ML19273B734
| ML19273B734 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 05/07/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Tallman W PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| References | |
| NUDOCS 7906120198 | |
| Download: ML19273B734 (2) | |
Text
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- g NUCLEAR REGULATORY COMMISSION Q(
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h KING OF PRUSSIA. PENNSYLVANIA 19406 Docket Nos. 50-443 D
50-444 Public Service Company of New Hampshire ATTN:
Mr. W. C. Tallman President 1000 Elm Street Manchester, New Hampshire 03105 Gentlemen:
This Information 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 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 or request specific licensee actions.
If you have questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely,
-~ _ p}!w -
/
Boyce H. Grier Director
Enclosures:
1.
IE Information Notice No. 79-1 2349 326 2.
List of Information Notices Issued in 1979 7906120/77 Q
Public Service Company of 2
New Hampshire cc w/encls:
John D. Haseltine, Project Manager 2349 327
UNITED STATES NUCLEAR REGULATORY 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.
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 iaaximum 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 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 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 Regional Office.
No written response to this information notice is required.
Enclosure:
List of IE Information Notices bk9
.g Issued in 1979 7906060158
F IE Information Notice No. 79-11 Date:
May 7, 1979 Page 1 of 1 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 (OL) or Construction 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 OL or CP 79-04 Degradation of 2/16/79 All power reactor Engineered facilities with an Safety Features OL or 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 power reactor Safety-Related Piping facilities with an 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 Resin facilities with an OL 79-10 Nonconforming Pipe 4/16/79 All power reactor Support Struts facilities with a CP 2 3 4 9
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