ML19224C484
| ML19224C484 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 06/20/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Goodwin C PORTLAND GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 7907020449 | |
| Download: ML19224C484 (1) | |
Text
'o UNITED STAT ES Tb E',
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NUCLEAR REGULATORY COMMISSION g
u -l Si REGION V s
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B SUITE 202, WALNUT CREEK PLAZA WALNUT CREEK, CAllFORNIA 94596 June 20, 1979 Docket No. 50-344 Portland General Electric Company 121 S. W. Salmon Street Portland, Oregon 97204 Attention: fir. Charles Goodwin, Jr.
Assistant Vice President Gentlemen:
This Information tiotice 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 tiRC evaluations so indicate, an IE Circular or Bulletin will be issued to recomnend or request specific licensee actions.
If you have questions regarding the matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, h Ih d.L~
R. H. Engelken Director
Enclosure:
IE Information flotice No. 79-17 cc w/ enclosures:
B. Wit'lers, PGE F. C. Gaidos, PGE 272 011 7 00702 0 '/t/ 7 -
Ui1ITED STATES tiUCLEAR REGULATORY COMMISSI0tl 0FFICE OF IrlSPE'TIO 1 AND EtlFORCEMENT WASHINGTON, D.C.
20555 June 20, 1979 IE Information Notice No. 79-17 SOURCE HOLDER ASSEMSLY DAMAGE FROM MISFIT BETWEEN ASSEMBLY AND REACTOR UPPER GRID PLATE 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 asssablies 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 NRC on May 6,1979, of the circum-stances.
During the current refueling outage at H. B. Psobinson 2, CP&L deter-mined that two secondary source holder assemblies had been damaged during the previous refueling in Feuruary 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 ccse did this bending result in fuel cladding perforation.
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 reactor head, which had already been reinstalled following completion of refueling, to correct this misf't protlem.
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 prio.- to return to operations.
The secondary source assembly isds are normally inserted into rod cluster control assemblies and placed at symmetrical locctions in the core.
Each such assembly contains a symmetrical grouping of four secondary 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 sopc @ l&r r r f ' ~
only at the core locations which con DUPLICATEDOCUMENT2!
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