ML19224C482
| ML19224C482 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 06/20/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| References | |
| NUDOCS 7907020447 | |
| Download: ML19224C482 (1) | |
Text
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'o UNITED STATES E'f3.cg(
NUCLEAR REGULATORY COMMISSION t.,(
(g."J REGION V
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1990 N. CALIFORNIA COULEVARD
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,e SUITE 202, WALNUT CREEK PLAZA
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WALNUT CREE K, CALIFOR'JI A 94596 June 20, 1979 Docket Nos. 50-528 50-529 50-530 Arizona Public Service Company P. O. Box 21666 Phoenix, Arizona 85036 Attention: Mrs E. E. Van Brunt, Jr.
Vice President, Cor.struction Projects Gentlemen:
This Information flotice 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.
ilo specific action or response is requested at this time.
If further flRC evaluations so indicate, an IE Circular or Bulletin will be issued to recommend or request specific licensee actions.
If you have questions regarding the matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, n
![E cl R. H. Engelken Director
Enclosure:
IE Information flotice flo. 79-17 cc w/ enclosures:
F. W. Hartley, APS 272 007 7 00702 0 t//[ 7
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 June 20, 1979 IE Information Notice No. 79-17 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-tior alsa 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. Ccok 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 th.s 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 betweer zero and twenty burnable poison rods.
Locations in the assembly not filledwithasourceorburnablepoiSon_ rod,c;ogJtn a thimble plug.
The lack
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of sufficient clearance for these s only at the core locations which co DUPLIr ATE DOCUMENT 272 0J8 Entire document previously entered into system under:
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