ML19224C473
| ML19224C473 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 06/20/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Jeffery Grant TOLEDO EDISON CO. |
| References | |
| NUDOCS 7907020437 | |
| Download: ML19224C473 (1) | |
Text
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gr GLEN ELLYN,ILLINulS 60137 JUN 2 01979 Docket No. 50-346
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Toledo Edison Company ATTN:
Mr. James S. Grant Vice President - Energy Supply Edison Plaza 300 Madison Avenue Toledo, OH 43652 Gentlemen:
This Information Notice No. 79-17 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.
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 recommend or request spe.-ific licensee actions.
If you have questions regarding this matter, please contact the Director of this office.
Sincerely,
,, % jd, s hn JamesG.KepNer Director
Enclosure:
IE Information Notice No. 79-17 cc w/ encl:
Mr. T. Murray, Station Superintendent Central Files Director, NRR/DPM Direct.~, NRR/ DOR PDR Local PDR NSIC TIC Harold W. Kohn, Power Sitiug Commission Helen W. Evans, State of Ohio 271 334 19 0 7 0 219'3 7 c 4
U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF JNSPECTION AND ENFORCIMENT REGION III June 20, 1979 IE Information Notice No. 79-17 SOURCE HOLDER ASSEMBLY D!. MAGE FROM MISFIT BETWEEN ASSEMBLY AND REACTOR LTPER 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 assemblies and the reactor upper grid plate.
The misfit problem was first identified by Carolina Power & Light, licensee for H. B. Robinson Unit 2, no informed the NRC or. 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 da= aged during the previous refueling in February 1978, by a misfit octween 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 asscebly hub ar. ' 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 e,ource holder assemblies. The deforma-tion also resulted in some bending of the fuel roda 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 uformed the NRC that the present refueling outage would be extend 2d 15 to 20 tays to remove the reactor head, which had already been reinstalled following c mpletion of refueling, to correct this misfit problem. They learned of.the preblem 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 u s found stuck in the assembly. The probles was corrected prior to return to operations.
The secondary source asse=bly rods are nc mally inserted into rod cluster control assefablies and placed at symmetrical locations 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 so a- --
only at the core locations which con DUPLICATE DOCUMENT 271 333 Entire document previously entered into system under:
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