ML19273B680
| ML19273B680 | |
| Person / Time | |
|---|---|
| Site: | Marble Hill |
| Issue date: | 05/07/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Coughlin J PSI ENERGY, INC. A/K/A PUBLIC SERVICE CO. OF INDIANA |
| References | |
| NUDOCS 7906120123 | |
| Download: ML19273B680 (1) | |
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.s GLE N E LLYN, IL LINols 60137 un, av Docket No. 50-546 Docket No. 50-547 Public Service of Indiana ATTN:
Dr. James Coughlin Vice President, Nuclear 1000 East Main Street Plainfield, IN 46168 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 recommend or request specific licensee actions.
If you have questions regarding this matter, please contact the Director of this office.
Sincerely,
-~D /;i %.
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James G. Keppler Director
Enclosure:
IE Information Notice No. 79-11 cc w/ encl:
Mr. R. M. Brown, Construction Project Engineer Central Files Director, NRR/DPM Director, NRR/ DOR} 997 PDR CI/ Local PDR NSIC TIC LeBoeuf, Lamb, Leiby & MacRae '700610014 3
t U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPFtrION 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 ASMI 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 love; 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. VEPCO 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 allowable stress and the yield stress for OBE. This Information Notica 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 Bulletin will be 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 response to this information notice is required. 2350 218
Enclosure:
Listing of IE Information Notices Issued in 1979 7906060158
\\ lE Information Notice No. 79-11 l May 7, 1979 LISTING OF IE INFORMATION NOTICES ISSUED IN 1979 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 Teatures 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 Tanks 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 Pesin facilities with an OL 79-10 Nonconforming Pipe 4/16/79 All power reactor Support Struts facilities with a CP 2350 219 Enclosure Page 1 of 1}}