ML19224C467
| ML19224C467 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 06/20/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Hines E DETROIT EDISON CO. |
| References | |
| NUDOCS 7907020426 | |
| Download: ML19224C467 (1) | |
Text
[ga ascgo UNITED ST ATES E ',,.,_, g(' g NUCLEAR REGULATORY COMMISSION
((7 "f r -
REGION ll1 h ((c 799 ROOSEVELT ROAD o, ' *,
GLEN ELLYN, ILLINOIS 60137
'ks JUN 2 01979 Docket No. 50-341 The Detroit Edison Company ATTN:
Mr. Edward Hines, Assistant Vice President and Manager Quality Assurance 2000 Second Avenue Detroit, MI 48226 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 hPC evaluations so indicate, an IE Circular or Bulletin will be issued to recommend or request specific licensee actions.
If you have questions regarding this matter, please contact the Director of this office.
Sincerely,
%e b M4
(/ James G. Ke er Director
Enclosure:
IE Information Notice No. 79-17 cc w/ encl:
Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local POR NSIC TIC Ronald Callen, Michigan Public Service Commission Eugene B. Thomas, Jr.,
Attorney 271 313
--79070E%%
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U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT REGION III June 20, 1979 IE Information Notice No. 79-17 SOURCE HOLDER ASSEMBLY DAMAGE FROM MISFIT BETWEEN ASSEMBLY AND REACTOR UPFER GRID PLATE Description of Circumstances:
Recently, the NRC was informed of a problem at two Westinghorse PWR facilities resulting from an apparent misfit between wecondarv source h >lder asy.cblies 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 refteling outage at H. B. Robinson 2, CP&L deter-mined that two secondary source holder assemblies had been d waged 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 deforrt. tion of the upper grid plate com-ponents at the core location and of the source holder assemblics. 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 cf D. C. Cook Unit 1 informed the NRC that the present refueling outage would be extend H 15 to 20 days to remove the reactor head, which had already been reinstalled following.:ompletion of refueling, to correct this misfit problem. They learned of.tbo problem from Westinghouse.
Subsequently, the licensee's inspection revealed that the source holder assembly hubs were in contact with the vana:..
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 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 poisoi
- Mgte nlue. The lack
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u sufficient clearance for these sour DUPLICATE DOCUMENT 271 319 only at the core locations which conta Entire document previously entered into system under:
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ANO No. of pages:
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