RA-09-006, Updated Information Regarding the Results of the Structural Analysis of the Oyster Creek Drywell Shell, Performed in Support of License Renewal

Updated Information Regarding the Results of the Structural Analysis of the Oyster Creek Drywell Shell, Performed in Support of License Renewal

ML092540596
Person / Time
Site:	Oyster Creek
Issue date:	09/09/2009
From:	Gallagher M Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RA-09-006
Download: ML092540596 (32)

Text

Michael P. GallagheT, PE Telephone 610.765.5958 Exelkn. Nudcear Vice President www.exeloncorp.com License Renewal Projects michaelp.gallagher@exeloncorp.com Exelon Nuclear 2o0 Exelon Way KSA/2-E Kennett Square, PA 19348 RA-09-066 September 09, 2009 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Oyster Creek Generating Station Facility Operating License No. DPR-16 NRC Docket No. 50-219

Subject:

Updated Information Regarding the Results of the Structural Analysis of the Oyster Creek Drywell Shell, Performed in Support of License Renewal

Reference:

Letter RA-09-010 from Exelon Generation Company LLC to USNRC, 'Results of Three-Dimensional (3D) Structural Analysis of the Oyster Creek Drywell Shell, Associated with License Renewal for Oyster Creek Nuclear Generating Station (TAC No. MC7624)," dated January 22, 2009 In the referenced letter, Exelon Generation Company, LLC provided the NRC with the results of its modern three-dimensional (3-D) structural analysis of the Oyster Creek drywell shell performed by Structural Integrity Associates (SIA), fulfilling an associated license renewal commitment. As part of preparation for an upcoming briefing of an Advisory Committee on Reactor Safeguards (ACRS) subcommittee on this drywell shell analysis, Exelon contracted Dr.

Clarence Miller, a highly experienced expert in the field of structural analysis and the principal author of an ASME Code Case (N-284-1) used in the 3-D analysis, to assist with ACRS meeting preparation activities. Dr. Miller subsequently reviewed the 3-D analysis and identified two simplifying approximations used by SIA that he recommended be changed. While these changes confirm Exelon's conclusion that a significant amount of margin beyond that required by the ASME Code remains for all areas of the drywell shell, Exelon is providing this information to ensure the NRC staff and ACRS have the latest relevant information.

In the area of interest (i.e., the drywell sand bed region), the use of the more precise information identified by Dr. Miller increases the margin between the ASME Code limits and the current drywell shell condition, above that reported in the referenced letter. However, for the upper spherical region of the drywell shell, these changes cause a decrease in the calculated safety factors. Regardless, a significant amount of margin beyond that required by the ASME Code remains for both the sand bed and upper spherical regions of the drywell shell. These conclusions are documented in Addenda to the 3-D Structural Analysis, which are transmitted with this letter.

M. P. Gallagher to USNRC September 9, 2009 Page 2 of 2 Since these simplifying approximations resulted in more margin to the ASME code limits in the sand bed region, we have concluded that the original analysis represents a satisfactory analysis of the margin above the Code required minimum for buckling. Accordingly, Exelon is not revising the 3-D Structural Analysis report it submitted on January 22, 2009.

If you have any questions regarding this update, please contact Mr. John O'Rourke of my staff, at 610-765-5089.

Respectfully, Michael P. Gallagher Vice President, License Renewal Exelon Generation Company

Attachment:

Structural Integrity Associates Letter to Exelon, "Oyster Creek Drywell Analysis:

Incorporation of Dr. Miller's Review Comments," dated September 1, 2009 cc: Regional Administrator, USNRC Region I USNRC Senior Project Manager, NRR - License Renewal USNRC Project Manager, NRR - Project Manager, OCGS USNRC Senior Resident Inspector, OCNGS Bureau of Nuclear Engineering, NJDEP File No. 05040

StructuralIntegrityAssociates, Inc.

3315 Almaden Expressway Suite 24 San Jose, CA 95118-1557 Phone: 408-978-8200 Fax: 408-978-8964 www.structint.com bsmith@structnt.com September 1, 2009 Report No 0006004.407, Rev. 0 Mr. John O'Rourke Exelon Nuclear 300 Exelon Way Kennett Square, PA 19348

Subject:

Oyster Creek Drywell Analysis: Incorporation of Dr. Miller's Review Comments

References:

1. Miller C. D., "Review of Structural Integrity Associates Report 0006004.401, Revision 1, Structural Evaluation of the Oyster Creek Drywell."

2. SI Report 0006004.403, Rev. 0, "Structural Evaluation of the Oyster Creek Drywell Summary Report."

3. SI Report 0006004.404, Rev. 0, "Oyster Creek Drywell Sandbed Region Wall Thinning Sensitivity Analyses Summary Report."

Dear Mr. O'Rourke:

Dr. Miller's review of the Structural Integrity Associates Report on the structural evaluation of the Oyster Creek Drywell (Reference 1) recommended that two simplifying approximations used in the analysis be modified:

1. L, the length between supports, used in the calculation of the capacity reduction factor for the spherical shell be based on the arc lengths versus elevation differences.

2. The inclusion of the lower beam support as a contributing stiffener for the calculation of the safety factors for the lower spherical shell and the sandbed region.

As these recommendations affect both the SI Reports 0006004.403, Rev. 0 (Reference 2) and 0006004.404, Rev. 0 (Reference 3), the proposed modifications have been applied to both analyses. Addenda to these reports are included in the attachments to this letter.

In summary, the implementation of Dr. Miller's recommendations has resulted in an increase in safety factors in the sandbed region, which is the area of interest. The minimum sandbed region safety factors and the magnitude of the increase are summarized as follows:

Annapolis, MD Austin, TX Centennial, CO Cerritos, CA Chattanooga, TN Huntersville, NC Ontario, Canada South Jordon, UT Stonington, CT Uniontown, OH 410-571-0861 512-533-9191 303-792-0077 562-402-3076 423-553-1180 704-597-5554 905-829-9817 801-676-0216 860-536-3982 330-899-9753

Mr. John O'Rourke September 1, 2009 0006004.407, Rev. 0 Page 2 of 2 Base Case

• Refueling: From 3.54 to 3.83; increase of 8.2%

• Flooding: From 2.02 to 2.12; increase of 5.0%/o Sensitivity Case 1

• Refueling: From 3.21 to 3'75; increase of 16.8%

• Flooding: From 2.01 to 2.10; increase of 4.5%

Sensitivity Case 2

• Refueling: From 3.46 to 3.81; increase of 10.1%

• Flooding: From 1.98 to 2.07; increase of 4.5%

If you have any questions or comments regarding this letter, please contact one of the undersigned.

Prepared by: Verified by:

09/01/09 09/01/09 Soo Bee Kok Date S. S. Tang, P.E. Date Associate Associate Approved by:

09/01/09 Marcos Legaspi Herrera, P.E. Date Senior Associate Attachments: A. Addenda to SI Report 0006004.403, Rev. 0, "Structural Evaluation of the Oyster Creek Drywell Summary Report."

B. Addenda to SI Report 0006004.404, Rev. 0, "Oyster Creek Drywell Sandbed Region Wall Thinning Sensitivity Analyses Summary Report."

cc: Project File: OC-15Q V StructuralIntegrity Associates, Inc.

Attachment A Addenda to SI Report 0006004.403, Rev. 0 Structural Evaluation of the Oyster Creek Drywell Summary Report Addenda to Report 0006004.403.RO V StructuralIntegrity Associates, Inc.

Page Al / Al I

1.0 INTRODUCTION

As part of the preparation associated with upcoming briefing for the Advisory Committee on Reactor Safeguards (ACRS) on the Oyster Creek Nuclear Power Plant drywell shell analysis, Exelon contracted Dr. Clarence Miller, a highly experienced expert in the field of structural buckling analysis and the author of the ASME Code Case N-284-1, to assist with ACRS meeting preparation activities. In Dr. Miller's review of the analysis, he recommended that two simplifying approximations used in the analysis be modified:

1. L, the length between supports, used in the calculation of the capacity reduction factor for the spherical shell be based on the arc lengths versus elevation differences.

2. The inclusion of the lower beam support as a contributing stiffener for the calculation of the safety factors for the lower spherical shell and the sandbed regions.

The above recommendations represent a more precise approach of calculating the length L, which is used for the calculation of the capacity reduction factors, and subsequently the safety factors. All these calculations pertain to the buckling evaluations of the drywell shell.

Dr. Miller's recommendations are fully implemented in this addenda to Structural Integrity (SI)

Report 0006004.403.RO. This addenda addresses the Base Case drywell shell buckling analysis.

The contents of this addenda consist of the following sections:

• Section 2.0 consists of the executive summary that provides the results summary and conclusions.

• Section 3.0 provides the detailed calculations of length L, capacity reduction factors, and safety factors.

StructuralIntegrity Associates, Inc.

Page A2 / Al11

2.0 EXECUTIVE

SUMMARY

2.1 RESULT

SUMMARY

The comparison of the safety factors are provided in Table 1.

Table 1: Safety Factor Comparison Refueling Level A/B Original Revised Difference Lloab Region Allowable Cylindrical 3.39 3.39 0.0% 2.00 Upper 4.27 3.45 -19.2% 2.00 Spherical Middle 3.60 3.84 6.7% 2.00 Lower 3.60 4.44 23.3% 2.00 Sandbed 3.54 3.83 8.2% 2.00 Flooding Region Original Revised Difference Level C Allowable Cylindrical 3.46 3.46 0.0% 1.67 Upper 7.57 6.60 -12.8% 1.67 Spherical Middle 4.76 4.82 1.3% 1.67 Lower 2.22 2.34 5.4% 1.67 Sandbed 2.02 2.12 5.0% 1.67 StructuralIntegrity Associates, Inc.

Addenda to Report 0006004.403.RO Page A3 / A1I

2.2 CONCLUSION

S With reference to the safety factor comparison in Table 1, it can be concluded that:

• In the area of interest (i.e., the drywell sandbed region), the use of Dr. Miller's recommendations increases the reported margin between the ASME Code limits and the current drywell shell conditions. The margins are increased by 8.2% and 5.0% for the refueling and the flooding load cases, respectively.

• The recalculation has no effect on the cylindrical shell region. The reported safety factor for the cylindrical shell region remains unchanged.

• The spherical upper shell region is the only region that shows a decrease in the safety factor margin. However, the safety factor for this region is not the lowest, and therefore, is not limiting.

• For all regions, a significant margin beyond that required by the ASME Code remains.

Addenda to Report 0006004.403.RO V StructuralIntegrity Associates, Inc.

Page A4 /A11

3.0 CALCULATIONS AND RESULTS 3.1 Length L Calculation Cylindrical Shell Center line of star truss insert plate: Elevation 82' 9" [Ref. 3a of SI Report 0006004.403.R0]

Insert Plate O.D.: 5' 3" [Ref. 3p of SI Report 0006004.403.RO]

Bottom of Stiffener: 4-3/8" from the bottom of Insert Plate [Ref. 3p of SI Report 0006004.403 .RO]

Top of the Knuckle: Elevation 71' 10-25/32" [Ref. 3z of SI Report 0006004.403.RO]

Bottom of Stiffener: Elevation 82' 9" - (5' 3")/2 + 4-3/8" = 80.49' Length L between stiffener (star truss to top of knuckle): 80.49' - 71' 10-25/32" =8.59'= 103" Upper Spherical Shell Bottom of Knuckle : Elevation 65' 2-7/16" [Ref. 3a of SI Report 0006004.403.R0]

Top of upper beam support: Elevation 49' 3" [Ref. 3w of SI Report 0006004.403.R0]

Shell radius, R = 35'-= 420" [Ref. 3ab of SI Report 0006004.403.RO]

Included angle, 0 = 33.00 Arc Length L (bottom of knuckle to upper beam support) = nRRO/180 = 242" Middle Spherical Shell Bottom of upper beam support : Elevation 44' 8" [Ref. 3w of SI Report 0006004.403.RO]

Top of lower beam support : Elevation 21' 5-7/8" [Ref. 3x of SI Report 0006004.403.RO]

Shell radius, R = 35'= 420" [Ref. 3ab of SI Report 0006004.403.RO]

Include angle, 0 = 45.3' (adjusted to include the largest inscribed circle between supports)

Arc Length L (upper beam support to lower beam support) 7rRO/1 80 = 332" Addenda to Report 0006004.403.RO Structural Integrity Associates, Inc.

Page A5 / All

Lower Spherical Shell and Sandbed Top of lower beam support: Elevation 21' 5-7/8" [Ref. 3x of SI Report 0006004.403.RO]

Bottom of Sandbed : Elevation 8' 11-1/4" [Figure 6-2 of SI Report 0006004.403.RO]

Shell radius, R = 35' = 420" [Ref. 3ab of SI Report 0006004.403.RO]

Included angle, 0 = 32.10 (adjusted to include the largest inscribed circle between supports)

Arc length L (lower beam support to concrete floor) = 7rRO/180 = 235"

% StructuralIntegrity Associates, Inc.

Addenda to Report 0006004.403.RO Page A6 / Al l

3.2 Capacity Reduction Factor Results Table 2: Capacity Reduction Factor ReinR t 1 / C(l Region(in) (in) M(in)aal Cylindrical 198 0.604 103 9.42 327.81 0.330 Upper 420 0.676 242 14.36 -- 0.278 Spherical Middle 420 0.678 332 19.67 -- 0.230 Lower 420 1.160 235 10.65 -- 0.333 Above I1V 420 0.826 235 12.62 -- 0.301 ByI Below I1' 420 0.826 235 12.62 -- 0.301 Above I1V 420 1.180 235 10.56 -- 0.335 By3 Below 11' 420 0.950 235 11.76 -- 0.314 By5 Above I1V 420 1.185 235 10.53 0.335 Below I1' 420 1.074 235 11.06 -- 0.325 Above I1' 420 1.133 235 10.77 -- 0.331 By7 Below I1V 420 1.034 235 11.28 -- 0.322 Above I1V 420 1.074 235 11.06 -- 0.325 By9 Below I1' 420 0.993 235 11.51 -- 0.318 Above 11F 420 0.860 235 12.36 -- 0.304 ByII Below I1V 420 0.860 235 12.36 -- 0.304 Above I1F 420 0.907 235 12.04 -- 0.309 Ba 3 Below I1F 420 0.907 235 12.04 -- 0.309 Above 11V 420 1.062 235 11.13 -- 0.324 Ba 5 Below 11F 420 0.935 235 11.86 -- 0.312 Above 11F 420 0.863 235 12.34 -- 0.305 Ba 7 Below I1V 420 0.963 235 111.69 -- 0.315 Above 11V 420 0.826 235 12.62 -- 0.301 Ba 9 Below I1F 420 0.826 235 12.62 -- 0.301 1

Bay I Local~ 420 0.696 235 13.74 -- 0.286 Bay 13 Local () 420 0.658 235 14.14 -- 0.281 1

Bay 15 Local~ 420 0.711 235 13.60 -- 0.288 Local () 420 0.663 235 14.08 -- 0.282 Bay 17 Local~1 420 0.850 235 12.44 -- 0.303 Bay 19 Local~' 420 0.720 235 13.51 -- 0.289 Note: (1) The local regions refer to the thinned areas within the individual bays.

Addenda to Report 0006004.403.RO 10 Structural Integrity Associates, Inc.

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3.3 Safety Factor Results Table 3: Refueling Buckling Evaluation (except Sandbed Region)

Spherical Region Cylindrical Upper Middle Lower R, Shell Radius (in) 198 420 420 420 t, Wall Thickness (in) 0.604 0.676 0.678 1.160 Gy, Yield Strength (ksi) 36.3 36.3 36.3 36.3 E, Young's Modulus (ksi) 29,000 29,000 29,000 29,000 X, Load Factor 7.229 9.800 10.652 11.150 a/alL, Capacity Reduction Factor 0.330 0.278 0.230 0.333 M, Meridional Compressive Stress (ksi) 3.41 3.91 4.78 4.52 M,Hoop Tension Stress (ksi) 9.41 2.29 4.61 4.22 Pbar 0.106 0.049 0.098 0.053 ap, Capacity Reduction Factor (due to tensile effect) 0.139 0.074 0.131 0.079 Cm, Modified Capacity Reduction Factor 0.469 0.352 0.361 0.412 A, Parameter( = amL Xo/ a) 0.318 0.372 0.506 0.572

, Plasticity Reduction Factor 1.000 1.000 1.000 0.967 Oje, Theoretical Buckling Stress (ksi) 11.55 13.49 18.37 20.07 SF, Safety Factor 3.39 3.45 3.84 4.44 q StructuralIntegrity Associates, Inc.

Addenda to Report 0006004.403.RO Page A8 / A11

Table 4: Flooding Buckling Evaluation (except Sandbed Region)

Spherical Region Cylindrical Upper Middle Lower R, Shell Radius (in) 198 420 420 420 t, Wall Thickness (in) 0.604 0.676 0.678 1.160 Cry, Yield Strength (ksi) 36.3 36.3 36.3 36.3 E, Young's Modulus (ksi) 29,000 29,000 29,000 29,000 X, Load Factor 9.148 14.704 14.704 7.344 a/alL, Capacity Reduction Factor 0.330 0.278 0.230 0.333 oM,Meridional Compressive Stress (ksi) 2.61 2.65 4.73 10.48 M2,Hoop Tension Stress (ksi) 2.65 6.66 16.15 22.59 Pbar 0.030 0.143 0.345 0.282 ap, Capacity Reduction Factor (due to tensile effect) 0.048 0.171 0.285 0.258 om, Modified Capacity Reduction Factor 0.378 0.449 0.515 0.591 A, Parameter ( = am X o,/ ay) 0.249 0.482 0.987 1.253

, Plasticity Reduction Factor 1.000 1.000 0.636 0.539 Oe, Theoretical Buckling Stress (ksi) 9.02 17.49 22.79 24.53 SF, Safety Factor 3.46 6.60 4.82 2.34 Addenda to Report 0006004.403.RO StructuralIntegrity Associates, Inc.

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Table 5: Refueling Buckling Evaluation, Sandbed Region Bay l(') Bay3 Bay5 Bay7 Bay9 Bay 11 Bay 13(1) Bay 15(l) Bay l70) Bay 9(1)

R, Shell Radius (in) 420 420 420 420 420 420 420 420 420 420 t, Wall Thickness (in) 0.696 0.950 1.074 1.034 0.993 0.860 0.658 0.711 0.663 0.720 Oy, Yield Strength (ksi) 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 E, Youngs Modulus (ksi) 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 k, Load Factor 11.584 11.584 11.584 11.584 11.584 11.584 11.584 11.584 11.584 11.584 a/alL, Capacity Reduction Factor 0.286 0.314 0.325 0.322 0.318 0.304 0.281 0.288 0.282 0.289 o-, Meridional Compressive Stress (ksi) 5.03 4.74 4.38 4.37 4.13 4.42 4.72 4.76 5.51 5.24 c;2, Hoop Tension Stress (ksi) 3.82 3.33 3.38 3.45 3.44 3.93 3.96 3.81 4.60 4.02 Pbar 0.079 0.051 0.046 0.048 0.050 0.066 0.087 0.078 0.100 0.081 ap, Capacity Reduction Factor (due to tensile effect) 0.111 0.076 0.070 0.073 0.076 0.095 0.119 0.109 0.133 0.112 xm, Modified Capacity Reduction Factor 0.397 0.390 0.395 0.395 0.394 0.399 0.400 0.397 0.415 0.401 A, Parameter( =cm ko 1 /y) 0.637 0.590 0.552 0.551 0.519 0.563 0.603 0.603 0.729 0.671

,n,Plasticity Reduction Factor 0.887 0.942 0.996 0.997 1.000 0.979 0.927 0.927 0.797 0.851 Ole, Theoretical Buckling Stress (ksi) 20.50 20.19 19.94 19.94 18.83 20.02 20.27 20.27 21.10 20.72 SF, Safety Factor 4.07 4.26 4.55 4.56 4.56 4.53 4.30 4.26 3.83 3.95 Note: (1) The thickness for these bays corresponds to the localized thinned area.

Addenda to Report 0006004.403.RO Structural IntegrityAssociates, Inc.

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Table 6: Flooding Buckling Evaluation, Sandbed Region 1.

Ba-yl_7' . Bay 3.. .[Ba

- -

Bay5 [

4--------------1---------I----.

ay7 Bay9-1 Bay ll Bay 13(1) Bay 15"') Bay 17(1) Bay 19(1) 4------------------- .........

.....

...-

R, Shell Radius (in) 420 420 420 420 420 420 420 420 420 420 t, Wall Thickness (in) 0.696 0.950 1.074 1.034 0.993 0.860 0.658 0.711 0.663 0.720 Gy, Yield Strength (ksi) 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 E, Youngs Modulus (ksi) 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 X,Load Factor 7.162 7.162 7.162 7.162 7.162 7.162 7.162 7.162 7.162 7.162 ct/alL, Capacity Reduction Factor 0.286 0.314 0.325 0.322 0.318 0.304 0.281 0.288 0.282 0.289 M,MeridionalCompressiveStress(ksi) 11.78 9.45 9.95 10.04 10.20 11.18 11.33 10.13 11.43 12.23 o2 , Hoop Tension Stress (ksi) 23.26 19.15 17.54 18.09 18.81 21.38 20.85 21.09 25.50 21.94 Pbar 0.484 0.292 0.237 0.253 0.274 0.360 0.459 0.430 0.557 0.441 Up, Capacity Reduction Factor (due to tensile effect) 0.330 0.263 0.235 0.244 0.254 0.291 0.323 0.315 0.348 0.318 am, Modified Capacity Reduction Factor 0.616 0.577 0.560 0.566 0.572 0.595 0.604 0.603 0.630 0.607 A,Parameter(=comXa,/oy) 1.432 1.076 1.099 1.121 1.152 1.313 1.351 1.205 1.421 1.465 1, Plasticity Reduction Factor 0.494 0.598 0.590 0.582 0.571 0.523 0.513 0.554 0.497 0.487 Oe, Theoretical Buckling Stress (ksi) 25.69 23.36 23.51 23.66 23.86 24.91 25.16 24.21 25.62 25.91 SF, Safety Factor 2.18 2.47 2.36 2.36 2.34 2.23 2.22 2.39 2.24 2.12 Note: (1) The thickness for these bays corresponds to the localized thinned area.

Addenda to Report 0006004.403.RO V StructuralIntegrity Associates, Inc.

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Attachment B Addenda to SI Report 0006004.404, Rev. 0 Oyster Creek Drywell Sandbed Region Wall Thinning Sensitivity Analyses Summary Report Addenda to Report 0006004.404.RO C StructuralIntegrity Associates, Inc.

Page BI /B17

1.0 INTRODUCTION

As part of the preparation associated with upcoming briefing for the Advisory Committee on Reactor Safeguards (ACRS) on the Oyster Creek Nuclear Power Plant drywell shell analysis, Exelon contracted Dr. Clarence Miller, a highly experienced expert in the field of structural buckling analysis and the author of the ASME Code Case N-284-1, to assist with ACRS meeting preparation activities. In Dr. Miller's review of the analysis, he recommended that two simplifying approximations used in the analysis be modified:

1. L, the length between supports, used in the calculation of the capacity reduction factor for the spherical shell be based on the arc lengths versus elevation differences.

2. The inclusion of the lower beam support as a contributing stiffener for the calculation of the safety factors for the lower spherical shell and the sandbed regions.

The above recommendations represent a more precise approach of calculating the length L, which is used for the calculation of the capacity reduction factors, and subsequently the safety factors. All these calculations pertain to the buckling evaluations of the drywell shell.

Dr. Miller's recommendations are fully implemented in this addenda to Structural Integrity (SI)

Report 0006004.404.RO. This addenda addresses the Sensitivity Case 1 and Sensitivity Case 2 drywell shell buckling analyses. The contents of this addenda consist of the following sections:

• Section 2.0 consists of the executive summary that provides the results summary and conclusions.

• Section 3.0 provides the detailed calculations of length L, capacity reduction factors, and safety factors.

Addenda to Report 0006004 .404.RO StructuralIntegrity Associates, Inc.

Page B2 / B 17

2.0 EXECUTIVE

SUMMARY

2.1 RESULT

SUMMARY

The comparison of the Sensitivity Case 1 and Sensitivity Case 2 safety factors are provided in Table 1 and Table 2, respectively.

Table 1: Sensitivity Case 1 Safety Factor Comparison Refueling Region Original Revised Difference Level A/B

(%) Allowable Cylindrical 3.34 3.34 0.0% 2.00 Upper 4.27 3.45 -19.2% 2.00 Spherical Middle 3.60 3.84 6.7% 2.00 Lower 3.39 4.33 27.7% 2.00 Sandbed 3.21 3.75 16.8% 2.00 Flooding Original Revised Difference Level C Region

(%) Allowable Cylindrical 3.45 3.45 0.0% 1.67 Upper 7.58 6.58 -13.2% 1.67 Spherical Middle 4.75 4.81 1.3% 1.67 Lower 2.19 2.31 5.5% 1.67 Sandbed 2.01 2.10 4.5% 1.67 Addenda to Report 0006004.404.RO V StructuralIntegrity Associates, Inc.

Page B3 / B 17

Table 2: Sensitivity Case 2 Safety Factor Comparison Refueling Region Original Revised Difference Level A/B

(%) Allowable Cylindrical 3.34 3.34 0.0% 2.00 Upper 4.27 3.45 -19.2% 2.00 Spherical Middle 3.60 3.84 6.7% 2.00 Lower 3.60 4.41 22.5% 2.00 Sandbed 3.46 3.81 10.1% 2.00 Flooding Region Original Revised Difference Level C

(%) Allowable Cylindrical 3.45 3.45 0.0% 1.67 Upper 7.56 6.56 -13.2% 1.67 Spherical Middle 4.75 4.81 1.3% 1.67 Lower 2.19 2.31 5.5% 1.67 Sandbed 1.98 2.07 4.5% 1.67 3 StructuralIntegrity Associates, Inc.

Addenda to Report 0006004.404.RO Page B4 / B 17

2.2 CONCLUSION

S With reference to the safety factor comparisons in Table 1 and Table 2, it can be concluded that:

• In the area of interest (i.e., the drywell sandbed region), the use of Dr. Miller's recommendations increases the reported margin between the ASME Code limits and the analyzed drywell shell conditions. The margins are increased by no less than 10.1% and 4.5% for the refueling and the flooding load cases, respectively.

• The recalculation has no effect on the cylindrical shell region. The reported safety factor for the cylindrical shell region remains unchanged.

• The spherical upper shell region is the only region that shows a decrease in the safety factor margin. However, the safety factor for this region is not the lowest, and therefore, is not limiting.

" For all regions, a significant margin beyond that required by the ASME Code remains.

Addenda to Report 0006004.404.RO V StructuralIntegrity Associates, Inc.

Page B5 / B17

3.0 CALCULATIONS AND RESULTS 3.1 Length L Calculation Cylindrical Shell Center line of star truss insert plate: Elevation 82' 9" [Ref. 3a of SI Report 0006004.403.R0]

Insert Plate O.D.: 5' 3" [Ref. 3p of SI Report 0006004.403.RO]

Bottom of Stiffener: 4-3/8" from the bottom of Insert Plate [Ref. 3p of SI Report 0006004.403.RO]

Top of the Knuckle: Elevation 71' 10-25/32" [Ref. 3z of SI Report 0006004.403.RO]

Bottom of Stiffener: Elevation 82' 9" - (5' 3")/2 + 4-3/8" = 80.49' Length L between stiffener (star truss to top of knuckle): 80.49' - 71' 10-25/32" =8.59' 103" Upper Spherical Shell Bottom of Knuckle : Elevation 65' 2-7/16" [Ref. 3a of SI Report 0006004.403.RO]

Top of upper beam support: Elevation 49' 3" [Ref. 3w of SI Report 0006004.403.RO]

Shell radius, R = 35'= 420" [Ref. 3ab of SI Report 0006004.403.RO]

Included angle, 0 = 33.00 Arc Length L (bottom of knuckle to upper beam support) = irRO/l180 = 242" Middle Spherical Shell Bottom of upper beam support : Elevation 44' 8" [Ref. 3w of SI Report 0006004.403.RO]

Top of lower beam support : Elevation 21' 5-7/8" [Ref. 3x of SI Report 0006004.403.RO]

Shell radius, R = 35' = 420" [Ref. 3ab of SI Report 0006004.403.RO]

Include angle, 0 = 45.3' (adjusted to include the largest inscribed circle between supports)

Arc Length L (upper beam support to lower beam support)= 7R0/1 80 = 332" Addenda to Report 0006004.404.RO V StructuralIntegrity Associates, Inc.

Page B6/B17

Lower Spherical Shell and Sandbed Top of lower beam support: Elevation 21' 5-7/8" [Ref. 3x of SI Report 0006004.403.RO]

Bottom of Sandbed : Elevation 8' 11-1/4" [Figure 6-2 of SI Report 0006004.403.RO]

Shell radius, R = 35'= 420" [Ref. 3ab of SI Report 0006004.403.RO]

Included angle, 0 = 32.10 (adjusted to include the largest inscribed circle between supports)

Arc length L (lower beam support to concrete floor) = 7rRO/180 = 235" Addenda to Report 0006004.404.RO V StructuralIntegrity Associates, Inc.

Page B7 / B17

3.2 Capacity Reduction Factor Results Table 3: Capacity Reduction Factor, Sensitivity Case 1 R t1 Region R ( I M R/t X/(x1L Cylindrical 198 0.604 103 9.42 327.81 0.330 Upper 420 0.676 242 14.36 --- 0.278 Spherical Middle 420 0.678 332 19.67 --- 0.230 Lower 420 1.160 235 10.65 --- 0.333 Bay 1 Above 11' 420 0.826 235 12.62 --- 0.301 Below 11' 420 0.826 235 12.62 --- 0.301 Bay 3 Above 11' 420 1.180 235 10.56 --- 0.335 Below 11' 420 0.950 235 11.76 0.314 Bay 5 Above 11' 420 1.185 235 10.53 --- 0.335 Below I1' 420 1.074 235 11.06 --- 0.325 Bay 7 Above 11' 420 1.133 235 10.77 --- 0.331 Below 11' 420 1.034 235 11.28 --- 0.322 Above 11' 420 1.074 235 11.06 --- 0.325 Bay 9 Below 11' 420 0.993 235 11.51 --- 0.318 Bay 11 Above ItV 420 0.860 235 12.36 --- 0.304 Below 11' 420 0.860 235 12.36 --- 0.304 Bay 13 Above 11' 420 0.907 235 12.04 --- 0.309 Below 11' 420 0.907 235 12.04 --- 0.309 Bay 15 Above 11' 420 1.062 235 11.13 ___

--- 0.324 Below 11' 420 0.935 235 11.86 --- 0.312 Bay 17 Above 11' 420 0.863 235 12.34 ___

--- 0.305 Below 11' 420 0.963 235 11.69 --- 0.315 Bay 19 Above 11' 420 0.826 235 12.62 --- 0.301 Below 11' 420 0.826 235 12.62 --- 0.301 Bay I Local(1) 420 0.596 235 14.85 --- 0.273 1

Bay 13 Local( 1 420 0.658 235 14.14 --- 0.281 Bay 15 Local(1) 420 0.711 235 13.60 --- 0.288 Local (1) 420 0.663 235 14.08 --- 0.282 Local 1*) 420 0.850 235 12.44 --- 0.303 Bay 19 Local( 1 f 420 0.720 235 13.51 --- 0.289 Note: (1) The local regions refer to the thinned areas within the individual bays.

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Addenda to Report 0006004.404.RO Page B8 / B17

Table 4: Capacity Reduction Factor, Sensitivity Case 2 (hain

,Region in) n M R/t CLX/QlL Cylindrical 1 198 0.604 103 9.42 327.81_ 0.330

[Upper 14201 0.676 242 14.36 -- 0.278 Spherical Middle 420 0.678 332 19.67 0.230 Lower 420 I 1.160 235 10.65 1 --- 0.333 BAbove 11 420 0.826 235 12.621 --- 0.3011 BaylI eol' 2 3 BelowlI'

'Abovel' V 420 0.826 235 1 12.62 1 --- I 0.301 420 1.180 235 10.56 0.335 Bay 3{

BelowlV 420 i0.950 235 11.76 1---

I 0.314 Bay I

AbovelI'F 1

420 1.185 235 1 10.53 --- 0 o.335

_Below ll 420 1.074 235 11.06 0.325 Bay 7 AbovelI1 yBelow I F 420 420 I' 1.133 235 235 10.77 11.28 1 --

--- 1 0.31 0.3 0.322 iBelow

[Above 11' IF 42 420 1.7 0.993 235 11.51 1 -- I032 10.32 AbveIF! 420 0.860 2 12.36 -- 0.304 B ay 9 I I --------

oBelow I 420 0.860 235 12.36 0.304 Abovelol' 420 0.907 I 235 12.04 --- 1 0.309 By131 Below 11' 420 0.907 235 12.04 i 0.309 Bay 15 Abovel'V 420 1 1.062 i 235 11.13 --- 0.324 701 iBelowll' 420 I 0.935 1 235 11.86 1 0.312 1 Ab 420 0.863 " 235 12.34 0.0 Bay17 _. "'" i 0.30517

ýBelowll' 420 1 0.963 235 111.69 0.315 BAbove l'I 420 i 0.776 235 13.02 I --- 1 0.295 Bay19 ___

Below

__ eow1V Il' 420 4 O 0.776 I 235 23__1.7 13.02 0.2865 0.295 1

Bay 1 Local1 420 0.696 235 13.74 I0.286 Bay 13 Local(1 420 0.658 235 14.14 --- 1 0.281 Bay 15 Local('* 420 1 0711 1 235 13.60 0.288 Bay l7 Local Loca235 420 420.04T[

0.663 1 235 14.08 --- 10.282

-- 01303 Local 420 0.850 1 235 12.44 --

_ Bayl9 Local( 11 1420 0.720 235 113.51 _--- _0.289 Note: (1) The local regions refer to the thinned areas within the individual bays.,

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3.3 Safety Factor Results Table 5: Refueling Buckling Evaluation (except Sandbed Region), Sensitivity Case 1 Spherical Region Cylindrical Upper Middle Lower R, Shell Radius (in) 198 420 420 420 t, Wall Thickness (in) 0.604 0.676 0.678 1.160 oy, Yield Strength (ksi) 36.3 36.3 36.3 36.3 E, Young's Modulus (ksi) 29,000 29,000 29,000 29,000 X, Load Factor 7.227 9.798 10.651 10.506 ca/a L, Capacity Reduction Factor 0.330 0.278 0.230 0.333 oC, Meridional Compressive Stress (ksi) 3.41 3.91 4.78 4.52

2, Hoop Tension Stress (ksi) 8.86 2.29 4.61 4.22 Pbar 0.100 0.049 0.098 0.053 ap, Capacity Reduction Factor (due to tensile effect) 0.133 0.074 0.131 0.079 am, Modified Capacity Reduction Factor 0.463 0.352 0.361 0.412 A IParameter ( = am Xoal/a ) 0.314 0.372 0.507 0.539 m Plasticity Reduction Factor 1.000 1.000 1.000 1.000 ole, Theoretical Buckling Stress (ksi) 11.40 13.50 18.39 19.56 SF, Safety Factor 3.34 3.45 3.84 4.33 Addenda to Report 0006004.404.RO V StructuralIntegrity Associates, Inc.

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Table 6: Flooding Buckling Evaluation (except Sandbed Region), Sensitivity Case I Spherical Region Cylindrical Upper Middle Lower R, Shell Radius (in) 198 420 420 420 t, Wall Thickness (in) 0.604 0.676 0.678 1.160 Gy, Yield Strength (ksi) 36.3 36.3 36.3 36.3 E, Youngs Modulus (ksi) 29,000 29,000 29,000 29,000 X, Load Factor 9.139 14.664 14.664 7.054 c/M/ L, Capacity Reduction Factor 0.330 0.278 0.230 0.333 mi, Meridional Compressive Stress (ksi) 2.61 2.65 4.73 10.50 o, Hoop Tension Stress (ksi) 2.66 6.66 16.15 22.61 Pbar 0.030 0.143 0.345 0.282 ap, Capacity Reduction Factor (due to tensile effect) 0.048 0.171 0.285 0.258 Qm, Modified Capacity Reduction Factor 0.378 0.449 0.515 0.591 A , Parameter ( = am ?, ac / oa) 0.248 0.480 0.985 1.206 rm Plasticity Reduction Factor 1.000 1.000 0.637 0.553 (je, Theoretical Buckling Stress (ksi) 9.02 17.43 22.77 24.22 SF, Safety Factor 3.45 6.58 4.81 2.31 Addenda to Report 0006004.404.RO V StructuralIntegrity Associates, Inc.

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Table 7: Refueling Buckling Evaluation (except Sandbed Region), Sensitivity Case 2 Spherical Region Cylindrical Upper Middle Lower R, Shell Radius (in) 198 420 420 420 t, Wall Thickness (in) 0.604 0.676 0.678 1.160 oy, Yield Strength (ksi) 36.3 36.3 36.3 36.3 E, Youngs Modulus (ksi) 29,000 29,000 29,000 29,000 k, Load Factor 7.224 9.795 10.649 11.146 a/alL, Capacity Reduction Factor 0.330 0.278 0.230 0.333 on, Meridional Compressive Stress (ksi) 3.41 3.91 4.79 4.56 02, Hoop Tension Stress (ksi) 8.86 2.29 4.61 4.23 Pbar 0.100 0.049 0.098 0.053 cip, Capacity Reduction Factor (due to tensile effect) 0.133 0.074 0.131 0.079 am, Modified Capacity Reduction Factor 0.463 0.352 0.361 0.412 A, Parameter(= am ?o 1 /oy) 0.314 0.372 0.507 0.577 m Plasticity Reduction Factor 1.000 1.000 1.000 0.960 Ole, Theoretical Buckling Stress (ksi) 11.40 13.50 18.39 20.10 SF, Safety Factor 3.34 3.45 3.84 4.41 Addenda to Report 0006004.404.RO C StructuralIntegrityAssociates, Inc.

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Table 8: Flooding Buckling Evaluation (except Sandbed Region), Sensitivity Case 2 Spherical Region Cylindrical Upper Middle Lower R, Shell Radius (in) 198 420 420 420 t, Wall Thickness (in) 0.604 0.676 0.678 1.160 oTy, Yield Strength (ksi) 36.3 36.3 36.3 36.3 E, Young~s Modulus (ksi) 29,000 29,000 29,000 29,000 X,Load Factor(1) 9.127 14.617 14.617 6.992 cL/alL, Capacity Reduction Factor 0.330 0.278 0.230 0.333 on, Meridional Compressive Stress (ksi) 2.61 2.65 4.73 10.46 oM,Hoop Tension Stress (ksi) 2.66 6.66 16.15 22.62 Pbar 0.030 0.143 0.345 0.282 cap, Capacity Reduction Factor (due to tensile effect) 0.048 0.171 0.285 0.258 otto, Modified Capacity Reduction Factor 0.378 0.449 0.515 0.591 A, Parameter ( = am (x o / oy) 0.248 0.480 0.982 1.192

, Plasticity Reduction Factor 1.000 1.000 0.638 0.558 Ole, Theoretical Buckling Stress (ksi) 9.00 17.41 22.75 24.12 SF, Safety Factor 3.45 6.56 4.81 2.31 StructuralIntegrity Associates, Inc.

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Table 9: Refueling Buckling Evaluation, Sandbed Region, Sensitivity Case 1 Bay 1(') Bay 3 Bay5 Bay 7 Bay 9 Bay 11 Bay 13(1) Bay 15(1) Bay 17(') Bay 19(')

R, Shell Radius (in) 420 420 420 420 420 420 420 420 420 420 t, Wall Thickness (in) 0.596 0.950 1.074 1.034 0.993 0.860 0.658 0.711 0.663 0.720 oy, Yield Strength (ksi) 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 E, Youngs Modulus (ksi) 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 X, Load Factor 10.506 10.506 10.506 10.506 10.506 10.506 10.506 10.506 10.506 10.506 a/a lL, Capacity Reduction Factor 0.273 0.314 0.325 0.322 0.318 0.304 0.281 0.288 0.282 0.289 Ma,Meridional Compressive Stress (ksi 5.20 4.76 4.38 4.37 4.13 4.42 4.73 4.76 5.51 5.24 02, Hoop Tension Stress (ksi) 3.80 3.33 3.38 3.45 3.44 3.93 3.96 3.82 4.60 4.03 Pbar 0.092 0.051 0.046 0.048 0.050 0.066 0.087 0.078 0.100 0.081 Cap, Capacity Reduction Factor (due to tensile effect) 0.124 0.076 0.070 0.073 0.076 0.096 0.119 0.109 0.133 0.112 am, Modified Capacity Reduction Factor 0.397 0.390 0.395 0.395 0.394 0.400 0.400 0.397 0.415 0.401 A, Parameter (=cm X*o / oy) 0.598 0.537 0.500 0.500 0.471 0.511 0.547 0.547 0.661 0.609 r1, Plasticity Reduction Factor 0.932 - 1.000 1.000 1.000 1.000 1.000 1.000 1.000 0.861 0.919

,e, Theoretical Buckling Stress (ksi 20.24 19.50 18.17 18.15 17.09 18.56 19.86 19.86 20.66 20.31 SF, Safety Factor 3.89 4.10 4.15 4.15 4.13 4.20 4.20 4.17 3.75 3.88 Note: (1) The thickness for these bays corresponds to the localized thinned area.

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Table 10: Flooding Buckling Evaluation, Sandbed Region, Sensitivity Case I Bay 1(1) Bay 3 Bay 5 Bay 7 Bay 9 Bayll1 Bay13(l) Bay 150) 1Bayl7IV) Bay ]9(1)

R, Shell Radius (in) 420 420 420 420 420 420 420 420 420 420 t, Wall Thickness (in) 0.596 0.950 1.074 1.034 0.993 0.860 0.658 0.711 0.663 0.720 Oy, Yield Strength (ksi) 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 E, Youngs Modulus (ksi) 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 k, Load Factor 7.054 7.054 7.054 7.054 7.054 7.054 7.054 7.054 7.054 7.054 C/Ac IL, Capacity Reduction Factor 0.273 0.314 0.325 0.322 0.318 0.304 0.281 0.288 0.282 0.289 M, Meridional Compressive Stress (ksj) 11.80 9.45 9.95 10.04 10.20 11.18 11.34 10.13 11.44 12.25 M2,Hoop Tension Stress (ksi) 26.08 19.18 17.55 18.10 18.82 21.38 20.85 21.10 25.52 21.96 Pbar 0.634 0.292 0.237 0.253 0.274 0.360 0.459 0.430 0.557 0.442 cXp, Capacity Reduction Factor (due to tensile effect) 0.364 0.263 0.235 0.244 0.255 0.291 0.323 0.315 0.348 0.318 crm, Modified Capacity Reduction Factor 0.637 0.577 0.560 0.566 0.573 0.595 0.604 0.603 0.630 0.607 A, Parameter (=axm k a,/cr) 1.460 1.060 1.083 1.104 1.135 1.293 1.331 1.187 1.401 1.446 i1, Plasticity Reduction Factor 0.488 0.605 0.596 0.587 0.577 0.528 0.518 0.559 0.501 0.491 Oe, Theoretical Buckling Stress (ksi) 25.88 23.26 23.41 23.55 23.75 24.78 25.03 24.09 25.49 25.78

......................

SF, Safety Factor .................................. --

2.19.-. . . . .....--

......----..-.....-......................--.

2.46 2.35 ......

2.34 ..... . . .2..

2.33 22. .

._....2.22 J... .

2.21 ._ ..

2.38

...

2.23

... i 2 1

.10 Note: (1) The thickness for these bays corresponds to the localized thinned area.

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Table 11 : Refueling Buckling Evaluation, Sandbed Region, Sensitivity Case 2 Bay 1(1) Bay 3 Bay 5 Bay 7 Bay9 1 Bay ll Bay 13(1) Bay 15(1) Bay 170')j Bay 19(1)

R, Shell Radius (in) 420 420 420 420 420 420 420 420 420 j 420 t, Wall Thickness (in) 0.696 0.950 1.074 1.034 0.993 0.860 0.658 0.711 0.663 0.720

., Yield Strength (ksi) 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 E, Young's Modulus (ksi) 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 k, Load Factor 11.345 11.345 11.345 11.345 11.345 11.345 11.345 11.345 11.345 11.345 cL/aIL, Capacity Reduction Factor 0.286 0.314 0.325 0.322 0.318 0.304 0.281 0.288 0.282 0.289 Mn,Meridional Compressive Stress (ksi) 5.03 4.75 4.38 4.37 4.14 4.42 4.73 4.77 5.51 5.42 M, Hoop Tension Stress (ksi) 3.82 3.33 3.38 3.45 3.44 3.93 3.96 3.82 4.60 4.13 Pbar 0.079 0.051 0.046 0.048 0.050 0.066 0.087 0.078 0.101 0.083 UP, Capacity Reduction Factor (due to tensile effect) 0.111 0.076 0.070 0.073 0.076 0.096 0.119 0.109 0.133 0.115 Qrn, Modified Capacity Reduction Factor 0.397 0.390 0.395 0.395 0.394 0.400 0.400 0.397 0.415 0.404 A ,Pammeter(=xmk o 1 /oy) 0.623 0.579 0.541 0.540 0.509 0.552 0.591 0.591 0.715 0.685 11,Plasticity Reduction Factor 0.902 0.957 1.000000 00o 1.000 0.995 0.941 0.941 0.810 0.837 oje, Theoretical Buckling Stress (ksi) 20.41 20.12 19.62 19.60 18.47 19.94 20.20 20.20 21.00 20.81 SF, Safety Factor 4.06 4.24 4.48 4.48 4.46 4.51 4.27 4.24 3.81 3.84 Note: (1) The thickness for these bays corresponds to the localized thinned area.

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I Table 12: Flooding Buckling Evaluation, Sandbed Region, Sensitivity Case 2 Bay 1(1) Bay3 BayI Bay7 I Bay9 Bayll lBayl3(') Bay 15(1) Bay 17(1) Bay 19(1)

R, Shell Radius (in) 420 420 420 420 1 420 420 420 420 420 420 t, WallThickness (in) 0.696 0.950 1.074 1.034 0.993 0.860 0.658 0.711 0.663 0.720 oy, Yield Strength (ksi) 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 36.3 E, Young's Modulus (ksi) 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000 29,000

?,, Load Factor 6.965 6.965 6.965 6.965 6.965 6.965 6.965 6.965 6.965 6.965 Capacity Reduction Factor OcL/IL, 0.286 0.314 0.325 0.322 0.318 0.304 0.281 0.288 0.282 0.289

-, MeridionalCompressive Stress (ksi) 11.79 9.46 9.96 10.05 10.21 . 11.19 11.34 10.14 11.44 12.52 MHoop Tension Stress (ks. 23.33 19.18 17.55 18.10 18.82 21.38 20.86 21.10 25.53 23.15 Pbar 0.485 0.292 0.237 0.254 0.275 0.360 0.459 0.430 0.558 0.466 Up, Capacity Reduction Factor (due to tensile effect) 0.331 0.263 0.235 0.244 0.255 0.291 0.323 0.315 0.348 0.325 Cxm, Modified Capacity Reduction Factor 0.617 0.577 0.560 0.566 0.573 0.595 0.604 0.603 0.630 0.614 A, Parameter (=m X c1 / Oy) 1.394 1.047 1.070 1.091 1.121 1.278 1.315 1.172 1.384 1.475 TI,Plasticity Reduction Factor 0.503 0.610 0.601 0.592 0.581 1 0.532 0.522 0.564 0.505 0.485 Oe, TheoreticalBuckling Stress (ksi) 25.45 23.18 23.32 23.46 23.66 24.68 24.93 24.00 25.38 25.97

........ ~~~....... ..... -----

SF, Safety Factor 2.16 2.45 2.34 2.33 2.32 1.2.21 2.20 2.37 2.22 2.07 Note: (1) The thickness for these bays corresponds to the localized thinned area.

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