ML071900420
| ML071900420 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 07/30/2007 |
| From: | Thomas Wengert NRC/NRR/ADRO/DORL/LPLIII-2 |
| To: | Bezilla M FirstEnergy Nuclear Operating Co |
| Wengert, Thomas J, NRR/DORL, 415-4037 | |
| References | |
| TAC MD3378 | |
| Download: ML071900420 (8) | |
Text
July 30, 2007 Mr. Mark B. Bezilla Site Vice President FirstEnergy Nuclear Operating Company Davis-Besse Nuclear Power Station Mail Stop A-DB-3080 5501 North State Route 2 Oak Harbor, OH 43449-9760
SUBJECT:
DAVIS-BESSE NUCLEAR POWER STATION, UNIT NO. 1 - EVALUATION OF SPRING 2006 REFUELING OUTAGE 14 STEAM GENERATOR TUBE INSPECTIONS (TAC NO. MD3378)
Dear Mr. Bezilla:
By letter to the Nuclear Regulatory Commission (NRC) dated April 6, 2006 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML061000237),
FirstEnergy Nuclear Operating Company, (FENOC, the licensee) submitted the steam generator (SG) tube plugging report for Refueling Outage (RFO) 14 in accordance with Technical Specification (TS) Section 4.4.5.5(a) for Davis-Besse Nuclear Power Station, Unit No. 1 (DBNPS). The licensee provided the License Condition 2.C(7) report for RFO 14 in a letter dated June 9, 2006 (ADAMS Accession No. ML061640113). The RFO 14 inservice inspection summary report was submitted by the licensee in a letter dated July 21, 2006 (ADAMS Accession No. ML062060183). By letter dated October 6, 2006 (ADAMS Accession No. ML062850098), FENOC submitted the 12-month SG tube inservice inspection report for RFO 14 in accordance with TS Sections 4.4.5.5.b and 6.9.1.5.b. In addition to these documents, additional information regarding RFO 14 was provided by the licensee during a conference call on March 21, 2006 (ADAMS Accession No. ML070260225), and a response to a request for additional information dated April 5, 2007 (ADAMS Accession No. ML070960442).
M. B. Bezilla The NRC staff has completed its review of these reports, and concludes that you have provided the information required by the DBNPS TSs and that no additional follow-up is required at this time. The NRC staffs review of the reports is enclosed.
Sincerely,
/RA/
Thomas J. Wengert, Project Manager Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-346
Enclosure:
Evaluation of Steam Generator Tube Inspection Reports cc w/encls: See next page
M. B. Bezilla The NRC staff has completed its review of these reports, and concludes that you have provided the information required by the DBNPS TSs and that no additional follow-up is required at this time. The NRC staffs review of the reports is enclosed.
Sincerely,
/RA/
Thomas J. Wengert, Project Manager Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-346
Enclosure:
Evaluation of Steam Generator Tube Inspection Reports cc w/encls: See next page DISTRIBUTION:
PUBLIC LPL3-2 R/F RidsNrrPMTWengert RidsNrrDciCsgb RidsOgcRp RidsRgn3MailCenter RidsAcrsAcnwMailCenter DHills, RIII RidsNrrLAEWhitt RidsNrrDorlLpl3-2 KKarwoski, NRR LMiller, NRR ADAMS Accession Number: ML071900420 NRR-106 OFFICE PM/LPL3-2 LA/LPL3-2 DCI/CSGB/BC BC/LPL3-2 NAME TWengert EWhitt AHiser RKuntz for RGibbs DATE 7/30/07 7/30/07 7/24/07 7/30/07 OFFICIAL RECORD COPY
Davis-Besse Nuclear Power Station, Unit No. 1 cc:
Manager, Site Regulatory Compliance Attorney General FirstEnergy Nuclear Operating Company Office of Attorney General Davis-Besse Nuclear Power Station 30 East Broad Street Mail Stop A-DB-3065 Columbus, OH 43216 5501 North State Route 2 Oak Harbor, OH 43449-9760 President, Board of County Commissioners of Ottawa County Director, Ohio Department of Commerce Port Clinton, OH 43252 Division of Industrial Compliance Bureau of Operations & Maintenance President, Board of County 6606 Tussing Road Commissioners of Lucas County P.O. Box 4009 One Government Center, Suite 800 Reynoldsburg, OH 43068-9009 Toledo, OH 43604-6506 Regional Administrator, Region III The Honorable Dennis J. Kucinich U.S. Nuclear Regulatory Commission United States House of Representatives Suite 210 Washington, D.C. 20515 2443 Warrenville Road Lisle, IL 60532-4352 The Honorable Dennis J. Kucinich United States House of Representatives Resident Inspector 14400 Detroit Avenue U.S. Nuclear Regulatory Commission Lakewood, OH 44107 5503 North State Route 2 Oak Harbor, OH 43449-9760 Joseph J. Hagan President and Chief Nuclear Officer Stephen Helmer FirstEnergy Nuclear Operating Company Supervisor, Technical Support Section Mail Stop A-GO-14 Bureau of Radiation Protection 76 South Main Street Ohio Department of Health Akron, OH 44308 35 East Chestnut Street, 7th Floor Columbus, OH 43215 David W. Jenkins, Attorney FirstEnergy Corporation Carol OClaire, Chief, Radiological Branch Mail Stop A-GO-15 Ohio Emergency Management Agency 76 South Main Street 2855 West Dublin Granville Road Akron, OH 44308 Columbus, OH 43235-2206 Danny L. Pace Zack A. Clayton Senior Vice President, Fleet Engineering DERR FirstEnergy Nuclear Operating Company Ohio Environmental Protection Agency Mail Stop A-GO-14 P.O. Box 1049 76 South Main Street Columbus, OH 43266-0149 Akron, OH 44308 State of Ohio Manager, Fleet Licensing Public Utilities Commission FirstEnergy Nuclear Operating Company 180 East Broad Street Mail Stop A-GO-2 Columbus, OH 43266-0573 76 South Main Street Akron, OH 44308
M. B. Bezilla Davis-Besse Nuclear Power Station, Unit 1 cc:
Director, Fleet Regulatory Affairs FirstEnergy Nuclear Operating Company Mail Stop A-GO-2 76 South Main Street Akron, OH 44308 Jeannie M. Rinckel Vice President, Fleet Oversight FirstEnergy Nuclear Operating Company Mail Stop A-GO-14 76 South Main Street Akron, OH 44308 Richard Anderson Vice President, Nuclear Support FirstEnergy Nuclear Operating Company Mail Stop A-GO-14 76 South Main Street Akron, OH 44308 James H. Lash Senior Vice President of Operations and Chief Operating Officer FirstEnergy Nuclear Operating Company Mail Stop A-GO-14 76 South Main Street Akron, OH 44308
OFFICE OF NUCLEAR REACTOR REGULATION EVALUATION OF STEAM GENERATOR TUBE INSPECTION REPORTS FROM SPRING 2006 REFUELING OUTAGE 14 DAVIS-BESSE NUCLEAR POWER STATION, UNIT NO. 1 DOCKET NO. 50-346
1.0 INTRODUCTION
By letter to the Nuclear Regulatory Commission (NRC) dated April 6, 2006 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML061000237),
FirstEnergy Nuclear Operating Company, (FENOC, the licensee) submitted the steam generator (SG) tube plugging report for Refueling Outage (RFO) 14 in accordance with Technical Specification (TS) Section 4.4.5.5(a) for Davis-Besse Nuclear Power Station, Unit No. 1 (DBNPS). The licensee provided the License Condition 2.C(7) report for RFO 14 in a letter dated June 9, 2006 (ADAMS Accession No. ML061640113). The RFO 14 inservice inspection summary report was submitted by the licensee in a letter dated July 21, 2006 (ADAMS Accession No. ML062060183). By letter dated October 6, 2006 (ADAMS Accession No. ML062850098), FENOC submitted the 12-month SG tube inservice inspection report for RFO 14 in accordance with TS Sections 4.4.5.5.b and 6.9.1.5.b. In addition to these documents, additional information regarding RFO 14 was provided by the licensee during a conference call on March 21, 2006 (ADAMS Accession No. ML070260225), and a response to a request for additional information dated April 5, 2007 (ADAMS Accession No. ML070960442).
2.0 BACKGROUND
DBNPS has two Babcock and Wilcox (B&W) once-through SGs designated SG 1B and SG 2A. Each SG has more than 15,000 Alloy 600 tubes in the mill-annealed condition. The tubes have a nominal outside diameter of 0.625 inches and a nominal wall thickness of 0.037 inches.
Both SG 1B and 2A contain tubes with sleeves and tubes with shop re-rolls.
The previous inspection of the DBNPS SGs was performed during a mid-cycle outage during Cycle 14 (summarized by NRC staff in a letter dated March 29, 2007 (ADAMS Accession No. ML070510609)).
3.0 RESULTS OF SPRING 2006 REFUELING OUTAGE 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.
ENCLOSURE
As a result of the review of the information provided by the licensee, the NRC staff has the following comments/observations:
No degradation was identified in dents or wear scars. However, clusters of new dents were observed around the lane and wedge region at or near the upper tube sheet (UTS). These clusters were reported to be the result of sludge collars developing at the UTS secondary face.
- The axial indications and circumferential indications located in the UTS tube ends were reported to be a result of primary water stress-corrosion cracking (PWSCC). The licensee indicated that these indications were identified in tubes with higher yield strengths, implying that higher yield strength tubes are more susceptible to PWSCC. The licensee reported that the most likely cause for several of the indications to be in adjacent tubes, is that the SGs were originally tubed in rows of similar heats of material.
- One crevice indication was discovered by bobbin coil in SG 1B, and was reported to be volumetric intergranular attack (IGA) based on Alloy 600 industry experience. This tube was plugged.
- Based on bobbin coil examination data, the licensee reported that the auxiliary feedwater (AFW) headers were not moving during Cycle 14. In addition, no indications due to AFW movement were reported.
- NRC staff participated in a conference call with DBNPS representatives on April 12, 2007. During this call, the licensee confirmed that the single and multiple axial indications outside of the tubesheet region is groove IGA. The licensee reported that the most likely cause for several of the indications to be in adjacent tubes, is that the tubes are exposed to a common environment, are from similar heats of material, have higher yield strengths, and have common axial loading history.
- The licensee indicated that the structural and leakage integrity requirements were met during Cycle 14.
- The NRC staff review did not address the acceptability of the best-estimate, primary-to-secondary leakage expected for a large-break, loss-of-coolant accident (LBLOCA). This best estimate determination was performed to satisfy a license condition to permit the use of a re-roll repair process for the DBNPS SGs.
The Pressurized-Water Reactor (PWR) Owners Group (PWROG) is addressing the LBLOCA of concern on a generic basis in a topical report that is applicable to DBNPS. The NRC staff is currently reviewing that topical report, which was submitted on January 4, 2007 (ML070330123). The NRC staff believes that the generic PWROG program is the proper place to address the LBLOCA issue since the technical nature of this issue is complex, and the issue is generic to Babcock and Wilcox plants.
4.0 CONCLUSION
S 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 DBNPS 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. As discussed above, the NRC staff is reviewing the best-estimate, primary-to-secondary leakage expected for a LBLOCA with the PWROG on a generic basis for all B&W plants.
Principal Contributor: L. Miller Date: July 30, 2007