ML19224D301
| ML19224D301 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 05/07/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Stewart W FLORIDA POWER CORP. |
| References | |
| NUDOCS 7907110322 | |
| Download: ML19224D301 (1) | |
Text
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[p*#109jo, NUCLEAR REGULATORY COMMISS;ON 9
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m 7 n7a In Reply Refer To:
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Florida Power Corporation Attn:
Mr. W. P. Stewart, Director Power Production P. O. Box 14042, Fbil Stop C-4 St. Petersburg, Florida 33733 Gentlemen:
This Information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipients vill review the information for possible applicability to their facilities.
To specific action or response is requested at this time.
If further NRC evalcations so indicate, an IE Circular or Bulletin vill be issued to recoc=end or request specific licensee actions.
If Jou have ques-tions regarding this matter, please contact the Director of the appro-riate NRC Regional Office.
Sincerely, O
b Director
Enclosure:
1.
IE Information Notice No. 79-11 2.
Draft Transmittal Letter cc w/ encl:
G. P. Beatty, Jr.
Nuclear Plant Manager P. O. Box 1228 Crystal River, Florida 32629 a N 790713g 3 ] Q 3% Xi 4
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCE 1 5 I WASHINGTON, D.C.
20555 May 7, 1979 IE Information Notice No. 79-11 LOWER REACTOR VESSEL HEAD INSULATION SUPPORT PROBLEM I
Virginia Electric and Power Co=pany, North Anna Power Station No.
reported on November 8, 1978, a field modification pertaining to the seismically lower vessel head insulation support system which was not the time of modification.
A subsequent stress analysis analyzed at indicated that the ASME Code allowable stress and the yield stress for the operating base earthquake (OBE) on so=c of the instrument guide tubes were exceeded.
For the North Anna No. 1 field modification, the lower vessel head
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insulation was supported by angle brackets that are cla: ped onto the 20 of the 53 instrument guide tubes. This additional gridwork to about load on the guide tubes was not considered in the es.ginal strees analysis.
The maxfmu= stress occurs in the socket velds between the Thieble guide tubes and the Instrur.ntatic nozzles that penetrate the vessel.
The about 70 itreent of the ultimate and, therefore, maximum stress wa; violation of the pressure boundary would not be expected.
VEPCO plans to modify the supporting arrange =snt by building a framework underneath the insulation, which will take the loading of f 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 Notice is provided aa an early notification of a It is expected that recipients vill review possibly significant eatter.
No the information for p.ssible applicability to their facilities.
If further NRC specific action or response is requested at this tiee.
evaluations so indicate, an IE Circular or Bulletin will be issued to recoc=end 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.
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_o 79000691.58
Enclosure IE Information Notice No. 79-11 Page 1 of 1 May 7, 1979 LISTING OF IE INFORMATION NOTICES ISSUED IN 1979 Date Issued To Information Subject Issued Notice No.
79-01 Bergen-Paterson Hydraulic 2/2/79 All power reactor facilities with an Shock and Sway Arrestor OL or a CP 79-02 Attempted Extortion -
2/2/79 All Fuel Facilities Low Enriched Uraniu=
79-03 1.imitorque Valve Geared 2/9/79 All power reactor facilities with an Limit Switch Lubricant OL or a CP 79-04 Degradation of 2/16/79 All power reactor facilities with an Engineered OL or a CP Safety Features 79-05 Use of I= proper Materials 3/21/79 All power reactor facilities with an in Saf ety-Related Co=ponents OL or CP Stress Analysis of
'3/23/79 All Holders of 79-06 Reactor OL or CP Safety-Related Piping 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 facilities with an Contaminated Syste=s with OL and Pu Processing Service Air Syste=s Used fuel facilities As the Source of Breathing Air 79-09 Spill of Radioactively 3/30/79 All power reactor facilities with an Contaminated Resin OL 79-10 Nonconforming Pipe 4/16/79 All power reactor facilities with a Support Struts CP 7
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