ML19261E288
| ML19261E288 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 06/20/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Koester G KANSAS GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7907050512 | |
| Download: ML19261E288 (1) | |
Text
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. f*"%q bkQif S '[, s y[h UNITED STATES h
NUCLEAR REGULATORY COMMISS!ON
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i REGION IV o, Jk 8
611 RYAN PLAZA DRIVE, SUITE 1000
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June 20, 1979 In Reply Refer To:
RIV Docket No.
STN 50-482/IE Information Notice No. 79-17 Kansas Gas & E_lectric Co.
Attn:
Mr. Glenn L. Koester Vice President-Operations Post office Box 208 Wichita, Kansas 57201 Gentlemen:
This IE Information Notice is provided as an early notification of a possib.1.y significant matter.
It is expected that recipients will review the informa-tion for possible applicability to their facilities.
No specific action or response is requested at this time.
If further NRC evaluations so indicate, an IE oircular or Bulletin will be issued to recommend or request specific licensee actions.
If you have questions regarding this matter, please contac; the Director of the appropriate NRC Regional Office.
Sincerely, h
/
/
?gb Karl V. Seyfri '
Director
Enclosures:
1.
IE Information Notice No. 79-17 2.
List of IE Information Notices Issu ' in 1979 cc: w/ enclosures lie rs.
Nicholas A. Petrick, SNUPPS D. T. McPhee, Kansas City Power and Light Company Gerald Charnoff, Shaw, Pittman, Potts & Trowbridge E. W. Creel, Kansas Gas and Electric Company
)S 790705osa
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Information Notice No. 79-17 Date: June 20, 1979 Page 1 of 2 SOURCE HOLDER ASSEMBLY DAMAGE FROM MISFIT BETWEEN ASSEMBLY AND REACTOR UPPER GRI9 PLATE Description of Circumstances:
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 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 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 components at the core location and of the source holder assemblies.
The deformation also resulted in some bending oi the fuel rods in the assembly, however, in no case did this bending result in fuel cladding perfcration.
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 follcwing 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 poison rod contain a t M%d";_JMaggfeEkl A.-au
- ri clearance for these source holder assemb1 x locations which contain thermocouple miri DUPLICATE DOCUME1EP Entire document previously entered into system under:
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