ML072770625
| ML072770625 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 12/03/2006 |
| From: | Gallagher M AmerGen Energy Co |
| To: | Document Control Desk, NRC/SECY |
| SECY RAS | |
| References | |
| 2130-06-20426, 50-219-LR, AmerGen-Applicant-12, RAS 14216, TAC MC7624 | |
| Download: ML072770625 (5) | |
Text
-Rtq5 NoVJt APPLICANT'S EXH. 12 AmerGen.
Michael P. Gallagher, PE Vice President License Renewal Projects ArnerGen 200 Exelon Way KSA/2-E Kennett Square, PA 19348 2130-06-20426 December 3, 2006 Telephone 61o.765.59S8 www.exeloncorp.com michaelp.gallagher@exeloncorp.com DOCKETED USNRC October 1, 2007 (10:45am)
OFFICE OF SECRETARY RULEMAKINGS AND ADJUDICATIONS STAFF An Exelon Company 10 CFR 50 10 CFR 51 10 CFR 54 U.S. NUCLEAR REGULATORY LUULV,,VdoIuI, In the Matter of MLhJ*
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Docket No. NaD-iA.R-g.
Official Exhibit No.
OFFERED by('nEtLnsee Intervenor NR, Sttf.
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ý_7- -itness/Panel 1((4 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Oyster Creek Generating Station Facility Operating Ucense No. DPR-6 NRC Docket No. 50-219 EJECTED WITHDRAWN Action Taken:
Subject:
Information from October 2006 Refueling Outage Supplementing AmerGen Energy Company, LLC (AmerGen) Application for a Renewed Operating License for Oyster Creek Generating Station (TAC No. MC7624)
References:
- 1. AmerGen's "Application for Renewed Operating License," Oyster Creek Generating Station, Letter 2130-05-20135, dated July 22, 2005
- 2. AmerGen's "Response to NRC Request for Additional Information, dated March 10, 2006, Related to Oyster Creek Generating Station License Renewal Application (TAC No. MC7624)," Letter 2130-06-20289, dated April 7, 2006
- 3. AmerGen's "Supplemental Information Related to the Aging Management Program for the Oyster Creek Drywell Shell, Associated with AmerGen's Ucense Renewal Application (TAC No. MC7624)," Letter 2130-06-20353, dated June 20, 2006
- 4. AmerGen's "Additional Information Concerning FSAR Supplement Supporting the Oyster Creek Generating Station License Renewal Application (TAC No.
MC7624)," Letter 2130-06-20358, dated July 7, 2006 In References 1 through 4, AmerGen provided detailed information describing aging management reviews, aging management programs and commitments for future actions associated with the primary containment drywell shell, as part of its license renewal application (LRA) for the Oyster Creek Generating Station (Oyster Creek). In its recently completed Oyster Creek refueling outage, AmerGen performed many of the drywell shell inspection actMties that it had committed to perform prior to the period of extended operation.
Per 10 C.F.R. § 5421, this submittal serves to update the LRA and the other referenced submittals with the results of the 2006 outage activities. For ease of review, various sections of the original LRA and related responses to NRC requests for additional information (RAIs) have been updated to reflect the latest information. To a great extent, the information learned during this outage confirmed the condition of the drywell as described in previous submittals.
Telvip tac 56cy-oa r-
December 3, 2006 Page 2 of 2 However, as a result of performing planned inspections of the internal surface of the drywell shell in the trenches excavated in the concrete floor in 1986, AmerGen identified an environment/materlaVaging effect combination that was not included in the LRA. Aging management reviews of this combination have been performed and, as a result, AmerGen has identified additional aging management activities that will be included in aging management programs associated with the drywell.
The Enclosure to this letter more fully describes these reviews and resultant aging management activities. Updates to the affected portions of the LRA are provided, including a revision to the Ucense Renewal Commitment Ust (LRA Appendix A, Section A.5). The Commitment Ust update clearly indicates the activities that are being added as part of this submittal.
AmerGen has performed a review to determine whether any additional aspects of the LRA require updating, given the recent identification of a new environment requiring evaluation in support of license renewal. Based on its review, AmerGen concludes that there are no additional revisions required to the LRA. This review has been documented in the corrective action program.
In addition, a consolidated summary of key drywell-related inspections conducted during the outage, with a summary of the results, is provided in the Enclosure.
If you have any questions, please contact Fred Polaski, Manager Ucense Renewal, at 610-765-5935.
I declare under penalty of perjury that the foregoing is true and correct.
Respectfully, Executed on Michael P. Gallagher Vice President, License Renewal AmerGen Energy Company, LLC
Enclosure:
LRA Supplemental Information, Post-2006 Refueling Outage cc:
Regional Administrator, USNRC Region I, w/ Enclosures USNRC Project Manager, NRR - License Renewal, Safety, w/Enclosures USNRC Project Manager, NRR - License Renewal, Environmental, w/o Enclosures USNRC Project Manager, NRR - Project Manager, OCGS, w/o Enclosures USNRC Senior Resident Inspector, OCGS, wt Enclosures Bureau of Nuclear Engineering, NJDEP, w/Enclosures File No. 05040
Enclosure Page 1 of 74 Enclosure License Renewal Application Supplemental Information Post-2006 Refueling Outage Oyster Creek Generating Station License Renewal Application (TAC No. MC7624)
Note: Bold font has been used to designate additions made by this submittal to previously submitted documents.
Enclosure Page 13 of 74 Monitoring and Maintenance Program. These Inspections would have documented any flaking, blistering, peeling, discoloration, and other signs of degradation of the coathig. The VT-I inspections found the coating to be in good condition with no degradation.
Based on these VT-1 Inspections, AmerGen has confirmed that no further corrosion of the drywell shell Is occurring from the exterior of the epoxy-coated sandbed region. Monitoring of the coating in accordance with the ASME Section XI, Subsection IWE and AmerGen's Protective Coating Monitoring and Maintenance Program will continue to ensure that the drywell shell maintains its Intended function during the period of extended operation.
Also during the 2006 refueling outage (1R21),AmerGen performed UT of the drywell shell In the sandbed region from inside the drywell, at the same 19 grid locations where UT was performed In 1992, 1994, and 1996. Location of the UT grid is centered at elevation 11'-3" in an area of the drywell shell that corresponds to the sandbed region.
The 2006 UT measurements were made and statistically analyzed in accordance with the enhanced Oyster Creek ASME Section XI, Subsection IWE (B1.27) Aging Management Program. The results of the statistical analysis of the 2006 UT data were compared to the 1992, 1994 and 1996 data statistical analysis results (see below).
Some of the 1996 data contained anomalies that are not readily Justifiable but the anomalies did not significantly change the results.
The comparison confirmed that corrosion on the exterior surfaces of the drywell shell In the sandbed region has been arrested.
Analysis of the 2006 UT data, at the 19 grid locations, indicates that the minimum measured 95% confidence level mean thickness in any bay Is 0.807" (bay #19). This Is compared to the 95% confidence level minimum measured mean thickness In bay #19 of 0.806" and 0.800" measured In 1994 and 1992 respectively. Considering the Instrument accuracy of 10.010" these values are considered equivalent. Thus the minimum drywell shell mean thickness at the grid locations remains greater than 0.736" as required to satisfy the worst case buckling analysis, and the minimum available margin of 64 mils for any bay reported prior to taking 2006 UT thickness measurements remains bounded.
In addition to the UT measurements at the 19 grid locations, a total of 294 UT thickness measurements were taken in the bay #5 trench and 290 measurements were taken In the bay #17 trench during the 2006 refueling outage. The computed mean thickness value of the drywell shell taken within the two trenches is 1.074" for bay #5 and 0.986" for bay #17. These values, when compared to the 1986 mean thickness values of 1.112" for the bay #5 trench and 1.024" for the bay #17 trench, Indicated that wall thinning of approximately 0.038" has taken place in each trench since 1986. Engineering evaluation of the results concluded that considering that the exterior surface of
Enclosure Page 14 of 74 bay #5 had experienced a corrosion rate of up to 11.3 mils/yr between 1986 and 1992 and the exterior surface of bay #17 had experienced a corrosion rate of up to 21.1 milslyr In the same period, the 0.038" wall thinning measured In 2006 Is due to corrosion on the exterior surface of the dryweUl between 1986 and 1992.
Additionally the 95% confidence level minimum computed drywell shell mean thickness based on 2006 UT measurements within the two trenches is greater by a margin of 250 mils than the minimum required thickness of 0.736" for buckling. Also this margin Is significantly greater than the minimum computed margin outside the trenches (64 mils). Individual points within the two trenches met the local thickness acceptance criterion of 0.490"for pressure computed based on ASME Section III, Subsection NE, Class MC Components, Paragraph NE-3213.2 Gross Structural Discontinuity, NE-3213.10 Local Primary Membrane Stress, NE 3332.1 Openings not Requiring Reinforcement, NE-3332.2 Required Area of Reinforcement and NE-3335.1 Reinforcement of Multiple Openings.
The Individual points also met a local buckling criterion of 0.536" previously established by engineering analysis.
The above UT thickness measurements were supplemented by additional UT measurements taken at 106 points from outside the drywell In the sandbed region, distributed among the ten bays. The locations of these measurements were established In 1992 as being the thinnest local areas based on visual inspection of the exterior surface of the dryweUl shell before it was coated. The thinnest location measured in 2006 Is 0.602" versus 0.618" measured In 1992.
The difference between the two Measurements does not necessarily mean a wallithinning of 0.016" has taken place since 1992. This Is because the 2006 UT data could not be compared directly with the 1992 data due to the difference In UT Instruments and measurement technique used In 2006, and the uncertainty associated with precisely locating the 1992 UT 'points. A review of the 2006 data for the 106 external locations Indicated that the measured local thickness Is greater than the local acceptance criteria of 0.490" for pressure and 0.536" for local bucking.
As stated above, the 2006 UT data of the locally thinned areas (106 points) could not be correlated directly with the corresponding 1992 UT data. This Is largely due to using a more accurate UT Instrument and the procedure used to take the measurements, which Involved moving the Instrument within the locally thinned area In order to locate the minimum thickness In that area. In addition the Inner drywell shell surface could be subject to some insignificant corrosion due to water Intrusion onto the embedded shell (see discussion below). For these reasons the Oyster Creek ASME Section Xl, Subsection IWE Program (B.1,27) will be further enhanced to require UT measurements of the locally thinned areas