ML19224C488
| ML19224C488 | |
| Person / Time | |
|---|---|
| Site: | Columbia, Washington Public Power Supply System, Satsop  |
| Issue date: | 06/20/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Strand N WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| References | |
| NUDOCS 7907020453 | |
| Download: ML19224C488 (1) | |
Text
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UN!TED STATES
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NUCLEAR REGULATORY COMMISSION
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1993 N. CALIFORNI A I!OULEVARD j
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SUITE 202, WALN"8T CRE E K PLAZA g
7 WALNUT CREEK, CALIFORNI A 9459G June 20, 1979 Docket flos. 50-397, 50-460 50-513, 50-503 50-509 Washington Public Power Supply System
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P. O. Box 968 3000 George Washington Way Richland, Washington 99352 Attention:
Mr. fl. O. Strand Managing Director 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 facilities.
flo specific action or response is requested at this time.
If further flRC 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 i!RC Regional Office.
Sincerely,
/ N~,db.~
R. H. Engelken Director
Enclosure:
IE Information Notice No. 79-17 cc w/ enclosure:
M. E. Witherspoo.i, WPPSS A. D. Kohler, WPPSS J. P. Thomas, WPPSS W. J. Talbott, WPPSS G. C. Sorensen, WPPSS 272 030 7 00702 0 YS3
UillTED STATES fiUCLEAR REGULATORY COMMISS10t1 0FFICE OF ItiSPECTI0tl AllD Ef1FORCEMErlT WASHItiGT01, D.C.
20555 June 20, 1979 IE Information flotice fio. 79-17 SOURCE HOLDER ASSEMBLY DAMAGE FROM MISFIT BETWEEN ASSEMBLY A!iD REACTOR OPPER GRID PLATE Description of Circumstances:
Recently, the liRC was informed of a problem at two Westinghouse PWR facilities resulting from an apparent misfit between secondary source holder assemblies and the reactor upper grid plate.
The misfit problem was first identified by Carolina Power & Light, licensee for H. B. Robinson Unit 2, who informed the f1RC on May 6,1979, of the circum-stances.
During the current refueling outage at H. B. Robinson 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 clearance (i.e. 1/2 to 3/4 inch) between the source holder assembly hub and the grid plate at the core locations containing thermocouple mixing vanes.
This lack of sufficient clearance caused minor deformation of the upper grid plate com-ponents at the core location and of the source holder assemblies.
The deforma-tion also resulted in some bending of the fuel rods in the assembly, however, in no case did this bending result in fuel cladding perforation.
On May 16, 1979, the licensee of D. C. Cook Unit 1 informed the tiRC that the present refueling outage would be extended 15 to 20 days to remove the reactor 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 holder assembly hubs were in contact with the vanes. The source holder was removed from one assembly readily with no apparent damage while in the other the source holder was found stuck in the assembly. The problem was corrected prior to return to operations.
The secondary source assembly rods are normally inserted into rod cluster control assemblies and placed at symmetric.
' mtions in the core.
Each such assembly contains a symmetrical grouping of ruu. acondary source rods and between zero and twenty burnable poison rods.
Locations in the assembly not filled with a source or burnable poison rod contain a thimble plug. The lack of sufficient clearance for these source holder assembigs_aoparontiv ovh only at the core locations which :oi gj L us' DUPLICATE DOCUMENT Entire document previously entered into system under:
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