ML19256B467
| ML19256B467 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 06/20/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Woolever E DUQUESNE LIGHT CO. |
| References | |
| NUDOCS 7907110367 | |
| Download: ML19256B467 (1) | |
Text
TW
/g>* %q%
r UNITED STATES
_y
$ g
^c, c ',e y3-NUCLEAR REGULATORY COMMISSION I
REGION I
^
. 8
%, '~. >, [ d o, ' fg 631 PARK AVENUE KING OF PRUSSIA, PENNSYLVANIA 19406
+....
June 20, 1979 Docket No. 50-412 Duquesne Light Company ATTN:
Mr. E. J. Woolever Vice President 435 Sixth Avenue Pittsburgh, Pennsylvania 15219 Gentlemen:
This Information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipients will review tne 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 this office.
Sincerely, Y6t' An Boyce H. Grier
~
Director
Enclosures:
1.
IE Information Notice No. 79-17 2.
List of IE Information Notices Issued in 1979 cc w/encls:
R. J. Washabaugh, Quality Assurance Manager 836 115 79071103G7 i 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, 1979 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 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 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 reamor 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 "ie 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 thimble plug.
The lack of sufficient clearance for these sourck' ?;'mr WM-
. MP a
m only at the core locations which contai jg 4
8 Entire document previously entered 1
jintosystemunder:
q
]
h h
ANO pp G
No. of pages:
7 q
1 d
.