ML19273B632
| ML19273B632 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 05/07/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Cavanaugh W ARKANSAS POWER & LIGHT CO. |
| References | |
| NUDOCS 7906120063 | |
| Download: ML19273B632 (1) | |
Text
CENTRAL FILES O
UNITED STATES
>R R800 9'o NUCLEAR HEGULATORY COMMISSION f
REGION IV o
bbIb 5..
611 RYAN PLAZA DRIVE, SUITE 1000
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AR LINGTON, TEXAS 76011 os,*****/
May 7, 1979 Docket Nos. 50-313 50-368 Arkansas Power and Light Company ATTN: Mr. William Cavanaugh III Vice President of Generation and Construction P. O. Box 551 Little Rock, Arkansas 72203 Gentlemen:
This IE Information Notice is provided as r.a 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 this matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely,
}
.[
IG Karl V. Se frit Director
Enclosures:
1.
IE Information Notice No. 79-11 2.
List of IE Infonnation Notices Issued in 1979 cc: James P. O'Hanlon, Plant Manager Adar.m Nuclear One P. O. Box 608 2350 121 Russellville, Arkansas 72801 L. Alexander, QC Supervisor 790612006'$
UNITT.D STATES NUCLEAR REGl'LATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C.
20555 IE Information Notice No. 79-11 Date: May 7, 1979 Page 1 of 1 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 (0BE) 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 allowable stress and the yield stress for OBE.
This Infomation Notice 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 actirn or response is requested at this time.
If further NRC evaluations su 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 Regional Office.
No written response to this infomation notice is required.
2350 122 7906060158
s IE Information Notice No. 79-11 May 7, 1979 LISTING 0F 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 Operating License (0L) or a Construc-tion Permit (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 Operating License (0L) or a Construc-tion Permit (CP) 79-04 Degradation of 2/16/79 All power reactor Engineered facilities with an Safety Features Operating License (0L) or a Construc-tion Permit (CP) 79-05 Use of Improper Materials 3/21/79 All power reactor In Safety-Related Components facilities with an Operating ' License (0L) or a Construc-tion Permit (CP) 79-06 Stress Analysis of 3/23/79 All Holders of an Safety-Related Piping Reactor Operating License (0L) or a Construction Permit (CP) 79-07 Rupture of Radwaste 3/26/79 All power reactor Tanks facilities with an Operating License (0L) or a Construc-tion Permit (CP)
Enclosure Page 1 of 2 2350 123
IE Information Notice No. 79-11 May 7, 1979 79-08 Interconnection of 3/28/79 All power reactor Contaminated Systems with facilities with an Service Air Systems Used Operating License As the Source of Breathing (0L) and Pu Proces-Air sing fuel facilities 79-09 Spill of Radioactively 3/30/79 All power reactor Contaminated Resin facilities with an Operating License (0L) 79-10 Nonconforming Pipe 4/16/79 All power reactor Support Struts facilities with a
, Construction Permit (CP) 2350 124 Enclosure Page 2 of 2