ML12286A022
| ML12286A022 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 09/30/2012 |
| From: | Westinghouse |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| WCAP-17649-NP, Rev 0 | |
| Download: ML12286A022 (105) | |
Text
Westinghouse Non-Proprietary Class 3 WCAP-17649-NP Septemb Revision 0 Peach Bottom Units 2 and 3 ASME Code Stress Report (Enclosure B.3)
WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17649-NP Revision 0 Peach Bottom Units 2 and 3 ASME Code Stress Report Hari Srivastava*
U.S. BWR Component Engineering September 2012 Reviewer:
Project Manager:
Approved:
Roger Brandstr~m dg-*Z Principal Engineer, Iant and Stress Analysis, SES Robert Mercer*
Project Manager, U.S. BWR Component Engineering George Tasick*, Manager U.S. BWR Component Engineering This document is the property of and contains Proprietary Information owned by Westinghouse Electric Company LLC and/or its subcontractors and suppliers. It is transmitted to you in confidence and trust, and you agree to treat this document in strict accordance with the terms and conditions of the agreement under which it was provided to you.
- Electronically approved records are authenticated in the electronic document management system.
Westinghouse Electric Company LLC 1000 Westinghouse Drive Cranberry Township, PA 16066, USA
© 2012 Westinghouse Electric Company LLC All Rights Reserved WCAP-17649-NP.docx-092612
TABLE OF CONTENTS LIST OF TA BLES........................................................................................................................................
iii LIST OF FIGU RES.....................................................................................................................................
iv EX ECU TIV E SU M M A RY...........................................................................................................................
v 1
IN TRO D U CTION........................................................................................................................
i-1 2
SU M M A RY AN D CON CLU SION S............................................................................................
2-1 2.1 AN A LY SIS......................................................................................................................
2-1 2.2 DESIGN M A RG IN S........................................................................................................
2-1 2.3 IN TERFA CE LO A D S....................................................................................................
2-1 3
AN A LY SIS IN PU T......................................................................................................................
3-1 3.1 LO A D S............................................................................................................................
3-1 3.1.1 G ravity.............................................................................................................
3-1 3.1.2 Pressure Loads.................................................................................................
3-1 3.1.3 Seism ic Loads..................................................................................................
3-2 3.2 LOAD COMBINATIONS............................................
3-2 3.3 ACCEPTANCE CRITERIA.........................................
3-4 3.4 M ATERIA L PROPERTIES.............................................................................................
3-5 4
AN A LY SIS AN D RESU LTS.....................................................................................................
4-1 4.1 AN A LY SIS M ATRIX.........
............................................. 4-1 4.2 AN A LY SIS 4-1 4.2.1 A nalysis M odel...............................................................................................
4-1 4.2.2 Boundary Conditions.............................................
.................................... 4-2 4.2.3 Load Application.........................................
4-2 4.2.4 Load Com bination A pproach...........................................................................
4-2 4.2.5 Com ponent Stresses.............
....................................... 4-3 4.2.6 W eld Stresses.................................................................................
......... 4-23 4.2.7 Interface Loads.............................................................................................
4-23 5
D ESIGN M A RG IN S...................................................................................................................
5-1 5.1.1 Stress Lim its.................................................................................................
5-1 5.1.2 Fatigue U sage........................................................................................
..... 5-1 6
REFEREN CES.............................................................................................................................
6-1 WCAP-17649-NP September 2012 Revision 0
LIST OF TABLES Table 2-1 Minimum Design Margins - Components (Service Level A)..................................................
2-4 Table 2-2 Minimum Design Margins - Welds (Service Level A).............................................................
2-6 Table 2-3 Minimum Design Margins - Components (Service Level B)................................................
2-10 Table 2-4 Minimum Design Margins - Welds (Service Level B)...........................................................
2-12 Table 2-5 Minimum Design Margins - Components (Service Level C)................................................
2-16 Table 2-6 Minimum Design Margins-Welds (Service Level C)...........................................................
2-18 Table 2-7 Minimum Design Margins - Components (Service Level D)................................................
2-22 Table 2-8 Minimum Design Margins - Welds (Service Level D)...........................................................
2-24 Table 2-9 R eaction L oads.......................................................................................................................
2-27 Table 3-1 Dryer Pressure Loads (Reference 4, Section 2 (46))................................................................
3-1 Table 3-2 TSV Loads on the Outer Hood (Reference 4)...........................................................................
3-2 Table 3-3 L oad C om binations...................................................................................................................
3-3 T ab le 3-4 Stress L im its.............................................................................................................................
3-4 Table 3-5 M aterial Properties (R eference 6).............................................................................................
3-5 Table 4-1 A nalysis M atrix.........................................................................................................................
4-1 Table 4-2 PB2 Dryer with Mast, Load Cases 2-14, Maximum Component Stresses............................... 4-7 Table 4-3 PB2 Dryer with Mast, Load Combinations, Component Maximum Stresses......................... 4-10 Table 4-4 PB2 Dryer Without Mast, Load Cases 2-14, Maximum Component Stresses........................ 4-12 Table 4-5 PB2 Dryer Without Mast, Load Combinations, Maximum Component Stresses................... 4-15 Table 4-6 PB3 Dryer, Load Cases 2-14, Maximum Component Stresses...............................................
4-17 Table 4-7 PB3 Dryer, Load Combinations, Maximum Component Stresses..........................................
4-20 Table 4-8 All Dryers, Service Levels, Maximum Component Stresses..................................................
4-22 Table 4-9 PB2 Dryer with Mast, Load Cases 2-14, Maximum Weld Stresses.................
4-24 Table 4-10 PB2 Dryer with Mast, Load Combinations, Maximum Weld Stresses.................................
4-30 Table 4-11 PB2 Dryer Without mast, Load Cases 2-14, Maximum Weld Stresses..................................
4-34 Table 4-12 PB2 Dryer Without Mast, Load Combinations, Maximum Weld Stresses........................... 4-40 Table 4-13 PB3 Dryer, Load Cases 2-14, Maximum Weld Stresses........................................................
4-44 Table 4-14 PB3 Dryer, Load Combinations, Maximum Weld Stresses..................................................
4-50 Table 4-15 All Dryers, Service Levels, Maximum Weld Stresses..........................................................
4-54 WCAP-17649-NP September 2012 Revision 0
iv LIST OF FIGURES Figure 2-1 PB2 Dryer with Instrumentation Mast: Analysis Model - Outline..........................................
2-2 Figure 2-2 PB2 Dryer with Instrumentation Mast: Analysis Model - Finite Element Mesh.................... 2-3 Figure 3-1 Seism ic R esponse Spectra.......................................................................................................
3-6 Figure 4-1 Boundary Conditions for Analyses with No Dryer Lift-Off.................................................
4-56 Figure 4-2 Boundary Conditions for Dryer Lift-Off Analysis...............................................................
4-57 Figure 4-3 Differential Pressure Loads - DPN, DPu, DPE, MSLBDp1 and MSLBDP2............................... 4-58 Figure 4-4 TSV Loads - TSV A, TSV F.....................................................................................................
4-59 Figure 4-5 H ood Stresses, D ead W eight.................................................................................................
4-60 Figure 4-6 Hood Stresses after Removing Comer Nodes, Dead Weight................................................
4-61 Figure 4-7 Hood Stresses, M SLBDP2 Pressure Load...............................................................................
4-62 Figure 4-8 Middle Hood Stresses, MSLBDP2 Pressure Load..................................................................
4-63 WCAP-17649-NP September 2012 Revision 0
V EXECUTIVE
SUMMARY
Exelon is planning extended power uprate (EPU) at Peach Bottom Atomic Power Station (PBAPS) Units 2 and 3 and plans to replace the existing stream dryers with replacement dryers at both units. Evaluation is performed to show compliance of the replacement dryers with the structural requirements of ASME B&PV Code,Section III, Division 1, SubsectionNG. The evaluation shows that the dryers meet the stress and fatigue usage limits of the ASME Code for the EPU duty cycles covering normal operation (Service Level A), upset conditions (Service Level B), emergency conditions (Service Level C), and faulted conditions (Service Level D).
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1 INTRODUCTION In 2002, after increasing power to 117 percent of the original licensed thermal power, a steam dryer in a boiling water reactor (BWR) had a series of structural failures. After extensive evaluation by various industry experts, root cause of the failures was determined to be fluctuating acoustic pressure loads on the steam dryer resulting from resonances produced by steam flow in the main steam lines (MSLs) across safety valve and relief valve inlets. The failures in the steam dryer led to changes in Regulatory Guide 1.20 (Reference 1) requiring plants to evaluate their steam dryers before any planned increase in power level.
Exelon is planning extended power uprate (EPU) at Peach Bottom Atomic Power Station (PBAPS) Units 2 (PB2) and 3 (PB3) and plans to replace the existing stream dryers with replacement dryers at both units.
The process used to qualify the replacement dryers for EPU operation involves scale model testing and multiple acoustic and structural analyses. High cycle fatigue calculations are performed using special purpose computer codes to calculate the acoustic loads together with finite element structural analyses using commercially available computer codes. The finite element models used for the acoustic analyses are also used in analyses to qualify the dryers for the ASME Code requirements.
The purpose of this report is to document analyses performed to show compliance of the replacement dryers with the structural requirements of ASME B&PV Code, Section Il, Division 1, Subsection NG (Reference 2). Evaluations are performed for the PB2 replacement dryer with and without instrumentation mast assembly and for the PB3 replacement dryer. The evaluations show that the dryers meet the stress and fatigue usage limits of the ASME Code for the EPU duty cycles covering normal operation (Service Level A), upset conditions (Service Level B), emergency conditions (Service Level C), and faulted conditions (Service Level D).
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2-1 2
SUMMARY
AND CONCLUSIONS 2.1 ANALYSIS The dryers were analyzed with ANSYS finite element code, Version 11.0 (Reference 3), running under Windows-7 operating system using 360-degree analysis models. Analysis model for the PB2 dryer with instrumentation mast is shown in Figures 2-1 and 2-2. Analysis model for the PB2 dryer without mast is similar except for removal of finite elements representing the mast assembly. Analysis model for the PB3 dryer is similar except for removal of finite elements representing the mast assembly and the hold-down rods.
Analyses were performed for deadweight, differential pressures, seismic loads, Turbine Stop Valve (TSV) acoustic and flow reversal loads, and Main Steam Line Break (MSLB) differential pressure loads. Dryer stresses for Flow Induced Vibration (FIV) loads (Reference 4, Section 2.0 (50)) and MSLB acoustic loads (Reference 4, Section 2.0 (49)) were obtained from separate analyses. Thermal loads were not considered because the dryer operates under isothermal conditions and the structural design does not have materials with different expansion coefficients.
The dryers were supported in vertical and circumferential directions at the support lugs for all analyses except for analyses for MSLB differential pressure loads, which produce a dryer lift-off. For lift-off analyses, the models were supported at the top of the dryer hold-down rods (PB2) or lifting rods (PB3) in the vertical direction and at the support lugs in the circumferential directions.
Pressures were applied as surface loads, gravity was applied as equivalent static acceleration, and OBE and SSE loads were analyzed by response spectrum analyses.
2.2 DESIGN MARGINS Calculated stresses were compared with ASME Code (Section III, Division 1, Subsection NG) stress limits to calculate design margins. Minimum calculated design margins considering all three dryer configurations (PB2 dryer with and without instrumentation mast, and PB3 dryer) are summarized in Tables 2-1 through 2-8. Adequate design margins are calculated for all the specified load combinations with conservative assumptions, which included 1) use of seismic response spectra for 0.5% damping for OBE and SSE, 2) addition of maximum stresses from different loads in a load combination while ignoring differences in locations of maximum stresses for the different types of loads, and with a few exceptions,
- 3) use of maximum local mid-wall and surface stresses for comparison to membrane and membrane +
bending stress limits without averaging or linearizing the stresses across component sections.
Fatigue usage for the dryer components and welds is insignificant [
]a~C compared to the ASME Code usage limit of 1.0.
2.3 INTERFACE LOADS Table 2-9 lists interface loads for use in evaluation of dryer support brackets and hold-down rods. The loads in the table are for a single support lug and a single hold-down bracket.
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2-2 U I II Figure 2-1 PB2 Dryer with Instrumentation Mast: Analysis Model - Outline WCAP-17649-NP September 2012 Revision 0
2-3 Figure 2-2 PB2 Dryer with Instrumentation Mast: Analysis Model - Finite Element Mesh WCAP-17649-NP September 2012 Revision 0
2-4 Table 2-1 Minimum Design Margins - Components (Service Level A) 1a,c WCAP-17649-NP September 2012 Revision 0
2-5
.Table 2-1 Minimum Design Margins - Components (Service Level A) (cont.)
a,c WCAP-17649-NP September 2012 Revision 0
2-6 4[Table 2-2 Minimum Design Margins - Welds (Service Level A)
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2-7 Table 2-2 Minimum Design Margins - Welds (Service Level A) (cont.)
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2-8
__Table 2-2 Minimum Design Margins - Welds (Service Level A) (cont.)
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2-9
.Table 2-2 Minimum Design Margins - Welds (Service Level A) (cont.)
a,c WCAP-17649-NP September 2012 Revision 0
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-[Table 2-3 Minimum Design Margins - Components (Service Level B) a__
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2-11 4J.able 2-3 Minimum Design Margins - Components (Service Level B) (cont.)
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2-12
._Table 2-4 Minimum Design Margins - Welds (Service Level B)
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2-13 4-4.Table 2-4 Minimum Design Margins - Welds (Service Level B) (cont.)
I a,
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2-14
_4_Table 2-4 Minimum Design Margins - Welds (Service Level B) (cont.)
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2-15 Table 2-4 Minimum Design Margins - Welds (Service Level B) (cont.)
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2-16 jTable 2-5 Minimum Design Margins - Components (Service Level C) a,c WCAP-17649-NP September 2012 Revision 0
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__Table 2-5 Minimum Design Margins - Components (Service Level C) (cont.)
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._Table 2-6 Minimum Design Margins - Welds (Service Level C) a,c WCAP-17649-NP September 2012 Revision 0
2-19 4_Table 2-6 Minimum Design Margins - Welds (Service Level C) (cont.)
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2-20 Table 2-6 Minimum Design Margins - Welds (Service Level C) (cont.)
ac WCAP-17649-NP September 2012 Revision 0
2-21 iTable 2-6 Minimum Design Margins - Welds (Service Level C) (cont.)
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2-22 4[Table 2-7 Minimum Design Margins - Components (Service Level D) 4-a,c WCAP-17649-NP September 2012 Revision 0
2-23
_[Table 2-7 Minimum Design Margins - Components (Service Level D) (cont.)
ac WCAP-17649-NP September 2012 Revision 0
2-24
,4 Table 2-8 Minimum Design Margins - Welds (Service Level D) 4 a,c WCAP-17649-NP September 2012 Revision 0
2-25
._Table 2-8 Minimum Design Margins - Welds (Service Level D) (cont.)
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2-26 1.
4-Table 2-8 Minimum Design Margins - Welds (Service Level D) (cont.)
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2-27
_[Table 2-8 Minimum Design Margins - Welds (Service Level D) (cont.)
-L a,c 4.Table 2-9 Reaction Loads a,c WCAP-17649-NP September 2012 Revision 0
3-1 3
ANALYSIS INPUT 3.1 LOADS Specified loads are Deadweight, Differential Pressures (DP) from the pressure drop across the dryer vane banks, and TSV and MSLB loads on the outer hoods. Thermal loads are not considered as the dryer operates in isothermal environment and the structural design does not involve materials with different thermal expansion coefficients.
3.1.1 Gravity Weight of the dryer components is included in the analysis models by specifying component dimensions and material densities.
3.1.2 Pressure Loads Normal Operation, Upset Condition, and Emergency Condition pressure differences across the dryer are listed in Table 3-1 as DPN, DPu and DPE, respectively. Pressures following MSLB are listed as MSLBDPI and MSLBDP2.
Reactor thermal cycles diagram (Reference 5) identifies [
], start-up cycles and 200 operational scrams. Because dryer loads during the scram events are not defined, the start-up and scram cycles were added to [
]a,c cycles, which was enveloped by using [
la,, load cycles for fatigue usage calculations.
TSV loads on the outer hoods are listed in Table 3-2. Acoustic load TSVA is shown as pressure distribution relative to the center line of the affected steam line. Reverse Flow Impingement load following the valve closure is listed as TSVF. TSVF, not to be combined with TSVA, acts on outer hood area corresponding to projection of the steam nozzle on the outer hood.
There are 1380 TSV stress cycles are specified for fatigue usage calculations (Reference 4).
FIV loads and MSLB acoustic loads are described and analyzed separately (Reference 4). Stresses from these analyses were combined with stresses calculated in present analyses as described in Section 4.
ITable 3-1 Dryer Pressure Loads (Reference 4, Section 2 (46))
DPN, Normal Operation pressure, psid
[
]a*'
DPu, Upset Condition pressure, psid(2)
[
]a*c DPE, Emergency Condition pressure, psid(2)
[
a]c MSLBDPI, MSLB outside containment, rated power and core flow condition, psid
[
]8,C MSLBDP2, MSLB outside containment, low power / high core flow condition, psid')
[
]a Note:
(I) Limit load analysis was performed to justify higher pressure (Reference 7)
(2) Slightly conservative values are used in the analysis.
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3-2
[Table 3-2 TSV Loads on the Outer Hood (Reference 4) 4 a,c 3.1.3 Seismic Loads Specified N-S and E-W response spectra for 0.5% damping (Reference 4) are shown in Figure 3-1. These spectra were enveloped and used as horizontal OBE and SSE loads. Two-thirds of the enveloped spectra in the figure were used for Vertical seismic loads (Reference 4).
For fatigue usage calculations, [
]a,c OBE stress cycles are used (Reference 4).
3.2 LOAD COMBINATIONS Table 3-3 lists the specified load combinations (Reference 4). When combining seismic loads, i) stresses from N-S and vertical excitations are to be combined using absolute summation, ii) stresses from E-W and vertical excitations are to be combined using absolute summation, and iii) the larger of the N-S-vertical seismic stresses and E-W-vertical seismic stresses are to be used with stresses from other loads to obtain stresses for specific load combinations.
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3-3 Table 3-3 Load Combinations Load Service Acceptance Criteria Operating Condition Load Combination (Service Level)
A Normal A
Normal Operation DW + DPN + FIV B-i Upset B
Turbine Stop Valve Closure DW + DPN + ((TSVA) 2 + (FIV)2)'/
(Acoustic Load)
B-2 Upset B
Turbine Stop Valve Closure DW + DPN +TSVF (Flow Reversal Load)
B-3 Upset B
Normal Operation plus OBE DW + DPN + ((OBE) 2 + (FIV) 2)1/2
_____________plus FIV B-6 Upset B
DW, Differential Pressure DW +/- DPu + FIV (Upset) plus FIV C-1 Emergency DW, Differential Pressure DW + DPE + FIV C-1_EmergenyC (Emergency) plus FIV D-3 Faulted D
Normal plus FIV plus SSE DW + DPN + ((MSLBAI )2 + (SSE) 2 + (FIV) 2)1"2 plus DBA D-4 Faulted D
Normal plus FIV plus SSE DW + DPN + ((MSLBA2) 2 + (SSE)2 + (FIV)2)112 plus DBA D-5 Faulted D
Normal plus FIV plus SSE DW + MSLBDPI + SSE plus DBA D-6 Faulted D
Normal plus FIV plus SSE DW + MSLBDP2 plus DBA Legend:
DW Deadweight (+ weight of entrapped water for dynamic analysis)
DPN Differential pressure - normal operation DPU Differential pressure - upset condition DPE Differential pressure - emergency condition FIV Flow induced vibration loads TSVA Acoustic load caused by closure of Turbine Stop Valve.
TSVF Flow impingement load caused by closure of Turbine Stop Valve.
OBE OBE inertia load (anchor displacement loads are negligible)
SSE SSE inertia load (anchor displacement loads are negligible)
DBA Design Basis Accident MSLBAI Acoustic rarefaction wave load due to MSLB outside the containment, rated power and core flow condition MSLBA2 Acoustic rarefaction wave load due to MSLB outside the containment, low power / high core flow condition MSLBDPI Differential Pressure load due to MSLB outside the containment, rated power and core flow condition MSLBDP2 Differential Pressure load due to MSLB outside the containment, low power / high core flow condition WCAP-17649-NP September 2012 Revision. 0
3-4 3.3 ACCEPTANCE CRITERIA Steam dryer is not an ASME B&PV Code component. However, it is evaluated as Internal Structure according to the design rules ofASME B&PV Code,Section III, Division 1, Subsection NG (Reference 2). The applicable design rules are summarized in Table 3-4.
Table 3-4 Stress Limits Service level Stress category Stress limit Service levels A & B Pm Sm Pm + Pb 1.5Sm Shear stress 0.6 Sm Bearing stress Sy, (1.5 Sy away from free edge)
Z fatigue usage 1.0 Service level C Pm 1.5 Sm Pm + Pb 2.25 Sm Shear stress 0.9 Sm Bearing stress 1.5 Sy, (2.25 Sy away from free edge)
Service level D Pm Min(2.4 Sm, 0.7 Su)
Pm + Pb Min(3.6 Sm, 1.05 Su)
Shear stress 1.2 Sm Bearing stress 2.0 Sy, (3.0 Sy away from free edge)
Legend:
Pm Primary membrane stress intensity Pb Primary bending stress intensity Sm Stress intensity limit SY Yield strength S,,
Ultimate strength WCAP-17649-NP September 2012 Revision 0
3-5 3.4 MATERIAL PROPERTIES Dryer structural components are made from SA-240 type 316L. Table 3-5 lists the material properties (Reference 6) used in the analysis.
Table 3-5 Material Properties (Reference 6)
Material property 70OF 551OF Sm, Stress intensity limit, psi 16,700 14,400 Sy, Yield strength, psi 25,000 16,000 S, Ultimate strength, psi 70,000 61,700 E, Young's modulus, psi 28.3 x 106 25.42 x 106 WCAP-17649-NP September 2012 Revision 0
3-6 Design Earthquake (OBE)
N-S I
6 E-W Fnvelone 5 4-l i 2
1 0.1 Frequency (Ift) 9 MxCredible Earthquake (SSE~)Fruwy()
N-S E-W FnvelIn r.
p-6 5
+/-
I 0.1 Frequency (Hz)
Figure 3-1 Seismic Response Spectra 10 WCAP-17649-NP September 2012 Revision 0
4-1 4
ANALYSIS AND RESULTS 4.1 ANALYSIS MATRIX Finite element analyses were performed for the PB2 dryer, PB2 dryer with instrumentation mast, and the PB3 dryer. In each case, analyses were performed for deadweight (DW), differential pressures (DPN, DPu, DPE, MSLBDP1, MSLBDP2), seismic loads (OBE, SSE), and TSV loads (TSVA, TSVF). FIV and MSLBA (MSLBAI and MSLB A2) loads are developed and analyzed separately (Reference 4). Maximum FIV and MSLBA stresses calculated in these analyses were conservatively combined with the results of present analyses.
Hydrodynamic mass of the skirt was included in analyses for static as well as dynamic loads to facilitate load combination and post-processing. This is not unduly conservative as the hydrodynamic weight in the model is only [
]a,c of the dryer deadweight.
Table 4-1 lists the load cases included in the present analyses.
Table 4-1 Analysis Matrix Load case Loads Load Combination (Table 3-3)
Static analyses I
DW Results not used 2
DW + DPN Used in Load Combination A 3
DW + DPN + TSVA Used in Load Combination B-1 4
DW + DPN + TSVF Load Combination B-2 5
DW + DPu Used in Load Combination B-6 6
DW + DPE Used in Load Combination C-1 7
DW + MSLBDP1 Used in Load Combinations D-5 8
DW + MSLBDP2 Load Combinations D-6 Response spectrum analyses 9
OBE (X)
Used in Load Combination B-3 10 OBE (Y)
Used in Load Combination B-3 II OBE (Z)
Used in Load Combination B-3 12 SSE (X)
Used in Load Combinations D-3, D-4, D-5 13 SSE (Y)
Used in Load Combinations D-3, D-4, D-5 14 SSE (Z)
Used in Load Combinations D-3, D-4, D-5 4.2 ANALYSIS 4.2.1 Analysis Model Analysis models include the dryer skirt and drain channels, gussets, center plate, and center ring, drain troughs and trough stiffeners, vane bank end plates, top plates, side plates, bank-to-bank attachment WCAP-17649-NP September 2012 Revision 0
4-2 plates, and perforated plates, hoods, and upper girder assembly, all modeled with shell elements, dryer support ring modeled with solid elements, and lifting rods, hold-down rods, and vane bank tie rods modeled with beam elements. Dryer vanes are modeled as solid elements with weight equal to the vane bank weight. Hydrodynamic mass is modeled by adjusting density of the under-water elements of the skirt. The analysis model for the PB2 dryer with instrumentation mast is shown in Figures 2-1 and 2-2.
Analysis models for the PB2 dryer without instrumentation mast and the PB3 dryer are similar except for the absence of the mast assembly in both of these models and the absence of the hold-down rods in the PB3 model.
4.2.2 Boundary Conditions Dryers were supported in vertical and circumferential directions at the dryer support lugs for all analyses except for the analyses for MSLBDPI and MSLBDP2 loads, which produce a dryer lift off. For lift-off analyses, the dryers were supported at the top of the lifting rods or hold-down rods in the vertical direction and at the support lugs in the circumferential direction.
Boundary conditions are shown in Figures 4-1 and 4-2.
4.2.3 Load Application For static analyses, pressure was applied as a surface load and gravity load was applied as Ig equivalent static acceleration. OBE and SSE loads were analyzed in response spectrum analyses.
TSV loads are specified in Table 3-2 as pressure distribution and impingement load on the hood relative to one of the four Main Steam Line (MSL) nozzles. For the analysis, the specified acoustic load pressure distribution was assumed to apply at all the four MSLs in order to envelop the effects of acoustic wave propagation through the steam circuit. For consistency, the flow impingement load was also assumed to apply to all the four MSLs.
Figure 4-3 shows pressure load application.
4.2.4 Load Combination Approach Analyses were performed for the 14 load cases listed in Table 4-1. Relatively large middle hood displacements were calculated for Load Cases 7 (DW+MSLBDPI) and 8 (DW+MSLBDP2) because of the large pressures acting on the thin hood plates. With small bending stiffness compared to in-plane stiffness of the hoods, large transverse displacements would be accompanied by in-plane tensile forces resisting the deformations. The stress-stiffening option of ANSYS was used for these load cases to account for coupling between the in-plane and out-of-plane deformations of the hoods. This was not a problem for the other analysis cases because of the small pressure loads.
Results of Load Cases 2, 3, 4, 5, 6, 7, and 8 were used directly for Load Combinations A, B-I, B-2, B-6, C-I, D-5, and D-6, respectively, in Table 3-3. OBE and SSE results for use in load combinations B-3, D-3, D-4, and D-5 were obtained from the response spectrum analyses of Load Cases 9 through14 using the following approach:
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4-3
- 1.
Modal responses for each of the Load Cases 9 through 14 were combined using the Square Root of the Sum of the Squares (SRSS) approach to obtain OBEx, OBEy, OBEz, SSEx, SSEy and SSEz responses where Z is the vertical direction.
- 2.
Vertical and horizontal direction responses were combined using absolute addition to obtain:
OBExz = IOBExI + JOBEzI OBEyz = OBEyj + IOBEzI SSExz = ISSExI + ISSEzI SSEyz = ISSEY1 + ISBEzI
- 3.
Maximum stress intensities for each dryer component were extracted for OBExz, OBEyz, SSExz, and SSEyz. These values were used to obtain maximum component seismic stress intensities as:
SIMAX-OBE = max (SI-OBExz, SI-OBEyz)
SIMAX-SSE = max (SI-SSExz, SI-SSEyz)
OBE stresses were combined with the maximum normal operation stresses (Load Case 2) and maximum FIV stresses to obtain stresses for Load Combination B-3 using the following relationship:
IDW + DPNIMAX + A{(SIMAx-OBE) 2+(FIVMAx) 2}
SSE stresses were combined with the maximum normal operation stresses (Load Case 2), maximum FIV stresses, and maximum MSLBA (MSLBAl and MSLBA2) stresses to obtain enveloping stresses for Load Combinations D-3 and D-4 using the following relationship:
IDW + DPNIMAX + 4 {(SIMAX-SSE) 2+(FIVMAx) 2+(MSLBA-MAX) 2}
SSE stresses were combined with the maximum (DW+MSLBDPI) stresses (Load Case 7) to obtain stresses for Load Combination D-5 using the following relationship:
IDW + MSLBDPIIMAX + SIMAX-SSE Because TSV + DW + DPN loads were analyzed together (Load Case 3), it was not possible to SRSS the TSV and FIV stresses. Therefore FIV stresses were added absolutely to the results for Load Case 3 to obtain stresses for Load Combination B-1.
It should be noted that the above approach of combining maximum stresses from different load cases to obtain maximum stresses for Load Combinations conservatively ignores the differences in the locations of maximum stresses for the different load cases.
4.2.5 Component Stresses Maximum stresses in the dryer components are highly localized at nodes on the weld lines. Usually such local stresses are used for fatigue calculations and stresses away from these nodes are averaged and linearized across the component sections and used for stress limit comparisons. However, the complex geometry of the dryer and the large stress gradients make it difficult to select sections for stress averaging.
Therefore following conservative approach was used for design margin calculations.
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4-4
- 1.
ANSYS post-processor was used to extract maximum mid-wall and surface stresses for each component modeled with shell elements including the elements at the weld lines and the maximum stresses anywhere in the components modeled with solid elements including the elements at the weld lines.
- 2.
Maximum mid-wall and surface stresses from different loads in load combinations were combined as described in Section 4.2.4 conservatively ignoring differences in their locations in the components.
- 3.
Maximum FIV surface stress amplitude of[
]a,c psi and maximum MSLBA (MSLBA, and MSLBA2) surface stress of [
]ac psi have been calculated in FIV and MSLBA analyses of the three dryer configurations (Reference 4). The high FIV stresses are located in the drain channel and the skirt. The high MSLBA stresses are in the outer hood region. Much lower stresses occur in other regions of the dryer. However, these maximum stresses were conservatively assumed to apply as surface stresses for all the components in the dryer.
As pressure loading produces primarily bending stresses with small membrane stresses, mid-wall stresses were enveloped by assuming mid-wall FIV stress of [
]a,, psi and mid-wall MSLBA stress of [
]a,c psi as mid-wall stresses for all the components in the dryer. The stresses were added to the maximum component stresses calculated in Step (2) as described in Section 4.2.4. The resulting mid-wall stresses were compared with membrane stress limits without any averaging, and surface stresses were compared with membrane + bending stress limits without any linearizing.
- 4.
In a few cases, maximum surface stresses described in Step (3) above exceeded the membrane plus bending stress limit. Stress distributions in these cases were investigated in greater detail as described in Section 4.2.5.4.
The approach described above was used for each of the three dryer analysis models. Analysis results for the three dryers are discussed in terms of the following components:
Troughs Gussets (thin section)
Gussets (thick section)
Gussets center plate Gussets center ring Trough stiffeners VB (Vane Bank) end plates VB top plates VB top steps VB top side plates Hoods VB to VB vertical plates VB to VB top plates Center cover plate Upper girder center ring Upper girders Support ring Drain channel Skirt Skirt slots VB vertical stiffener VB rails Horizontal rails Perf plate beam stiffeners 4.2.5.1 PB2 Dryer with Instrumentation Mast Maximum mid-wall and surface stresses for components of the PB2 dryer with instrumentation mast are listed in Table 4-2 for load cases 2 through 8 and for OBE and SSE with directional earthquake stresses combined and maximized as described in Section 4.2.4.
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4-5 Maximum stresses listed in Table 4-2 are combined following the approach described above to obtain mid-wall and surface stresses for various load combinations. These stresses are listed in Table 4-3. In listing the stresses, maximums of the stresses for Load Combinations D-3 and D-4 are reported in a common column. Similarly, maximums of the stresses from Load Combinations D-5 and D-6 are reported in a common column.
4.2.5.2 PB2 Dryer without Instrumentation Mast Maximum mid-wall and surface stresses for components of the PB2 dryer without instrumentation mast are listed in Table 4-4 for load cases 2 through 8 and for OBE and SSE with directional earthquake stresses combined and maximized as described in Section 4.2.4.
Maximum stresses listed in Table 4-4 are combined following the approach described above to obtain mid-wall and surface stresses for various load combinations. These stresses are listed in Table 4-5. In listing the stresses, maximums of the stresses for Load Combinations D-3 and D-4 are reported in a common column. Similarly, maximums of the stresses from Load Combinations D-5 and D-6 are reported in a common column.
4.2.5.3 PB3 Dryer Maximum mid-wall and surface stresses for components of the PB3 dryer are listed in Table 4-6 for load cases 2 through 8 and for OBE and SSE with directional earthquake stresses combined and maximized as described in Section 4.2.4.
Maximum stresses listed in Table 4-6 are combined following the approach described above to obtain mid-wall and surface stresses for various load combinations. These stresses are listed in Table 4-7. In listing the stresses, maximums of the stresses for Load Combinations D-3 and D-4 are reported in a common column. Similarly, maximums of the stresses from Load Combinations D-5 and D-6 are reported in a common column.
4.2.5.4 All Dryers Stresses listed in Tables 4-3, 4-5, and 4-7 for the three dryer configurations were compared to extract maximum stresses for the 10 load combinations (reported with combined maximum values for Load Combinations D-3 and D-4, and D-5 and D-6), which were further compared to obtain maximum stresses for the four ASME Code Service Levels. These stresses are listed in Table 4-8 together with the membrane and membrane + bending stress limits for the four Service Levels.
The conservatively calculated maximum stresses are within the ASME Code limit with two exceptions:
- 1.
Middle Hood Service Level A ([
c psi) and Service Level B ([
]apc psi), and Outer hood Service Level B ([
]a,c psi) surface stresses are close to or exceed the ASME Pm+Pb stress limit of [
]a,c psi. Contributors to the high local stresses were investigated and stress distribution for dead weight was selected to decrease the conservatism in the evaluation. As shown in the stress distribution for dead weight loading in Figure 4-5, the large surface stresses occur at nodes located at intersections of multiple plates in the hoods. Figure 4-6 shows that WCAP-17649-NP.
September 2012 Revision 0
4-6 removal of these isolated nodes from consideration decreases the peak surface stresses by I
]a,c psi from [
]a,c psi to [
]a,c psi. The same effect was noted for other load combinations as well because dead weight contributes directly to all the load combinations.
Because the loads at these points are clearly local stresses, Service level A and B Pm+Pb stress estimates for the inner hood and Service Level B Pm+Pb stress estimates for the outer hood were decreased by [
]ac psi to [
]a,c psi, [
]a,c psi, and I
]a~c psi when calculating design margins (in Tables 2-1 and 2-3).
- 2.
Middle hood surface stress of [
]a psi exceeds the ASME Code Service Level D Pm+Pb limit of [
]a,c psi for elastic analysis. Figure 4-7 shows that overstress condition occurs in the middle hood.
With the stress limit for elastic analysis exceeded, collapse analyses were performed (Reference
- 7) for the middle hood assuming elastic-perfectly plastic behavior and a yield stress of
[
]ac psi following Appendix F of the ASME Code (Reference 8). A quarter-model of the hood was analyzed with symmetry boundary conditions applied at the symmetry (vertical) boundaries. Analyses were performed with the upper and lower edges of the hood 1) fixed against displacements, and 2) fixed against displacements and rotations. Increasing pressure load was applied until collapse was indicated by rapid increase in displacements and lack of convergence.
Collapse pressures of [
a psi and [
]a,c psi were calculated for the case with upper and lower edges of the hood fixed only against displacements, and case with the edges fixed against displacements and rotations, respectively. Using the ASME design limit of 0.9 x collapse pressure (Reference 8) with the lower value of collapse pressure gives a pressure limit of S]ac psi, which provides adequate design margin for the MSLBDP2 pressure of
[
]a,c psi.
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4-7
_[Table 4-2 PB2 Dryer with Mast, Load Cases 2-14, Maximum Component Stresses WCAP-17649-NP September 2012 Revision 0
4-8 q
-C 8
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4-9 T__able 4-2 PB2 Dryer with Mast, Load Cases 2-14, Maximum Component Stresses (cont.)
I-WCAP-17649-NP September 2012 Revision 0
4-10 Table 4-3 PB2 Dryer with Mast, Load Combinations, Component Maximum Stresses 4-1 a,c WCAP-17649-NP September 2012 Revision 0
4-11
_jable 4-3 PB2 Dryer with Mast, Load Combinations, Maximum Component Stresses (cont.)
qa~c WCAP-17649-NP September 2012 Revision 0
4-12 Ta ble 4-4 PB2 Dryer Without Mast, Load Cases 2-14, Maximum Component Stresses 1-ac WCAP-17649-NP September 2012 Revision 0
4-13 Table 4-4 PB2 Dryer Without Mast, Load Cases 2-14, Maximum Component Stresses (cont.) 4.
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4-14 Table 4-4 PB2 Dryer Without Mast, Load Cases 2-14, Maximum Component Stresses (cont.)
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4-15 4fTable 4-5 PB2 Dryer Without Mast, Load Combinations, Maximum Component Stresses 4-1 a,c WCAP-17649-NP September 2012 Revision 0
4-16 Table 4-5 PB2 Dryer Without Mast, Load Combinations, Maximum Component Stresses (cont.)
_4_
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4-17
_Table 4-6 PB3 Dryer, Load Cases 2-14, Maximum Component Stresses I"
ac WCAP-17649-NP September 2012 Revision 0
4-18 LT-able 4-6 PB3 Dryer, Load Cases 2-14, Maximum Component Stresses (cont.)
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4-19 Table 4-6 PB3 Dryer, Load Cases 2-14, Maximum Component Stresses (cont.)
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4-20 T.able 4-7 PB3 Dryer, Load Combinations, Maximum Component Stresses 4
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4-21
.T_ ble 4-7 PB3 Dryer, Load Combinations, Component Maximum Stresses (cont.)
Iaq WCAP-17649-NP September 2012 Revision 0
4-22 JiLble 4-8 All Dryers, Service Levels, Maximum Component Stresses T__able WCAP-17649-NP September 2012 Revision 0
4-23 4.2.6 Weld Stresses Weld stresses were calculated using the same approach as used for component stress calculations in that maximum weld stresses for individual loads were extracted and combined according to specified load combinations without taking credit for differences in locations of maximum stresses, and local maximum stresses were used~for stress comparison without averaging over potential failure lengths.
Different FIV and MSLBA stresses were used in weld calculations compared to the component stresses.
Maximum surface stress amplitude of [
1a,c psi reported for FIV stresses was divided by the Stress Intensification factor (SCF) f= 1.8 used in FIV weld stress calculations giving maximum FIV weld stress of [
]a~c psi. Maximum weld stress calculated in MSLBA (MSLBAI and MSLBA2) analyses is I
]a,c psi as opposed to the maximum component stress of [
]a,c psi. Based on these results, FIV and MSLBA surface stresses at all welds were assumed to be [
]a,c psi and [
]ac psi, respectively, and FIV and MSLBA mid-wall stresses at all welds were assumed to be [
]a, psi and
[
]a,, psi, respectively.
Stresses for the individual load cases for PB2 dryer with mast, PB2 dryer without mast, and PB3 dryer are shown in Tables 4-9, 4-11, and 4-13, respectively. Corresponding stresses for the various load combinations are shown in Tables 4-10, 4-12, and 4-14. Finally, maximum weld stresses for the four Service Levels obtained by comparing stresses for the three dryers for all the load combination for each Service Level are listed in Table 4-15.
All the welds (with one exception discussed below) are full-penetration welds with weld quality factor of n = 0.75. ASME Code stress limits for these welds are listed in Table 4-15 together with the Service Level stresses. Comparison of the stresses with the stress limits gave negative margins for a few weld locations, which are identified in Table 4-15. The high stresses were concentrated at single nodes, generally triple-plate junctions. These stresses were resolved by removing the highest-stress node from consideration, which is acceptable because the stress limits are to be applied to average stresses in a section. Fatigue evaluation was still based on the stress at the highest stress node location.
Exceptions to this approach were: 1) Welds between the middle hood plates where high stresses extend over relatively large lengths as shown in Figure 4-8. In this case, the inspection requirement was modified to permit n of 0.9 instead of 0.75, which was sufficient to meet the stress limits. 2) Welds at the base of the middle hood welds that were passed by using FIV analysis results for these welds performed in a detailed sub-model analysis.
4.2.7 Interface Loads Table 2-9 lists the maximum reaction loads imposed by the dryer on the dryer support lugs and the lifting-rod hold-down brackets. The loads were calculated considering static equilibrium of pressure loads, seismic loads based on ZPA, and dryer weight. It was considered acceptable to use ZPA because the frequency of the structural components in the dryer is [
]a " Hz, which is close to the response spectra ZPA (Figure 3-1). The loads are the maximum loads on a support bracket, hold-down rod (PB2), or a lifting rod (PB3).
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4-24
-[
ble 4-9 PB2 Dryer with Mast, Load Cases 2-14, Maximum Weld Stresses
+t a,c WCAP-17649-NP September 2012 Revision 0
4-25
_.4iable 4-9 P132 Dryer with Mast, Load Cases 2-14, Maximum Weld Stresses (cont.)
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4-26
]Table 4-9 PB2 Dryer with Mast, Load Cases 2-14, Maximum Weld Stresses (cont.)
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4-27
_ Table 4-9 PB2 Dryer with Mast, Load Cases 2-14, Maximum Weld Stresses (cont.)
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4-28
- Table 4-9 PB2 Dryer with Mast, Load Cases 2-14, Maximum Weld Stresses (cont.)
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4-29 Table 4-9 PB2 Dryer with Mast, Load Cases 2-14, Maximum Weld Stresses (cont.)
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4-30 Tkable 4-10 PB2 Dryer with Mast, Load Combinations, Maximum Weld Stresses WCAP-17649-NP September 2012 Revision 0
4-31
_[T.ble 4-10 PB2 Dryer with Mast, Load Combinations, Maximum Weld Stresses (cont.)
4-31 WCAP-17649-NP September 2012 Revision 0
4-32 jTable 4-10 PB2 Dryer with Mast, Load Combinations, Maximum Weld Stresses (cont.)
=k WCAP-17649-NP September 2012 Revision 0
4-33 Table 4-10 PB2 Dryer with Mast, Load Combinations, Maximum Weld Stresses (cont.)
l WCAP-17649-NP September 2012 Revision 0
4-34
-Table 4-11 PB2 Dryer Without mast, Load Cases 2-14, Maximum Weld Stresses ac WCAP-17649-NP September 2012 Revision 0
4-35
_*Table 4-11 PB2 Dryer Without Mast, Load Cases 2-14, Maximum Weld Stresses (cont.)
-4 a,c WCAP-17649-NP September 2012 Revision 0
4-36 I Table 4-11 PB2 Dryer Without Mast, Load Cases 2-14, Maximum Weld Stresses (cont.)
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4-37 LTable 4-11 PB2 Dryer Without Mast, Load Cases 2-14, Maximum Weld Stresses (cont.)
4 a,c WCAP-17649-NP.
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4-38 IT-able 4-11 PB2 Dryer Without Mast, Load Cases 2-14, Maximum Weld Stresses (cont.)
a,c WCAP-17649-NP September 2012 Revision 0
4-39 Table 4-11 PB2 Dryer Without Mast, Load Cases 2-14, Maximum Weld Stresses (cont.)
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4-40 LTable 4-12 PB2 Dryer Without Mast, Load Combinations, Maximum Weld Stresses a2K WCAP-17649-NP September 2012 Revision 0
4-41 i
T__able 4-12 PB2 Dryer Without Mast, Load Combinations, Maximum Weld Stresses (cont.)
-4 a,c WCAP-17649-NP September 2012 Revision 0
4-42 Table 4-12 PB2 Dryer Without Mast, Load Combinations, Maximum Weld Stresses (cont.)
Ia WCAP-17649-NP September 2012 Revision 0
4-43 Table 4-12 PB2 Dryer Without Mast, Load Combinations, Maximum Weld Stresses (cont.)
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4-44 Table 4-13 PB3 Dryer, Load Cases 2-14, Maximum Weld Stresses a,c WCAP-1 7649-NP September 2012 Revision 0
4-45 Table 4-13 PB3 Dryer, Load Cases 2-14, Maximum Weld Stresses (cont.)
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4-46 I1able 4-13 PB3 Dryer, Load Cases 2-14, Maximum Weld Stresses (cont.)
a,c WCAP-17649-NP September 2012 Revision 0
4-47 1,
ITable 4-13 PB3 Dryer, Load Cases 2-14, Maximum Weld Stresses (cont.)
-L a,c WCAP-17649-NP September 2012 Revision 0
4-48 T__able 4-13 PB3 Dryer, Load Cases 2-14, Maximum Weld Stresses (cont.)
ha,c WCAP-17649-NP September 2012 Revision 0
4-49 jTable 4-13 PB3 Dryer, Load Cases 2-14, Maximum Weld Stresses (cont.)
a,c WCAP-17649-NP September 2012 Revision 0
4-50 t Table 4-14 PB3 Dryer, Load Combinations, Maximum Weld Stresses a,c WCAP-17649-NP September 2012 Revision 0
4-51 41iTable 4-14 PB3 Dryer, Load Combinations, Maximum Weld Stresses (cont.)
-4 ac WCAP-17649-NP September 2012 Revision 0
4-52 Table 4-14 PB3 Dryer, Load Combinations, Maximum Weld Stresses (cont.)
1ac WCAP-17649-NP September 2012 Revision 0
4-53 L
Table 4-14 PB3 Dryer, Load Combinations, Maximum Weld Stresses (cont.)
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4-54
]Table 4-15 All Dryers, Service Levels, Maximum Weld Stresses ia,c WCAP-17649-NP September 2012 Revision 0
4-55 T.able 4-15 All Dryers, Service Levels, Maximum Weld Stresses (cont.)
4 ac WCAP-17649-NP September 2012 Revision 0
4-56 II kU MCircumferential and vertical support at the support lugs Figure 4-1 Boundary Conditions for Analyses with No Dryer Lift-Off WCAP-17649-NP September 2012 Revision 0
4-57 Vertical hold-down at the top of hold-down rods I
Circumferential support at the support lugs Figure 4-2 Boundary Conditions for Dryer Lift-Off Analysis WCAP-17649-NP September 2012 Revision 0
4-58 Figure 4-3 Differential Pressure Loads - DPN, DPu, DPE, MSLBDPI and MSLBDP2 WCAP-17649-NP September 2012 Revision 0
4-59 acoustic pressure load Flow impingement load PRES-NORM
-6.784 1 -6.236 m
-5.689
-5.141 m
-4.593 m
-4.046
-3.498
-2.951 m
-2.403 m
-1.855 Pressure, psi Pressure, psi Figure 4-4 TSV Loads - TSVA, TSVF WCAP-17649-NP September 2012 Revision 0
4-60 SMN =19.329 SMX =3340 19.329 388.24 l757.15 mm1126 1495 1864 2233 2602 2971
-B 3340 mid-wall stress intensity, psi surface stress intensity, psi Figure 4-5 Hood Stresses, Dead Weight WCAP-17649-NP September 2012 Revision 0
4-61 High stress corner nodes Surface stress intensity, psi Lx Surface stress intensity, psi After removing high-stress corner nodes NOUAL SOLU STEP-i SUB -1 TIME-i SI
(
TOP DMX -. 0262 SMN -24.57 SMX -14948 SMXB-17666 24.57 1683 3341 4999 6657 8316 9974 11632
-m 13290 14948 NODAL SOL STEP-i SUB -i TIME-i SI TOP DMX -. 026 SMN -24.5 SMX -8177 SMXB-9980 24.5 930.
1836 2742 3648 4554 5460 86366 7271 8177 Figure 4-6 Hood Stresses after Removing Corner Nodes, Dead Weight WCAP-17649-NP September 2012 Revision 0
4-62 Surface stress intensity, psi All hoods 176.5:
6011 11845 17679 23513 29347 35181 41016 46850 52684 Surface stress intensity, psi Inner and outer hoods 176.5:
I--I 2538 II4900 7262 9624 11985 14347 16709 19071 21432 Figure 4-7 Hood Stresses, MSLBDP2 Pressure Load WCAP-17649-NP September 2012 Revision 0
4-63 Mid-wall stress intensity, psi Surface stress intensity, psi m
m-mD 143.
1106 2068 3030 3992 4954 5916 6878 7840 8802 3086 8597 14108 1961S 2513C 3064C 36151 41662 47172 52684 Figure 4-8 Middle Hood Stresses, MSLBDPZ Pressure Load WCAP-17649-NP September 2012 Revision 0
5-1 5
DESIGN MARGINS 5.1.1 Stress Limits Component design margins are calculated in Tables 2-1, 2-3, 2-5, and 2-7 for Service Levels A, B, C, and D, respectively. Weld design margins are calculated in Tables 2-2, 2-4, 2-6, and 2-8 for Service Levels A, B, C, and D, respectively.
The dryer components and welds for all the dryer configurations meet the ASME Code stress limits.
5.1.2 Fatigue Usage Maximum Service Level B stresses for threedryer configurations are [
c psi (Table 4-8) for the components and [
p, psi (Table 4-15) for the welds. Therefore the largest fatigue usage will be at the welds. Using fatigue strength reduction factor of 2 for full penetration welds and ignoring the fact that the weld stresses do not cycle, cyclic stress range will be [
]a,c psi, and the stress amplitude will be 28345 psi.
For fatigue usage calculations, the stress amplitude is multiplied by the modulus ratio (EROOM TEMPERATURE / EOPERATION ) = [
]ac to give a stress amplitude of I
]a,c psi. ASME Code (Reference 8) permits [
]ac cycles operation at this stress amplitude. Assuming the stress cycle to apply to all the cyclic loads, fatigue usage will be [
]a,c start-up-shutdown cycles + [
]a'c OBE cycles / [
]ac, which is insignificant.
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6-1 6
REFERENCES
- 1.
U. S. Nuclear Regulatory Commission, Regulatory Guide 1.20, Rev. 3, Comprehensive Vibration Assessment Program for Reactor Internals during Preoperational and Initial Startup Testing, March 2007.
- 2.
American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section III, Division 1 - Subsection NG, Core Support Structures, 2007 Edition with 2008 Addenda.
- 3.
ANSYS Release 11.0, ANSYS, Incorporated.
- 4.
425A69, Design Specification, Exelon Replacement Steam Dryers for PBAPS 2&3, Rev. 2.
- 5.
GEH (APED) Drawing 729E762, Reactor Thermal Cycles.
- 6.
American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section II, 2007 Edition with 2008 Addenda.
- 7.
SES12-207, Rev. 0, Exelon Replacement Steam Dryer - Limit Analysis of the Middle Hoods for Peach Bottom 2 RSD.
- 8.
American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section III, Division I -Appendix F, 2007 Edition with 2008 Addenda.
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