=pted Extortion -
2/2/79 All Fuel Facilities Low Enriched Uranium 79-03 Limitorque Valve Geared 2/9/79 All power reactor facilities with an Limit Switch Lubricant OL or a CP 79-04 Degradation of 2/16/79 All power reactor facilities with an Engineered OL or a CP Safety Featurea 79-05 Use of Icproper Materials 3/21/79 All power reactor facilities with an in Safety-Related Components 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 f acilities with an OL or CP 79-08 Interconnection of 3/28/79 All power reactor Contaminated Systems with facilities with an OL and Pu Processing Service Air Syste=s 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 Nonconforming Pipe 4/16/77 All power reactor facilities with a Support Struts a a CP I
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