ML090640189
| ML090640189 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 03/05/2009 |
| From: | David M Plant Licensing Branch III |
| To: | Pardee C Exelon Nuclear |
| marshall david 415-1547 | |
| References | |
| TAC ME0598, TAC ME0599 | |
| Download: ML090640189 (5) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 1'1arch 5, 2009 Mr. Charles G. Pardee President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555 SUB..IECT:
BRAIDWOOD STATION, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO RELIEF REQUEST 13R-04 (TAC NOS. ME0598 AND ME0599)
Dear Mr. Pardee:
By letter to the Nuclear Regulatory Commission (NRC) dated February 5, 2009, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML090370190), as supplemented by letter dated February 26, 2009 (ADAMS Accession No. ML090580290),
Exelon Generation Company, LLC (the licensee) submitted Request for Relief /3R-04 to request relief from the requirement of Title 10 of the Code of Federal Regulations, Section 50.55a, "Codes and standards," paragraph (g)(6)(ii)(E), Footnote 1, which would require the performance of a bare-metal visual examination of the reactor pressure vessel bottom mounted instrumentation penetrations during the next refueling outage after January 1, 2009. The request was submitted to support the Braidwood Station, Unit 1, spring 2009 refueling outage (A1R14) and the Braidwood, Unit 2, fall 2009 refueling outage (A2R14).
The NRC staff is reviewing your submittal and has determined that additional information is required to complete its review. The specific information requested is addressed in the enclosure to this letter. Please provide a response within 7 days from the date of this letter.
The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1547.
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I Mars all J. David, Senior Project Manager Plant' icensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-456 and STN 50-457
Enclosure:
Request for Additional Information cc w/encl: Distribution via ListServ
REQUEST FOR ADDITIONAL INFORMATION BRAIDWOOD STATION, UNITS 1 AND 2 DOCKET NOS. STN 50-456 AND STN 50-457 By letter to the Nuclear Regulatory Commission (NRC) dated February 5, 2009 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML090370190), as supplemented by letter dated February 26,2009 (ADAMS Accession No. ML090580290),
Exelon Generation Company, LLC (Exelon, the licensee) submitted Request for Relief 13R-04 to request relief from the requirement of Title 10 of the Code of Federal Regulations, Section 50.55a, "Codes and standards," paragraph (g)(6)(ii)(E), Footnote 1, which would require the performance of a bare-metal visual examination of the reactor pressure vessel bottom mounted instrumentation (BMI) penetrations during the next refueling outage after January 1, 2009. The request was submitted to support the Braidwood Station, Unit 1, spring 2009 refueling outage (A1 R14) and the Braidwood, Unit 2, fall 2009 refueling outage (A2R14). In order to complete its review, the NRC staff requests the following additional information, which relates to the Electric Power Research Institute's Technical Report MRP-166, "Demonstration of Equipment and Procedures for the Inspection of Alloy 600 Bottom Mounted Instrumentation (BMI) Head Penetrations," dated March 2006.
Question 1 What are the critical flaw locations and orientations? How were these critical flaws incorporated in the demonstration?
Our understanding is that the mockups contained radial and circumferential flaws located on the wetted surface of the attachment weld. Our understanding from ultrasonic testing (UT) examination of control rod drive mechanism (CRDM) penetrations is that UT is unable to detect stress-corrosion cracking (SCC) in the J-groove welds unless the SCC is very close to the interface between the penetration and the weld. Since the report indicates that all flaws were detected, please explain how the defects located on the wetted surface of the attachment weld were detected in view of the experience with UT of CRDM penetrations.
Question 2 For the Westinghouse 3-and 4-loop design:
a) Please characterize the flaw population distribution for the mockups (i.e., range of flaw length and depth, orientation, and types)?
b) What types of implants were used to generate flaws?
c) If cold isostatic processing (CIP) flaws were used in the mockups, please provide information on the degree of squeezing during the CIP process and whether the squeezed notches are representative of SCC. Please provide the radius of the CIP flaw tips or a direct comparison with flaws used by Performance Demonstration Initiative in Appendix VIII qualifications, and any reports that compare the response of the flaws used in the mockups with the responses from SCCs.
ENCLOSURE
- 2 d) Did the mockups have any flaws that are representative of fabrication defects? Please provide information on how the UT examiners know the difference between indications from a service induced defect and a fabrication defect.
e) Do the mockups include a lack of fusion at the weld/tube interface?
Question 3 Please provide the criteria that will be used to determine recordable indications. For reporting criteria, how are service induced defects differentiated from fabrication indications, particularly if the mockups do not contain fabrication indications.
Question 4 In general, is there any particular flaw type/orientation/size/location that may be missed? More specifically, time-of-flight diffraction (TOFD) UT has a known limitation for near surface inspection in that the presence of the lateral wave may obscure the detection of small flaws near the scan surface. Is this a concern for these inspections? Why/why not?
Question 5 MRP-166 notes that the vendor's procedure will identify responsibilities and qualification requirements for personnel carrying out several functions including documenting minimum personnel training requirements and qualifications for acquisition and analysis. In light of the fact that a high degree of operator skill is required to correctly interpret TOFD UT inspection results, please provide a summary of the training and qualification requirements for personnel who carried out the TOFD UT data acquisition and analysis.
Question 6 MRP-166 is dated March 2006; however, most of the information it contains dates back to 2004.
Please identify which of the three demonstrated systems in MRP-166 was used at Braidwood. Is the system as described in MRP-166 the same as used at Braidwood? If not, what has been done since 2004? Has this equipment been demonstrated on mockups?
Question 7 The equipment from two vendors was evaluated in MRP-166. The regression analyses presented in MRP-166 seem to indicate that the Vendor A system significantly out-performed the Vendor B system for length and depth measurements for the Westinghouse 3-and 4-loop Design. Why is that? Would the Vendor B system at the time of the Braidwood inspections perform as well as the Vendor A system in MRP-166?
Question 8 What is the implication of the Vendor B system's significant undersizing of length and depth measurements as shown in the regression analyses in MRP-166?
- 3 Question 9 MRP-166 notes in Attachment 1 that it is possible that inspection vendors will be provided confidential information on the flaw characteristics of a limited set of flaws contained in the mockups in cases where vendor weaknesses were identified. Per this statement, confirm whether the examinations used to demonstrate this technique were conducted only on the blind mockups.
Question 10 Per the introduction section of MRP-166, it is noted that both Vendor A and Vendor B are still developing eddy current (ET) equipment for inspecting the wetted surface of the attachment weld. Additionally, there is little information in MRP-166 reporting on the ET portion of the examination. Please clarify what criteria were used to qualify the ET examination technique.
Please elaborate on the results, limitations, status, etc. of the ET examinations. Do the regression analyses include results obtained via ET examination?
Question 11 In Section 3.1 of MRP-166, the discussion of the Vendor B Demonstration, a statement is made that the J-groove ET exam had an issue with being unable to examine the entire area of interest.
Has this been addressed? At the time of the Braidwood inspection what was the status of Vendor B's upgrade of their examination tool? Please address whether a new tool was successfully demonstrated.
Question 12 MRP-166 includes demonstrations of several inspection systems applied to several plant configurations. Please clarify which demonstration in MRP-166 applies to Braidwood including specific information on: (1) the nominallD of the appropriate mockup and how that compares to the nominallD found at Braidwood, and (2) the examination equipment used for the demonstration that applies to Braidwood.
March 5, 2009 Mr. Charles G. Pardee President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
BRAIDWOOD STATION, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO RELIEF REQUEST 13R-04 (TAC NOS. ME0598 AND ME0599)
Dear Mr. Pardee:
By letter to the Nuclear Regulatory Commission (NRC) dated February 5,2009, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML090370190), as supplemented by letter dated February 26, 2009 (ADAMS Accession No. ML090580290),
Exelon Generation Company, LLC (the licensee) submitted Request for Relief 13R-04 to request relief from the requirement of Title 10 of the Code of Federal Regulations, Section 50.55a, "Codes and standards," paragraph (g)(6)(ii)(E), Footnote 1, which would require the performance of a bare-metal visual examination of the reactor pressure vessel bottom mounted instrumentation penetrations during the next refueling outage after January 1, 2009. The request was submitted to support the Braidwood Station, Unit 1, spring 2009 refueling outage (A1R14) and the Braidwood, Unit 2, fall 2009 refueling outage (A2R14).
The NRC staff is reviewing your submittal and has determined that additional information is required to complete its review. The specific information requested is addressed in the enclosure to this letter. Please provide a response within 7 days from the date of this letter.
The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1547.
Sincerely, IRA!
Marshall J. David, Senior Project Manager Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-456 and STN 50-457
Enclosure:
Request for Additional Information cc w/encl: Distribution via ListServ DISTRIBUTION:
PUBLIC LPL3-2 R/F RidsNrrDorlLpl3-2 Resource RidsNrrPMBraidwood Resource RidsNrrLAEWhitt Resource ESullivan, NRR RidsAcrsAcnw_MailCTR Resource RidsNrrDciCvib Resource NRR CNove, NRR RidsRgn3MailCenter Resource GCheruvenki, NRR RidsNrrDorlDpr Resource RidsOgcRp Resource ADAMS Accession Number' ML090640189 NRR-088 OFFICE LPL3-2/PM LPL3-2/LA DSS/CVIB/BC LPL3-2/BC NAME MDavid THarris for EWhitt MMitchell RGibbs DATE 3/5/09 3/5/09 3/5/09 3/5/09 OFFICIAL RECORD COpy