ML19273B654
| ML19273B654 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 05/07/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Davidson D CLEVELAND ELECTRIC ILLUMINATING CO. |
| References | |
| NUDOCS 7906120097 | |
| Download: ML19273B654 (1) | |
Text
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UNITED STATES c
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,t NUCLEAR REGULATORY COMMISSION f,I L h
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- , 4 e GLE N E LL Y N. 0L LINOIS 60137 0""**
yay 7 1979 Docket No. 50-440 Docket No. 50-441 The Cleveland Electric Illuminating Company ATTN:
Mr. Dalwyn R. Davidson Vice President - Engineering P. O. Box 5000 Cleveland, OH 44101 Gentlemen:
This IE Information Notice No. 79-11 is provided as an early notification of a possibly significant matter.
It is expected that recipients will review the information for possible appli-cability 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 recotmnend or request specific licensee actions.
If you have questions regarding this matter, please contact the Director of this office.
Sincerely, f
}mh AQ:y :.~
L Joames G. Keppier Director
Enclosure:
IE Information Notice No. 79-11 cc w/ encl:
Central Files Director, NRR/DPM Director, NRR/ DOR 2350 168 al PDR NSIC TIC Harold W. Kohn, Power Siting Commission Mr. Daniel D. Wilt.
Attorney 7906120097 g
U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT REGION III May 7, 1979 IE Information Notice No. 79-11 LOWER REACTOR VESSEL HEAD INSULATION SUPPORT PROBLEM Virginia Electric and Power Company, North Anna Power Station No. I 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. I field modification, the lower vessel head insulation was supported by anyle 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.
VEPCO plans to modify the supporting arrangement by building a framework underneath the insulation, which will take the loading off the guide tubts.
All holders of operating licenses and/or construction permits should be aware of the potential problem of exce.m.-3 tne allowable stress and the yield stress for OBE.
This Information Notice is provided as an early notification of a possibly significant matter.
It 14 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 Bulletin will te issued to recommend or request specific licensee actions.
If you have questions regarding the: matter, please contact the Director of the appropriate NRC Begional Office.
No written relpzag to zhis information notice is required.
2350 169
Enclosure:
Listing of IE Information Notices Issued in 1979 7906060'5S
IE Information Notice No. 79-11 May 7, 1979 i
LISTING OF IE INFORMATION NOTICES ISSUED IN 197t' Information Subject Date Issued To Notice No.
Issued 79-01 Bergen-Paterson Hydraulic 2/2/79 All power reactor Shock and Sway Arrestor facilities with an 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 Limit Switch Lubricant facilities with an OL or a CP 79-04 Degradation of 2/16/79 All power reactor Engineered facilities with an Safety Features OL or a CP 79-05 Use of Improper Materials 3/21/79 All power reactor in Safety-Related Components facilities with an OL or CP 79-06 Stress Analysis of 3/23/79 All Holders of Safety-Related Piping Reactor OL or CP 79-07 Rupture of Radwaste Tsuks 3/26/79 All power reactor facilities with an OL or CP 79-08 Interconnection of 3/28/79 All power reactor Contaminated Systems with facilities with an Service Air Systems Used OL and Pu Processing As the Source of Breathing fuel facilities Air 79-09 Spill of Radioactively 3/30/79 All power reactor Contaminated Resin facilities with an OL 79-10 Nonconforming Pipe 4/16/79 All power reactor Support Struts facilities with a CP 2350 170 Enclosure Page 1 of 1