ML19320A601

Final Significant Const Deficiency Rept 16 Re Control Element Drive Mechanism Guide Cones & Penetration Assemblies Interface.Offset Condition Exists Which Could Produce Interference on Control Assembly Shaft

ML19320A601
Person / Time
Site:	Waterford
Issue date:	06/27/1980
From:	LOUISIANA POWER & LIGHT CO.
To:
Shared Package
ML19320A598	List: ML19320A597 ML19320A601
References
NUDOCS 8007020405
Download: ML19320A601 (2)

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LOUISIANA POWER & LIGHT COMPANY WATERFORD SES UNIT NO. 3 Final Report of Significant Construction Deficiency No. 16 Control Element Drive Mechanism Guide Cones Off-Set Reviewed by _

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Crnich - Site Manager Reviewed by b 20!,90 jd.'J. Milhiser -/Proj ect " Superintendent '

Reviewed .Aa r / (4 t** h*?! I~ $h yfJ. Hart-ProjectLicensingyngineer Reviewed by

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~20-/ b R. A. H'artnett - Q. A. Site Supervisor June 20, 1980 8007020406 l

FINAL REPORT SIGNIFICANT CONSTRUCTION DEFICIENCY NO. 16 CONTROL ELEMENT DRIVE MECHANISM GUIDE CONES OFF-SET Introduction This report is submitted pursuant to 10CFR50.55(e) . It describes a deficiency between the Control Element Drive Mechanism (CEDM) Guide Cones and CEDM penetra-tion assemblies interface.

Background

By telephone conversation on May 29, 1980, Louisiana Power & Light notified the Nucl?ar Regulatory Commission concerning a deficiency that had been identified during an inspection conducted at the Waterford 3 Site by Combustion Engineering.

The deficiency involved an apparent offset (non-concentric) condition located at the shoulder interface between the top of the guide cones and bottoc of the CEDM penetration assemblies. The CEDM guide cones are installed (threaded and tack welded) on the underside of the reactor vessel head at each CEDM nozzle location.

These cones serve to guide the tips of the CEA extension shafts into the nozzles and motoc housings when the head is lowered onto the vessel. They do not serve any other function.

Description of Deficiency On May 7,1980, a Combustion Engineering Field Engineering Service Engineer, a Combustion Engineering Site Representative and a Nuclear Installation Services Company (NISCO) Inspector examined all ninety-one (91) of the CEDM housing as-semblies from the underside of the reactor vessel head for the purpose of estab-11shing corrective action for conditions previously identified by NISCO. This examination detected that an apparent offset (non-concentric) condition existed in some of the CEDM assemblies. Subsequently, Combustion Engineering confirmed that sixteen (16) guide cones were offset by approximately 1/32", five (5) as being offset by approximately 1/16", and one (1) as being offset by approximately 1/8". Further, Combustion Engineering established that this condition existed j at the time of shipment. An initial evaluation conducted by CE Windsor Engineer-ing and Licensing indicated that the offset condition could possibly produce some rubbing or interference on a Control Element Assembly (CEA) extension shaf t during a scram which could increase the time for the rod to insert completely.

Analysis of Safety Implications The engineering review performed to determine the safety significance of this condition determined that the cones do not form a part of the Reactor Coolant Pressure Boundary, and the integrity of the Reactor Vessel was not in any way affected.

The FSAR, Subsection 15.0.2, states that the Chapter 15 accident analyses are

. based on the CEA's reaching their ninety percent insertion position in 2.7 seconds.

It is possible that the offset of affected guide cones in the Reautor Vessel Head 1 I

could, if lef t uncorrected, produce some rubbing or interference on a CEA exten-sion shaft during a scram, thereby increasing the drop time. j l

l Corrective Action Combustion Engineering completed corrective repairs during the period from May 29 through June 2,1980, and issued a Report of Welded Repair or Alteration, Form R-1, dated June 4, 1980.

Corrective action was accomplished in accordance with the disposition to Noncon-formance Report W3-2107 and instructions provided by CE Traveler No. 99709527-001, dated May 28, 1980.

The repair consisted of mechanically grinding the twenty-two (22) cones to reduce the offset to zero (0) by using an air motor with carbide burrs to remove the offset metal. The air motor was mounted to an expanded mandrel set in the CEDM assembly. The zero offset was checked through'the use'of a straight edge placed against the assembly wall surfaces and extending down onto the guide cone wall surfaces. The guide cone surfaces were liquid penetrant examined, visually in-spected, and verified as having met the requirements as delineated in the traveler.