RS-09-113, Response to Request for Additional Information Regarding Relief Request CR-26

Response to Request for Additional Information Regarding Relief Request CR-26

ML092380634
Person / Time
Site:	LaSalle
Issue date:	08/25/2009
From:	Simpson P Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-09-113
Download: ML092380634 (9)

Text

Exelon Nuclear www.exeloncorp .corn Exellon 4300 Winfield Road Nuclear Warrenville, IL 60555 RS-09-113 August 25, 2009 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 LaSalle County Station, Units 1 and 2 Facility Operating License Nos . NPF-11 and NPF-18 NRC Docket Nos. 50-373 and 50-374

Subject:

Response to Request for Additional Information Regarding Relief Request CR-26 References : 1 . Letter from P. R . Simpson (Exelon Generation Company, LLC) to U .S. NRC, "Relief Request CR-26, Inservice Inspection Program Relief Regarding Examination Coverage for Second 10-Year Inservice Inspection Interval,"

dated October 1, 2008

2. Letter from C. S. Goodwin (U.S. NRC) to C . G. Pardee, "LaSalle County Station, Units 1 and 2 - Request for Additional Information Related to Request for Relief No. CR-26 (TAC Nos. MD9817 and MD9818)," dated August 13, 2009 In Reference 1, Exelon Generation Company, LLC (EGC) requested relief from the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," for LaSalle County Station (LSCS) Units 1 and 2. Specifically, CR-26 requested relief on the basis that compliance with the specified requirements is impractical due to plant design . This relief applies to the second 10-year interval inservice inspection program, which concluded on October 1, 2007 .

In Reference 2, the NRC requested additional information to complete its review. In response to this request, EGC is providing the attached information.

August 25, 2009 U.S. Nuclear Regulatory Commission Page 2 There are no regulatory commitments contained in this submittal. Should you have any questions concerning this letter, please contact Mr. Kenneth M. Nicely at (630) 657-2803.

Patrick R. Simpson Manager - licensing cc: NRC Regional Administrator, Region III NRC Senior Resident Inspector - LaSalle County Station Attachments :

1 . Response to Request for Additional Information

2. Supporting Information

ATTACHMENT 1 Response to Request for Additional Information NRC Request 1 Provide further information to adequately demonstrate the impracticality associated with Weld RH-HX1 B-1 on Residual Heat Removal Heat Exchanger 1 B. Include sketches or drawings as necessary, to show coverage obtained and describe the materials and the ultrasonic techniques applied.

Response

ASME Code Component Affected RH-HX1 B-1, Residual Heat Removal Heat Exchanger 1 B, Shell Head to Nozzle Weld Applicable_Code Reau_irements Table IWC-2500-1, Examination Category C-B, Item Number C2 .21 and Figure IWC-2500-4(a)

ImpracticaLity of Compliance The heat exchanger shell head and nozzle materials are carbon steel. During the ultrasonic examination of the shell head to nozzle, reduced coverage was obtained . The coverage reported represents the aggregate coverage from all scans performed on the weld and adjacent base material . Scanning is limited in the transverse direction . The ultrasonic transducers cannot maintain contact due to the curvature of the nozzle base material in the area of the weld.

Scanning from the nozzle forging side of the welds is not possible due to tapered areas in the forgings . Due to the cladding on the inside diameter, two directional coverage from one side is not possible . In order to scan all of the required volume for this weld, the nozzles would need to be redesigned to allow scanning from the nozzle side of the welds, which is impractical.

Sketches and Drawinas Residual Heat Removal Heat Exchanger 1 B is shown on Struthers Wells Corporation drawing 1-71-09-3097103, Revision 9. This drawing was previously submitted to the NRC in the referenced letter on page 244 of Attachment 4. Weld RH-HX1 B-1 is the head to nozzle weld associated with nozzle N3, and the weld is shown in quadrant C7 of the drawing. A plan view is shown in quadrant C8 of the drawing.

Details on the N3 nozzle on Residual Heat Removal Heat Exchanger 1 B are shown on Struthers Wells Corporation drawing 1-71-04-30971 C3, Revision 2, which is included in .

Ultrasonic Technictues Weld RH-HX1 B-1 was examined in 1996 . The ultrasonic examination is documented on data sheet 96-229, which is included in Attachment 2.

ATTACHMENT 1 Response to Request for Additional Information NRC Request State whether the ASME Code surface examination was completed on the subject weld . If the examinations were performed, what were the results of the examinations?

Response

The ASME Code surface examination was completed on weld RH-HX1 B-1 . There were no limitations and no indications identified during the 1996 examination. The magnetic particle examination data sheet for weld RH-HX1 B-1 (i .e., data sheet # 96-230) is provided in .

NRC Request 3 Address whether or not additional coverage of the subject weld could have been achieved if advanced inspection technologies (e .g., phased array ultrasonic transducers) had been applied .

Response

The components within the scope of relief request CR-26 were examined during the second Inservice Inspection interval, which encompassed the period from October 17, 1994, through September 31, 2007. Accepted inspection technologies for that time period were utilized to complete these examinations . These included updated equipment based on computer modeling of the Residual Heat Removal Heat Exchanger nozzles, and technology resulting from advances in ultrasonic examinations due to the Performance Demonstration Initiative (PDI). At the time, phased array technology was not generally developed by the industry to the point where it could be utilized to perform qualified examinations . Specifically, Exelon Generation Company, LLC's (EGC's) inspection vendor does not yet have a qualified phased array technique for examination of vessel welds . When such advances are available to deliver qualified examinations, they will be assessed to determine whether they can achieve increased inspection coverage .

Reference Letter from P. R. Simpson (Exelon Generation Company, LLC) to U .S. NRC, "Response to Request for Additional Information Regarding Relief Request CR-26," dated May 26, 2009

ATTACHMENT 2 Supporting Information Struthers Wells Corporation drawing 1-71-04-30971C3, Revision 2 (1 page)

Ultrasonic Testing Data Sheet No.96-229 (2 pages)

Magnetic Particle Examination Data Sheet # 96-230 (1 page)

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