RS-12-070, Response to Follow-up RAI Questions Related to Exelon Response to RAI Question 7
| ML12104A021 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 04/12/2012 |
| From: | Gullott D Exelon Generation Co, Exelon Nuclear |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| RS-12-070 | |
| Download: ML12104A021 (5) | |
Text
clear Exelon Generation Company, LLC www.exeloncorp.com 4300 Winfield Road Warrenville, IL 60555 RS-1 2-070 April 12, 2012 10 CFR 50.55a U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Quad Cities Nuclear Power Station, Unit 2 Renewed Facility Operating License No. DPR-30 NRC Docket No. 50-265
Subject:
Response to Follow-up RAI Questions Related to Exelon Response to RAI Question #7
References:
1)
Letter from P. R. Simpson (Exelon Generation Company, LLC) to NRC, "Relief Request 14R-1 9 Associated with the Reactor Pressure Vessel Nozzle Repairs,"
dated April 6, 2012 2)
Email from Joel Wiebe (NRC) to D. M. Gullott (Exelon Generation Company, LLC), "Final RAIs Regarding Quad Cities, Unit 2 Relief Request 14R-19," dated April 11, 2012 3)
Letter from D. M. Gullott (Exelon Generation Company, LLC) to NRC, "Response to Request for Additional Information Regarding Relief Request 14R-1 9 Associated with the Reactor Pressure Vessel Nozzle Repairs," dated April 11, 2012 4)
Email from Joel Wiebe (NRC) to D. M. Gullott (Exelon Generation Company, LLC), "Followup RAI Questions Related to Exelon Response to RAI Question
- 7," dated April 12, 2012 In Reference 1, in accordance with 10 CFR 50.55a, "Codes and standards," paragraph (a)(3)(i),
Exelon Generation Company, LLC (EGC), requested NRC approval of a relief request associated with the Fourth Inservice Inspection (ISI) Interval for Quad Cities Nuclear Power Station (QCNPS), Unit 2. Note that the fourth interval of the QCNPS ISI program complies with the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section Xl, 1995 Edition with addenda through 1996.
U. S. Nuclear Regulatory Commission April 12, 2012 Page 2 During review of the subject relief request, the NRC concluded that additional information would be needed to complete their review. The NRC transmitted the Request for Additional Information (RAI) to EGC in Reference 2. This request contained 10 individual items; however, during a telephone conversation between J. Wiebe (NRC) and D. M. Gullott (EGC), it was agreed that RAIs 1 -7 would be addressed immediately; and RAIs 8-10 would be addressed in a follow -up near term response. The responses to RAIs 1-7 were provided in Reference 3. In Reference 4, the NRC transmitted follow-up questions to the EGC response to RAI 7 in Reference 3. The responses to RAI 7 follow-up questions are provided in Attachment 1 to this letter.
There are no regulatory commitments contained in this letter.
Should you have any questions concerning this letter, please contact Mr. Joseph A. Bauer at (630) 657-2804.
Respectfully, David M. Gullott Manager - Licensing Exelon Generation Company, LLC : Response to Follow-up RAI Questions Related to Exelon Response to RAI Question #7
ATTACHMENT 1 Response to Follow-up RAI Questions Related to Exelon Response to RAI Question #7 In Reference 1, in accordance with 10 CFR 50.55a, "Codes and standards," paragraph (a)(3)(i),
Exelon Generation Company, LLC (EGC), requested NRC approval of a relief request associated with the Fourth Inservice Inspection (ISI) Interval for Quad Cities Nuclear Power Station (QCNPS), Unit 2. Note that the fourth interval of the QCNPS ISI program complies with the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section Xl, 1995 Edition with addenda through 1996.
As noted in Reference 1, during a recent pressure test of the reactor pressure vessel, one instrument penetration, N-11 B, was found to have approximately 60 drops per minute of leakage. Currently, there is not a qualified or demonstrated technique to perform volumetric non-destructive examination (NDE) of the partial penetration weld in this configuration that can be used to accurately characterize the location, orientation, or size of a flaw in the weld; therefore, as an alternative to performing the NDE required to characterize the flaw in penetration N-11 B, EGC proposed analyzing a maximum postulated flaw that bounds the range of flaw sizes that could exist in the J-groove weld and nozzle.
During review of the subject relief request, the NRC concluded that additional information would be needed to complete their review. The NRC transmitted the Request for Additional Information (RAI) to EGC in Reference 2. This request contained 10 individual items; however, during a telephone conversation between J. Wiebe (NRC) and D. M. Gullott (EGC), it was agreed that RAIs 1-7 would be addressed immediately; and RAIs 8-10 would be addressed in a follow-up near term response. The responses to RAIs 1-7 were provided in Reference 3. In Reference 4, the NRC transmitted follow-up questions to the EGC response to RAI 7 in Reference 3. The responses to RAI 7 follow-up questions are provided below.
1.
What is the temporary tooling (after which the response states Code Case N-638-4 requires another surface examination)? N-638-4 requires another surface examination after weld-attached thermocouples are removed in paragraph 4a(3).
Response
The temporary attachments used are capacitor discharge welded studs utilized for mounting the machining equipment and the machine welding head. A surface (MT) examination was performed prior to attaching the studs and a surface (MT) examination will be performed following removal. With regards to this repair, weld-attached thermocouples were not used.
Page 1 of 3
ATTACHMENT 1 Response to Follow-up RAI Questions Related to Exelon Response to RAI Question #7 2.
Code Case N-638-4 Paragraph 4(a)(4) states that "Acceptance criteria for surface and volumetric examination shall be in accordance with Construction Code or Section III." For some of the examinations, the response to RAI 7 references [ASME] Section III, 1992 Edition, while for other examinations, [ASME Code] Section III, 1965 Edition, Summer 1965 Addenda is referenced. Code Case N-416 -3 references the ASME Code, Section lll, 1992 Edition for NDE methods and acceptance criteria. Explain the logic for referencing the original construction code of record (Section III, 1965 Edition, Summer 1965 Addenda) for some examinations and Section Ill, 1992 Edition for other examinations
Response
Surface examination of the base metal weld area prior to welding activities references the original code of construction, ASME Section III, 1965 Edition, Summer 1965 Addenda, since no welding has taken place on the area.
Once welding activities occur on the weld area, which is part of the pressure retaining boundary, the conditions within Code Case N-416-3 require NDE methods in accordance with ASME Section III, 1992 Edition. This limitation is written into this revision of the code case.
3.
Confirm that Code Cases N-405-1 and N-416-3 are incorporated in the QCNPS ISI Program.
Response
Code Case N-405-1 is referenced in the QCNPS ISI Program Plan and was approved unconditionally in RG 1.84, "Design, Fabrication, and Materials Code Case Acceptability, ASME Section III," Revision 35, dated October 2010. Code Case N-416-3 is referenced in the QCNPS ISI Program Plan and was approved unconditionally in RG 1.147, "Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1," Revision 15, dated October 2007. QCNPS has not yet updated its ISI Program Plan to incorporate Code Case N-416-4 which is conditionally acceptable in RG 1.147 Revision 16, dated October 2010.
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ATTACHMENT 1 Response to Follow-up RAI Questions Related to Exelon Response to RAI Question #7 REFERENCES 1.
Letter from P. R. Simpson (Exelon Generation Company, LLC) to NRC, "Relief Request 14R-19 Associated with the Reactor Pressure Vessel Nozzle Repairs," dated April 6, 2012 2.
Email from Joel Wiebe (NRC) to D. M. Gullott (Exelon Generation Company, LLC), "Final RAls Regarding Quad Cities, Unit 2 Relief Request 14R -19," dated April 11, 2012 3.
Letter from D. M. Gullott (Exelon Generation Company, LLC) to NRC, "Response to Request for Additional Information Regarding Relief Request 14R-19 Associated with the Reactor Pressure Vessel Nozzle Repairs," dated April 11, 2012 4.
Email from Joel Wiebe (NRC) to D. M. Gullott (Exelon Generation Company, LLC),
"Followup RAI Questions Related to Exelon Response to RAI Question #7," dated April 12, 2012 Page 3 of 3