3F0597-04, Forwards Summary Document Describing Qualification of Focused Transducer Sys Used During Refuel 10,per Request for Info in 970129 Meeting

Forwards Summary Document Describing Qualification of Focused Transducer Sys Used During Refuel 10,per Request for Info in 970129 Meeting

ML20141D924
Person / Time
Site:	Crystal River
Issue date:	05/14/1997
From:	Holden J FLORIDA POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20141D931	List: 3F0597-04, Forwards Summary Document Describing Qualification of Focused Transducer Sys Used During Refuel 10,per Request for Info in 970129 Meeting ML20141D940
References
3F0597-04, 3F597-4, NUDOCS 9705200241
Download: ML20141D924 (2)

Text

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s Florida Power CORPORATION ouras esaur May 14, 1997 3F0597-04 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001

Subject:

Qualification of Focused Transducer System and Personnel

References:

A.

FPC to NRC letter, 3F0994-02, dated September 2, 1994 B.

FPC to NRC letter, 3F0896-16, dated August 14, 1996 C.

FPC to NRC letter, 3F1294-12, dated December 16, 1994 D.

NRC to FPC letter, 3N1094-15, dated October 19, 1994

Dear Sir:

This letter is being submitted by Florida Power Corporation (FPC) to provide the NRC with a summary document describing the qualification of the focused transducer system (FTS) used during Refuel 10 to re-inspect a subsurface flaw in the weld connecting the pressurizer nozzle to the lower head, initially detected in Refuel 9, Spring 1994.

The attachment provides a document (prepared by Framatome Technologies Inc. for FPC) discussing the development of the focused transducer used during Refuel 10 to re-size the indication detected in the weld connecting the pressurizer nozzle to the lower head, the demonstration which quantified the focusing effect of the transducer, and the results of the re-examination.

The qualification certification of the individual who performed the FTS examination is also provided. This information is provided pursuant to NRC's request for information in a meeting held on January 29, 1997.

BACKGROUND:

/

During a Refuel 9 examination, a subsurface flaw was detected in the weld connecting the pressurizer nozzle to the lower head (Reference A). The flaw was detected with a 2.25 MHz 1/2" x 1" standard 60 degree transducer. During Refuel f

10, the flaw was re-examined by repeating the standard ASME Section XI T examination that identified the flaw during Refuel 9.

The detailed results of this inspection were provided in Reference B.

Those results showed that using the same type of transducer, the Refuel 10 re-examination resulted in a smaller size flaw than originally reported during Refuel 9 although the size was still larger than allowed by ASME Section XI.

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9705200241 970514 PDR P

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i U. S. Nuclear Regulatory Commission 3F0597-04

'Page 2 During Refuel 10, FPC had also scheduled the re-examination of the flaw using the FTS. The FTS was developed to more accurately estimate the through-wall size of the flaw. The use of the FTS reduced the exaggerated effects of beam spread by converging the energy at the focal point.

The results obtained using the FTS revealed that the indication is a slag inclusion, not a linear defect as it had been previously reported.

The FTS also established that the size of the indication is below the ASME acceptance criteria of 2.0% a/t where "a" -is a measure of the dimension of the flaw in the through-wall direction and "t" is a measure of the pressure boundary thickness (Reference B).

SUMMARY

FPC requested NRC concurrence (Reference B) to remove the pressurizer surge nozzle from the increased frequency schedule and return the examination frequency to the normal schedule required by the 1983 Edition of ASME Section XI, Inspection Program B.

Based on the results of the FTS, the indication's size is within the ASME Section XI acceptance criteria, therefore, FPC is requesting NRC review of the attached documents; closure of TAC No. M90489 (Reference D);

and authorization to return the pressurizer surge nozzle to normal examination frequency.

Sincerely, Y~

J. J. Holden, Director Nuclear Engineering and Projects JJH/LVC Attachment xc:

Regional Administrator, Region II Senior Resident inspector NRR Project Manager

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