ML19224A901
| ML19224A901 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/07/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Herbein J METROPOLITAN EDISON CO. |
| References | |
| NUDOCS 7906120169 | |
| Download: ML19224A901 (2) | |
Text
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION
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Docket No. 50-289 7 MAy ;pg 50-320 Metropolitan Edison Company ATTN:
J. G. Herbein Vice President P. O. Box 542 Reading, Pennsylvania 19640 Gentlemen:
This Information Notice is provided as an early notification of a possibly significant matt'.'.
It is expected that recipients will review the information for possible applicability to their facili-ties.
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 recommend ce request specific licensee actions.
If you have questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, o
/
A nt E7yce H. Grier
' Director Er. closures:
1.
IE Information Notice No. 79-11 2.
List of Information Notices Issued in 1979 1/3 279 7906120lQ '
Metropolitan Edison Company 2
cc w/encls:
E. G. Wallace, Licensing Manager J. J. Barton, Project Manager R. C. Arnold, Vice President, Generation L. L. Lawyer, Manager - Generation Operations G. P. Miller, Manager - Generating Station - Nuclear J. B. Logan, Unit 2 Superintendent G. A. Kunder, Unit 2 Superintendent - Technical Support I. R. Finfrock, Jr.
Mr. R. Conrad G. F. Trowbridge, Esquire Miss Mary V. Southard, Chairman, Citizens for a Safe Environment 1/:
280
W UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Information Notice No. 79-11 Date:
May 7, 1979 P
Page 1 of 1 LOWER REACTOR VESSEL HEAD INSULATION SUPPORT PROBLEM Virginia Electric and Power Company, North Anna Power Station No.
1 reported on November 8,1978, a field modification pertaining to the lower vessel head insulation support system which was not seismically analyzed at the time of modification.
A subsequent stress analysis indicated that the ASME Code allowable stress and the yield stress for the operating base earthquake (OBE) on some of the instrument guide tubes were exceeded.
For the North Anna No. 1 field modification, the lower vessel head 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 Thimble 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.
VEPC0 plans to modify the supporting arrangement by building a framework underneath the insulation, which will take the loading off the guide tubes.
All holders of operating licenses and/or construction permits should be aware of the potential problem of exceeding the allowa-ble stress and the yield stress for OBE.
This Information hotice is provided as an early notification of a possibly significant matter.
It is expected that recipients will 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 Bulljt}n3 2 8 }
will be issued to recommend or request specific licensee y t y ( _ _
If you have questions regarding
,a Director of the appropriate NRC DUPLICATE DOCUMENT No written response to this infc Entire document previously entered int > system under:
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f Information Notices ANO Issued in 1979 No. of pages:
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