ML19224C468
| ML19224C468 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 06/20/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Gerstner W ILLINOIS POWER CO. |
| References | |
| NUDOCS 7907020429 | |
| Download: ML19224C468 (1) | |
Text
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UNITED STATES 8'
'l-h' %..J'!
NUCLEAR REGULATORY COMMISSION 3.
REGION lli g, ' v[h[j F
799 ROOSEVELT ROAD i
o, 8
GLEN ELLYN, ILLINOIS 60137
+...*
JUN 2 01979 Docket No. 50-461 Docket No. 50-462 Illinois Power Company ATTN:
Mr. W. C. Gerstner Executive Vice President 500 South 27th Street Decatur, IL 62525 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
._ formation for possible applicability to their facilities.
No specif'c action or response is ra3eested at this time.
If furtner NRC evaluati<ns so indicate, an IE Circala or Bulletin will be issued to recommerd or request specific licensee actions.
If you have questions regarding this matter, please contact the Director of this office.
Sincerely,
$ $n"Y James G. KeppTer Director
Enclosure:
IE Information Notice No. 79-17 cc w/ encl:
Central Files Director, NRR/DPM Director, NRR/ DOR PDR I,ocal PDR NSIC TIC lic. Dean Hacsell, Office of Assistant Attorney General 271 322 iUO70jr.b,c/
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U.S. NUCLEAR REGULATORY COMMISSION OFFICE 6F INSPECTION AND ENFORCEMENT REGION III June 20, 1979 IE Information Notice No. 79-17 SOURCE HOLDER ASSDBLY DAMAGE FROM MISFIT BETWEEN ASSEMBLY AND REACTOR UPPER GRID PLATE Description of Circumstances:
Recently, the NRC was informed of a prcblem at two Wes;inghouse PWR facilities resulting fror an apparent misfit between secondsry source holder assemblies and the reactor upper grid plate.
The misfit problem vas 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. 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 reactcr 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 venes. This lack of sufficient clearance caused minor deformation of tne 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 df1 this bending result in fuel cladding perforation.
On May 16, 1979, the licensae 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 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 rccoved from one assembly readily with no eparent decage 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 sycnetrical locations in the core. Each such assembly contains a symmetrical grouping of four secondary source rods and rods.
Locations in the asseu ly not between zero and twenty burnable poison ~
filled with a source or burnable po
% 1M of sufficient clearance for these s DUPI.ICATE DOCUMENT E
only at the core locations which co 2[f} p Previously entered nt sy e under ^uo39QM 96p20 No. Of pages: //}}