ML071970121
| ML071970121 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 08/06/2007 |
| From: | Robert Kuntz NRC/NRR/ADRO/DORL/LPLIII-2 |
| To: | Crane C Exelon Generation Co |
| kuntz, Robert , NRR/DORL, 415-3733 | |
| References | |
| TAC MD2658 | |
| Download: ML071970121 (6) | |
Text
August 6, 2007 Mr. Christopher M. Crane President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
BRAIDWOOD, UNIT 1 - EVALUATION OF SPRING 2006 REFUELING OUTAGE 12 STEAM GENERATOR INSERVICE INSPECTION
SUMMARY
REPORT (TAC NO. MD2658)
Dear Mr. Crane:
By letter dated May 8, 2006 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML061280652), Exelon Generation Company, LLC (the licensee) submitted the steam generator (SG) tube plugging report for refueling outage (RFO) 12 in accordance with Technical Specification (TS) Section 5.6.9.a. By letter dated July 25, 2006 (ADAMS Accession No. ML062060599), the licensee submitted the annual SG tube inservice inspection report for RFO 12 in accordance with TS Section 5.6.9.b. Additional information regarding the RFO 12 SG tube inspections was provided by the licensee in letters dated June 28, 2006 (ADAMS Accession No. ML062090368), and May 21, 2007 (ADAMS Accession No. ML071420119).
The staff has completed its review of these reports and concludes that the licensee provided the information required by their TSs and that no additional follow-up is required at this time.
Sincerely,
/RA/
Robert F. Kuntz, Project Manager, Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-456
Enclosure:
As stated cc w/encl: See next page
Braidwood Station Units 1 and 2 cc:
Document Control Desk - Licensing via e-mail Mr. Dwain W. Alexander, Project Manager Westinghouse Electric Corporation via e-mail Ms. Bridget Little Rorem Appleseed Coordinator via e-mail Howard A. Learner Environmental Law and Policy Center of the Midwest 35 East Wacker Dr., Suite 1300 Chicago, IL 60601-2110 U.S. Nuclear Regulatory Commission Braidwood Resident Inspectors Office 35100 S. Rt. 53, Suite 79 Braceville, IL 60407 Ms. Lorraine Creek RR 1, Box 182 Manteno, IL 60950 Illinois Emergency Management Agency Division of Disaster Assistance &
Preparedness 1035 Outer Park Dr Springfield, IL 62704 County Executive via e-mail Attorney General 500 S. Second Street Springfield, IL 62701 Plant Manager - Braidwood Station via e-mail Site Vice President - Braidwood via e-mail Senior Vice President - Operations Support via e-mail Chairman, Ogle County Board Post Office Box 357 Oregon, IL 61061 Manager Regulatory Assurance - Braidwood via e-mail Director - Licensing and Regulatory Affairs via e-mail Associate General Counsel via e-mail Senior Vice President - Midwest Operations via e-mail Vice President - Regulatory Affairs via e-mail Manager Licensing - Braidwood, Byron and LaSalle via e-mail
ML062060599), the licensee submitted the annual SG tube inservice inspection report for RFO 12 in accordance with TS Section 5.6.9.b. Additional information regarding the RFO 12 SG tube inspections was provided by the licensee in letters dated June 28, 2006 (ADAMS Accession No. ML062090368), and May 21, 2007 (ADAMS Accession No. ML071420119).
The staff has completed its review of these reports and concludes that the licensee provided the information required by their TSs and that no additional follow-up is required at this time.
Sincerely,
/RA/
Robert F. Kuntz, Project Manager, Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-456
Enclosure:
As stated cc w/encl: See next page DISTRIBUTION:
PUBLIC LPL3-2 R/F RidsNrrPMRKuntz RidsOgcRp DHills, RIII KKarwoski RidsNrrDorlLpl3-2 RidsAcrsAcnwMailCenter LMiller RidsNrrLAEWhitt RSkokowski, RIII RidsRgn3MailCenter RidsNrrDciCpnb ADAMS Accession Number: ML071970121 NRR-106
- with edit OFFICE PM:LPLIII-2 LA:LPLIII-2 BC:CSGB BC:LPLIII-2 NAME RKuntz EWhitt AHiser*
RGibbs DATE 7/30/07 7/30/07 7/30/07 8/6/07
ENCLOSURE OFFICE OF NUCLEAR REACTOR REGULATION EVALUATION OF STEAM GENERATOR INSPECTION REPORTS FROM 2006 REFUELING OUTAGE BRAIDWOOD STATION, UNIT 1 DOCKET NO. STN 50-456
1.0 INTRODUCTION
By letter dated May 8, 2006 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML061280652), Exelon Generation Company, LLC (the licensee) submitted the steam generator (SG) tube plugging report for refueling outage (RFO) 12 in accordance with Technical Specification (TS) Section 5.6.9.a. By letter dated July 25, 2006 (ADAMS Accession No. ML062060599), the licensee submitted the annual SG tube inservice inspection report for RFO 12 in accordance with TS Section 5.6.9.b. Additional information regarding the RFO 12 SG tube inspections was provided by the licensee in letters dated June 28, 2006 (ADAMS Accession No. ML062090368), and May 21, 2007 (ADAMS Accession No. ML071420119).
2.0 BACKGROUND
The four SGs at Braidwood Unit 1 were replaced in 1998 with SGs fabricated by Babcock and Wilcox International. During RFO 12, SG A and SG B were inspected. Each SG contains approximately 6,633 thermally-treated Alloy 690 tubes. Each tube has a nominal outside diameter of 0.6875-inch and a nominal wall thickness of 0.040-inch. The tubes were hydraulically expanded at both ends for the full-length of the tubesheet and are supported by a number of stainless steel tube supports (lattice grid). The tubes installed in Rows 1 through 21 were thermally-stress relieved after bending.
3.0 RESULTS OF SPRING 2006 INSPECTION The licensee provided the scope, extent, methods, and results of their SG tube inspections in the documents referenced above. In addition, the licensee described corrective actions (i.e., tube plugging) taken in response to the inspection findings.
The licensee included information regarding the examination and evaluation procedures used during the SG eddy current inspection which included two independent analyses of the eddy current data, using automated data screening analysis systems.
The licensee clarified that only one hot-leg dent/ding greater than or equal to 2.0-volts was detected during RFO 12. This dent/ding was found in Tube Row 8 Column 11 of SG 1A and no degradation was identified. In addition, the licensee clarified that no other dents/dings were inspected during RFO 12.
During the inspection, the licensee continued to monitor the potential for tubes to be in close proximity as part of the 100-percent full-length bobbin coil inspections. The licensee did not identify any tube degradation associated with the tubes being in close proximity. The licensee stated that this condition will continue to be monitored during future SG inspections.
The licensee plugged and stabilized 18 tubes as a result of loose parts or wear attributed to loose parts. The parts were detected by a variety of methods including visual inspection and eddy current testing. Some of the wear indications attributed to loose parts were only identified with a rotating probe (and not with the bobbin probe). Although the indications not detected with a bobbin probe were small (the largest measuring approximately 23-percent through-wall),
all were near the top of the tubesheet. As a result, even if these indications were larger, it is not clear whether they would have been detected with a bobbin probe (with a turbo mix applied) given the interfering signal from the top of the tubesheet and expansion transition.
4.0 CONCLUSION
S AND FUTURE INSPECTION PLANS Based on a review of the information provided, the staff concludes that the licensee provided the information required by their TSs. In general, the SG tube inspections at Braidwood Station Unit 1, appear to be consistent with the objective of detecting potential tube degradation and the inspection results appear to be consistent with industry operating experience at similarly-designed and operated units.
Principal Contributor: L. Miller Date: August 6, 2007