ML062790232
| ML062790232 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 08/31/2006 |
| From: | General Electric Co |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| DRF 0000-0051-5975, DRF 0000-0056-5341, TAC MC3743, TAC MC3744, TAC MC3812, TVA-BFN-TS-418, TVA-BFN-TS-431 GE-NE-0000-0053-7413-R4-NP | |
| Download: ML062790232 (186) | |
Text
ENCLOSURE 2 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)
UNITS 1, 2, AND 3 TECHNICAL SPECIFICATIONS (TS) CHANGES TS-431 AND TS-418 -
EXTENDED POWER UPRATE (EPU) - STEAM DRYER STRESS REPORT, REVISION 4 (TAC NOS. MC3812, MC3743, AND MC3744)
GE ENGINEERING REPORT NO. GE-NE-0000-0053-7413-R4-NP (NON-PROPRIETARY VERSION)
Attached is the Non-Proprietary Version of GE Engineering Report No.
GE-NE-0000-0053-7413-R4-NP, "Browns Ferry Nuclear Plant, Units 1, 2, and 3 Steam Dryer Stress, Dynamic, and FaLigue Analyses for EPU Conditions."
An affidavit attesting to the proprietary nature of GE Report No.
GE-NE-0000-0053-7413-R4-P is contained in this enclosure.
WGE NuclearEnergy GeneralElectric Company 1989 Lfttle OrchardStreet, San Josp CA 95125 Non-ProprietaryVersion GE-NE-0000-0053-7413-R4-NP DRF Section 0000-0056-5341 DRF 0000-0051-5975 Class I August 2006 Engineering Report Browns Ferry Nuclear Plant Units 1, 2, and 3 Steam Dryer Stress, Dynamic, and Fatigue Analyses for EPU Conditions
GE-NE-0000-0053-7413-R4-NP NON-PROPRIETARY VERSION IMPORTANT NOTICE REGARDING THE CONTENTS OF THIS REPORT Please Read Carefully Non-Proprietary Notice This is a non-proprietary version of the document GE-NE-0000-0053-7413-R4-P, which has the proprietary information removed. Portions of the document that have been removed are indicated by an open and closed double brackets as shown here (( 3].
IMPORTANT NOTICE REGARDING CONTENTS OF THIS REPORT Please Read Carefully The only undertakings or the General Electric Company (GE) respecting information in this document are contained in the contract between Tennessee Valley Authority, Browns Ferry Nuclear Plant and GE, 00001704 Release 00248, effective February 5, 2003, as amended to the date of transmittal of this document, and nothing contained in this document shall be construed as changing the contract. The use of this information by anyone other than Tennessee Valley Authority, Browns Ferry Nuclear Plant, for any purpose other than that for which it is furnished by GE, is not authorized; and with respect to any unauthorized use, GE makes no representation or warranty, express or implied, and assumes no liability as to the completeness, accuracy, or usefulness of the information contained in this document, or that its use may not infringe privately owned rights.
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General Electric Company AFFIDAVIT I, George B. Stramback, state as follows:
(1) I am Manager, Regulatory Services, General Electric Company ("GE") and have been delegated the function of reviewing the information described in paragraph (2) which is sought to be withheld, and have been authorized to apply for its withholding.
(2) The information sought to be withheld is contained in the GE proprietary report GE-NE-0000-0053-7413-R4-P, EngineeringReport, Browns Ferry Nuclear Plant Units 1, 2, and 3 Steam Dryer Stress, Dynamic, and FatigueAnalysesfor EPUConditions, Revision 4, Class III (GE Proprietary Information), dated August 2006. The proprietary information is delineated by a double underline inside double square brackets. Figures and large equation objects are identified with double square brackets before and after the object. In each case, the sidebars and the superscript notation( 3 ) refers to Paragraph (3) of this affidavit, which provides the basis for the proprietary determination.
(3) In making this application for withholding of proprietary information of which it is the owner, GE relies upon the exemption from disclosure set forth in the Freedom of Information Act ("FOIA"), 5 USC Sec. 552(b)(4), and the Trade Secrets Act, 18 USC Sec. 1905, and NRC regulations 10 CFR 9.17(a)(4), and 2.390(a)(4) for "trade secrets" (Exemption 4). The material for which exemption from disclosure is here sought also qualify under the narrower definition of "trade secret", within the meanings assigned to those terms for purposes of FOIA Exemption 4 in, respectively, Critical Mass Energy Project v. Nuclear Regulatory Commission, 975F2d871 (DC Cir. 1992), and Public Citizen Health Research Group v. FDA, 704F2d1280 (DC Cir. 1983).
(4) Some examples of categories of information which fit into the definition of proprietary information are:
- a. Information that discloses a process, method, or apparatus, including supporting data and analyses, where prevention of its use by General Electric's competitors without license from General Electric constitutes a competitive economic advantage over other companies;
- b. Information which, if used by a competitor, would reduce his expenditure of resources or improve his competitive position in the design, manufacture, shipment, installation, assurance of quality, or licensing of a similar product; GBS-06-05-afBF Dryer Stress Dynamic & Fatigue at EPU GENE-53-7413-R4-P.doc Affidavit Page I
- c. Information which reveals aspects of past, present, or future General Electric customer-funded development plans and programs, resulting in potential products to General Electric;
- d. Information which discloses patentable subject matter for which it may be desirable to obtain patent protection.
The information sought to be withheld is considered to be proprietary for the reasons set forth in paragraphs (4)a., and (4)b, above.
(5) To address 10 CFR 2.390 (b) (4), the information sought to be withheld is being submitted to NRC in confidence. The information is of a sort customarily held in confidence by GE, and is in fact so held. The information sought to be withheld has, to the best of my knowledge and belief, consistently been held in confidence by GE, no public disclosure has been made, and it is not available in public sources. All disclosures to third parties including any required transmittals to NRC, have been made, or must be made, pursuant to regulatory provisions or proprietary agreements which provide for maintenance of the information in confidence. Its initial designation as proprietary information, and the subsequent steps taken to prevent its unauthorized disclosure, are as set forth in paragraphs (6) and (7) following.
(6) Initial approval of proprietary treatment of a document is made by the manager of the originating component, the person most likely to be acquainted with the value and sensitivity of the information in relation to industry knowledge. Access to such documents within GE is limited on a "need to know" basis.
(7) The procedure for approval of external release of such a document typically requires review by the staff manager, project manager, principal scientist or other equivalent authority, by the manager of the cognizant marketing function (or his delegate), and by the Legal Operation, for technical content, competitive effect, and determination of the accuracy of the proprietary designation. Disclosures outside GE are limited to regulatory bodies, customers, and potential customers, and their agents, suppliers, and licensees, and others with a legitimate need for the information, and then only in accordance with appropriate regulatory provisions or proprietary agreements.
(8) The information identified in paragraph (2), above, is classified as proprietary because it contains details of steam dryer stress, dynamic and fatigue analyses of the design of the BWR Steam Dryer. Development of this .information and its application for the design, procurement and analyses methodologies and processes for the Steam Dryer Program was achieved at a significant cost to GE, on the order of approximately two million dollars.
The development of the dryer performance evaluation process along with the interpretation and application of the analytical results is derived from the extensive experience database that constitutes a major GE asset.
GBS-06-05-afBF Dryer Stress Dynamic & Fatigue at EPU GENE-53-7413-R4-P.doc Affidavit Page 2
(9) Public disclosure of the information sought to be withheld is likely to cause substantial harm to GE's competitive position and foreclose or reduce the availability of profit-making opportunities. The information is part of GE's comprehensive BWR safety and technology base, and its commercial value extends beyond the original development cost. The value of the technology base goes beyond the extensive physical database and analytical methodology and includes development of the expertise to determine and apply the appropriate evaluation process. In addition, the technology base includes the value derived from providing analyses done with NRC-approved methods.
The research, development, engineering, analytical and NRC review costs comprise a substantial investment of time and money by GE.
The precise value of the expertise to devise an evaluation process and apply the correct analytical methodology is difficult to quantify, but it clearly is substantial.
GE's competitive advantage will be lost if its competitors are able to use the results of the GE experience to normalize or verify their own process or if they are able to claim an equivalent understanding by demonstrating that they can arrive at the same or similar conclusions.
The value of this information to GE would be lost if the information were disclosed to the public. Making such information available to competitors without their having been required to undertake a similar expenditure of resources would unfairly provide competitors with a windfall, and deprive GE of the opportunity to exercise its competitive advantage to seek an adequate return on its large investment in developing these very valuable analytical tools.
I declare under penalty of perjury that the foregoing affidavit and the matters stated therein are true and correct to the best of my knowledge, information, and belief.
Executed on this 34&a day of 2006.
"GergeB. Stranback General Electric Company GBS-06-05-afBF Dryer Stress Dynamic & Fatigue at EPU GENE-53-7413-R4-P.doc Affidavit Page 3
GE-NE-0000-0053-7413-R4-NP NON-PROPRIETARY VERSION REVISION HISTORY for GE-N E-0000-0053-74 13 The May 2006, Revision 0 issue of the Report " Browns Ferry Nuclear Plant Units 1, 2, and 3 Steam Dryer Stress, Dynamic, and Fatigue Analyses for EPU Condition", GE-NE-0000-0053-7413-RO addressed the original Finite Element Analysis for OLTP and EPU. This report also indicated that there is a need for modifications to improve the stress margins at locations, which experience higher stress at EPU conditions. The proposed modifications were not analyzed in Revision 0.
In June of 2006, Report GENE-0000-0055-2994-Ri, "Addendum to Browns Ferry Nuclear Plant Units 1, 2, and 3 Steam Dryer Stress, Dynamic, and Fatigue Analyses for EPU Condition", was issued. This addendum provided the analysis of the selected modification option that would qualify the steam dryer for EPU conditions. This addendum also indicated that additional modifications would be required since application of local stress intensification factors resulted in some components of the dryer exceeding the design Fatigue curve endurance limit. This addendum also identified the need for Power Ascension curves that will be used to ensure that the dryer stresses will be maintained below endurance limit during power ascension to EPU.
Revision I of Report GE-NE-0000-0053-7413 supersedes Rev. 0 and the Addendum to Rev.0.
This report revision incorporated a modification option, which consists of a replacement outer hood and cover plate of one-inch thickness, along with reinforcements made to undersized welds. It supersedes the Revision O/Addendum proposed modification. Revision I included a new Section 9, which discusses the evaluation of the BFN dryer structure analysis uncertainty and established the total uncertainty. These uncertainties are used as inputs the development of the power ascension limit curves. A discussion of the Power Ascension Limit Curves (Section
- 10) was included in this report. The uncertainties developed in Section 9 were used to adjust the power ascension limit curves presented in a new Section 10.
Revision 2 of Report GE-NE-0000-0053-7413 Sections 1 through 8 is identical to Rev. I with some minor changes and clarifications to Sections 9 and 10. Section 10 has been revised to incorporate clarifications to the uncertainty values. Figures 10-1 through 10-8 of Revision I have been enhanced to include a complementary logarithmic scale plot to better illustrate the power ascension limit curve values at higher pressures. Figurers 10-9 through 10-16 were added to show the affect of a 50% increase in uncertainty to the power ascension limit curves. Two iii
GE-NE-0(O00-0053-7413-R4-NP NON-PROPRIETARY VERSION new tables 10-1 and 10-2 and explanatory text were provided to illustrate the stress margins and factor of safety introduced by the operation limit curves.
Revision 3 of Report GE-NE-0000-0053-7413 is technically identical to Revision 2. The changes are limited to (1) the addition and deletion of proprietary markings, (2) the addition of the revision history, (3) the addition of revision bars which indicate the changes in the report relative to Revision 2, and (4) the correction of typographical errors regarding missing figure numbers and a fragmented sentence in Section 11.
Revision 4 of Report GE-NE-0000-0053-7413 is technically the same as Revisions 2 and 3. The changes in Revision 4 are limited to (1) correcting proprietary markings, which were inadvertently removed in a small number of locations in the report, (2) deleting proprietary markings for information that was released in Revision 0, (2) updating the revision history, and (3) the addition of revision bars to identify the changes made relative to Revision 2. The changes involve the addition of revision bars in various locations to indicate the changes regarding proprietary markings, and correction of a typographical error where the word 'Table' was repeated twice. As in Revision 3, the revision bars indicate the changes made in the report relative to Revision 2.
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GE-NE-0000-0053-7413-R4-NP NON-PROPRIETARY VERSION TABLE OF CONTENTS Section Page R E V ISIO N H ISTO R Y ................................................................................................................... iii ACRONYMS AND ABBREVIATIONS ..................................................................................... xii I EXECUTIVE
SUMMARY
................................................................................................ 1 2 INTRODUCTION AND BACKGROUND ....................................................................... 3 2.1 Dryer Design Basis and Historical Development ............................................. 3 2.2 Browns Ferry Dryer Experience ........................................................................ 4 2.3 Motivation for Additional FIV and Structural Analysis ................................... 8 3 DYNAMIC ANALYSIS APPROACH .............................................................................. 9 3.1 Dynamic Loading Pressure Time Histories ...................................................... 9 3.2 Stress Recovery and Evaluation Methodology. ............................................... 9 4 MATERIAL PROPERTIES .............................................................................................. 10 5 DE SIG N C R ITE R IA .............................................................................................................. 10 5.1 Fatigue C riteria ................................................................................................. 10 5.2 ASME Code Criteria for Load Combinations ................................................. 11 6 OLTP and EPU FATIGUE ANALYSIS for ORGINAL DRYER ......................................... 1 6.1 Full Dryer Shell Finite Element Model .......................................................... 12 6.2 Dynam ic Loads ................................................................................................. 13 6.3 Frequency Content of Loads ............................................................................ 13 6.4 M odal A nalysis ................................................................................................. 14 6.5 Structural Response to Loads .......................................................................... 14 6.6 Stress Results from Time History Analyses ................................................... 14 6.7 W eld Factors ..................................................................................................... 17 6.8 Lower Tie Bar Stress Analysis ........................................................................ 20 6.9 Fatigue Analysis Results ................................................................................ 20 7 EPU FATIGUE ANALYSIS FOR MODIFIED DRYER ................................................. 22 7.1 Dryer Modifications ....................................................................................... 22 7.2 Structural Response to Loads .......................................................................... 22 7.3 Stress Results from Modified Dryer Time History Analyses .......................... 22 7.4 W eld Factors ................................................................................................... 25 7.5 Lower Tie Bar Stress Calculation ................................................................... 26 V
GE-NE-(K)(II-0053-7413-R4-NP NON-PROPRIETARY VERSION 7.6 Fatigue Analysis Results ................................................................................. 26 8 ASME CODE ANALYSES ............................................................................................... 27 8.1 ASME Code Load Combinations .................................................................... 27 8.2 ASME Code Load Case Stress Results - Original Dryer ............................... 31 8.3 ASME Code Load Case Stress Results - Modified Dryer .............................. 34 9 BFN DRYER STRUCTURAL ANALYSIS UNCERTAINTY EVALUATION ............. 37 9.1 Load D efinition ............................................................................................ . . 37 9.2 Scale Model Test ............................................................................................ 37 9.2.1 Modeling Uncertainties .............................................................................. 37 9.2.2 Test Measurement Uncertainties ............................................................. 40 9.2.3 Application Uncertainties ......................................................................... 41 9.2.4 SMT Load Modification ................................................................................ 43 9.3 QC2 In-Plant Measurement Uncertainties ..................................................... 45 9.4 CDI Acoustic Circuit Model ........................................................................... 45 9.5 Selection of Analysis Segment Interval ......................................................... 48 9.6 Structural Analysis .......................................................................................... 51 9.7 Modeling Uncertainties .................................................................................. 51 9.8 Application and Measurement Uncertainties .................................................. 52 9.9 Power Ascension Testing ................................................................................ 53 9.10 Total Uncertainty Associated with BFN Limit Curves ................................... 54 10 POWER ASCENSION LIMIT CURVES ................................................................. 59 1I CONCLUSIONS ...................................................................................................... 65 12 REFERENCES ........................................................................................................ 66 vi
GE-NE-0000-0053-7413 -R4-NP NON-PROPRIETARY VERSION List of Tables Table 2-1 BFNP Unit I Steam Dryer Inspection Data and Disposition for EPU ...................... 5 Table 2-2 BFNP Unit 2 Steam Dryer Inspection Data and Disposition for EPU ....................... 6 Table 2-3 BFNP Unit 3 Steam Dryer Inspection Data and Disposition for EPU ....................... 7 Table 4-1 Properties of SS304 [Reference 6] ........................................................................... 10 Table 5-1 ASM E Code Stress Limits [Reference 7] ................................................................... II Table 6-1 Original Dryer Time History Analysis Results from ANSYS: OLTP ..................... 15 Table 6-2 Original Dryer Time History Analysis Results from ANSYS: EPU ....................... 16 Table 6-3 Original Dryer Time History Results with Weld factors: OLTP ............................ 18 Table 6-4 Original Dryer Time History Results with Weld factors: EPU ............................... 19 Table 6-5 Original Dryer Final Stress Results: Design Margins for OLTP and EPU .............. 21 Table 7-1 Modified Dryer Time History Analysis Results from ANSYS: EPU ..................... 24 Table 7-2 Modified Dryer Maximum Stress Intensity with Weld Factors and Design Margin ....25 Table 8-1 A SM E Load Combinations .................................................................................... 30 Table 8-2 Original Dryer OLTP ASME Results for Normal and Upset Conditions: Average S tresses ....................................................................................................................... 32 Table 8-3 Original Dryer OLTP ASME Results for Faulted Conditions: Average Stresses ......... 33 Table 8-4 Modified Dryer EPU ASME Results for Normal and Upset Conditions: Average S tresses ....................................................................................................................... 35 Table 8-5 Modified Dryer EPU ASME Results fbr Faulted Conditions: Average Stresses .......... 36 Table 9-1 Measured and Predicted RMS Pressures (Quad Cities Unit 2 Dryer) ...................... 46 Table 9-2 Uncertainty when Comparing Pi.,s Values ............................................................. A7 Table 9-3 S/RV Peak Ratios for Analysis Increment .............................................................. 49 Table 9-4 Peak Amplitude for Analysis Increment ................................................................. 51 Table 9-5 Limit Curve Uncertainties Based on SMT Data ..................................................... 56 Table 9-6 Limit Curve Uncertainties Based on BFN Main Steam Line Data .......................... 58 Table 10-1 Level I Limit Curve Stress M argins ..................................................................... 63 Table 10-2 Level 2 Limit Curve Stress M argins ...................................................................... 63 vii
GE-NE-4000-0053-7413-R4-NP NON-PROPRIETARY VERSION List of Figures Figure 6-1 Raleigh Damping Curve Used in Time History Analysis ................................... 67 Figure 6-2 Original BFN Steam Dryer Finite Element Model with Boundary Conditions ......... 68 Figure 6-3 Original BFN Steam Dryer Finite Element Model ................................................ 69 Figure 6-4 Original BFN Steam Dryer Finite Element Model ................................................ 70 Figure 6-5 Original BFN Steam Dryer Finite Element Model ................................................ 71 Figure 6-6 EPU Applied Pressure Load to Original BFN Dryer ........................................... 72 Figure 6-7 Frequency Content of Applied Load at EPU (Outer Hoods) ................................. 73 Figure 6-8 Original Dryer Modal Analysis Results: Skirt Frequencies ((" ....74 Figure 6-9 Original Dryer Modal Analysis Results:Skirt Frequencies [ 11 ....75 Figure 6-10Original Dryer Modal Analysis Results: Outer Hoods ......................................... 76 Figure 6-11 Original Dryer Modal Analysis Results: Inner Hoods ........................................ 77 Figure 6-12Original Dryer Stress Time Histories for Several Dryer Components at EPU .......... 78 Figure 6-13 Original Dryer Outer Hood Pressure VS Stress for EPU Nominal Case ............. 79 Figure 6-14Original Dryer Outer Hood FFT's for Nominal and +/-10% Cases at EPU .......... 80 Figure 6-15Original Dryer Inner Hood FFT's for Nominal and +/-10% Cases at EPU .......... 81 Figure 6-16Original Dryer Cover Plate FFT's for Nominal and +/-10% Cases at EPU ...... 82 Figure 6-17Original Dryer Trough FFT's for Nominal and +/-10% Cases at EPU ................ 83 Figure 6-18Original Dryer Skirt FFT's for Nominal and +/-10% Cases at EPU ..................... 84 Figure 6-19Original Dryer Stress Intensity at EPU: Cover Plate ........................................... 85 Figure 6-200riginal Dryer Stress Intensity at EPU: Manway Cover ....................................... 86 Figure 6-21 Original Dryer Stress Intensity at EPU: Outer Hood .......................................... 87 Figure 6-22 Original Dryer Stress Intensity at EPU: Exterior Hood Plates - Outer Banks ....... 88 Figure 6-23 Original Dryer Stress Intensity at EPU: Exterior Vane Bank End Plates - Outer B an k s .......................................................................................................................... 89 Figure 6-24 Original Dryer Stress Intensity at EPU: Hood Top Plates .................................... 90 Figure 6-25 Original Dryer Stress Intensity at EPU: Vane Bank Top Plates ........................... 91 Figure 6-26Original Dryer Stress Intensity at EPU: Outer Hood Stiffeners ........................... 92 Figure 6-27 Original Dryer Stress Intensity at EPU: Vane Bank Inner End Plates (2) ........... 93 Figure 6-28 Original Dryer Stress Intensity at EPU: Outer Bank Closure Plates .................... 94 viii
GE-NE-0X00-0053-74 I 3-R4-NP NON-PROPRIETARY VERSION Figure 6-29Original Dryer Stress Intensity at EPU: Inner Hoods ............................................ 95 Figure 6-300riginal Dryer Stress Intensity at EPU: Inner Bank Exterior Hood Plates .......... 96 Figure 6-31 Original Dryer Stress Intensity at EPU: Vane Bank End Plates ............................ 97 Figure 6-32Original Dryer Stress Intensity at EPU: Inner Hood StifTeners (1) ...................... 98 Figure 6-33 Original Dryer Stress Intensity at EPU: Inner Hood StifTeners (2) ...................... 99 Figure 6-34Original Dryer Stress Intensity at EPU: Vane Bank Inner End Plates (1) ............... 100 Figure 6-35 Original Dryer Stress Intensity at EPU: Vane Bank Inner End Plates (3) ............... 101 Figure 6-36Original Dryer Stress Intensity at EPU: Inner Bank Closure Plates ........................ 102 Figure 6-37Original Dryer Stress Intensity at EPU: Steam Dams .............................................. 103 Figure 6-38 Original Dryer Stress Intensity at EPU: Steam Dam Gussets .................................. 104 Figure 6-39Original Dryer Stress Intensity at EPU: Baffle Plate ............................................... 105 Figure 6-400riginal Dryer Stress Intensity at EPU: Trough ....................................................... 106 Figure 6-41 Original Dryer Stress Intensity at EPU: Base Plate .................................................. 107 Figure 6-42Original Dryer Stress Intensity at EPU: Support Ring ............................................. 108 Figure 6-43 Original Dryer Stress Intensity at EPU: S k irt ........................................................... 10 9 Figure 6-44Original Dryer Stress Intensity at EPU: Drain Pipes ................................................ 110 Figure 6-45 Original Dryer Stress Intensity at EPU: Skirt Bottom Ring ..................................... 111 Figure 6-46W eld Factors Used in Steam Dryer Fatigue Analysis .............................................. 112 Figure 7-1 Proposed BFN Steam Dryer Modifications: (Outer Hood and Cover Plate) ........... 113 Figure 7-2 Proposed BFN Steam Dryer Modifications: (Outer Hood and Cover Plate) ........... 114 Figure 7-3 Proposed BFN Steam Dryer Modifications: (Outer Hood and Cover Plate) ........... 115 Figure 7-4 Proposed BFN Steam Dryer Modifications: (Outer Hood and Cover Plate) ........... 116 Figure 7-5 Modified Dryer Stress Time Histories for Several Dryer Components at EPU ....... 117 Figure 7-6 Modified Dryer Outer Hood Pressure VS Stress for EPU Nominal Case ................ 118 Figure 7-7 Modified Dryer Outer Hood FFT's for Nominal and +/-10% Cases at EPU ........... 119 Figure 7-8 Modified Dryer Inner Hood FFT's for Nominal and +/-10% Cases at EPU ............ 120 Figure 7-9 Modified Dryer Cover Plate FFT's for Nominal and +/-10% Cases at EPU ........... 121 Figure 7-10Modified Dryer Trough FFT's for Nominal and +/-10% Cases at EPU .................. 122 Figure 7-11 Modified Dryer Skirt FFT's for Nominal and +/-10% Cases at EPU ...................... 123 Figure 7-12Modified Dryer Stress Intensity at EPU: Cover Plate .............................................. 124 Figure 7-13 Modified Dryer Stress Intensity at EPU: Outer Hood .............................................. 125 Figure 7-14Modified Dryer Stress Intensity at EPU: Exterior Hood Plates - Outer Banks ........ 126 ix
GE-NE-00)0-O()053-74 ! 3-R4-NP NON-PROPRIETARY VERSION Figure 7-15 Modified Dryer Stress Intensity at EPU: Exterior Vane Bank End Plates - Outer B an ks ........................................................................................................................ 12 7 Figure 7-16Modified Dryer Stress Intensity at EPU: Exterior Vane Bank End Plates - Outer B ank s ........................................................................................................................ 12 8 Figure 7-17Modified Dryer Stress Intensity at EPU: Hood Top Plates ...................................... 129 Figure 7-18Modified Dryer Stress Intensity at EPU: Vane Bank Top Plates ............................. 130 Figure 7-19 Modified Dryer Stress Intensity at EPU: Vane Bank Inner End Plates (2) .............. 131 Figure 7-20 Modified Dryer Stress Intensity at EPU: Closure Plates - Outer Banks .................. 132 Figure 7-21 Modified Dryer Stress Intensity at EPU: Inner Hoods ............................................. 133 Figure 7-22 Modified Dryer Stress Intensity at EPU: Outer Hood: close-up .............................. 134 Figure 7-23 Modified Dryer Stress Intensity at EPU: Inner Hood: close-up ............................... 135 Figure 7-24 Modified Dryer Stress Intensity at EPU: Inner Bank Exterior Hood Plates ............ 136 Figure 7-25 Modified Dryer Stress Intensity at EPU: Vane Bank End Plates ............................. 137 Figure 7-26Modified Dryer Stress Intensity at EPU: Inner Hood Stiffeners (1) ........................ 138 Figure 7-27Modified Dryer Stress Intensity at EPU: Inner Hood Stiffeners (2) ........................ 139 Figure 7-28 Modified Dryer Stress Intensity at EPU: Vane Bank Inner End Plates (1) .............. 140 Figure 7-29Modified Dryer Stress Intensity at EPU: Vane Bank Inner End Plates (3) .............. 141 Figure 7-3OModified Dryer Stress Intensity at EPU: Inner Bank Closure Plates ....................... 142 Figure 7-31 Modified Dryer Stress Intensity at EPU: Steam Dams ............................................. 143 Figure 7-32 Modified Stress Intensity at EPU: Steam Dam Gussets ........................................... 144 Figure 7-33 Modified Dryer Stress Intensity at EPU: Baffle Plate .............................................. 145 Figure 7-34 Modified Dryer Stress Intensity at EPU: Trough ..................................................... 146 Figure 7-35 Modified Dryer Stress Intensity at EPU: Trough Detail .......................................... 147 Figure 7-36 Modified Dryer Stress Intensity at EPU: Base Plate ................................................ 148 Figure 7-37Modified Dryer Stress Intensity at EPU: Support Ring ........................................... 149 Figure 7-38 Modified Dryer Stress Intensity at EPU: Skirt ......................................................... 150 Figure 7-39Modified Dryer Stress Intensity at EPU: Drain Pipes .............................................. 151 Figure 7-40Modified Dryer Stress Intensity at EPU: Skirt Bottom Ring ................................... 152 Figure 9-1 Uncertainty in Limit Curves when Developed Based on SMT Data ..... :................. 153 Figure 9-2 Uncertainty in Limit Curves when Developed Based on BFN MSL Pressure M easurem ents ................................................................... ....... ......................... 154 Figure 10-1 Power Ascension Limit Curve MSL A Upper .......................................................... 155 Figure 10-2 Power Ascension Limit Curve MSL A Lower ......................................................... 156 x
GE-NE-O(000-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION Figure 10-3 Power Ascension Limit Curve MSL B Upper .......................................................... 157 Figure 10-4 Power Ascension Limit Curve MSL B Lower ......................................................... 158 Figure 10-5 Power Ascension Limit Curve MSL C Upper .......................................................... 159 Figure 10-6 Power Ascension Limit Curve MSL C Lower ......................................................... 160 Figure 10-7 Power Ascension Limit Curve MSL D Upper .......................................................... 161 Figure 10-8 Power Ascension Limit Curve MSL D Lower ......................................................... 162 Figure 10-9 Power Ascension Limit Curve MSL A Upper .......................................................... 163 Figure 10-10 Power Ascension Limit Curve MSL A Lower ................................................... 164 Figure 10-11 Power Ascension Limit Curve MSL B Upper .................................................... 165 Figure 10-12 Power Ascension Limit Curve MSL B Lower ................................................... 166 Figure 10-13 Power Ascension Limit Curve MSL C Upper .................................................... 167 Figure 10-14 Power Ascension Limit Curve MSL C Lower ................................................... 168 Figure 10-15 Power Ascension Limit Curve MSL D Upper ................................................... 169 Figure 10-16 Power Ascension Limit Curve MSL D Lower ................................................... 170 xi
GE-NE-(iOOO-0053-741I3.R4-NP NON-PROPRIETARY VERSION ACRONYMS AND ABBREVIATIONS Item Short Form Description 1 ACM Acoustic Circuit Methodology used for predicting pressure loads on the dryer based on pressure measurements taken from main steam line sensors 2 ASME American Society of Mechanical Engineers 3 BWR Boiling Water Reactor 4 BFN Browns Ferry Nuclear Plant, Units 1, 2 and 3 5 CDI Continuum Dynamics Inc.
6 EPU Extended Power Uprate 7 FEA Finite Element Analysis 8 FEM Finite Element Model 9 FFT Fast Fourier Transform 10 FIX' Flow Induced Vibration II GE General Electric 12 GENE General Electric Nuclear Energy 13 Hz Hertz 14 IGSCC Intergranular Stress Corrosion Cracking 15 Mlbm/hr Million pounds mass per hour 16 MS Main Steam 17 MSL Main Steam Line 18 MW,1 Megawatt Thermal 19 NA Not Applicable 20 NRC Nuclear Regulatory Commission 21 OBE Operational Basis Earthquake 22 OLTP Original Licensed Thermal Power 23 Pb Primary Bending Stress 24 Pm Primary Membrane Stress 25 Psi Pounds per square inch 26 Ref. Reference 27 RMS Root-Mean-Squared 28 RPV Reactor Pressure Vessel 29 SCF Stress Concentration Factor 30 SRSS Square Root Sum of Squares 31 SRV Safety Relief Valve 32 TVA Tennessee Valley Authority xii
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION EXECUTIVE
SUMMARY
Tennessee Valley Authority's Browns Ferry Nuclear Plant (BFN) Units 1,2, and 3 are 25 1"diameter BWR/4 plants with the BWR/4 slant hood steam dryer. Structural analyses of the steam dryer were performed using a full three-dimensional finite element model of the BFN dryer in support of the Unit I restart and Extended Power Uprate (EPU) programs for Units 1,2, and
- 3. The analyses consisted of time history dynamic analyses, frequency calculations, and stress and fatigue evaluations. Predictions of the fluctuating pressure loads on the dryer were developed in GE's scale model test (SMT) facility for use as input to the FIV analysis. The scale model test loads were processed using an acoustic circuit model by Continuum Dynamics Inc. (CDI) to develop the detailed dryer pressure loads for the time history analyses. In addition, ASME Code based load combinations were also analyzed using the dryer finite element model. This report summarizes the dynamic, stress and fatigue analyses for the BFN Units 1,2, and 3 steam dryer at original licensed thermal power (OLTP) and EPU conditions based on scale model test data.
The criterion used in the evaluation to predict fatigue susceptibility of the individual dryer components is the ASME fatigue limit peak stress intensity greater than 13,600 psi. The load definitions based on the SMT methodology are conservative due to the nature of the boundary condition modeled in the test apparatus and due to the amplitude scaling used to bound the uncertainties in the SRV resonance frequency range. Due to the conservative nature of the SMT-based pressure loads, the analysis predicted that the majority ofthe steam dryer components are not vulnerable to fatigue at the OLTP conditions; however, there are a few locations that are at or near the fatigue stress limit in the original dryer configuration. As an example, the 3/8-inch thick outer cover plate and manway cover are attached with 1/4-inch fillet welds. These welds are considered undersized and could lead to fatigue initiation at EPU conditions in the original dryer configuration. This manway cover will be eliminated in the modified dryer configuration.
The results of the evaluation based on the ASME load combinations and associated stress acceptance criteria show acceptable stress margins for all operating conditions: normal, upset and faulted. The analyses show that the outer hood and cover plate locations are also regions of higher stress at EPU conditions. Proposed modifications to improve the stress margins at these locations are identified in this report.
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GE-NE-0000-0053-7413-R4-NP NON-PROPRIETARY VERSION The stress analysis results for OLTP demonstrate that the BFN dryer stresses are gencrally below the fatigue endurance level screening criteria. When conservative stress concentration factors (SCF) are applied to address local stress concentration, a few dryer components are predicted to exceed the endurance level in the original dryer configuration.
Evaluation of EPU load conditions showed potential fatigue failure at several components in the original dryer configuration. To allow increased stress margin to accommodate EPU loads, a modified dryer configuration was analyzed. The modified dryer configuration includes a replacement outer hood and cover plate of one-inch thickness, along with reinforcements made to undersized welds. The outer hood stiffeners and cover plate access hole and manway cover are eliminated.
The Unit 1, 2, and 3 dryers have operated at OLTP for a period of eleven (11) to fifteen (15) years. Additionally the Unit 2 and 3 reactors have operated at 105% OLTP for over six (6) years. Dryer inspections conducted throughout these operating periods have identified no unusual damage due to flow-induced vibration. Inspection has revealed some dryer tie-bar damage and drain channel cracking. Necessary modifications have been implemented to address these issues. The overall BFN dryer experience is representative of the fleet experience for BWR/4 slant hood dryers operating at stretch and EPU power levels.
The fact that no damage has been observed in dryer components predicted to have stresses exceeding the fatigue stress limit is an indication of conservatism in the BFN SMT-based load definition. This conservatism has been carried forward into the analysis for the stress predictions for EPU operating conditions. Carrying forward load-definition conservatism to EPU conditions assured conservative identification of dryer components that may require reinforcement modification, further analysis, or monitoring to assure that the endurance criteria are met under EPU conditions. The analyses for the modified dryer demonstrate that the stresses on the modified dryer components are within the fatigue endurance limits under EPU conditions, even with the conservatism in the SMT-based load definition. In addition, the conservatism incorporated in the power ascension limit curves provides further assurance that the uncertainties in the analysis and plant monitoring are bounded and that the stresses in the modified BFN steam dryers will remain well within the acceptance criteria. Therefore, the modified BFN steam dryers are acceptable for EPU operation.
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GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION 2 INTRODUCTION AND BACKGROUND 2.1 Dryer Design Basis and Historical Development The function of the steam dryer is to remove any remaining liquid in the steam exiting from the array of axial flow steam separators. GE BWR steam dryers use commercially available modules of dryer vanes that are enclosed in a GE designed housing to make up the steam dryer assembly. The modules or subassemblies of dryer vanes, called dryer units, are arranged in parallel rows called banks. Six banks are used for the BFN dryers (BWR 4). Dryer banks are attached to an upper support ring, which is supported by four steam dryer support brackets that are welded attachments to the RPV. The steam dryer assembly does not physically connect to the shroud head and steam separator assembly and it has no direct connection with the core support or shroud. A cylindrical skirt attaches to the upper support ring and projects downward forming a water seal around the array of steam separators. Nonnal operating water level is approximately at quarter-height on the dryer skirt.
Wet steam flows upward from the steam separators into an inlet plenum.
horizontally through the dryer vane banks, vertically into an outlet plenum and into the RPV dome. Steam then exits the reactor pressure vessel (RPV) through steam outlet nozzles. Moisture (liquid) is separated from the steam by the vane surface and the hooks attached to the vanes. The captured moisture flows downward under the force of gravity to a collection trough that carries the liquid flow to drain pipes and vertical drain channels. The liquid flows by gravity through the vertical drain channels to the lower end of the skirt where the flow exits below normal water level. The outlet of the drain channels is below the water surface in order to prevent reentrainment of the captured liquid.
GE BWR steam dryer technology evolved over many years and several product lines. In earlier BWR/2 and BWR/3 dryers, the active height of the dryer vanes was set at 48 inches. In BWR/4 steam dryer designs like BFN the active vane height was increased to 72 inches. Perforated plates were included on the inlet and outlet sides of the vane banks of the 72-inch height units in order to distribute the steam flow more uniformly through the bank.
The addition of perforated plates resulted in a more uniform velocity over the height of the vanes. The performance for BWR/4 and dryer designs was established by testing in steam.
M'tost of the steam dryer is located in the steam space, with the lower section of the skirt extending below normal water level. These environments are 3
GE-NE-NOOO0053-7413-R4-NP NON-PROPRIETARY VERSION highly oxidizing. All of the BWR/2-6 steam dryers are welded assemblies constructed from Type 304 stainless steel. The Type 304 stainless steel used in BWR/2-6 steam dryers was generally purchased with a maximum carbon content specification of 0.08% (typical ASTM standard). Therefore, the weld heat affected zone material is likely to be sensitized during the fabrication process making the steam dryer susceptible to intergranular stress corrosion cracking (IGSCC). Temporary welded attachments may have also been made to the dryer material that could result in unexpected weld sensitized material.
Steam dryer parts such as support rings and drain channels were frequently cold formed, also increasing IGSCC susceptibility. Many dryer assembly welds included crevice areas at the weld root, which were not sealed from the reactor environment. Cold formed 304 stainless steel dryer parts were generally not solution annealed after forming and welding. Because of the environment and material conditions, most steam dryers have exhibited IGSCC cracking.
Average steam flow velocities through the dryer vanes at OLTP conditions are relatively modest (2 to 4 feet per second). However, the outer hoods near the steam outlet nozzles are continuously exposed to steam flows in excess of 100 feet per second. These steam velocities have the potential for exciting acoustic resonances in the steam dome and steamlines, provided appropriate conditions exist, resulting in fluctuating pressure loads that act on the dryer.
The dryer is a passive, non-safety related component that was included in Class I seismic analyses. The steam dryer performs no safety functions. The steam dryer assembly is classified as an "internal structure" per ASME Boiler and Pressure Vessel Code,Section III, Subsection NG. Therefore the steam dryer needs only to be analyzed for those faulted load combinations for which loss of structural integrity of the steam dryer could interfere with the required performance of safety class equipment due to generation of loose parts that may interfere with closure of the MSIVs or affect the core support structure integrity (shroud, top guide, core support and shroud support).
2.2 Browns Ferry Dryer Experience The operating experience for the three Browns Ferry steam dryers has been typical of the overall BWR fleet experience with no unusual indications. The steam dryer inspection data and disposition of the indications for EPU is summarized in Table 2-1 through Table 2-3 for each unit.
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GE-NE-((100-0053-7413-R4-NP NON-PROPRIETARY VERSION BFNI has been inactive since 1985 and is currently undergoing recovery and restart activities. BFNI operating experience has been limited to OLTP conditions. Dryer performance has been satisfactory. Limited drain channel weld cracks have been found similar to other BWR plants and will be repaired prior to renewed operations.
BFN2 and BFN3 were restarted at OLTP in 1992 and 1995, respectively.
Both units were subsequently uprated to 105% OLTP in 1998. These dryers have operated satisfactorily at OLTP and 105% OLTP. Earlier drain channel cracking had been repaired and reinforced. Subsequent inspections have shown no recurrence of cracking in the repaired welds. BFN3 has experienced limited tie bar cracking. These bars have been replaced with a modified design. The drain channel weld reinforcement and the modified tie-bar design will be implemented into the BFN I dryer prior to restart operation.
The analysis of the BFN1 dryer, as described in this report, has simulated this modified BFN I dryer condition.
Table 2-1 BFNP Unit I Steam Dryer Inspection Data and Disposition for EPU Location Year Indication Disposition for EPU Refison for Disposition Drain Apr-92 Indications reponted in three Cause: Fatigue (drain Reinforcing the Channel vertical drain channel to skirt clunncl cracks): welds will reduce fillct wclds (Clannel 2 right Installation or removal the stress.
side approximately 12 in. (bcnt support bracket) long. Clannel 3 left side Welded repairs approximately 10 in. long. recommended forthree Clitincl 4 right sidc drain channel weld approximately 14 in. long), crcks. It was also In Channel I right side a ecorncded 1Ihw alsl drain channel welds be small (less than I in. long) indication transvcrse to the draitignled (increase weld. In addition. a broken 118" fillet welds size to locking Fillet weld and bent 1/48 ifor t least lower support bracket were 76 inches. Transverse reported se in the 84-degre indication on Channel leveling screw. I classificd as a scratch.
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GE-NE-000X-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION Table 2-2 BFNP Unit 2 Steam Dryer Inspection Data and Disposition for EI'U Location Year Indication Disposition for Reason for EPU Disposition Guidc Brackct May-93 Steam di.er lower guide Cause: Contact wilh Daimage unrelated bracket damage at 180 dcg guide rod during to frltigue or EPU.
installation.
Undcnvatcr weldcd repair by divers was donc at next outagc Support Ring Nov-S8 Support ring cracks. Cause: IGSCC. None Damage unrclalcd required to fatigutc or EPU.
Drain Nov-88 Cracks were reportcd in ihrcc Cause: Fatigue Reinforcing welds Channel orcight vertical drain channel Weld retmirdrain will reduce thc welds. Cracking was localcd clmnncl cracks. plus strcss.
in throat of vertical drain maitigation of all drain channel to skirn 1/8-in, fillct clunucl wclds welds. Two of tie cracks (increased l/8" fillet were approximnilcly 12 weld size to 14" inches long and thc (hird wis minimum for at least approximatcly 24 inches lower 76" ot each long. vcrtical drain channel
_weld).
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GE-NE-0000-0053-7413-R4-NP NON-PROPRIETARY VERSION Table 2-3 BFNP Unit 3 Steam Drcr lnspcction Data and Disposition for EPU Location Year Indication Disposition for Reason for EPU Disposition Drain Nov-91 Indications iwcre reported in Cause: Fatigue Mitigation welds Chamncl three of eight 'crtical drain Undenvatcr wcld will reducc the channel to skirt welds (Channcl I repair plus mitigation stress.
right side approxiinatcly 12 welds applied to all inches long. Channel 2 left side channels (1/8" fillet approxinmaely 12 inchcs long. size increascd to 1/4" Channel 3 right side for at Icast lower 76 approxinatcly 10 inchies long). inches ofcach Indications wcrc located in throat cnical wecld).
the of the l/8-inch fillet wclds at lower end of the welds.
Tic Bar Jun-03 During a mid-c.'cle outage Cause: Fatigue froim Replaced with (Cycle I1I), it was reported that an unknown cyclic biggcr and all three of the ccntcr bankk lic loading stronger tic bars.
bars were brokcn. These V x V Divcrs removed the Failure of this x 3/16" angle cross section lie brokcn tie bars and cotupoiCnent will bars provide lateral bracing wcldcd three larger not result in a across the lop of the centerstcatn section (1.5" x 2.7") situation where dr'cr banks (banks 3 and 4 of 6 replacement tic bars steam could total banks). In each case. one adjaccnt to the bypass the dnycr end of the tie bar had a fracture original tic bar and require an through the full bar cross section. locations. Outer unplauncd plant A linear indication was reported bank hoods and cover slitldown to at the unbroken end of one tic platcs wcre also repair.
bar. Although the bars were inspcctcd and no bent. thcre was no cvidcncc of indications were plastic dcfornution at ihe reported.
fracture surface. No indications were foutnd as a result orvisuallv exanining the other I0 tic bars.
Support Mar-04 Numbcr of gouges and contact Cause: Installation or Unrelated to bracket and marks removal EPU interfacing Take precautions dn'cr seismic during mnovcnieti of block the dr'er 7
GE-NE-0000-0053-7413-R4-NP NON-PROPRIETARY VERSION 2.3 Motivation for Additional FIV and Structural Analysis The dryer fatigue cracking experiences at Quad Cities and Dresden demonstrated the need to better understand the nature of the loading and the dynamic structural response of the steam dryers during normal operation. The expense involved with inspection and repair of the dryers for the extended life of the plants provide motivation for more accurately determining the plant-specific FIV loads acting on the dryers and quantifying the stresses in tile dryers at EPU conditions.
In response to these needs, this evaluation was initiated to derive plant-specific loads and perform a comprehensive structural assessment for the BFN dryer design to assure that it could operate at EPU conditions. The loads affecting the steam dryer were determined by BFN plant-specific SMT, using the same SMT methodology benchmarked to the instrumented QC2 replacement dryer and used as input to a three-dimensional finite element model of the BFN steam dryer. Loads considered in the assessment included steady state pressure, fluctuating, and transient loads, with the primary interest in the steady state fluctuating loads that affect the fatigue life of the dryer.
Additionally, ASME Code-based design load combinations for normal upset and faulted service conditions were evaluated. Detailed finite element analyses using the dryer model, subjected to these design loads, were performed. The analytical results identified the peak stresses and their locations. The results of the analyses also included the computationally determined structural natural frequencies for the different key components and locations in the dryer. This report summarizes the dynamic, stress, and fatigue analyses performed based on the scale model load measurements; it provides the basis for design modifications that increase stress margins and reduce the likelihood of fatigue cracking at EPU conditions.
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GE-NE-000(-0053-7413-R4-NP NON-PROPRIETARY VERSION 3 DYNAMIC ANALYSIS APPROACH 3.1 Dynamic Loading Pressure Time Histories The primary dynamic loads of concern on the dryer are tile fluctuating pressure loads during normal operation that may lead to fatigue damage.
Scale model testing was performed using the BFN Unit I configuration in order to determine the fluctuating pressure loads. The overall scale model testing methodology is documented in Reference I.
The BFN-specifie testing is documented in Reference 2. Originally it was anticipated that a load definition would be developed based upon a load interpolation algorithm (LIA) that was being developed by GE. It was also anticipated that a load definition would be developed based on using acoustic circuit methodology by CDI that has been previously reviewed by the NRC.
The load interpolation algorithm is still being developed and validated.
Therefore, it was decided to use the CDI Acoustic Circuit Model (ACM) to develop the structural load definition. Additional details on the CD1 acoustic circuit model are provided in Reference 3. Pressure measurements were taken from the steamlines in the SMT [Reference 2] and used as input to the ACM.
The ACM was then used to predict the plant-scale pressure loading on the steam dryer. This approach uses the ACM in the same manner as it would be used with in-plant measured data. Because this approach is a departure from the methodology described in References I and 2, a benchmark comparison was performed by CDI in order to demonstrate the validity of the approach.
This benchmark is documented in Reference 3 and submitted separately by TVA. The pressure predicted from the scale model testing and CDI acoustic circuit model were applied as time history forcing functions to the structural finite element shell model of the dryer [Reference 2] through [Reference 3].
3.2 Stress Recovery and Evaluation Methodology The entire shell finite element model developed using ANSYS was divided into components with every element assigned to a component. An ANSYS
[Reference 4] macro was written to sweep through each time step on every dryer model component to determine the time and location of the maximum stress intensity. The element stresses at all integration points (4 for quadrilateral and 3 for triangular elements) for the top and bottom element surfaces were surveyed. In addition, membrane stresses were extracted for use in the ASME load combination calculations. ANSYS maximum stress intensity results generated from this macro are presented in Table 6-1 and 9
GE-NE-(000-0053-7413-R4-NP NON-PROPRIETARY VERSION Table 6-2 for the original dryer, OLTP and EPU respectively. Table 7-1 summarizes the maximum stress intensity results for the modified dryer at EPU.
4 MATERIAL PROPERTIES The BFN dryer assemblies were manufactured from solution heat-treated Type 304 stainless steel conforming to the requirements of the material and fabrication specifications [Reference 5]. ASME material properties were used in the ANSYS dryer finite element model [Reference 6]. The applicable properties are shown in Table 4-1.
Table 4-1 Properties of SS304 IReference 61 Room temperature Operating temperature Material Property 70 0F 5450 F S,, Stress Intensity Limit, psi 20000 16900 Sy, Yield strength, psi 30000 18900 S,, Ultimate strength, psi 75000 63400 E, Elastic modulus, psi 28000000 25600000 5 DESIGN CRITERIA 5.1 Fatigue Criteria The fatigue evaluation consists of calculating the maximum alternating stress intensities from flow induced vibration (FIV) pressure loading at all locations in the steam dryer structure and comparing them to the allowable fatigue design threshold stress intensity. The fatigue threshold stress intensity from ASME Code Curve C is 13600 psi. The fatigue design criteria for the dryer is based on Figure 1-9.2.2 of ASME Section III [Reference 7], which provides the fatigue threshold values for use in the evaluation of stainless steels.
ASME Code fatigue Curve C assumes a mean stress equal to the material yield strength and is the most conservative applicable fatigue curve. Since the actual weld geometry is not a part of the shell finite element model ofthe dryer, additional weld factors are applied to the maximum stress intensities obtained from the shell finite element time history analyses at weld locations
[Reference 8]. A key component of the fatigue alternating stress calculation at a location is the appropriate value of the stress concentration factor (SCF).
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GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION The stress intensities with the applied weld stress concentration factors are then compared to the fatigue criteria givcn above.
5.2 ASME Code Criteria for Load Combinations The ASME Code stress limits used in the evaluation of the BFN dryers arc listed in Table 5-1.
Table 5-1 ASME Code Stress Limits IRcfercnce 71 Stress Service level category Class 1 Components Stress limits (NB)
Service levels A & B Pm Sm Stress Limit, ksi 16.9 J
Pm + Pb 1.5Sm 25.35 Service level D Pm Min(.7S, or 2.4 Sm,) 40.56
_Pm + Pb I 1.5(Pm Allowable) 60.84 Le%,end:
P ,: Gcncrl prinviry mcnibranc stress intcnsity Pt,: Primar. bcnding stress intcnsity S.,: ASME Code stress intensity limit Siy: Ultintnac strength 6 OLTP and EPU FATIGUE ANALYSIS for ORGINAL DRYER Time history analyses were performed using ANSYS Versions 8.1 and 9.0
[Reference 4], The direct integration time history analysis method was used for all of the cases described in this report. ((
)). "'o account for dryer frequency uncertainty, the time step sizes were increased by 11
GE-NE-0000-0053-7413-R4-NP NON-PROPRIETARY VERSION plus 10% and minus 10% from the nominal case for the pressure loads. ((
))
Additional time history analysis cases were run fbr the dryers of two other plants at intervals of less than 10% ((
)) stresses in the dryer, which would be expected if there was a structural resonant condition occurring at these intemiediate time-step intervals. (( I 11 6.1 Full Dryer Shell Finite Element Model The three-dimensional shell model of the BFN dryer is shown in Figure 6 2 through Figure 6 5. The model incorporates distributed masses in the vane banks and submerged portion of the skirt. The steam dryer is built primarily of welded plates. ((
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GE-NE-O000-0053-74 I 3-R4-NP NON-PROPRIETARY VERSION Tile mass on the skirt used to represent the water was determined from a study using a dctailcd model of the skirt and watcr super-clement. ((
6.2 Dynamic Loads The primary dynamic loads of concern are the steam-flow induced fluctuating pressure loads during normal operation. These are the loads responsible for the fatigue damage experienced at EPU conditions by all four of the Dresden and Quad Cities steam dryers. As described in Section 3.1, BFN plant-specific scale model test loads adjusted to plant scale were used as input to CDI's acoustic circuit model to predict the pressures acting on the dryer
[Reference 3]. Figure 6-6 shows the applied load at the time when the pressure amplitude is a maximum for EPU operation.
The loads used in this analysis are based on measurements simulating Original Licensed Thermal Power (OLTP) of 3293 MWt and the EPU power level of 3952 MWt.
6.3 Frequency Content of Loads The frequency content of the BFN SMT loads is shown in Figure 6-7. ((
))
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GE-NE-(000-0053-7413-R4-NP NON-PROPRIETARY VERSION 6.4 Modal Analysis Frequency calculations were performed with tile original dryer model supported from the RPV dryer support brackets. The boundary conditions described in Section 6.1 were applied to the dryer finite element model for the modal analysis. The entire original dryer was surveyed for the component natural frequencies. However, the focus of the survey was on the outer dryer surfaces. Calculated component natural frequencies for the skirt are shown in Figure 6-8 and Figure 6-9. ((
6.5 Structural Response to Loads Stress time histories for various components arc plotted in Figure 6-12. A comparison of the pressure time history and resulting structural response for the outer hood is shown in Figure 6-13. FFT's of the stress time-histories for various components are shown in Figure 6-14 through Figure 6-18. ((
6.6 Stress Results from Time History Analyses Maximum stress intensity results from ANSYS for all components of the dryer are shown in Table 6-1 and Table 6-2 (for OLTP and EPU, respectively) for three load cases (each powcr level evaluated at nominal, +10% and -10%
frequency shifts for (( 1] and plotted in Figure 6-19 through Figure 6-45. These stresses are listed without the weld and weld stress concentration undersize factors discussed in Section 6-7. Each component has the case that produced the highest stress intensity highlighted. (( I
.1 Design margins for both OLTP and EPU power levels are summarized in Table 6-5 and discussed in Section 6.8.
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GE-NE-OOO0-0O53-74 ! 3-R4-NP NON-PROPRIETARY VERSION Table 6-1 Original Dryer Time History Analysis Results from ANSYS: OLTP 1]
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GE-NE-4000-(053-7413-R4-NP NON-PROPRIETARY VERSION Table 6-2 Original Dryer Time History Analysis Results from ANSYS: EPU
((I 16
GE-NE-(X0)0-0053-7413-R4-NP NON-PROPRIETARY VERSION 6.7 Weld Factors The calculation of fatigue alternating stress intensity using the prescribed stress concentration factors in ASME Code Subsection NG is straightforward when the nominal stress is calculated using the standard strength of material formulas. However, when a finite element analysis (FEA) approach is used, the available stress component information is more detailed than that which would be obtained from tile standard strength-of-materials formulas and requires added guidance for determining a fatigue stress intensity to be used in conjunction with the ASME Code S-N design curve. Reference 8 provides the basis for calculating the appropriate fatigue factors for use in the S-N evaluation to assess the adequacy of these welds based on the FEA results.
Figure 6-46 summarizes the Reference 8 criteria. For the case of full penetration welds, the recommended SCF value is 1.4. The recommended SCF is 1.8 for a fillet weld when the FEA maximum stress intensity is used.
The finite element maximum stress intensity is directly multiplied by the appropriate SCF to determine the fatigue stress.
Note that the above discussion of stress concentration effects (SCF's, fatigue factors, weld factors) only applies to the fatigue evaluation. SCF, "fatigue factor," and "weld factor" are used interchangeably. For the BFN dryer ASME primary stress evaluation, the weld quality factor used was 1.0. This was because all of the welds occur at discontinuities. Stresses at discontinuities are by definition secondary or peak stress. The ASME analysis retrieves "primary" stresses away from the weld discontinuities.
Therefore, a weld quality factor as defined in Table NG-3352-I of Reference 7 is not required.
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GE-NE-)XJO-(0053-7413-R4-NP NON-PROPRIETARY VERSION Tablc 6-3 Original Drycr Time History Rcsults with Wcld factors: OLTP I]
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GE-NE-0000-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION Table 6-4 Original Dr'er Time -liston' Results with Weld factors: EPU
((I
))
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GE-NE-4000-0053-7413-R4-NP NON-PROPRIETARY VERSION 6.8 Lower Tie Bar Stress Analysis The I" by '/" tie-rod is welded with a 1/4/" fillet weld to the inner-hood of' the steam dryer. With the weld factor included, the maximum shear stress in the weld is calculated to be (( )) psi. The limiting fatigue condition occurs in the original dryer with EPU +10% loading conditions. The allowable fatigue limit for normal stresses is 13,600 psi. The allowable limit for shear stresses is taken as 0.6 of that for normal stresses. 8160 psi. This is consistent with the guidance provided in ASME section III, paragraphs NB-3227.2 and NG 3227.2. The tie-rod weld maximum stresses are below the allowable ASME shear stress threshold of 8160 psi resulting in a design margin of
(( 11 6.9 Fatigue Analysis Results The fatigue analysis results are from a shell finite element model used to assess the acceptability of the steam dryer against the fatigue design criteria.
Tile maximum stresses directly from the ANSYS shell finite element analysis are summarized in Table 6-1 and Table 6-2. The stresses with the appropriate weld factors applied are summarized in Table 6-3 and Table 6-4. All nodes and elements in the steam dryer finite element model are included in one of the model components. The highest stress Intensity results and thus the lowest design margins for each of these dryer model components are presented in Table 6-5. The outer hood and cover plate are the limiting components for OLTP and EPU cases, respectively. The components with the lowest design margins are highlighted in the tables.
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GE-NE-()00-0053-7413-R4-NP NON-PROPRIETARY VERSION Table 6-5 Original Drycr Final Stress Results: Design Margins for OLTP and EPU
((
))
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GE-NE-O000-0053-7413 -R4-NP NON-PROPRIETARY VERSION 7 EPU FATIGUE ANALYSIS FOR MODIFIED DRYER 7.1 Dryer Modifications A modification consisting of a thickened hood and cover plate is planned for the BFN dryer as part of the Unit I restart program and Units 2 and 3 prior to extended power operation. This and other modifications are based on the previous BFN dryer operating experience.
Tile existing half inch hood and three-eights coverplate will be replaced with one inch hood and coverplate. A portion of the original outer hood around the perimeter will be retained as backing strip for the weld placement of the new hood. The outer hood stiffeners will be removed. Constnictability enhancements implemented during installation will be reconciled to the design requirements. Modifications are shown in Figure 7-1 through Figure 7-4.
7.2 Structural Response to Loads Stress time histories for various modified dryer components are plotted in Figure 7-5. A comparison of the pressure time history and resulting structural response for the outer hood is shown in Figure 7-6. FFT's of the stress time-histories for various components are shown in Figure 7-7 through Figure 7-11.
In general, the components show a higher response to the lower loading frequencies associated with the +10% time step shift.
7.3 Stress Results from Modified Dryer Time History Analyses Maximum stress intensity results from ANSYS Finite Element Analysis (FEA) for all dryer structural components enveloped for three load cases (nominal, +10% and -10% frequency shifts for (( ))damping) of the dryer are listed in Table 7-1 and plotted in Figure 7-12 through Figure 7-40.
Each component has the load case that produced the highest stress intensity highlighted.
All components of the modified dryers have their peak stresses within ASME Design Fatigue Curve C stress limit of 13.6 ksi.
As indicated in Table 7-2, the limiting components of the modified dryer are the (( )), which have their highest peak stress intensity
(()) the fatigue limit stress of 13600 psi. The predicted peak stress intensity of these components is conservative due to modeling 22
GE-NE-OOO-00053-7413-R4-NP NON-PROPRIETARY VERSION assumptions distributing vane masses along tie rods, tied into the top plates.
(( ))
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GE-NE-t)OOO-()053-74 i 3-R4-NP NON-PROPRIETARY VERSION Table 7-1 Modified Drver Time History Analysis Results from ANSYS: EPU I]
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GE-NE-OOC04)053-74 13-R4-NP NON-PROPRIETARY VERSION 7.4 Weld Factors Table 7-2 Modified Dryer Maximum Stress Intensity with Weld Factors and Design Margin 1]
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GE-NE-)O00-(053-7413-R4-NP NON-PROPRIETARY VERSION 7.5 Lower Tie Bar Stress Calculation With the weld factor included, the peak shear stress in the fillet weld is calculated to be (( )) psi occurring in the BFN Modified Dryer with EPU +10% loading conditions. The tie-rod weld peak stresses are below the allowable shear stress fatigue threshold of 8160 psi resulting in a design margin of((
7.6 Fatigue Analysis Results The fatigue analysis results are from a shell finite element model used to assess the acceptability of the steam dryer against the fatigue design criteria. The maximum stresses directly from the ANSYS shell finite element analysis are summarized in Table 7-1, The stresses with the appropriate weld factors applied are summarized in Table 7-2. All structural nodes and elements in the steam dryer finite element model are included in one of the model components. As discussed earlier, the f[
))are the limiting component due to their conservative modeling approach. The components with the lowest design margins are highlighted in Table 7-2. All of the dryer components have FIV induced peak stress intensities below the endurance fatigue limit of 13600 psi.
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GE-NE-)000-0053-7413-R4-NP NON-PROPRIETARY VERSION 8 ASME CODE ANALYSES The BFN steam dryer was analyzed for the ASME Code load combinations (primary stresses) shown in Table 8-1. The acceptance criteria used for these evaluations are specified in Section 5.2 and are the same as those used for safety related components.
8.1 ASME Code Load Combinations Browns Ferry is not a "New Loads" plant; therefore, annulus pressurization and jet reaction loads are not part of the design and licensing basis for the plant and are not considered in these load combinations. The resulting load combinations for each of the service conditions are summarized in Table 8-1.
The steam dryer structural analyses consider the transient and accident events listed in Browns Ferry UFSAR Tables 14.4-1 and 14.4-2. The transient and accident events that are of particular interest for the evaluation of reactor internal pressure difference (RIPD) loading on vessel internals are events with one or more of the following characteristics: 1) pressurization, 2) depressurization, 3) core coolant flow increase, or 4) moderator temperature decrease. The load combinations for the limiting transient and accident events evaluated are listed in Table 8-1. The turbine stop valve closure transient (Upset I and Upset 2 in Table 8-1) is the limiting transient event for reverse pressure loading on the dryer. The Upset 3 load case bounds the remaining transient events. The Faulted I and Faulted 2 load cases address the main steamline break accident outside containment (the design basis event for the dryer). The Faulted 3 load cases address the remaining loss of coolant accidents. Positive reactivity insertion events (e.g., rod withdrawal error, rod drop accident) do not result in a significant change in the reactor system pressure or steam flow rate and, therefore, are not significant with respect to the RIPD loading on the steam dryer.
Each of the load combination cases is briefly discussed below:
Normal: The deadweight, normal differential pressure, and FIV loads are combined for the normal service condition. ((
)) There is a significant pressure variation across the outer vertical hood.
Upset 1: This load combination represents the acoustic wave portion of the turbine stop valve closure transient (TSVI). ((
27
GE-NE-000)-0053-74113-R4-NP NON-PROPRIETARY VERSION
)). Deadweight and OBE seismic loads are also included.
Upset 2: This load combination represents the flow impingement portion of the turbine stop valve closure transient (TSV2). ((
11 Deadweight and OBE seismic loads are also included.
Upset 3: This load combination bounds the other transient events. ((
Deadweight and OBE seismic loads are also included.
Faulted IA: This load combination is for the main steamline break outside containment accident with the reactor at full power. The faulted differential pressure load (ACI) represents the acoustic rarefaction wave impacting the dryer. (( I
)) Deadweight and SSE seismic loads are also included.
Faulted 1B: This load combination is for the main steamline break outside containment accident with the reactor at full power. The faulted differential pressure load (DPf) represents the loading due to the two-phase level swell impacting the dryer. The interlock condition value of DPf((( ))psid) was used for DPf because the vessel blow down and level swell are more severe at the interlock condition. ((
)) Deadweight and SSE seismic loads are also included.
Faulted 2A: This load combination is for the main steamline break outside containment accident with the reactor at low power/high core flow (interlock) conditions. The faulted differential pressure load (AC2) represents the acoustic 28
GE-NE-oO0-0053-7413-R4-NP NON-PROPRIETARY VERSION rarefaction wave impacting the dryer. ((
)) Deadweight loads are also included.
Faulted 2B: This load combination is for the main steamline break outside containment accident with the reactor at low power/high core flow (interlock) conditions. The faulted differential pressure load (DPf) represents the loading due to the two-phase level swell impacting the dryer. ((
]1 Deadweight loads are also included.
Faulted 3: This load combination is for pipe breaks other than the main steamline break. ((
))g. The normal operating differential pressure load (DPn) was conservatively assumed for the differential pressure load. Deadweight and SSE seismic loads are also included.
29 i
GE-NE-0000-0053-7413-R4-NP NON-PROPRIETARY VERSION Table 8-I ASME Load Combinations Screening Fatigue Service Load Combination Criteria Acceptance Condition Criteria Pm<1 1.0 Sm FIVn <13,600 psi Normal DW + DPn + FIVn (Pm + Pb) <_1.5 Note 3 Sm Pm _<1.0 Sm FIVn <13,600 psi Upset I DW + DPn + [TSVl 2 + OBE 2']' + FIVn (Pm + Pb) *< 1.5 Notes 2 and 3 Sm (Note 5)
Pm _ 1.0 Sm Not Applicable Upset 2 DW +DPn + [ TSV2 ' + OBEE]1' 2 (Pm + Pb)
- 1.5 Sm (Note 5)
Pm<* 1.0 Sm FIVu < 13,600 psi Upset 3 DW + DPu + OBE+ FIVu (Note 4) (Pm + Pb) _*1.5 Notes 2 and 3 Sm (Note 5)
DW + DPn + [ SSE 2 + ACI (Hi-Power) ]
2 Pm _2.4 Sm Not Applicable Faulted IA + FIVn (Pm + Pb)
- 3.6 Sm Pm
- 2.4 Sm Not Applicable Faulted 1B DW + [ DPfl 2 + SSE 2 ]V2 (Pm + Pb) < 3.6 Sm Pm < 2.4 Sm Not Applicable Faulted 2A DW + DPn + AC2 (interlock) + FIVn (P + Pb) *5 3.6 Sm Pm _2.4 Sm Not Applicable Faulted 2B DW + DPf2 (Pm + Pb) *< 3.6 Sm Pm:9 2.4 Sm Not Applicable Faulted 3 DW + DPn + SSE (Pm + Pb) *5 3.6 Sm Notes:
1.These criteria are for screening purposes and are not requirements for the dryer components.
- 2. These transient events are of a short duration; therefore, fatigue is not a critical consideration.
- 3. The value of 13,600 psi is based on austenitic si ainless steel.
30
GE-NE-O000()053-7413-R4-NP NON-PROPRIETARY VERSION
- 4. ((
)) therefore, this load is not explicitly included in the dryer analysis
- 5. Upset Condition stress limits are increased by 100%o above the limits shown in this table per NG-3223 (a) and NB-3223 (a)(1).
8.2 ASME Code Load Case Stress Results- Origi ial Dryer The maximum stresses reported from the ANSY,* analysis runs are peak stresses and not general primary membrane or membrane plu! bending stresses. In order to determine primary stress, contour plots were obtained for each of the components that do not meet the Code stress limits using the conscrvative peak stress intensity values.
The stress contour plots were evaluated, and a va'ue of primary stress was determined by eliminating high peak stress areas resulting fr in discontinuities, badly shaped elements, etc. The primary stress values were thl n used in the calculation of total stress for the ASME load combination calculatiot s. Table 8-2 and Table 8-3 summarize the primary stresses for the OLTP cas ,s for normal, upset, and faulted conditions. From these results, the locations whi h do not meet the ASME limits (Table 5-1) using these very conservative maximucm stresses are reviewed in more detail to obtain the average stresses required for c *mpliance with the ASME Code stress limits. Some of the stresses in Tables 8-2 aid 8-3 are based on conservative peak stresses, which were not re-evaluated to obt, in average stresses because they meet the stress limits. All of the stresses for the (,LTP cases meet the ASME Code stress limits. The ASME Code case evaluations a: EPU were performed and the ASME Code case evaluations have met the stress limits.
31
GE-NE-4000-0053-74 i 3-R4-NP NON-PROPRIETARY VERSION Table 8-2 Original Dryer OLTP ASME Results for Norn al and Upset Conditions: Average Stresses
((
32
GE-NE-A000-(K053-7413-R4-NP NON-PROPRIETARY VERSION Table 8-3 Original Dryer OLTP ASME Results for Faulted Conditions: Average Stresses
((I 33
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION 8.3 ASME Code Load Case Stress Results- Modified Dryer Similar to the evaluation of the original dryer, the maximum stresses reported from the ANSYS analysis runs for the modified dryer are peak stresses and not general primary membrane or membrane plus bending stresses. These stresses usually occur at discontinuities and contain a significant amount of stress concentration. In order to determine primary stress, ANSYS post-processing runs were made to scan each component of the dryer for stresses an element or two away from the maximum stress location but still containing some concentration effect. These conservatively calculated primary stress values were then used in the calculation of total stress for the ASME load combination calculations. Table 8-4 and Table 8-5 summarize the primary stresses for the EPU cases for normal, upset, and faulted conditions. All of the stresses for the EPU cases meet the ASME Code stress limits.
34
GE-NE)O(X)-0053-7413-R4-NP NON-PROPRIETARY VERSION Table 8-4 Modified Dryer EPU ASME Results for Normal and Upset Conditions: Average Stresses
((I 35
GE-NE4)0000-0053-7413-R4-NP NON-PROPRIETARY VERSION Table 8-5 Modified Dryer EPU ASME Results for Faulted Conditions: Average Stresses
((I
))
36
GE-NE-O00000)53-7413-R4-NP NON-PROPRIETARY VERSION 9 BFN DRYER STRUCTURAL ANALYSIS UNCERTAINTY EVALUATION This section summarizes the development of the end-to-end uncertainty for the Browns Ferry steam dryer structural analysis. This uncertainty consists of uncertainties in the predicted load definition and in the dynamic structural analysis.
In general, the uncertainties consist of uncertainties associated with the pressure load prediction methodology, uncertainties associated with plant-specific application of the load methodology, and uncertainties associated with the measurements made or used as input to the execution of the methodology (either in development of the load definition or for monitoring during plant power ascension). These uncertainties are used as input to both the initial power ascension limit curves based on the scale model test load predictions and for the revised power ascension limit curves based on in-plant measurements.
9.1 Load Definition The load definition methodology used for predicting the BFN dryer fluctuating pressure loads is based on scale model test measurements. The uncertainties associated with the generation of such a plant-specific load definition consist of uncertainties and assumptions inherent in the scale model test methodology, test measurement and scaling uncertainties, and plant-specific modeling uncertainties.
9.2 Scale Model Test The scale model test (SMT) is used to provide a prediction of the fluctuating pressure loads acting on the steam dryer. The assumptions and simplifications used in the SMT methodology are the primary sources of uncertainties introduced in the dryer load definition.
9.2.1 Modeling Uncertainties The modeling uncertainties consist of the assumptions and simplifications used to model the plant system and in scaling the model test results to plant conditions:
- Components eliminated
- Components simplified
- Boundary conditions
- Damping 37
GE-N E-0000-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION
- Scaling laws (the selection of significant nondimensional parameters for preservation)
- Fluid properties of low pressure air versus high pressure saturated steam
- Scale model speed of sound
- Scaling based on preserving Mach number versus Reynolds number
- Load distribution
- Inlet and exit boundary conditions (e.g. test rig blower vs. steam flow from separators and replacement of high pressure turbine inlet by can with orifice at atmospheric pressure)
A qualitative assessment of the overall effect of these uncertainties is included in the Quad Cities Unit 2 (QC2) scale model test benchmark report [1]. This report also includes a detailed quantitative comparison of the QC2 scale model test predictions with the QC2 plant data acquired during the 2005 power ascension test program conducted by GE. Currently, this benchmark is the only valid assessment of the impact that the modeling simplifications and uncertainties listed above have on the empirical load predictions given by the GE SMT methodology.
Reference [I] shows that SMT predictions exhibit different behaviors in the ((
)) The following average bias error and standard deviation of the SMT predictions in this frequency band were calculated using data from Reference
[1], Table 9:
Uncertainty of SMT predictions for (( ))Hz-frequency band (RMS Values):
Average Conservative Bias Standard Deviation of Sample Errors [
38
GE-NE-00(X)-0053-7413-R4-NP NON-PROPRIETARY VERSION
)) and 11:
Uncertainty of SMT predictions for (( 11Hz freauencv band (Peak Values):
Average Non - Conservative Bias (( ]
Standard Deviation of Sample Errors [1 ))
Uncertainty of SMT predictions for (( ))hz freguency-band (Peak Values):
Average Non - Conservative Bias liii I]
Standard Deviation of Sample Errors 1]
The bias errors associated with each of the three frequency bands of interest are associated with the assumptions and simplifications used in the SMT methodology.
39
GE-NE-0000-0053-74 13-R4-NP NON-PROPRIETARY VERSION Part or the variability detected in the predictions (random errors) can be explained by the test measurement uncertainties analyzed in the following section. Other random or not well understood effects might cause the other part of the variability observed in the SMT predictions.
9.2.2 Test Measurement Uncertainties Tile test measurement uncertainties consist of the uncertainties introduced in the parameter measurement process. In general, these uncertainties consist of the sensor accuracy, sensor and sensor loop calibration, environmental influences (e.g.,
reference leg temperature effect on the plant pressure measurement), and signal conversion (e.g., differential pressure to flow). The parameters of interest in the SMT load definition process are:
- Scale model static pressure
- Plant static pressure
- Scale model fluctuating pressure
- Plant steamline flow velocity
- Scale model steamline flow velocity
- Scale model air temperature
- DAS transfer function (analog input to digital storage and front end digital signal processing)
The overall effect of these uncertainties has been addressed generically in Attachment B of Reference [I]. This reference document also contains a theoretical study showing how each uncertainty propagates through the measurement processes.
The following numerical values applicable to the BFN1 test measurement uncertainties have been taken from Section 9 of Reference [2]:
A. Frequency band: (( ))
B. Frequency band: (( ))
40
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION C. Frequency band: (( ]
D. Frequency band: ((
E. Frequency band: (( ]
It is worth noting that Frequency Band E (( ]Jis contained inside Frequency Band D (( ))This was done in order to better capture the non-linear behaviors of the SIRV resonances exhibited by BFNI in Band E and thus obtain a more accurate uncertainty value for this narrow band of interest.
Since all instruments used in the SMT methodology are calibrated and carry calibration certificates, there is no systematic error or bias associated with the test measurements, It is also worth noting that random uncertainties due to measurement errors may explain part of the variability observed in the errors of the QC2 SMT predictions documented in Section 9.2.1. It is apparent that part of the random errors observed in the QC2 benchmark were caused by the measurement uncertainties described herein. Therefore, the variability observed in the sample errors of the benchmark is not independent from the random measurement errors of the SMT.
However, for the purpose of calculating a conservative end-to-end uncertainty of the entire process, we will assume that both errors are independent.
9.2.3 Application Uncertainties Uncertainties can be introduced when applying the SMT load definition methodology to a plant analysis. In general, these uncertainties are introduced by the following:
- Plant geometric tolerances
- Model geometric tolerances
- For multi-unit sites, one common test versus separate tests for each individual unit As described in Attachment B of Reference [I], plant and model geometric tolerances translate into frequency uncertainties in the SMT predictions. The model geometric tolerances combined with the air temperature uncertainty for BFN I tests result in a predicted frequency uncertainty of approximately (( ))%. This uncertainty is bounded by the -10 % uncertainty in load frequencies included in the structural analysis methodology.
41
GE-N E-000)-0053-7413-R4-NP NON-PROPRIETARY VERSION Geometric tolerances in the S/RV standpipes have an effect on the amplitude of the high frequency resonances predicted by the SMT. In fact, the SMT benchmark comparisons show that the SMT prediction is generally conservative except for the prediction of the effect of SRV standpipe acoustic resonances on the dryer. This prediction is sensitive to the geometrical tolerances in both the plant (the accuracy of the as-built dimension information) and the accuracy of the scale model fabrication.
In order to bound this uncertainty, parametric tests were performed during BFNI scale model testing, as described in Section 6.2.1 of Reference [2]. Based on the results from these characterization tests and from the QC2 benchmark, the BFNI SMT pressure loads in the standpipe resonance frequency range were amplified in order to bound this uncertainty. This load amplification is described in Section 9.2.4.
Browns Ferry is a multi-unit site so a similarity comparison was required in order to determine whether the BFN1 SMT predictions are representative of the other two units. This similarity comparison considered parameters such as reactor operating conditions, dryer and steam dome geometry, MSL geometry, location of branch lines and SR/V standpipes on the MSLs, and SR/V configuration. This comparison showed that the three plants are virtually identical. The following conclusions were reached:
- a. For the (( ))Hz frequency band (up to the SR/V band range), the BFN 2 and 3 acoustic behaviors are expected to be the same as predicted for BFNI using BFNI SMT test data. Therefore, the BFNI predictions are directly applicable to BFN 2 and 3 without the need for further testing or scaling.
- b. BFN2 loads in the S/RV frequency band are bounded by BFN1 loads.
- c. The location of one S/RV for BFN3 was just outside the assessment criteria used in the similarity comparison when compared to the other two units.
Based on the location of this valve, there is the potential that the BFN3 loads in the S/RV frequency band may be up to (( ))higher than the BFNI loads. The onset and amplitude of S/RV resonances is governed by the complex interaction of several phenomena and the (( ))increase was based on a bounding assessment of the potential effect due to the differences in a few basic parameters. It is not clear if, in fact, BFN3 will show any difference at all in the amplitude of these loads. Therefore, the potential (( ))will be treated as an uncertainty in this evaluation. The MSL pressure measurements taken during power ascension monitoring will be evaluated to determine if there are unit-specific differences in the pressure loading on the steam dryer.
42
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION 9.2.4 SMT Load Modification From Sections 9.2.1 through 9.2.3, it is clear that the SMT process contains two types of uncertainties:
- a. Bias error observable from the SMT Benchmark Report [1].
- b. Testing process random error as described in Appendix B of [1]
In order to obtain a load definition that bounds the uncertainties associated with the SMT methodology and that is not overly conservative, it was decided to correct the SMT test amplitudes for the test process uncertainty as follows:
I$*
owirrcted -Telst I,.vr, (1 or
/I .,.,a= "
,'.ITest 1'",,rr ,pc (2)
Where: Peorrde.: Corrected SMT pressures P,,,, "Measurements from the SMT apparatus F,,,, Test process uncertainty (see Section 9.2.2)
F1,.,., ,: Amplitude correction factor obtained from analysis of the SMT benchmark data in the (( ))range (conservative case).
F,,_,. : Amplitude correction factor obtained from analysis of the SMT benchmark data in the (( fl.
Equation (1) is used in the (( ))Hz range whereas Eq. (2) is used for correcting the S/RV resonance SMT predictions.
The amplitude correction factor for the (( ))Hz range, F,,_,, is calculated by reducing the average bias error by two times the standard deviation of the benchmark sample in order to assure 95% coverage of the distribution. According to the data provided in Section 9.2.1 of this document, F,=r would be (( )). This approach assumes that the distribution of the SMT error is normal. However, if the distribution 43
GE-N E-o000-0053-7413-R4-NP NON-PROPRIETARY VERSION of the error is examined, it can be seen that the distribution of SMT overpredictions in the (( ))frequency band exhibits two outliers on the skirt (factors of ((
)) compared to the average (( ))). These one-sided outliers contribute to the large standard deviation. Because the outliers are truly one-sided, it is not appropriate to reduce the average conservatism by two times the standard deviation of this sample. If these points are removed in order to obtain a representative sample, then the new average and standard deviation of the error are((
This results in a bias error correction factor of I[ R].
I]
The above calculation assumes that the variability associated with the benchmark bias error is independent from the random measurement errors. However, it is worth noting that, as discussed in previous sections, since the bias error (a) was calculated using SMT pressure measurements, the variability associated with this bias error is in part caused by the testing process random error (b). Therefore, (a) and (b) are not completely independent, which means that the final correction factor of (( ))
still has significant conservatism in it.
The worst-case bias error from the QC2 Benchmark Report [1] is given by the SV predictions, which were approximately (( ))low on average as indicated in Section 9.2. 1. The standard deviation of these errors was (( ))which is well within the uncertainty associated with the SMT measurement process ((
J]Therefore, in this case we can assume that all the variability in the bias errors sample is due to the random uncertainty associated with the SMT process and only the greater of the two will be considered for calculating the final correction factor for the S/RV frequency range, which gives: (( 11 The summary of the correction factors applied to the SMT data is given below:
- ))Hz frequency band:(( ]
S[))Hz frequency band: (( ))
As discussed in this document, all the bias errors and random uncertainties associated with the BFNI SMT methodology are bounded by the load definition obtained after 44
GE-NE-0000-0053-7413-R4-NP NON-PROPRIETARY VERSION applying the above correction factors. Therefore, all structural analyses performed for BFN I using this load definition will include all SMT uncertainties with 95%
confidence level.
Based on the results of the similarity evaluation summarized in Section 9.2.3. the BFN 2 loads are bounded by BFN I SMT predictions. Therefore, (( ))Hz scaling factor of(( ))is also bounding for BFN2 loads. Since the same limit curves have to apply to Units 1, 2 and 3, the potential non-conservatism of the SMT loads for BFN3 is taken into account by including a (( ))uncertainty term in the end-to-end uncertainty of the load definition process. This bias will generate conservative limit curves for Units I and 2 but will bound the potential non-conservatism associated with the SMT predictions for BFN3. It is worth noting that this 17% uncertainty term needs to be applied to the limit curves in only the ((
))Hlz range.
9.3 QC2 In-Plant Measurement Uncertainties The SMT load modification described in Section 9.2.4 was performed assuming that the QC2 plant measurements used for the SMT benchmark were perfectly accurate.
That is, no uncertainty in the QC2 plant measurements was taken into account for calculating the correction factors that were applied to the SMT pressure predictions.
The QC2 plant measurement uncertainty was calculated to be +/- (( )) as described in Section 4.1.4 of Reference [12]. Since QC2 data was used for determining the scaling factors required for correcting the SMT pressure predictions, the + (( ]luncertainty affects the SMT predictions and, therefore, will be included in the end-to-end uncertainty associated with the BFN limit curves.
9.4 CDI Acoustic Circuit Model The ACM (Reference [I 1]) uses SMT pressure data as input to generate the pressure time histories that are applied to the nodes of the structural FE model. The contribution of the ACM to the overall uncertainty in the BFN analysis consists of the following: the uncertainty from collecting data on the main steam lines at locations other than the locations on Quad Cities Unit 2 (QC2), and the uncertainty in the Bounding Pressure model.
45
GE-NE-O000-53-7413-1R4-NP NON-PROPRIETARY VERSION
- 1. The uncertainty associated with the location of the SMT MSL microphones that were used to acquire the ACM input data is 6.7%
- 2. Quad Cities Unit 2 dryer data at OLTP conditions were used to generate an uncertainty analysis of the Acoustic Circuit Methodology (ACM) [2] for BFNI.
The analysis follows the analysis previously undertaken for a prior application of the ACM. Typically, three to five PSD maximums are present between 148.9 Hz and 156.1 Hz, depending on the pressure sensor examined. Each peak is integrated from trough to trough and combined with the other peaks. The RMS pressure is found by taking the square root of this sum.
The fifteen pressure sensor locations on the outer bank hood (P1 to P12 opposite main steam lines A and D, and P18, P20, and P21 opposite main steam lines C and D) are compared in this analysis. Table 9-1 summarizes the RMS pressures at the specified pressure sensor locations on the Quad Cities Unit 2 dryer.
Table 9-1 Measured and Predicted RMS Pressures (Quad Cities Unit 2 Dryer).
Location Measured Predicted Pivis xPiMs (psid) (psid)
P1 0.1243 0.1232 P2 0.1453 0.1694 P3 0.1444 0.2227 P4 0.0846 0.0638 P5 0.0881 0.0588 P6 0.1170 0.1254 P7 0.1069 0.1093 P8 0.1507 0.1517 P9 0.1567 0.1613 Plo 0.1051 0.1060 Pll 0.1249 0.1134 P12 0.2064 0.1844 P18 0.1715 0.2627 P20 0.1827 0.3627 P21 0.3354 0.3509 The predicted and measured data can be compared to characterize bias as well as a nominal uncertainty.
46
GE-NE-t000-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION The bias is computed by taking the difference between the measured and predicted values at each point and dividing the mean of the differences by the mean of the measured data.
The ACM individual point uncertainty is defined in this analysis as the fraction computed by the expression (Pmeas/Ppred) - 1.0 where Pmeas is the measured pressure and Ppred is the predicted pressure. Negative numbers imply that the predictions are conservative. The standard deviation of the ACM individual point uncertainties can be computed to provide an average ACM uncertainty. This uncertainty can be combined with other random uncertainties, typically by SRSS methods, to determine an overall uncertainty. The overall uncertainty is then combined algebraically with any bias terms that exist to determine a total uncertainty factor to be applied.
With the data found in Table 9-1, the ACM bias and uncertainty standard deviation (in percentage) can be computed, and are shown in Table 9-2. In the end-to-end uncertainty evaluation, no credit will be taken for the 14.3% conservative bias error in the ACM.
Table 9-2 Uncertainty when Comparing PRMIS Values.
ACM Bias (%) -14.3* (conservative)
Standard Deviation of Point 24.5 ACM Uncertainty (%)
- 0% assumed in the end-to-end uncertainty evaluation.
47
GE-N E-()000-0053-7413-R4-NP NON-PROPRIETARY VERSION 9.5 Selection of Analysis Segment Interval Currently, the structural analysis process uses time domain load inputs on the dryer to predict stresses. The structural analysis process utilizes approximately ((
))record lengths. The scale model data acquisition produced time records of 120 seconds to 200 seconds in length (plant scale), so only a short portion of the test record is used as input to the structural analysis process. The process used to select the representative segment is described in Reference [10]. The goal of the process is to select a time segment for the structural analysis that best captures the peak amplitudes of the significant frequency peaks while providing a good representation of the frequency content. The (( )) analysis segments generally slightly overestimate the linear average result from the whole time record but do not necessarily capture the peak hold average from the whole time record completely. For the peak hold average, the chosen segment often captures the amplitude of one or several significant peaks well. However, it is unlikely that the (( ))
analysis segment will capture the peak amplitude for all of the significant frequency peaks. This potential underprediction of the pressure load must be included in the end to end uncertainty.
Microphones M:2, M:3, M:9 and M: 10 on the dryer hoods were used as indicator sensors for selecting the (( ))ACM time segment as described in Reference [10]. Previous SMT work with a large number of sensors has shown that the dryer outer hood sensors are generally representative of the response of the dryer as a whole in terms of selecting a high amplitude segment. Therefore, it is justified to use these four sensors for obtaining a representative uncertainty associated with the selection of the ACM time segment.
Peak hold spectra are always conservative because they keep the highest measured value for every frequency band. In general, the amplitudes of peak hold spectra increase as we increase the duration of the recorded time interval. This is due to the fact that the probability of recording spurious phenomena increases as we increase the duration of the time record. These phenomena may cause high pressure amplitudes that are not necessarily representative of the steady state operation of the system and usually have very short durations. When computing the peak hold spectra, these short-duration, high-amplitude transients contribute to increasing the amplitude of the final overall peak hold spectra.
As discussed above, peak hold power spectra calculated using long time records are generally very conservative and are not representative of the steady-state operation of the system. This is especially true when the system of interest experiences short-48
GE-NE-000)-0053-7413-R4-NP NON-PROPRIETARY VERSION duration, high amplitude peaks due to flow instabilities and other unstable phenomena, which is the case of the SMT system. Therefore, the application of a bias error relative to peak-hold spectra would result in a significant overprediction of the typical loads applied to the dryer over a long period of time. Linear averaging of long time records usually gives a more realistic representation of the steady-state.
continuous operation of a system because it tends to flatten the peaks caused by short-duration, transient phenomena.
Figures 89 and 90 of Reference [10] show a comparison of the linear average of the representative time segment used as ACM input to the linear average of the whole time record. It is apparent that the selected time record is conservative for the entire frequency range of interest. A representative bias term can be calculated by comparing the RMS values of the significant load peaks between ((
)) (SMT scale). Each peak was integrated from trough to trough in order to obtain the RMS pressure associated with each peak. This was done for the whole time record, as well as for the reduced time segment used as ACM input. The ratios for each peak are shown in Table 9-3 below.
Table 9-3 S/RV Peak Ratios for Analysis Increment RMS Values for RMS Values for Whole Time ACM Input [Pa] Ratio Record [Pa]
Sensor M:3 (SMT scale)
Sensor M:10 (SMT scale)
Sensor M:2 (SMT scale)
Sensor M:9 (SMT scale) 49
GE-NE-)000-0053-7413-R4-NP NON-PROPRIETARY VERSION Ih,'erilailmy al.X'ociale( iwili (( ],,mew,Basaedon LinearA verage
'Yw)ecll'r Average Conservative Bias []
Standard Deviation of Sample If we reduce the average bias error by two times the standard deviation of the sample in order to assure 95% coverage of the distribution it is still possible to assure with a 95% confidence level that the selected time segment is conservative with respect to the whole time record. Therefore, no bias penalty due to the selection of the ((
))segment is needed in the end-to-end uncertainty.
The analysis described above was performed using the frequency spectra of the complete and reduced time records without considering the actual time history data.
As discussed in the beginning of this section, tile whole time record may contain some points with higher amplitudes than the reduced segment due to short duration transients and unstable phenomena. It has been shown that the dryer stresses follow the trend of the load time history so the peak amplitude in the selected segment will most likely generate the peak stress in the structural analysis. Therefore, it is advisable to analyze the amplitude distributions of the time histories for both time records in order to assess whether an additional uncertainty term based on time history data is required.
The following steps were taken in order to evaluate this uncertainty term:
- 1. Generate histograms of the amplitude for the selected time segment and for the whole time record.
- 2. Determine the 9 5 tl' percentile values for both distributions.
- 3. Calculate the uncertainty as follows: 95-where J7,7' ,,,fd is the 95"' percentile amplitude value for the whole time record and rcrd a 95th,,a rerurd I)ACAt is the 955111o percentile amplitude value for the reduced time record used as ACM input. The Table 9-4 gives the values obtained from the calculations described above.
50
GE-NE-0000-0053-741I3-R4-NP NON-PROPRIETARY VERSION Table 9-4 Peak Amplitude for Analysis Increment 9 5 th percentile for 95th percentile for DPW.A6o ,
rdC Whole Record ACM Input , - 1 (0-30.68 seconds) (11.41 to 11.66 sec)
Sensor M:3 ((
Sensor M: 10 Sensor M:2 Sensor M:9 ))
Therefore, the uncertainty associated with the selection of the (( )) time I segment used in the ACM is given by:
Uncertainty associated with (( ))Segment Based on 9 5 "hPercentiles Average Conservative Bias Standard Deviation of Sample [Ii1 Once again, we can assure with approximately 95% confidence that the selected time segment is conservative with respect to the entire time record. Therefore, it can be concluded that no additional penalty is required for the uncertainty associated with the selection of the reduced time segment used for the ACM calculations.
9.6 Structural Analysis The finite element structural analysis has a similar set of modeling, application, and measurement uncertainties.
9.7 Modeling Uncertainties Uncertainties in the finite element analysis can come from:
- Mesh size 51
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION
- Time step size
- Component natural frequency The mesh size used in the finite element model is based on a convergence study for the structural mode shapes. The time step size chosen for the analysis is based on accurately describing the pressure load frequencies through the range of interest (through the SRV standpipe acoustic resonance range). Differences between the modeled and actual component natural frequencies are addressed in the structural analysis by modifying the load time step interval to produce a +/-10% shift in the load frequency.
9.8 Application and Measurement Uncertainties Uncertainties can be introduced when applying the finite element methodology to a plant analysis. In general, these uncertainties can be introduced by the following:
- Modeling assumptions (components eliminated or simplified)
- Material characteristics (e.g., elastic modulus, fatigue endurance, weld metal properties)
- Dimensional tolerances (e.g., plate thickness)
- Fabrication (e.g., weld quality, as-built versus as-designed fitup)
- Residual stresses (e.g., weld residual stresses, cold work stresses)
The primary effect of the dimensional uncertainties is on the natural frequency of the dryer components. This uncertainty is addressed in the structural analysis by the +/-
10% frequency shift cases described above. The maximum peak stresses obtained from these cases will be used for defining the final BFN1 limit curves.
Uncertainties introduced by material characteristics and residual stresses arc bounded by using the lower limit of the ASME fatigue curve as the fatigue acceptance criterion which is based on a high mean stress.
52
GE-NE-0000-0053-7413 -R4-NP NON-PROPRIETARY VERSION It has already been mentioned that the structural analysis performed for BFNI may not be bounding for BFN3. However, as discussed in Section 9.2.4, a ((
))uncertainty term will be included in the end-to-end uncertainty in order to account for potential non-conservatism of the BIFNI loads when applied to BFN3.
Therefore, the limit curves that are calculated using BFNI loads will be applicable to all three units, including BFN3.
9.9 Power Ascension Testing Monitoring is performed during power ascension in order to confirm the load definition predictions and, if necessary, to provide input into a corrected load definition for updating the structural analysis. The technique that will be employed at BFN I will be to measure the dynamic pressures in the steamlines and use the steamline pressures to infer the loading on the steam dryer. In the past, plants have installed strain gauges to measure the hoop stress in the pipe; the pressure inside the steamline is then calculated based on the hoop stress. This indirect approach for measuring pressure can introduce uncertainties associated with converting strain to pressure (e.g., variations in pipe thickness) and the potential for introducing signal content from sources other than the steamline pressure (e.g., pipe bending mode vibrations, pump vibration). In order to avoid these issues and achieve a more accurate and reliable pressure measurement, TVA will be installing pressure transducers in the steamlines at BFNI.
The uncertainties associated with power ascension testing measurements are:
- Pressure measurements (sensor accuracy, calibration, and analog to digital conversion)
- Methodology for inferring pressure on dryer based on steamline pressures
- Low frequency resolution (distance between measurement locations on a steamline)
TVA is considering Vibro-Meter CP 103 and CP 211 pressure transducers used in conjunction with charge converter IPC 629 and galvanic separator GSI 130. The uncertainty of the Vibro-Meter transducers using the VC 2 piezoelement is extremely low and limited to the test equipment and mounting-remounting uncertainty. The VC2 transducers are designed to operate up to temperature of more than 700'C (I,300'F); therefore, the deviation due to temperature at reactor operating 53
GE-NE-t000-0053-7413-R4-NP NON-PROPRIETARY VERSION temperatures is very small. For dynamic pressure transducers like the CP 103 and CP 211. the typical global uncertainty is as follow:
- Measurement equipment to calibrate the transducers, uncertainty of 1 %
- CP linearity error, +/- 1%
- Temperature deviation at 600'F, +/- 5%
- Charge converter IPC 629 transfer error, +/- 1%
- Galvanic separation unit transfer error, +/- 1%
The typical error of measurement is the quadratic average of the above and for the overall measuring chain is +/-5.4%.
The uncertainty in the methodology for inferring pressure on dryer based on steamline pressures must also be assessed as part of the power ascension monitoring.
The plant ACM described in Reference [I I] will be used as part of the power ascension monitoring program. As described above in Section 9.4, the ACM has a conservative bias error of 14.3% and a total random uncertainty of 24.7%. In the end-to-end uncertainty evaluation, no credit will be taken for the 14.3% conservative bias error in the ACM. The ACM random uncertainty should be combined by SRSS with the measurement uncertainty given above in order to obtain the overall random uncertainty associated with the power ascension monitoring as discussed in Section 9.10 below.
9.10 Total Uncertainty Associated with BFN Limit Curves Two different sets of limit curves will be used for assessing the structural integrity of the Browns Ferry dryer when operating above OLTP levels. The first set of curves will be based on the SMT load definition and will only be used for licensing. Once the lead unit reaches 100% power, steam line data will be taken and a new ACM load definition developed. This ACM load derived from actual main steam line data will be used in order to perform a new stress analysis for generating the second set of limit curves. Figure 9-1 and Figure 9-2 shows the uncertainties that should be included in each set of limit curves.
Table 9-5 and Table 9-6 summarize the different uncertainties shown in the flow charts in Figures 9-1 and 9-2. An uncertainty value of 0% means that the uncertainty is already included in one of the steps of the limit curve calculation and, therefore, does not need to be accounted for at the end of the process. It should be noted that efforts have been made to ensure that the BFN dryer analysis results are conservative by ensuring that the load definition used in the analysis and the treatment of the structural FEA results are conservative. The degree of conservatism included in each 54
GE-NE-0000-0053-7413-R4-NP NON-PROPRIETARY VERSION of the terms is shown in Tables 9-5 and 9-6. This conservatism is also reflected in the stress results shown in Table 7-2. Because of the conservatism included in the analysis. the additional uncertainty that is required for the power ascension limit curves is relatively small and primarily reflects the uncertainties associated with measuring the MSL pressures in the plant and projecting the loads back onto the dryer.
55
GE-NE-oooot)O-53-741I3.R4-NP NON-PROPRIETARY VERSION Table 9-5 Limit Curve Uncertainties Based on SMT Data SVource of Uncertaint, Bias Termi RandIom Error SMT Methodology QC2 Plant Measurements Potential S/RV Non-conservatism for BFN3 Selection of ((
))Segment ACM Methodology 0y (3)
(load definition inchtdes 14.3% +/--25.6% (4) bias)
Structural FEA BFN Pressure Data from Main Steam Lines Total Uncertainties TOTAL (6)
TOTAL with 50%
increase to be applied to Power Ascension Curve 56
GE-NE-4)0OO-0053-7413-R4-NP NON-PROPRIETARY VERSION (1) This uncertainty is bounded by the amplitude correction factors described in Section 9.2.4. No additional uncertainty is required.
(2) The (( ))time segment selected for the ACM analysis is conservative as shown in Section 9.5. Therefore, no additional penalty is required.
(3) The ACM methodology is conservative as shown in Section 9.4. Therefore, no additional penalty is required.
(4) Includes +/-6.7% error due to location error of main steam line microphones and
(( )) error associated with the pressure sensors used in the QC2 steam dryer.
(5) This uncertainty is addressed by using the peak stresses from the +/-10%
frequency shift cases described in Section 9.8.
(6) The total uncertainty has been calculated by combining the random uncertainty with the bias term algebraically. However, the random errors associated with the ACM methodology were calculated by computing the standard deviations of the sample errors as discussed in Section 9.4. Therefore, the bias error should be reduced by two times the random errors in order to assure 95% coverage of the distribution.
Only one standard deviation has been used for consistency with the process described in Reference [ II ]. It should be noted that reducing the bias error by just one standard deviation as done above results in less than 70% coverage of the distribution.
57
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION Table 9-6 Limit Curve Uncertainties Based on BFN Main Steam Line Data Limit Curve Uncertainties Based on BFN Main Steam Line Data Source of Uncertainty Bias Terin Ranlom Error BFN Pressure Data from
.4-5.4 %
Main Steam L ines ACM Methodology 0%
(load definition includes +/-24.7% (1) 14.3% bias)
Structural FEA BFN Pressure Data from
+/-5.4%
Main Steam Lines Total Uncertainties I TOTAL1')
(1) Does not include +/-6.7% error due to location error of main steam line microphones because this error applies only to the SNIT. (( )) error associated I with the pressure sensors used in the QC2 steam dryer is included in this uncertainty tem.
(2) This uncertainty is addressed by using the peak stresses from the +/- 10%
frequency shift cases described in Section 9.8.
I (3) The total uncertainty has been calculated by combining the random uncertainty with the bias term algebraically. However, the random errors associated with the ACM methodology -were calculated by computing the standard deviations of the sample errors as discussed in Section 9.4. Therefore, the bias error should be reduced by two times the random errors in order to assure 95% coverage of the distribution.
Only one standard deviation has been used for consistency with the process described in Reference [11]. It should be noted that reducing the bias error by just one standard deviation as done above results in less than 70% coverage of the distribution.
58
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION 10 POWER ASCENSION LIMIT CURVES The power ascension limit curves are defined to ensure that the steam dryer stresses will be maintained below the fatigue endurance limit. Since the steam dryer stresses cannot be directly monitored, a plant parameter that can be related to the dryer stresses and readily monitored is chosen as the basis for tile power ascension limit curves. As described in Reference I. the RPV steam dome and Main Steamlines (MSLs) form a coupled system that determines the pressure loading on the dryer.
Therefore, the stresses on the dryer can be inferred by measuring the fluctuating pressure in the MSLs. Because it is practical to install instrumentation on the MSLs for measuring pressure (either pressure transducers or strain gauges), tile MSL fluctuating pressure is a practical parameter upon which to base the power ascension limit curves. Monitoring the MSL pressures also facilitates the development of a dryer load definition based on in-plant measurements and updating of the limit curves if necessary.
The pressure load definition for the BFN steam dryer structural analysis was developed based on Scale Model Testing (SMT) (Reference 2). As described in Reference 3, pressure measurements were taken from the MSLs in the SMT and used as input to the CDI acoustic circuit model to develop the load definition used in the structural analysis (see Section 3.1). The same SMT MSL pressure measurements, converted to the plant scale, are used as the basis for the power ascension limit curves. This ties the power ascension limit curves directly to the structural analysis.
The basic approach for developing the limit curves is similar to the reactor protection system instrument setpoint methodology and is described below:
- 1. The MSL pressure measurements from the SMT that were used to develop the load definition for the structural analysis are used as the starting point for developing the limit curves. Limit curves will be developed for each MSL pressure measurement location used in developing the dryer load definition (2 per MSL, 8 total).
- 2. The dryer structural analyses are performed and the limiting stress is determined. If the limiting stress is below the acceptance criterion, the power ascension limit curves are linearly scaled up until the limiting stress 59
GE-NE-0000-0053-7413-R4-NP NON-PROPRIETARY VERSION is at the acceptance criterion. If the limiting stress is above tile acceptance criterion, the power ascension limit curves are linearly scaled down until the limiting stress is at the acceptance criterion. The scaled curves become the "Analytical Limit" curves. When scaling, the amplitude of the limit curve is scaled while maintaining the same frequency content.
- 3. The "Analytical Limit" Curves are then reduced by the end-to-end analysis and measurement uncertainty determined in Section 9 in order to provide assurance that the dryer stresses will not exceed the fatigue acceptance criterion. These curves are further reduced by increasing the uncertainty an additional 50%. These curves become the "Level 1" maximum operating limit curves. The "Level I" operating limit curves assure that there is sufficient conservatism in the operating limits to maintain the stresses in the dryer components below the fatigue endurance limit. Table 10-1 shows the stress margin and factor of safety against the fatigue endurance limit introduced by the Level I operating limit curves.
- 4. A second set of limit curves, the "Level 2" curves, is established at 80% of the Level I curves. The Level 2 limit curves provide a threshold for initiating engineering evaluations before reaching a power level where the Level I curves are challenged. Table 10-2 shows the additional stress margin and factor of safety against the fatigue endurance limit introduced by the Level 2 operating limit curves.
The structural analysis is a linear analysis; scaling the amplitude of the input loads while maintaining the same frequency content and spatial distribution will result in a linear scaling of the stresses in the dryer. Scaling the input loads so that the stresses in the dryer are at or below the acceptance criteria, then maintaining plant operation such that the measured MSL pressures remain below the pressures assumed in the analysis (after scaling) will assure that the stresses in the dryer components are maintained below the fatigue endurance limit. With the inclusion of the end-to-end uncertainty, the "Level I" operating limit curves assure that there is sufficient conservatism in the operating limits to maintain the stresses in the dryer components below the fatigue endurance limit.
At predefined reactor power level steps during EPU power ascension, the MSL pressure measurements will be monitored and compared against the limit curves. The 60
GE-NE-IO000-0053-7413-R4-NP NON-PROPRIETARY VERSION following actions will be taken when a limit curve is exceeded at any point in the defined spectrum:
When a Level 2 limit curve is reached or exceeded:
- Engineering evaluations are performed to determine if there is sufficient margin to accommodate the increase resulting from the next power level step without exceeding the Level 1 limit curve.
- If there is sufficient margin, tile power level may be raised to the next step.
When a Level I limit curve is reached or if it is determined that there is insufficient margin to accommodate the next power level step Without exceeding the Level I curve:
- Power ascension is stopped.
- MSL pressure measurements are taken.
- An evaluation is performed to determine if it is acceptable for the plant to remain at tile current power level or if the power should be reduced.
- A new load definition is developed based on the in-plant measurements.
- A new dryer structural analysis is performed.
- Revised power ascension limit curves are developed based on tile new structural analysis results If necessary, this process can be repeated until either the full EPU power level is reached or the dryer structural analysis indicates the remaining margin is insufficient to continue power ascension.
The power ascension limit curves for the eight MSL measurement locations are shown in Figure 10-1 through Figure 10-8. The analytical limit curves were calculated by multiplying the analysis input limit curve amplitudes by the ratio of the stress limit to the limiting stress intensity from the structural analysis, The limiting 61
GE-NE-O000-0053-74 I 3-R4-NP NON-PROPRIETARY VERSION stress intensity in Table 7-2 is (( )) psi, which is just below the acceptance criterion of 13,600 psi. The analytical limit curves were calculated by multiplying the analysis input limit curve amplitudes by a factor of 13,600/(( J]
The Level I limit curves are calculated by reducing the analytical limit curve amplitudes by the end-to-end uncertainty. A detailed evaluation of the end-to-end uncertainty is provided in Section 9. That evaluation determined that the end-to-end uncertainty to be applied to the limit curves is (( ))in the ((
))range and for frequencies above (( ))and (( ]in the ((
l]range. The analytical limit curve amplitudes determined above were reduced by these amounts to form the Level I limit curves. The Level 2 limit curves are simply 80% of the Level I curves. Figures 10-9 through 10-16 provide similar limit curves with the above uncertainty values increased by 50% to provide additional margin.
Table 10-1 shows the stress margin and factor of safety against the fatigue endurance limit introduced by the Level I operating limit curves. The Level I operating limit curves impose an upper level stress limit of (( )) frequency range and for the frequency range above (( fland an upper level stress limit of (( ))range. The Level I operating limit curves provide a factor of safety of (( ))against the fatigue limit in the (( ))range and for frequencies above (( ))range. The Level 2 limit curves provide additional margin beyond that provided by the Level 1 operating limit curves. Table 10-2 shows that the Level 2 limit curves impose an upper level stress limit of (( f]frequency range and for the frequency range above (( ))and an upper level stress limit of ((
))range. The Level 2 operating limit curves provide a factor of safety of 2.1 against the fatigue limit in the (( ))range and for frequencies above ((
)) range.
62
GE-NE-(O(X1-0053-7413-R4-NP NON-PROPRIETARY VERSION Table 10-1 Level I Limit Curve Stress Margins Usable Upper Margin to Factor of Frequency Calculated Adjusted Increase Total Stress Fatigue Safety Range Uncertainty in Uncertainty"' Uncertainty Limit Limit"' Against (Hz) (%) (%) (%) (ksi) (%) Fatigue Limit (1) 50% of Calculated Uncertainty (2) Fatigue Limit =13.6 ksi Table 10-2 Level 2 Limit Curve Stress Margins Usable Adjusted Upper Margin to Factor of Frequency Calculated Increase in Total Stress Fatigue Safety Range Uncertainty Uncertainty"t' Uncertainity Limit`:' Limit"' Against (Hz) (%) (%) (%) (ksi) (%) Fatigue Limit (1) 50% of Calculated Uncertainty (2) 80% of Level I Limit (3) Fatigue Limit =13.6 ksi The power ascension limit curves will be initially applied when the plant enters the EPU power operating range above 3293 MWt (OLTP for BFN Unit 1) and 3458 MWt (CLTP for BFN Units 2 and 3). BFN has accumulated substantial operating experience, beginning in 1998, at these power levels with no significant dryer structural issues. BNF Unit I has approximately six years of full power operation at OLTP. A comparison of the plant, dryer, MSL and SRV configuration for the three units was performed to determine if there were any differences that would affect the dryer loading on each of the units. That comparison shows that the three units are 63
GE-NE-)OO()4)053-74 ! 3-R4-NP NON-PROPRIETARY VERSION virtually identical and that the stretch power uprate operating experience at Units 2 and 3 would be directly applicable to Unit i.
Even though the limit curves are reduced from the analysis input curves, it is expected that there will be sutficient margin in the curves to support EPU power ascension. As described in Reference 2, there is a significant amount of conservatism in the SMT load definition, which contributes substantially to the high predicted stress intensity values presented in Table 7-2. This conservatism is included in the analysis input curves. The load definition conservatism includes a scaling factor of
[ J))that was applied to provide a bounding load definition in the ((
))Hz SRV resonance range. The structural analysis results in Section 7 show that the majority of the stresses result from the SRV resonance load content. The ((
))scaling factor includes a worst case average bias error of 4 based on the Quad Cities 2 SMT benchmark (Reference 1). The (( ))SRV resonance amplitude observed in Quad Cities 2 was significantly higher than the SRV resonances observed in other plants with instrumented dryers, in part due to the high MSL flow velocities at EPU in Quad Cities. The EPU MSL flow velocities at BFN are comparable with those at the other plants with instrumented dryers and the SRV resonance amplitude at BFN is expected to be much lower than that at Quad Cities. Therefore, it is expected that there will be sufficient margin in the limit curves to support power ascension.
64
GE-NE-(O(0-0053-7413-R4-NP NON-PROPRIETARY VERSION 11 CONCLUSIONS The stress analysis results for OLTP demonstrate that the BFN dryer stresses are generally below the endurance level screening criteria. When conservative stress amplification factors are applied to address local stress intensification, a few dryer components arc predicted to be at or near the endurance level.
The Unit 1, 2, and 3 dryers have operated at OLTP for a period of eleven (11) to fifteen (15) years. Additionally the Unit 2 and 3 reactors have operated at 105%
OLTP for over six (6) years. Dryer inspections conducted throughout these operating periods have identified no unusual damage due to flow-induced vibration. Inspection has revealed some dryer tie-bar damage and drain channel cracking. Necessary modifications have been implemented to address these issues. The overall BFN dryer experience is representative of the fleet experience for BWR/4 slant hood dryers operating at stretch and EPU power levels.
Consequently, the analytical predictions of the original dryer stresses exceeding the acceptance criteria for several dryer components are indicative of the conservatism that has been utilized in the BFN load definition. This conservative approach has been carried forward into the analysis for the stress predictions for EPU operating conditions. The fact that no damage has been observed in dryer components predicted to have stresses exceeding the fatigue stress limit is an indication of conservatism in the BFN SMT-based load definition. This conservatism has been carried forward into the analysis for the stress predictions for EPU operating conditions. The analyses for the modified dryer demonstrate that the stresses on the steam dryer components will be within the fatigue endurance limits under EPU conditions, even considering the conservatism in the SMT-based load definition. In addition, the conservatism incorporated in the power ascension limit curves provides further assurance that the uncertainties in the analysis and plant monitoring are bounded and that the stresses in the modified BFN steam dryers will remain well within the acceptance criteria. Therefore, the modified BFN steam dryers are acceptable for EPU operation.
65
GE-NE-4000-0053-7413-R4-NP NON-PROPRIETARY VERSION 12 REFERENCES III GENE-0000-0045-9086-01. "General Elcctric Boiling Water Reactor Stcam Drycr Scale Model Test Based Fluctuating Load Definition Methodology - March 2006 Benchmark Report." March 2006.
121 GENE-0000-0052-3661-01. "Test Report # I Browns Fcrry Nuclear Plant. Unit I Scale Model Test."
April 2006.
131 C.D.I. Report No. 06-1 IP. "Hydrodynamic Loads on Browns Ferry Unit I Stean Drycr to 200 Hz."
Revision 2. July 2006.
141 ANSYS Release 8.1 and 9.0. ANSYS Incorporated. 2004.
151 Purchase Specification. "Standard Requirements for Steam Dryers" 21A3316 Rev.
161 American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section Ii.
1989 Edition with no Addenda.
171 American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section III, Appendix 1, 1989 Edition with no Addenda 181 "'Recommended Weld Quality and Stress Concentration Factors for use in the Strnctural Analysis of the Exclon Replacement Steam Drycr". GENE 0000-0034-6079. February 2005.
191 Sommerville. D.. "General Electric Boiling Water Reactor Steam Dryer Scale Model Test Based Fluctuating Load Definition Methodology - March 2006 Benchmark Report". GENE-0000-0045-9086-01. March 2006. GENE. San Jose. CA. GE Proprietary Information.
1101 Nciheiscel, M., "Test Report #1, Browns Ferry Nuclear Plant, Unit 1. Scale Model Test". GENE-0000-0052-3661-01. April 2006. GENE. San Jose, CA. GE Proprietary Infornation.
II1I Bilanin, A. "Hydrodynamic Loads on Browns Fern' Unit I Steam Dryer to 200 Hz". CDI Report No.
06-11 P. Revision 2. July 2006. Continuum Dynamics, Inc. Ewing, NJ.
1121 Dayal, Y. "Quad Cities Unit 2 Nuclear Power Plant Dryer Vibration Instrumentation Uncertainty".
GENE-0000-0037-1951-01. Rev. 0. April 2005. GENE. San Jose, CA.
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GE-NE4-(IOO-0053-7413-R4-NP NON-PROPRIETARY VERSION
((
11 Figure 6-1 Raleigh Damping Curve Used in Time History Analysis 67
GE-NE-(0OO-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION 1]
Figure 6-2 Original BFN Steam Dryer Finite Element Model with Boundary Conditions 68
GE-NE-0(0)l()-(053-7413-R4-NP NON-PROPRIETARY VERSION 1]
Figure 6-3 Original BFN Steam Dryer Finite Element Model 69
GE-NE-0O(X)-(K)53-74113-R4-NP NON-PROPRIETARY VERSION 1]
Figure 6-4 Original BFN Steam Dryer Finite Element Model 70
GE-NE-O000-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION Figure 6-5 Original BFN Steam Dryer Finite Element Model 71
GE-NE-O000-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION JI Figure 6-6 EPU Applied Pressure Load to Original BFN Dryer 72
GE-NE-t)0000-053-74 i 3-R4-NP NON-PROPRIETARY VERSION
((
Figure 6-7 Frequency Content of Applied Load at EPU (Outer Hoods) 73
GE-NE-(0004)053-7413-R4-NP NON-PROPRIETARY VERSION 11 Figure 6-8 Original Dryer Modal Analysis Results: Skirt Frequencies (( 11 I 74
GE-NE-000)-0053-7413-R4-NP NON-PROPRIETARY VERSION 1]
Figure 6-9 Original Dryer Modal Analysis Results:Skirt Frequencies (( 11 1 75
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION Figure 6-10 Original Dryer Modal Analysis Results: Outer Hoods 76
GE-NE-0000-0053-74 I 3-R4-NP NON-PROPRIETARY VERSION It JI Figure 6-11 Original Dryer Modal Analysis Results: Inner Hoods 77
GE-NE-000(0-R053-7413-R4-NP NON-PROPRIETARY VERSION Figure 6-12 Original Dryer Stress Time Histories for Several Dryer Components at EPU 78
GE-NE-4000-0053-7413-R4-NP NON-PROPRIETARY VERSION Figure 6-13 Original Dryer Outer Hood Pressure VS Stress for EPU Nominal Case 79
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION Figure 6-14 Original Dryer Outer Hood FFT's for Nominal and +1-10% Cases at EPU 80
GE-NE-W00-0053-74 I 3-R4-NP NON-PROPRIETARY VERSION
((
Figure 6-15 Original Dryer Inner Hood FFT's for Nominal and +/-10% Cases at EPU "81
GE-NE-I(XO(-0053.7413-R4-NP NON-PROPRIETARY VERSION
((
Figure 6-16 Original Dryer Cover Plate FFT's for Nominal and +1-10% Cases at EPU 82
GE-NE-0000-0053-7413-R4-NP NON-PROPRIETARY VERSION 1]
Figure 6-17 Original Dryer Trough FFT's for Nominal and +1-10% Cases at EPU 83
GE-NE-O0()O-0053-7413 -R4-NP NON-PROPRIETARY VERSION
((
11 Figure 6-18 Original Dryer Skirt FFT's for Nominal and +1-10% Cases at EPU 84
GE-NE-0000-0053-7413-R4-NP NON-PROPRIETARY VERSION
))
Figure 6-19 Original Dryer Stress Intensity at EPU: Cover Plate 85
GE-NE-0)00-0.J053-7413-R4-NP NON-PROPRIETARY VERSION Figure 6-20 Original Dryer Stress Intensity at EPU: Manway Cover 86
GE-NE.4)l00-053-7413-R4-NP NON-PROPRIETARY VERSION
[I
))
Figure 6-21 Original Dryer Stress Intensity at EPU: Outer Hood 87
GE-NE-0000-()053-7413-R4-NP NON-PROPRIETARY VERSION 11 Figure 6-22 Original Dryer Stress Intensity at EPU: Exterior Hood Plates - Outer Banks 88
GE-NE-O000-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION JI Figure 6-23 Original Dryer Stress Intensity at EPU: Exterior Vane Bank End Plates -
Outer Banks 89
GE-NE-O000-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION Figure 6-24 Original Dryer Stress Intensity at EPU: Hood Top Plates 90
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION
))
Figure 6-25 Original Dryer Stress Intensity at EPU: Vane Bank Top Plates 91
GE-NE-(000(-O053-7413-R4-NP NON-PROPRIETARY VERSION
((
11 Figure 6-26 Original Dryer Stress Intensity at EPU: Outer Hood Stiffeners 92
GE-NE-)0(X)-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION Figure 6-27 Original Dryer Stress Intensity at EPU: Vane Bank Inner End Plates (2) 93
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION 1]
Figure 6-28 Original Dryer Stress Intensity at EPU: Outer Bank Closure Plates 94
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION JI Figure 6-29 Original Dryer Stress Intensity at EPU: Inner Hoods 95
GE-NE-:4)000-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION Ii 1]
Figure 6-30 Original Dryer Stress Intensity at EPU: Inner Bank Exterior Hood Plates 96
GE-NE-4000-0053-7413-R4-NP NON-PROPRIETARY VERSION Figure 6-31 Original Dryer Stress Intensity at EPU: Vane Bank End Plates 97
GE-NE-O000-O053-74 !3-R4-NP NON-PROPRIETARY VERSION Figure 6-32 Original Dryer Stress Intensity at EPU: Inner Hood Stiffeners (1) 98
GE-NE-O000-0053-74 I 3-R4-NP NON-PROPRIETARY VERSION JI Figure 6-33 Original Dryer Stress Intensity at EPU: Inner Hood Stiffeners (2) 99
GE-NE-O000-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION Figure 6-34 Original Dryer Stress Intensity at EPU: Vane Bank Inner End Plates (1) 100
GE-NE)f0oo-O053-7413-R4-NP NON-PROPRIETARY VERSION JI Figure 6-35 Original Dryer Stress Intensity at EPU: Vane Bank Inner End Plates (3) 101
GE-NE-(OOO-0053-7413-R4-NP NON-PROPRIETARY VERSION 1]
Figure 6-36 Original Dryer Stress Intensity at EPU: Inner Bank Closure Plates 102
GE-NE-O000-0053-74 i 3-R4-NP NON-PROPRIETARY VERSION Figure 6-37 Original Dryer Stress Intensity at EPU: Steam Dams 103
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION JI Figure 6-38 Original Dryer Stress Intensity at EPU: Steam Dam Gussets 104
GE-NE-(000-0053-7413-R4-NP NON-PROPRIETARY VERSION
((
1)
Figure 6-39 Original Dryer Stress Intensity at EPU: Baffle Plate 105
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION 11 Figure 6-40 Original Dryer Stress Intensity at EPU: Trough 106
GE-NE-O0(XJ-O053-7413-R4-NP NON-PROPRIETARY VERSION 1]
Figure 6-41 Original Dryer Stress Intensity at EPU: Base Plate 107
GE-NE-OO(X)-0053-74 i 3-R4-NP NON-PROPRIETARY VERSION
((
11 Figure 6-42 Original Dryer Stress Intensity at EPU: Support Ring I08
GE-NE-O00(-(0053-7413-R4-NP NON-PROPRIETARY VERSION
]1 Figure 6-43 Original Dryer Stress Intensity at EPU: Skirt 109
GE-NE-(00o-o053-7413 -R4-NP NON-PROPRIETARY VERSION
[1 Figure 6-44 Original Dryer Stress Intensity at EPU: Drain Pipes 110
GE-NE-O000-O053-7413-R4-NP NON-PROPRIETARY VERSION Figure 6-45 Original Dryer Stress Intensity at EPU: Skirt Bottom Ring I11
GE-NE-0000-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION Figure 6-46 Weld Factors Used in Steam Dryer Fatigue Analysis 112
GE-NE-OOOO-0053-7413-R4-NP NON-PROPRIETARY VERSION
[i Figure 7'-1 Proposed BFN Steam Dryer Modifications: (Outer Hood and Cover Plate) 113
GE-NE-(00)0-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION Figure 7-2 Proposed BFN Steam Dryer Modifications: (Outer Hood and Cover Plate) 114
GE-NE-O000-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION Figure 7-3 Proposed BFN Steam Dryer Modifications: (Outer Hood and Cover Plate) 115
GE-NE-(O0(O-0053-7413-R4-NP NON-PROPRIETARY VERSION Figure 7-4 Proposed BFN Steam Dryer Modifications: (Outer Hood and Cover Plate) 116
GE-NE-(OO0-0053-7413-3R4-NP NON-PROPRIETARY VERSION 1]
Figure 7-5 Modified Dryer Stress Time Histories for Several Dryer Components at EPU 117
GE-NE-4000-0053-74113-R4-NP NON-PROPRIETARY VERSION I[
1]
Figure 7-6 Modified Dryer Outer Hood Pressure VS Stress for EPU Nominal Case 118
GE-NE-0((0(-0053-7413-R4-NP NON-PROPRIETARY VERSION It Figure 7-7 Modified Dryer Outer Hood FFT's for Nominal and +1-10% Cases at EPU 119
GE-NE-(000-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION
((
11 Figure 7-8 Modified Dryer Inner Hood FFT's for Nominal and +1-10% Cases at EPU 120
GE-NE-O(OOOi-(X)53-74113-R4-NP NON-PROPRIETARY VERSION Figure 7-9 Modified Dryer Cover Plate FFT's for Nominal and +/-10% Cases at EPU 121
GE-NE-O000-O053-7413-R4-NP NON-PROPRIETARY VERSION 11 Figure 7-10 Modified Dryer Trough FFT's for Nominal and +1-10% Cases at EPU 122
GE-NE-0000-O053-7413-R4-NP NON-PROPRIETARY VERSION 1]
Figure 7-11 Modified Dryer Skirt FFT's for Nominal and +1-10% Cases at EPU 123
GE-NE-O000-0053-74 I3-R4-NP NON-PROPRIETARY VERSION Figure 7-12 Modified Dryer Stress Intensity at EPU: Cover Plate 124
GE-NE-4000-0053-7413-R4-NP NON-PROPRIETARY VERSION
))
Figure 7-13 Modified Dryer Stress Intensity at EPU: Outer Hood 125
GE-NE-(K0i 53-74 ! 3-R4-NP NON-PROPRIETARY VERSION Figure 7-14 Modified Dryer Stress Intensity at EPU: Exterior Hood Plates - Outer Banks 126
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION Figure 7-15 Modified Dryer Stress Intensity at EPU: Exterior Vane Bank End Plates -
Outer Banks 127
GE-NE-O)((l-0053-7413-R4-NP NON-PROPRIETARY VERSION I((
Figure 7-16 Modified Dryer Stress Intensity at EPU: Exterior Vane Bank End Plates -
Outer Banks 128
GE-NE-(OOO-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION
))
Figure 7-17 Modified Dryer Stress Intensity at EPU: Hood Top Plates 129
GE-NE-0000-0033-7413-R4-NP NON-PROPRIETARY VERSION
((
11 Figure 7-18 Modified Dryer Stress Intensity at EPU: Vane Bank Top Plates 130
GE-NE-OO0O-0053-7413-R4-NP NON-PROPRIETARY VERSION Figure 7-19 Modified Dryer Stress Intensity at EPU: Vane Bank Inner End Plates (2) 131
GE-NE-X00J-0053-74 I 3-R4-NP NON-PROPRIETARY VERSION 11 Figure 7-20 Modified Dryer Stress Intensity at EPU: Closure Plates - Outer Banks 132
GE-NE-O000O-0053-7413-R4-NP NON-PROPRIETARY VERSION 11 Figure 7-21 Modified Dryer Stress Intensity at EPU: Inner Hoods 133
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION
((
Figure 7-22 Modified Dryer Stress Intensity at EPU: Outer Hood: close-up 134
GE-N E-4000(-0053-7413-R4-NP NON-PROPRIETARY VERSION
))
Figure 7-23 Modified Dryer Stress Intensity at EPU: Inner Hood: close-up 135
GE-NE-00O-0053-7413-R4-NP NON-PROPRIETARY VERSION
((
Figure 7-24 Modified Dryer Stress Intensity at EPU: Inner Bank Exterior Hood Plates 136
GE-NE-000(-0053-7413-R4-NP NON-PROPRIETARY VERSION Figure 7-25 Modified Dryer Stress Intensity at EPU: Vane Bank End Plates 137
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION 11 Figure 7-26 Modified Dryer Stress Intensity at EPU: Inner Hood Stiffeners (1) 138
GE-NE-000()-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION Fn Figure 7-27 Modified Dryer Stress Intensity at EPU: Inner Hood Stiffeners (2) 139
GE-NE-(X)(fl-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION
))
Figure 7-28 Modified Dryer Stress Intensity at EPU: Vane Bank Inner End Plates (1) 140
GE-NE-O0004)053-74 i 3-R4-NP NON-PROPRIETARY VERSION
((
Figure 7-29 Modified Dryer Stress Intensity at EPU: Vane Bank Inner End Plates (3) 141
GE-NE-O000-)053-74 ! 3-R4-NP NON-PROPRIETARY VERSION 1]
Figure 7-30 Modified Dryer Stress Intensity at EPU: Inner Bank Closure Plates 142
GE-NE-00(X)-0053-7413-R4-NP NON-PROPRIETARY VERSION 1]
Figure 7-31 Modified Dryer Stress Intensity at EPU: Steam Dams 143
GE-NE-OOO*-(0053-74 !3-R4-NP NON-PROPRIETARY VERSION
((
))
Figure 7-32 Modified Stress Intensity at EPU: Steam Dam Gussets 144
GE-N E-0000-0053-7413-R4-NP NON-PROPRIETARY VERSION
))
Figure 7-33 Modified Dryer Stress Intensity at EPU: Baffle Plate 145
GE-NEI.00(0-0053-7413-R4-NP NON-PROPRIETARY VERSION Figure 7-34 Modified Dryer Stress Intensity at EPU: Trough 146
GE-NE-00004-053-74 ! 3.R4-NP NON-PROPRIETARY VERSION Figure 7-35 Modified Dryer Stress Intensity at EPU: Trough Detail 147
GE-NE-0(000-0(53-7413-R4-NP NON-PROPRIETARY VERSION Figure 7-36 Modified Dryer Stress Intensity at EPU: Base Plate 148
GE-NE-O000-0053-741 3-R4-NP NON-PROPRIETARY VERSION
((
1]
Figure 7-37 Modified Dryer Stress Intensity at EPU: Support Ring 149
GE-NE-4X0(0-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION
))
Figure 7-38 Modified Dryer Stress Intensity at EPU: Skirt 150
GE-NE4X)00-0X)53-7413-R4-NP NON-PROPRIETARY VERSION
))
Figure 7-39 Modified Dryer Stress Intensity at EPU: Drain Pipes 151
GE-NE-OO(X)-0053-7413-R4-NP NON-PROPRIETARY VERSION
))
Figure 7-40 Modified Dryer Stress Intensity at EPU: Skirt Bottom Ring 152
GE-NE-O000-0053-7413-R4-NP NON-PROPRIETARY VERSION I1 Figure 9-1 Uncertainty in Limit Curves when Developed Based on SMT Data 153
GE-NE-(O(X)-0053-7413-R4-NP NON-PROPRIETARY VERSION 1]
Figure 9-2 Uncertainty in Limit Curves when Developed Based on BFN MSL Pressure Measurements.
154
GE-NE-0000-0053-7413-R4-NP NON-PROPRIETARY VERSION
((
1]
Figure10-1 Power Ascension Limit Curve MSL A Upper 155
GE-NE-t)000-0053-7413-R4-NP NON-PROPRIETARY VERSION
[1 1]
Figure 10-2 Power Ascension Limit Curve MSL A Lower 156
GE-NE-O0(X)-O053-7413.R4-NP NON-PROPRIETARY VERSION
((I Figure 10-3 Power Ascension Limit Curve MSL B Upper 157
GE-NE-O00)-0053-7413-R4-NP NON-PROPRIETARY VERSION 1]
Figure 10-4 Power Ascension Limit Curve MSL B Lower 158
GE-NE-400*X-0(053-7413-R4-NP NON-PROPRIETARY VERSION 1]
Figure 10-5 Power Ascension Limit Curve MSL C Upper 159
GE-NE-t)OO0-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION 1]
Figure 10-6 Power Ascension Limit Curve MSL C Lower 160
GE-NE-00004)053-74 ! 3-R4-NP NON-PROPRIETARY VERSION
[I Figure 10-7 Power Ascension Limit Curve MSL D Upper 161
GE-NE-O00(-0053-7413-R4-NP NON-PROPRIETARY VERSION 11 Figure 10-8 Power Ascension Limit Curve MSL D Lower 162
GE-NE-O(OI(-0053-7413-R4-NP NON-PROPRIETARY VERSION Figure 10-9 Power Ascension Limit Curve MSL A Upper 163
GE-NE-0000-0053-74 ! 3-R4-NP NON-PROPRIETARY VERSION Figure 10-10 Power Ascension Limit Curve MSL A Lower 164
GE-NE4)0(X)-(X)53-7413-R4-NP NON-PROPRIETARY VERSION Figure 10-11 Power Ascension Limit Curve MSL B Upper 165
GE-NE-000(-0053-74 I 3-R4-NP NON-PROPRIETARY VERSION 1]
Figure 10-12 Power Ascension Limit Curve MSL B Lower 166
GE-NE-000(-0053-74 i 3-R4-NP NON-PROPRIETARY VERSION 1]
Figure 10-13 Power Ascension Limit Curve MSL C Upper 167
GE-NE-400(X0-)53-7413-R4-NP NON-PROPRIETARY VERSION
((
Figure 10-14 Power Ascension Limit Curve MSL C Lower 168
GE-NE-O000-0053-74 I 3-R4-NP NON-PROPRIETARY VERSION
[I 11 Figure 10-15 Power Ascension Limit Curve MSL D Upper 169 j
GE-NE-OO(XJ-0053-74 13-R4-NP NON-PROPRIETARY VERSION
((
Figure 10-16 Power Ascension Limit Curve MSL D Lower 170