ML19224C465
| ML19224C465 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point, Palisades File:Consumers Energy icon.png |
| Issue date: | 06/20/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Dewitt R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| NUDOCS 7907020423 | |
| Download: ML19224C465 (1) | |
Text
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o, Gl.EN E LLYN. ILLINOIS 60137 JUN 2 01979 Docket No. 50-155 Docket No. 50-255 Consumers Power Company ATTN:
Mr. R. B. DeWitt Manager of Nuclear Plant Operations 212 West Michigan Avenue Jackson, MI 49201 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 specific licensee actions.
If you have questions regarding this matter, please contact the Director of this office.
Sincerely, James G. Keppler Director
Enclosure:
IE Information Notice No. 79-17 cc w/ encl:
Mr. C. J. Hartman, Local PDR Plant Superintendent NSIC Mr. J. G. Lewis, Plar.t TIC Superintendent Ronald Callen, Michigan Public Central Files Service Commission Director, NRR/DPM Anthony Roisman, Esq.,
Director, NRR/ DOR Attorney PDR Myron M. Cherry, Chicago 271 3N 9 0ibj cq33
I U.S. NUCLEAR REGULATORY C0" MISSION OFFICE DF INSPECTION AND ENFORCEMENT REGION III June 2^,
1979 IE Information Notice No. 79-17 SOURCE HOLDER ASSEMBLY DAMAGE FROM MISFIT BETWEEN ASSEMBLY AND REACTOR UPPET GRID PLATE Descripticn of Circumstances:
Recently, the NRC was informed of a problem at two Westinghouse PWR f acilities resulting from an apparent misfit between secondary source holder assemblies and the reactor upper grid plate.
The misfit problem wes 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 1979, 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 c1ceraace caused minot deformation of the upper grid plate com-ponents at the core location and of the source holder assemblies. The defon a-tion also resulted in some bending of the fuel rods in the assembly, however, in ao case did this bending result in fuel cladding perforation.
.;n May 16, 1979, the license 2 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 f.911owing completion of refueling, to correct this misfit problem. They learned of.the problem from Westinghouse.
Subsequently, the licensee's inspection revealed that the ;ource 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 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 nd placed at syc=etrical 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 essembly not filled with a source or burnable poir Mkh of sufficient clearance for these so DUPLICATE DOCUMENT only at the core locations which con 7j} ,Fntire docurent previously entered into system under: 7lO(o290220 no No. of pages: k}}