ML19224C478
| ML19224C478 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 06/20/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Cavanaugh W ARKANSAS POWER & LIGHT CO. |
| References | |
| NUDOCS 7907020443 | |
| Download: ML19224C478 (1) | |
Text
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UNITED STAT 3S PR yg f (g'
,o NUCLEAR REGULATORY COMMISSION 3
tISIC 5 c,jWidf E REGION IV
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611 RYAN PLAZA DRIVE, SUITE 1000 fid AR LINGToN, TE X AS 76012
'49 June 20, 1970 Docket Nos.
50-313 50-368 Argansas Power and Light Company ATTN:
Mr. William Cavanaugh III Vice President of Generation and Construction P. O. Box 551 Little kock, Arkansas 72203 Gentlemen:
This IE Information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipiente will review the informa-tion 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 recontend or request specific licensee actions.
If you have questicas regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, Karl V. Seyfrit Directar
Enclosures:
1.
IE Information Notice No. 79-17 2.
List of IE Information Notices Issued in 1979 cc: James P. O'Hanlon, Plant IL1 nager Arkansas Nuclear One P. J. Box 608 Russellville, Arkansas 72801 L. Alexander, QC Supervisor 271 %
7 9' 702 0 /N t
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Information Notice No. 79-17 Date: June 20, 1979 Page 1 of 2 SOURCE HOLDER ASSEMBLY DAMAGE FROM MISFIT BETWEEN ASSEMBLY AND REACTOR UPPER GRID PL*TE Description of Circumstances:
Recently, the NRC was informed of a problem at two Westinghouse PWR facilities resulting from an apparent misfit between secondary source holder assemblies and the rcactor upper grid plate.
The misfit problem was first identified by Carolina Power & Light, licensee for H. B. Robinson Unit 2, who informed the NRC on May 6,1979, of the circum-stances. During the current refueling outage at H. B. Robinac-2, CP&L deter-mined that two secondary source holder assemblies had been damaged during the previous refueling in February 1978, by a misfit between the assembly and the reactor upper grid plate. The misfit resulted from insufficient cleara' e (i.e. 1/2 to 3/4 inch) between the source holder assembly hub and the gr'.o plate at the core' locations containing thermocouple mixing vanes.
This lack of sufficient clearance caused minor deformation of the upper grid plate ccar,onents il the core location and of the source holder assemblies.
The deformation also resulted in some bending of the fuel rods in the assembly, however, in no case did this bending result in fuel cladding pe.-foration.
On May 16, 1979, the licensee of D. C. Cook Unit 1 informed the NRC that the present refueling outage would be extended 15 to 20 days to remove the reacte r head, which had already been reinstalled following completion of refueling, to correct this misfit problem.
They learned of the problem from Westinghouse.
Subsequently, the licensee's inspection revealed that the source hc 1 der assembly hubs wece in contact with the vanes. The source holder was removed from one assemoly readily with no apparent damage, while in the other, the sot.rce holder was found stuck in the assembly. The proalem was corrected prior to return to operations.
The secondary source assembly rods are normally inserted into rod
" ter control assemblies and placed at symmetrical locations in the core.
F' cssembly contains a symmetrical grouping of four secondary source rod
.ec zero and twenty burnable poison rods.
Locations in the assembly n ated with a source or burnable poison rod contain
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clearance for these source holder asse DUPLICATE DOCUMENT lecations which contain thermocouple m Entire document pre i i sly 3 hrJ.ered 7
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