ML19273B619
| ML19273B619 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 05/07/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| References | |
| NUDOCS 7906120043 | |
| Download: ML19273B619 (1) | |
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UNITED STATES j
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Arizona Public Seryice Company P. O. Box 21666 Phoenix, Arizona 85036 Attention: l!r. E. E. Van Brunt, Jr.
Vice President, Construction Projects Gentlemen:
This Information flotice 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.
flo specific action or response is requested at this time.
If further NRC evaluations so indicate, an IE Circular or. Bulletin will be issued to recomend or request specific licensee actions.
If you*have questions regarding this matter, please contact.the Director. of the appropriate NRC Regional Office.
Sincerely, 14859-t R. H. Engelken
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Director J(i
Enclosure:
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IE Information flotice flo. 79-11 t
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7906120043 Q -
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UNITED STATES NUCLEAR REGULATORY COMISSI0tt 0FFICE OF IflSPECTION AND EllFORCEliENT WASHINGTON, D.C.
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!!ay 7, 1979 IE Information Notice No. 79-11 LOWER REACTOR VESSEL HEAD INSULATION SUPPORT PROBLEfi Virginia Electric and Power Conpany, florth Anna Power Station No. I reported on November 8,1978, a field modification pertaining to the lower vessel head insulation support setem 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 fio.1 field modification, the lower vessel head insulation was supported by angle brackets that are clamped onto the gridwork to about 20 of the E3 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 perjetrate the vessel.
The maximum stress was about 70 percent of the ultirate and, therefore, violation of the pressure boundary would nct 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 apd/or construction permits shoulC be aware of the potential problem of exceeding the allowable stress and the yield stress for OBE.
This Information flotice 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. flo 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.
fio written response to this information notice is required.
04
Enclosure:
List of IE Information Notices Issued in 1979 1 of 1 7906030158
'IE Information Notice No. 79-11 Enclosure May 7, 1979 Page 1 of 1 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. Features OL or e CP 79-05 Use of Imprope.r 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 Resin facilities with an OL 79-10 Honconforming Pipe 4/16/79 All power reactor Support Struts facilities with a CP 2350 105
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