ML19256B465
| ML19256B465 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 06/20/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Counsil W CONNECTICUT YANKEE ATOMIC POWER CO. |
| References | |
| NUDOCS 7907110363 | |
| Download: ML19256B465 (1) | |
Text
~1EQFQ v **av a
p
,g UNITED STATES
+
g y;%
g NUCLEAR REGULATORY COMMISSION
- (
'7, j'
.. [
631 PARK AVENUE t
REGION I O, '
' %+"
,o KING OF PRUSSIA, PENNSYLVANI A 19406
+....
June 20,1979 Docket No. 50-213 Connecticut Yankee Atomic Power Company ATTN: Mr. W. G. Counril Vice President - Nuclear Engineering and Operations P. O. Box 270 Hartford, Connecticut 06101 Gentlemen:
This Information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipients will review the information
/or 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 reaarding this matter, please contact this office.
Sincerely, A
y Boyce H. Grier Director
Enclosures:
1.
IE Information Notice No. 79-17 y <3 j})
2.
List of IE Information Notices I
Issued in 1979 cc w/encls:
R. Graves, Plant Superintendent D. G. Diedrick, Manager of Quality Assurance J. R. Himmelwright, Licensing Safeguards Engineer 79071101;(,y '
Q
9 E] CLOSURE 1 UNITED STATES NUCLEAR REGULA10RY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHING 10N, D C.
20555 IE Informati;n Notice No. 79-17
~
Date:
June.20, 1979 Page 1 of 2 5OURCE HOLDER ASSEMBLY DAMACE FROM MISFIT BETWEEN ASSEMBLY AND REACTOR UPPER GRID PLATE Description of Circumstances:
Recently, the NRC was infer.ned of a problem at two Westinghouse PWR facilities resulting from an apparent misfit between secondary source holder assetblies and the reactor upper grid, plate.
The misfit problem was Erst identified by Carolina Lower & Light, iicensee for H. B. Robinson Unit 2, who informed the NRC on May 6, 19'9, of the circur stances.
During the current refueling outage at H. B. Robinson 2, CP&L deter"-
nined that two secendary source holder assemblies had haen danged during the previous refteling 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 thermccoupla mixing vanes.
This lack of sufficient clearance caused minor deformation of the upper grid plate com-Jonents at the cera 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 berding result in fuel cladding perforation.
On May 15,,1s79, the licensee of D. J Ccok Unit 1 informed the NRC that the present.refueli.ig outtge would be e nended 15 to 20 aays to remove the reactor
- head, hich had already been reinstalled following completion of refuel og, to correct this misfit problen.
Thr.v learned of the problem from Westinghouse.
Sucsequently, the licensee 5 nspection reveahd that the source holder assembly hubs were in contact with the vanes.
The scurce 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.
Theseconda[ysourceassemblyrodsarenormallyinsertedirtorodcluster controi assemblies and placed at symmetrical locations in the core.
Each such assembly contains a symmetrical grouping of four secondary source rods and betwee zero and twent; burnable poison.cds.
Locations in the assembly not filled with a source or burnable poison Wee '-thi-Mmrh Tba J act..
.q q
~"
of sufficient clearance for these sourcc g
g only at the core locations which contair DUPLICATE DOCUMENT
}
j j '}
l%
Ii t
Entire document previously entered N
into system under:
O ANO 7 N [o 2 9 d ) 2 d i'o. of pages :
+
.