ML19256B469
| ML19256B469 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 06/20/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Daltroff S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| References | |
| NUDOCS 7907110381 | |
| Download: ML19256B469 (1) | |
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g UNITED STATES ggd y } ).,(/(,g NUCLEAR REGULATORY COMMISSION 3 / \\ "df c
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o, 631 PARK AVENUE KtNG OF PRUSSIA, PENNSYLVANIA 19406 Docket Nos. 50-277 June 20,1979 50-278 Philadelphia Electric Company ATTN: Mr. S. L. Daltroff Vice President Electric Production 2301 Market Street Philadelphia, Pennsylvania 19101 Gentlemen:
This Information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipien u aill review the informs ' 4 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 recomend or request specific licensee actions.
If you have questions regarding this matter, please contact this office.
P Sincerely, M
A Boyce H. Grier Director
Enclosures:
1.
IE Information Notice No. 79-17 2.
List of IE Information Notices Issued in 1979 cc w/encls:
W. T. Ullrich, Station Superintendent
. b o-3 Troy B. Conner, Jr., Esquire 830 i
Eugene J. Bradley, Esquire Raymond L. Hovis, Esquire Warren Rich, Esquire 7907110#/ ' Q
ENCLOSURE 1 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Information Notice No. 79-17 Date:
June 20, 197.
Page 1 of 2 SOURCE HOLDER ASSEMBLY DAMAGE FROM MISFIT BETWEEN ASSEMBLY AND REACTOR UPPER GRID PLATE Description of Circumstances:
Recently, the NRC was informed of a problem at two Westingbouse PWR facilities resulting from in apparent misfit between secondary source holder assemblies and the reactor upper grid plate.
The misfit problem was first identified by Carolina Power & Light
'icensee 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 twc secondary source holder m3semblies had ber @maged during the previous refut..ing in February 1978, by a misfit betwee, the assembly and tne reactor upper grid plate.
The misfit resulted from irr:s fficiect clearance (i.e. 1/2 to 3/4 inch) between the source holder assem :y Mb and the grid plate at the core locations containing thermocouple mixinc anas.
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.
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 pc h a G
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