ML19224C472
| ML19224C472 | |
| Person / Time | |
|---|---|
| Site: | Marble Hill |
| Issue date: | 06/20/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Coughlin J PSI ENERGY, INC. A/K/A PUBLIC SERVICE CO. OF INDIANA |
| References | |
| NUDOCS 7907020436 | |
| Download: ML19224C472 (1) | |
Text
[pa an cg#'o, UNITED STATES y \\*
/ 'n NUCLEAR REGULATORY COMMISSION I L Eb >
5 c
REGION ill
'o, hl J
'g be e
GLEN E LLYP., ILLINOIS 60137 Docket No. 50-546 Docket No. 50-547 Public Service of Indiana ATTN:
Dr. James Coughlin Vice President, Nuclear 1000 East Main Street Plainfield, IN 46168 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, z. IE Circular or Bulletin will be issued to recommend or request specifv 1.icensee actions.
If you have questions regarding this matter, please contact the Director of this office.
Sincerely,
- i. _, Om JamesG.Ndpier Director
Enclosure:
IE Information Notice No. 79-17 cc w/ encl:
Mr. R. M. Brown, Construction Project Superintendent Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC LeBoeuf, Lamb, Leiby & MacRae 271 332 790702 *36 n
1
U.S. NUCLEAR REGULATCRY COMMISSION OFFICE 0F INSPECTION AND ENFORCEMENT REGION III June 20, 1979 IE Information Notice No. 79-17 SOURCE HOLDER ASSEMBLY DAMAGE FROM MISFIT BETWEEN ASSEMBLY AND REACTOR LTPER GRID PLATE Description of Circumstances:
Recently, the NRC was informed of a problem at two Westinghouse PWR f acilities resulting from an appsicr.t aisfit between secondary source holder assemblies and the reactor upper grid plate.
The misfit problem was first identified by Carolina Power 6 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 da= aged 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 bendit.g of the fuel rods in the assembly, however, in no case did this bending result in fuel cladding perforation.
On May 16, 1979, the Jicensee 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 rJ.sfit 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 assenbij readily with no apparent damage while in the other the source holder was found stuck in the assembly. The problem was estrected prior to return to operations.
The secondary source assembly rods are normally inserted into rod cluster control assemblies and placed at sy= metrical 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 poi
.. chl lu The lack of sufficient clearance for these so only at the ccre locations which con DUPLICATE DOCUMENT I
)
Entire document previously entered into system under:
h)h h_
ANO No. of pages:
h A