ML19224C460
| ML19224C460 | |
| Person / Time | |
|---|---|
| Site: | Zimmer |
| Issue date: | 06/20/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Borgmann E CINCINNATI GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7907020416 | |
| Download: ML19224C460 (1) | |
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'o UNITED STATES IlC
[ ',, ',",. g(',j NUCLEAR REGULATORY COMMISSION
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JUN 2 01979 Docket No. 50-358 Cincinnati Gas and Electric Company ATTN:
Mr. Earl A. Borgmann Vice President Engineering Services and Electric Production 139 East 4th Street Cincinnati, OH 45201 Gentlemen:
Thi t, 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 specific licensee actions.
If you have questions regarding this matter, please coraact the Director of this office.
Sincerely, A
James G. Kepp er Director
Enclosure:
IE Information Notice No. 79-17 cc w/ enc 1:
Mr. J. R. Schott, Plant
'd W. 1:ohn, Power Superintendent
.iting Commission Central Files Citizens Against a Radioactive Director, NRR/DPM Environment Director, NRR/ DOR Helen W. Evans, State of PDR Ohio Local PDR NSIC TIC 271 305 50p/)~5,a7-g
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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..JLDER ASSEMBLY DAMAGE F u n MISFIT BETWEEN ASSEMBLY AND REACTOR UPPER GRID PLATE Description of Circ.2 stances:
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, who informed the NRC on May 6, 1979, of the circum-stances. During the current _efueling outage at H. B. Robinson 2, CP&L deter-mined that twc secondary source holder assemblies had been damaged during the previous refueling in February 1978, by a misfit between the assembly and the reactor upper g;-id 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 n* the core locations cuntaining 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 case 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 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. Tb2 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 Each such control assemblies and placed at symmetrical locations in the core.
assembly contains a symmetrical grouping of four secondary source rods and between zero and twenty burnable poison rods. Locations in the e.ssembly not The lack filled with a source or burnable poisgr rod contain a thimble plug.
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of sufficient clearance for these sou only at the core locations which cont DUPLICATE DOCUMENT
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