ML20247E667
| ML20247E667 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 03/31/1989 |
| From: | Chang K, Raju Patel, Schmertz J WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| To: | |
| Shared Package | |
| ML19302D776 | List: |
| References | |
| WCAP-12219, NUDOCS 8904030201 | |
| Download: ML20247E667 (242) | |
Text
. . _ _ - - _ - - - - - - - _ _ _ - - _ - _ - - _ _
WESTINGHOUSE CLASS 3 WCAP-12219
/
EVALUATION OF THERMAL STRATIFICATION FOR THE V0GTLE UNIT 2 PRESSURIZER SURGE LINE March, 1989 R. L. Brice-Nash R. Krishnan S. A. Swamy B. J. Coslow T. H. Liu E. L. Cranford L. M. Valasek B. F. Maurer F. J. Witt K. R. Hsu J. F. Petsche
," E. R. Johnson D. H. Roarty i Verified by: ////
K. L. Chang d- -
Verified by: O M -i C 8 M Q (/. G. Schmertz #
Approved by:
R. B. Patel, Man 4(er Approved by: N Piping Analysis and /5. 5/Falusamy, Manager "
Engineering Structural Materials Engineering WESTINGHOUSE ELECTRIC CORPORATION Nuclear and Advanced Technology Division P.O. Box 2728
,, Pittsburgh, Pennsylvania 15230-2728 .
8904030201 890322
TABLE OF CONTENTS Section Title Page
SUMMARY
xvii 10 INTRODUCTION AND UPDATE OF DESIGN TRANSIENTS 1-1 1.1 Introduction 1-1 1.1.1 System Description 1-1 1.1.2 Thermal Stratification In The Surge Line 1-2 1.1.3 Surge Line Stratification Program 1-3 1.2 Update of Design Transients 1-4 1.2.1 System Design Information 1-4 1.2.2 Stratification Effects Criteria 1-5 1.2.3 Plant Monitoring 1-5 1.2.4 Heat Transfer and Stress Analyses 1-10 1.2.5 Stratification Profiles 1-30
,' 1.2.6 _ Development of Conservative Normal and 1-12 Upset Transients -
?
1.2.7 Temperature Limitations During Heatup 1-13 and Cooldown 1.2.8 Historical Data 1-13 1.2.9 Development of Heatup and Cooldown Design 1-14 Transients With Stratification 1.2.9.1 [ )"'C Transients 1-15 1.2.9.2 [ Ja.c.e Transients 1-19 1.2.10 Striping Transients 1-19 1.3 Conclusions 1 1-20
. - 2.0 STRESS ANALYSES 2-1 2.1 Piping System Structural Analysis 2-1
.- 2.1.1 Introduction 2-1 2.1.2 Discussion 2-2 l
iii 4 1
w
TABLE OF CONTENTS (cont.)
Section Title Page a
2.1.3 Results 2-5 2.1.4 Additional Information on Linear Equivalent 2-6 Techniques 2.1.4.1 Introduction 2-6 2.1.4.2 Theory 2-6 2.1.4.3 Application 2-9 2.1.4.4 Discussion 2-9 2.1.5 Conclusions 2-9 2.2 Local Stress Due to Non-Linear Thermal Gradient 2-10 2.2.1 Explanation of Local Stress 2-10 2.2.2 Superposition of Local and Structural Stresses 2-10 2.2.3 Finite Element Model of Pipe for Local Stress 2-11 2.2.4 Pipe Local-Stress Results 2-11 l 2.2.5 Unit Structural Load Analyses For Pipe 2-12 2.2.6 RCL Hot Leg Nozzle Analysis 2-12 2.2.7 Reducer Analysis 2-13 2.2.8 Conservatism 2-13 2.3 Thermal Striping 2-13 I 2.3.1 Background 2-13 2.3.2 Additional Background Informatiori 2-14 2.3.3 Thermal Striping Stresses 2-16 2.3.4 Summary of Striping Stress Considerations 2-17 2.3.5 Thermal Striping Total Fluctuations and Usage 2-18 Factor 2.3.6 Conservatism 2-19 3.0 ASME SECTION III FATIGUE USAGE FACTOR EVALUATION 3-1 3.1 Code and Criteria
- 3-1 -
3.2 Previous Design Methods l 3-1 i
3.3 Analysis for Thermal Stratification 3-1 #
3.3.1 Stress Input 3-2 se in 1
l TABLE OF CONTENTS (cont.)
s' Section Title Page 3.3.2 Classification and Combination of Stresses 3-2 3.3.3 Cumulative Fatigue Usage Factor Evaluation 3-3 3.3.4 Simplified Elastic-Plastic Analysis 3-4 3.3.5 Fatigue Usage Results 3-4 3.4. Conservatism in Fatigue Usage Calculation 3-5 3.5 References 3-5 4.0 FATIGUE CRACK GROWTH 4-1 4.1 Introduction 4-1 4.2 Initial Flaw Size 4-2 4.3 Critical Locations for FCG 4-2 4.4 Results of FCG Analysis 4-3 4.5 References 4-3 5.0 REASSESSMENT OF LEAK-BEFORE-BREAK 5-1 ,
g 5.1 Introduction 5-1 5.2 Naterial Properties 5-1
' 5.3 Loading Conditions 5-2 5.4 Leak Rate Calculation 5-2 5.5 Reactor Coolant System (RCS) Cooldown Stratification 5-3 Temperature Considerations 5.5.1 Reactor Coolant Temperatures 5-3 5.5.2 Pipe Versus System Temperature Difference 5-5 5.5.3 Conclusions 5-5 5.6 Evaluation of Flux Welds 5-6
.- 5.7 Results 5-6 5.8 References 5-7
..=
6.0 CONCLUSION
S 6-1 APPENDIX A - LIST OF COMPUTER PROGRAMS A-1 as esano y
LIST OF TABLES Table Title Page 1-1 ' IMPORTANT DIMENSIONLESS GROUPS FOR SIMILITUDE IN 1-21
, HYDRODYNAMIC TESTING 1-2 STRATIFICATION POTENTIAL BASED ON RICHARDSON NUMBER 1-22 1-3 SURGELINE TRANSIENTS WITH STRATIFICATION HEATUP (H) 1-23 AND C00LDOWN (C) - 200 CYCLES TOTAL I-4 SURGE LINE TRANSIENTS WITH STRATIFICATION NORMAL AND 1-24 UPSET TRANSIENT LISV 1-5 STRATIFICATION PROFILES 1-26 1-6 HEATUP - C00LDOWN TRANSIENTS 1-27 1-7 DESIGN TRANSIENTS WITH STRATIFICATION 1-28 1-8 OPERATIONS SURVEY 1-29 1-9 HEATUP DATA
SUMMARY
(PIR - HOT LEG) TEMP. DIFFERENCE AND 1-30 TIME DURATION FOR EACH PHASE i
1-10 COOLDOWN DATA
SUMMARY
(PZR - HOT LEG) TEMP. DIFFERENCE AND 1-31 TIME DURATION FOR EACH PHASE
, 1-11 TRANSIENT TYPES 1-32 1-12
SUMMARY
OF FATIGUE CYCLES FROM [ Ja,c.e 1 33 1-13
SUMMARY
OF PLANT MONITORING TRANSIENTS WITH STRENGTH OF 1-34 STRATIFICATION (RSS) 1-14
SUMMARY
OF MONITORED TRANSIENT CYCLES (ONE HEATUP) 1-36 1 15
SUMMARY
OF % TIMES AT MAXIMUM TEMPERATURE POTENTIAL RMTP 1-37 g
1-16 SURGE LINE TRANSIENTS - STRIPING FOR HEATUP (H) AND 1-38 CDOLDOWN (C) 2-1 COMPARISON OF WECAN AND ANSYS RESULTS FOR LINEAR 2-20 STRATIFICATION - Case 2 2-2 COMPARISON OF WECAN [ ']a,c.e AND 2-21
.. ANSYS [ Ja.c.e RESULTS FOR CASE 3 b
3064s 4 31844 10 ygg
i LIST OF TABLES (cont.)
Table Title Page .,
2-3 TEMPERATURE DISTRIBUTIONS IN PRESSURIZER SURGE LINE 2-22 '
2-4 THE EQUIVALENT LINEAR COEFFICIENTS J jg 2-23 2-5 V0GTLEUNIT2SURGELIN['gAf!MUMLOCALAXIALSTRESSES 2-24 AT [ ]
2-6
SUMMARY
OF LOCAL STRATIFICATION STRESSES IN THE SURGE LINE 2-25 AT THE RCL N0ZZLE 2-7
SUMMARY
OF PRESSURE AND BENDING INDUCED STRESSES IN THE 2-26 SURGE LINE RCL N0ZZLE FCR UNIT LOAD CASES 2-8 STRIPING FREQUENCY AT 2 MAXIMUM LOCATIONS FROM 15 TEST RUNS 2-27 2-9 FLOW RATES AND RICHARDSON NUMBER FOR WATER MODEL FLOW TESTS 2-28 2-10 RESULTS FROM TWO HIGHEST THERMOCOUPLE LOCATIONS 2-29 4-1 FATIGUE CRACK GROWTH RESULTS FOR 10% WALL INITIAL FLAW SIZE 4-4 5-1 STEPS IN A LEAK-BEFORE-BREAK ANALYSIS 5-8 5-2 LBB CONSERVATISM 5-9 -
5-3 ROOH TEMPERATURE MECHANICAL PROPERTIES OF SURGE LINE 5-10 ,
MATERIALS AND WELDS OF THE V0GTLE UNIT 2 PLANT -
5-4 TENSILE,Pg0gERTIESFORTHESURGELINEMATERIALAT 5-11
( ) AND E53*F 5-5 TYPES OF LOADINGS 5-12 5-6 NORMAL AND FAULTED LOADING CASES FOR LBB EVALUATIONS 5-13 5-7
SUMMARY
OF LOADS AND STRESSES AT THE CRITICAL LOCATIONS 5-14 5-8 ASSOCIATED LOAD CASES FOR ANALYSES 5-15 5-9 LOAD CASES, LOCATION AND TEMPERATURES CONSIDERED FOR LEAK- 5-16 BEFORE-BREAK EVALUATIONS 5-10 LEAKAGE FLAW SIZES, CRITICAL FLAW SIZES AND MARGINS 5-17 5-11 SIGNIFICANT THERMAL TRANSIENTS 5-18 mu. mien in yjjj
LIST OF FIGURES Figure Title Page 1-1 Simplified Diagram of the RCS 1-39 ;
1-2 Reactor Coolant System Flow Diagram (Typical Loop) 1-40 1-3 RCS Pressurizer 1-41 1-4 Estimate of. Flow Stratification Pattern in Elbow Under 1-42 Pressurizer 1-5 Vogtle Unit 2 Pressurizer Surge Line Stratification ASME III 1-43 and Qualification Program 1-6 Transient Development Flow Chart 1-44 1-7 Vogtle Unit 2 Pressurizer Surge Line Monitoring Locations 1-45 1-8 [ Ja,c.e Pressurizer Surge Line Monitoring Locations 1-46 1-9 [ Ja,c.e Pressurizer Surge Line Monitoring Locations 1-47 1-10 [ Ja,c.e Pressurizer Surge Line Monitoring Locations 1-48
, 1-11 Reactor Coolant Pump Cut-off Transient Location Approximately 1-49 10' From RCL Nozzle Safe-End 1-12 Reactor Coolant Pump Cut-off Transient RCL Nozzle Safe-End 1-50 HL 1-13 Transient Typical of RC Pump Cut-off 1-51 1-14 Temperature Profile (6.5-inch ID Pipe) 1-52 1-15 Dimensionless Temperature Profile (14.3-inch ID pipe) 1-53 1-16 Surge Line Stratification 1-54 1-17 Surge Line Hot-Cold Interface Locations 1-55 1-18 Hot-Cold Interface Location From Temperature Measurements 1-56 1-19 Typical [ ]C# Temperature Profiles 1-57 nmmen io ix i
LIST OF FIGURES (cont.)
Figure Title Page ,
20 Inadvertent RCS Depressurization (AT = 260'F in Surge Line) 1-58 ,
1-21 Steam Bubble Mode Heatup 1-59 '
1-22 Steam Bubble Mode Cooldown 1-60 1-23 Heatup [ Ja,c.e 1-61 1-24 Cooldown [ Ja,c.e 1-62 1-25 Heatup [ ]C 1-63 1-26 Cooldown [ Ja.c.e 1-64 2-27 Heatup [ Ja,c.e 1-65 1-28 Cooldown [ la c.e 1-66 1-29 Heatup [ Ja,c.e 1-67 1-30 Cooldown [ la,c e 1-68 1-31 Heatup[ Ja.c.e 1-69 .
1-32 Cooldown [ Ja,c.e 1-70 1-33 [ Ja,c.e (PAT) System Vs. Pipe AT 1-71 '.
1-34 [ Ja.c.e Location 1 - Heatup (7 Days) 1-72 1-35 [ Ja,c.e Location 1 - Heatup (4 Days) 1-73 l 1-36 Vogtle Unit 2 Surge Line Stratification 1-74
.1-37 Vogtle Unit 2 Surge Line Stratification 1-75 2-38 Vogtle Unit 2 Surge Line Stratification 1-76 1-39 Vogtle Unit 2 Surgo Line Stratification 1-77 1-40 Vogtle Unit 2 Surge Line Stratification 1-78 1-41 Vogtle Unit 2 Surge Line Stratification . 1-79 O*
aeos.mseen so
t i
l LIST OF FIGURES (cont.)
Figure Title
- Page 1-42 Vogtle Unit 2 Surge Line Stratification 1-80 s 1-43 Vogtle Unit 2 Surge Line Stratification 1-81 1-44 Vogtle Unit 2 Surge Line Stratification 1-82
,1-45 Vogtle Unit 2 Surge Line Stratification 1-83 1-46 Vogtle Unit 2 Surge Line Stratification 1-84 1-47 [ la,c,e Location 1 Fatigue Cycles - Heatup (11 Days) 1-85 1-48 Thermal Cycle Distribution Assumed For One Heatup Cycle 1-86 1-49 [
,,,,, 1-87 1-50 Initiation of Striping Thermal Cycles Assumed For One Heatup 1-88 1-51 Comparison of Design to Monitored Transients 1-89 1-52 Comparison of Design to Monitored Transients 1-90 f 2-1 Determination of the Effects of Thermal Stratification 2-30 2-2 Stress Analysis 2-31 '
2-3 Typical Pressurizer Surge Line Layout 2-32 2-4 Cases 1 to 4: Radial Temperature Profiles 2-33 2-5 Case 5: Radial and Axial Temperature Profile 2-34 2-6 Finite Element Model of the Pressurizer Surge Line Piping 2-35 General View 2-7 Finite Element Model of the Pressurizer Surge Line Piping 2-36 Hot Leg Nozzle Detail 2-8 Thermal Expansion of the Pressurizer Surge Line Under 2-37 Uniform Temperature 2-9 Case 2 (linear) Temperature Profile at Hot Leg Nozzle 2-38 seesemises 10 xj
LIST OF FIGURES (cont.)
Figure Title
- Page -
2-10 Case 2 (linear) Temperature Profile at Pressurizer Elbow 2-39 4
2-11 Thermal Expansion of Pressurizer Surge Line Under Linear Temperature Gradient 2-40 2-12 Bowing of Beams Subject to Top-to-Bottom Temperature Gradient
. 2-41 2-13 Case 3 (Mid-Plane Step): Temperature Profile at Hot Leg Nozzle 2-42 2-14 Case 3 (Mid-Plane Step): Temperature Profile at Pressurizer Nozzle 2-43 2-15 Case'4 (Top Half Step): Temperature Profile at Hot Leg Nozzle 2-44 2-16 Case 4 (Top Half Step): Temperature Profile at Pressurizer Elbow 2-45 2-17 Case 5: Axial and Radial Temperature Profile 2-46 2-18 Case 5: Axial and Radial Temperature Profile at Hot Leg Nozzle 2-47 2-19 Case 5: Axial and Radial Temperature Profile at Pipe Bend 2-48 .
2-20 Case S: Axial and Radial Temperature Profile at Pressurizer Elbow 2-49 2-21 [ la c.e Profile 2-50 2-22 Comparison of Measured and Calculated Pipe Displacements 2-51 2-23 Equivalent Linear Temperature 2-52 2-24 Local Stress in Piping Due to Thermal Stratification l 2-53 2-15 Independence of Local and Structural Thermal Stratification 2-54 i Stresses Permitting Combination by Superposition 2-26 Test Case for Superposition of Local and Structural Stresses i 2-55 2-27 Local Stress - Finite Element Models/ Loading 2-56 2-28 Piping Local Stress Model and Thermal Boundary Conditions 2-57 2-29 Surge Line Temperature Distribution at [ la,c,e Axial Locations 2-58 mm.mnwo xii
\
(1 LIST OF FIGURES (cont.)
Figure Title Page 2-30 Surge Line Local Axial Stress Distribution at [ Ja,c.e 2-59 Axial Locations 2-31 Surgegige,LocalAxialStressonInsideSurfaceat 2-60
[ ] Axial Locations-2-32 Surge (ige,LocalAxialStressonOutsideSurfaceat 2-61 l
[ ] Axiel Locations 2-33 Surge Line Temperature Distribution at Location [ ]"'C 2-62 2-34 SurgeLineLoga}'gxialStressDistributionat 2-63 Location [ ]
2-35 Surge Line Temperature Distribution at Location [ 3a,c.e 2-64 2 SurgeLineLoga}'gxialStressDistributionat 2-65 Location [ ] s 2-37 Surge Line Temperature Distribution at Location [ Ja,c.e 2-66 2-38 SurgeLineLoga}'gxialStressDistributionat 2-67
.,. Location [ ]
2-39 Surge Line Temperature Distribution at Location [ ]a,c.e 2 f 2-40 SurgeLineLoga}'gxialStressDistributionat 2-69 Location [ ]
2-41 Surge Line Temperature Distribution at Location [ ]a,c.e 2-70 2-42 SurgeLineLoga}'gxialStressDistributionat 2-71 Location [ ]
2-43 Surge Line RCL Nozzle 3-D WECAN Model #1 2-72 2-44 Surge Line RCL Nozzle 3-D WECAN Model #2 2-73 2-45 Surge Line Nozzle Temperature Profile Due to Thermal 2-74 Stratification
. - 2-46 Surge Line Nozzle Stress Intensity Due to Thermal 2-75 Stratification
. 2-47 Surge Line Nozzle Stress in Direction Axial to Surge Line Due 2-76 to Thermal Stratification me.. ween to
, LIST OF FIGURES (cont.)
Figure Title Page .
2-48 . Surge Line Nozzle Stress Intensity Due to Pressure 2-77 2-49 Surge Line Nozzle Stress Intensity Due to Pressure 2-78 2-50 Surge Line Nozzle Stress Intensity Due to Bending 2-79 2-51 Surge Line Nozzle Stress in Direction Axial to Surge Lira 2-80 i Due to Bending Showing Magnified Displacement 2-52 Surge Line Nozzle Stress Intensity Due to Bending Showing 2-81 Magnified Displacement 2-53 Surge Line Nozzle Stress Intensity.Due to Bending 2 S2 2-54 Finite Element Model of the Reducer 2-83 2-55 Thermal Striping Fluctuation 2-84 2-56 Stratification and Striping Test Models 2-85 'l 2-57 Water Model of LMFBR Primary Hot Leg 2-86 2-58 Attenuation of Thermal Striping Potential N Molecylar 2-87
- Conduction (Interface Wave Height of [ a '
2-59 Thermal Striping Temperature Distribution 88 ,
2-60 Striping Finite Element Model 2-89 4-1 Determination of the Effects of Thermal Stratification 4-5 on Fatigue Crack Growth 4-2 Fatigue Crack Growth Methodology 4-6 4-3 Fatigue Crack Growth Rate Curve for Austenitic Stainless Steel 4-7 4-4 Fatigue Crack Growth Equation for Austenitic Stainless Steel . 4-8 4-5 Fatigue Crack Growth Critical Locations 4-9 i 4-6 Fatigue Crack Growth Controlling Positions at Each Location 4-9 5-1 Average True Stress-True Strain Curve for SA316 TP316 5-20 Stainless Steel at 653*F .,
5-2 Minimum True Stress-True Strain Curve for SA316 TP316 5-21 >
Stainless Steel at 653*F secesssiane ta Xiv
LIST OF FIGURES (cont.)
Figure Title Page 5-3 MinimumTrueStress-TrueSgrgigCurveforSA316TP316 5-22 ,
Stainless Steel at [ ]
5-4 Sketch of Analysis Model for Vogtle Unit 2 Pressurizer Surge 5-23 Line Showing Node Points, Critical Locations, Weld Locations and Type of Welds 5-5 RCS Cooldown 5-24 5-6 [ Ja,c.e Actual Cooldown Due To An RCS Leak 5-25 5-7 [ Ja,c.e Actual Cooldown 5-26 5-8 [ )"'C Location 1 Cooldown System AT and Pipe 5-27 AT vs. Time 5-9 Vogtle Co'oldown System vs. Pipe Delta Temperature 5-28 e
3004s 4 31800 10 gy
_ - - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - - _ _ _ _ _ - ___-__A
SUMMARY
e This report presents the methods, data, analysis and qualification results for the Vogtle Unit 2 pressurizer surge lines including thermal stratification.
The report is divided into six sections. Sections I thru 6 cover the pressurizer surge line. Appendix A is a list of computer codes used in this work.
The sections are presented in order, reflecting the logical progression of evaluations and analyses:
o Section 1.0 " Introduction and Update of Design Transients" presents the methods and data used to update the design thermal transients to incorporate the effects of flow stratification in the surge line.
1 o Section 2.0 " Stress Analysis" describes the global and local stress effects of stratification, including striping.
, o Section 3.0 "ASME III Fatigue Usage Factor Evaluation" provides I the evaluation results of the ASME III fatigue life of the surge line subject to all design transients plus the effects of stratification.
o Section 4.0 " Fatigue Crack Growth" describes the methods and results of fatigue crack growth predictions in the surge line subject to stratification.
o Section 5.0
" Leak Before Break" (LBB) is a reassessment of the LBB
. evaluations to account for the effects of stratification. , l o Section 6.0
" Conclusions" summarizes the results of the evaluations of the effects of stratification in the surge line.
l l s se .Sonno xvii
o' Appendix A " Computer Codes" is a list and description of computer codes used in this-work.
The work presented in this report leads to the following conclusions:
(a) Based on plant monitoring results from [ )"'C Westinghouse PWR's (including Vogtle Unit 2) and flow stratification test data, the thermal design transients for the surge-line have been updated to incorporate the effects of stratification.
(b) _ The global structural and local stresses and loads in the surge line piping and support system meet ASME III Code allowables, with cupport H006 replaced by snubber and spring hanger. The maximum cumulative fatigue usage factor is [ Ja,c.e for 40 year design life, compared to the Code allowable of 1.0.
(c) Fatigue crack growth (FCG) analyses show that a postulated 10%
initial crack will not propagate beyond 35% of the pipe wall in 40 years design life.
(d) 1.eak-Before-Break (LBB) is confirmed for all loading combinations, including maximum postulated stratification, using the methods of ~
SRP 3.6.3 and NUREG 1061, Vol. 3.
In summary, based on the current understanding of the thermal stratification phenomenon, it is concluded that thermal stratification has very limited impict on integrity of the pressurizer surge line of the Vogtle Unit 2 nuclear power plant. The forty year design life is not impacted.
e me musse io xyjjj .
SECTION
1.0 INTRODUCTION
AND UPDATE OF DESIGN TRANSIENTS 1.1 Int.oduction r
1.1.1 System Description The primary function of the reactor coolant system (RCS) is to transport heat from the reactor core to the steam generators for the production of steam.
The Vogtle Unit 2 RCS consists of four similar heat transfer loops connected to the reactor vessel (figure 1-1). Each loop contains a reactor coolant pump (RCP) and a steam generator. The system also includes a pressurizer, connecting piping, pressurizer safety and relief valves, and a relief tank.
The flow path for a typical reactor coolant loep is from the reactor vessel to the inlet plenum of the steam generator (figure 1-2). High temperature reactor coolant flows through the U-tubes in the steam generator, transferring heat to the secondary water, out of the tubes into the outlet plenum to the suction of the reactor coolant pump. The reactor coolant pump increases the pressure head of the reactor coolant which flows back to the reactor vessel.
The pressurizer vessel (figure 1-3) contains steam and water at saturated conditions with the steam-water interface level between 25 and 60% of the volume depending on the plant operating conditions. From the time the steam bubble is initially drawn during the heatup operation to hot standby conditions, the level is maintained at approximately 25%. During power ascension, the level is increased to approximately 60%.
As illustrated in figure 1-2, the bottom of the pressurizer vessel is connected to the hot leg of one of the coolant loops by the surge line, a 16
. - inch schedule 160 stainless steel pipe connected to a portion of 14 inch schedule 160 pipe by a 16 in. x 14 in. reducer. The layout is almost
, horizontal, that is, sloped down toward the hot leg.
nu./mm in 11
The simplified diagram shown in figure 1-2 indicates the auxiliary systems that. interface with the RCS. Of particular significance to surge line stratification are the normal charging and letdown function provided by the -
Chemical and Volume Control System (CVCS), and the suction and return lines associated with the Residual Heat Removal System (RHRS). The former directly '
controls the RCS mass inventory and therefore affects flow in the surge line.
The RHRS is used to remove heat from the RCS and thereby influences coolant temperature and consequently coolant volume through thermal expansion and contraction. .
Other systems which affect surge line flow conditions are main spray flow supplied to the pressurizer from one or two cold legs and the pressurizer electric heaters. Spray operation does not significantly alter the total RCS mass inventory, but does reduce system pressure by condensing some of the steam in the pressurizer. The pressurizer heaters when energized generate steam and as a result increase RCS pressure.
1.1.2 Thermal Stratification In the Surge Line d
Thermal stratification in the pressurizer surge line is the direct result of the difference in densities between the pressurizer water and the generally ,
cooler hot leg water. The lighter pressurizer water tends to float on the cooler heavier hot leg water. The potential for stratification is increased as the difference in temperature between the pressurizer and the hot leg increases and as the insurge or outsurge flow rates decrease.
1 At power, when the difference in temperature between pressurizer and hot leg is relatively small (less than 50'F) the extent and effects of stratification I have been observed to be small. However, during certain modes of plant heatup and cooldown, this difference in system temperature could be as large as 320'F, in which case the effects of stratification must be accounted for.
)
A common approach for assessing the potential for stratification is to .
svaluate the Richardson Number (tables 1-1 and 1-2) which is the ratio of the !
thermal density head diametrically across the pipe to the fluid flow dynamic ,
h!ad, or m ..m = in 1-2
f* !
l !'
l L
{
Ri = gBDAT
' U where Ri =
Richardson number g- = gravitation constant U =- hot fluid velocity AT =
hot-to-cold fluid temperature difference L
. D = ipe inside diameter
( 8 =
coefficient of thermal expansion of water For a range of surge line flow rates from approximately 700 gpm down to a bypass flow of approximately 1 to 5 gpm and AT = 320'F, the Richardson number is greater than the value of 1 which is required to initiate stratification. Thus under this range of conditions, the flow has the potential to be stratified due to the relatively large hot-to cold fluid
, temperature difference combined with the low hot fluid velocity. To eliminate stratification-(i.e., Ri smaller than 1) a flow velocity of over 2.4 fps (approximately 700 gpm) is needed (figure 1-4). -
1.1.3 Surge Line Stratification Program The surge line stratification program for Vogtle Unit 2 consists of three major parts:
(a) Plant monitoring and update of design transients (b) ASME III stress, fatigue cumulative usage factor (CUF), fatigue crack growth (FCG) and leak-before-break (LBB) analyses (c) Confirmatory monitoring. !
I nu.ma "
1-3
Figure 1-5 shows the steps required to complete this program.
1.2 Update of Design Transients
- The method used to update the design transients for stratification is '
illustrated in figure 1-6 and is discussed in this section.
1.2.1 System Design Information The thermal design transients for the Vogtle Unit 2 Reactor Coolant System, including the pressurizer surge line, are defined in Westinghouse Systems Standard Design Criteria (SSDC) documents SSDC 1.3.
The design transients for the surge line consist of two major categories:
(a) Heatup and Cooldown transients (b) Normal and Upset operation transients. By definition, the emergency and faulted transients are not considered in the ASME III Section NB ',
fatigue life assessment of components.
In the evaluation of surge line stratification, the FSAR chapter 3.9 definition of normal and upset design events and the number of occurrences of the design events remains unchanged.
The total number of current heatup-cooldon cycles (200) remains unchanged.
However, sub-events and the associated number of occurrences (" Label", " Type" and " Cycle" columns of tables 1-3 and 1-4) are defined to reflect monitoring data, as described later.
In all cases, the surge line fluid temperature distribution is modified from the original uniform temperature to a stratified distribution with the maximum temperature differentials and the associated nominal temperatures (" MAX .
AT strat " and " Nominal" columns on tables 1-3 and 1-4).
nu.mius to 14 j
_ _ ~ --_ _ __ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1.2.2 Stratification E,ffects Criteria To determine the normal and upset pipe top-to-bottom temperature difference, "AT strat " (tables 1-3 and 1-4), the following conservatism is introduced. -
For a given event, the AT strat in the pipe will be the difference between the maximum pressurizer temperature and the minimum hot leg temperature, even though they do not occur simultaneously.
[
t ya,c.e 1.2.3 Plant Monitoring Surge line stratification data have been obtained from [ Ja,c.e Westinghouse plants, including Vogtle Unit 2. Figures 1-7 through 1-10 show the instrumentation configuration for four of these plants. The data was obtained by continuous monitoring of the piping OD temperature, displacements and plant parameters. The pipe temperatures were obtained from RTD's located on the outside o' surge line. Plant parameters were obtained from the plant i computer. Figure 1-7 represents the Vogtle Unit 2 monitoring configuration.
' 1 Temperature data from the Vogtle Unit 2 surge line were reviewed and compared f
l with [ Ja,c.e other reference plants. The data, in all cases, shows the I presence of stratification in the surge lines. The stratification observed is }
j l
m..mine in 1-5
(
assumed to behave under the influence of gravity and consequently will have an axial profile defined by'the slope of the pipe. .The data interpretation herein is an attempt to classify and characterize observed thermal conditions. ~.
There are two basic causes of thermal stratification. Thermal stratification
- can be initiated either by [ ja,c.e or the [
Ja,c.e This is the condition which this report addresses.
l e
e e
. \
,)a,c.e ,
'""'*** 1-6
i L <
l l
[
l l .*
ja,c e The establishment of a highly stratified condition is best described by I .considering the following typical transient example. This transient is based on an observed reference plant transient which was caused by the cut-off'of the RCP in the same loop as the surge line.
1 i Typical Transient
Description:
(RCP Cutoff figure 1-11)
[
e 9
O 9
ja.c.e 1
seessic3 nee 10
}.]
[
ja.c.e One interpretation of the cause and effects of the transient just described is as follows:
[
4 e
e 6
4 "a
l Ja,C,e I
a .mi n a in 1-8 l
[
l .=
I 1
l l
)a,c.e 4
The data are sufficient to characterize stratification temperatures in the pipe during critical operating transients and heatup-cooldown operation.
Also, the data are sufficient to verify that the pipe movements are consistent with analytical predictions, within an accuracy normally expected from hot functional and/or power ascension tests, as discussed in section 2.1.
The monitoring of plant parameters is sufficient to correlate measured temperature fluctuations to changes in operation. In particular, it is apparent that temperature fluctuations are due to flow insurge (into the pressurizer) and outsurge (out of the pressurizer) which in turn are due to differential pressure in the system. While a simple quantitative mechanistic relationship between plant operation and insurge and outsurge has not been found, the data indicate that a steady state stratified condition can be
, altered by any of the following events:
9 8""'"""
1-9
a) Expansion of the pressurizer bubble b) RCP trip in the surge line loop ,
c) Safety injection i
d) Large charging - letdown mismatch l e) Large spray rates in light of these observations, the update of design transients is based on plant monitoring results, operational experience and plant operational procedures. Conservatism have been incorporated throughout the process in the definition of transients (cycles, AT) and in the analysis, as described in the report.
1.2.4 Heat Transfer and Stress Analyses The correlation of measured pipe OD temperature to ID temperature distribution is achieved by heat transfer analysis as well as previous experience with flow at large Richardson' numbers (Ri 1)(figures 1-14and1-15).
These analyses and test data available to date show that a stratified flow condition,[
]a,c e is a proper and conservative depiction of the flow condition inside the pipe at large AT and low flow rates (Ri>1).
An additional conclusion from the heat transfer and stress analyses is that
[
3a,c.e 1.2.5 Stratification Profiles Table 1-5 summaries the major stratification profile characteristics. The monitored data shows a consistent axial temperature profile along the
- horizontal portions of the [ ]a,c.e surge lines monitored.
mm.mine in 1-10
1 The axial temperature profile is a function of the geometric characteristics of each line. Each line monitored showed a definite relationship between l
,, axial length of stratification and slope of the line. Figure 1-16 depicts a !
typical axial stratification profile. Note that the actual length of
, stratification is dependent on the volume of the insurge. Low volume insurges tend to stratify a shorter distance along the line. Similarly large volume insurges stratify longer distances provided the slope of the line is low enough. As the slope increases, smaller sections of the line will be affected by stratification. The slope also affects the type of stratification <
interface. As the slope is increased the flow characteristics of the interface are affected. There are two basic interface types; one which is narrow and highly defined is characteristic of laminar flow. The other is i characteristically wide and a product of turbulent flow. The flow becomes turbulent at the interface when forced to a higher lvel than gravity v:ould normally dictate. Flow velocity is also an integral part of this relationship.
Figure 1-17 shows a cross section of the pipe with the various hot and cold fluid' interface levels created by a laminar flow or static steady state '
. conditions.
~
, The Vogtle surge line data showed a definite change in flow conditions after a rise in the line of one diameter. In addition, the flow restriction created by the reducer enhanced this effect. The effect produced by these geometric differences was the transition from laminar flow to turbulent flow during the dynamic portion of an insurge. This means that only the portion of the line up to the reducer sees the discrete interface between hot and cold fluid that is associated with laminar or static flow conditions. Beyond that point enough turbulent mixing occurs to consider a reduced AT across the diameter of the pipe. The enveloping value determined for this portion of the Vogtle surge line was a 35% reduction in the pipe AT (i.e. temperature at the bottom of the pipe was T Hot - 0.65 (THot -TCold). Note, the 35%
reduction used was the worst case transient observed; all other transients showed larger reductions in pipe AT. The axial profile developed for the Vogtle surge line is shown in figure 1-18.
l .
..=...
3 33
)
1.2.6 Development of Conservative Normal and Upset Transients j
~
Transients in the surge line were characterized as either due to insurges or outsurges (1/0) from the pressurizer or fluctuations. Insurges and outsurges are the more severe transients and result in the greatest change in tempera- 'i ture in the top or bottom of the pipe. An insurge may cool the bottom of the )
pipe significantly, to very close to the temperature of the RCS hot leg.
Conversely, an outsurge can sweep the line and heat the pipe to close to the temperature of the pressurizer. The thermal transients are shown in figure 1-19.
Fluctuations, as opposed to the insurge outsurge transients, are caused by relatively insignificant surges and result in variations in the hot-cold interface level. These variations in the interface level do not change the overall global displacement of the pipe and hence are modeled as changes in the depth of the interface zone.
The redefinition of the thermal fluid conditions experienced by the surge line ,
during normal and upset transients was necessary in order to neglect the -
indirectly observed fluid temperature distributions. These redefined thermal fluid conditions were developed based on the existing design transient system parameters assumed to exist at the time of the postulated transient and the knowledge gained from the monitoring programs. The redefined thermal fluid conditions conservatively account for the thermal stratification phenomena.
Several conservatism were introduced in the redefined normal and upset thermal transients (tables 1-3, 1-4, 1-6 and 1-7).
[
ja,c.e 1
(b) Full stratification cycles are assumed for all transients, except for steady state fluctuations, unit loading and unloading, and reduced '
temperature return to power, where level fluctuations are sufficiently conservative based on flow rate and observations.
- nu.ma . in l 1-12 1
.- --A
(c) The temperature of stratification was based on the minimum hot leg temperature at any time during the transient (for bottom of pipe) and the maximum pressurizer temperature (for top of pipe). Figure 1-20 shows a case where this resulted in a very conservative 260*F stratification transient although the maximum temperature difference at any point in time was about 50'F.
(d) The current number of design cycles of each event is unchanged.
The normal and upset transients modified to account for the stratification phenomena are listed in tables 1-3 and 1-4.
1.2.7 Temperature Limitations During Heatup and Cooldown The maximum permitted temperature difference between the pressurizer and the hot leg for Vogtle Unit 2 is less than 320*F. Therefore the maximum possible top-to-bottom temperature stratification is 320'F.
With the RCL cold, the pressurizer pressure (and therefore temperature) is limited by the cold overpressure mitigation system (COMS). ~
Practically, plants operate to minimize downtinse and heatup cooldown time, when power is not being generated. The times at large AT are therefore reasonably limited, as discussed later.
1.2.8 Historical Data Since not all heatup and cooldown parameters affecting stratification are formally limited by Technical Specification or Administrative controls, it is necessary to reconsider plant operational procedures and heatup cooldown practices to update the original heatup and cooldown design transient curves of SSDC 1.3 (figures 1-21 and 1-22).
4 m..maiune 1-13
To this end, a review of procedures, operational data, operator experience, and historical records was conducted for [ Ja,c.e Westinghouse PWR plants (table 1-8). Similarly, operations procedures for Vogtle Unit 2 were reviewed .
and heatup cooldown curves developed (shown in figures 1-23 and 1-24).
a The heatup and cooldown operations information acquired from this review is summarized in tables 1-9 and 1-10, [
ja c.e The information is divided into heatup and cooldown tables and diagrams. The diagram presents the pressurizer water and hot leg temperature profiles versus time. The various phases of the process are identified by letters along the diagrams' abscissa and in tables 1-9 and 1-10.
1.2.9 Development of Heatup and Cooldown Design Transients With Stratification As described above, the database of information used to update the heatup and cooldown transients included the following:
a) Typical heatup and cooldown curves, as developed from review of procedures, operational data and operators experience. ,
b) Transients as monitored at [ Jac.e plants c) Historical records of critical heatup and cooldown temperatures The heatup and cooldown transients are presented in the following sections as
[ )"'C and in similar fashion to the normal and upset transients. Table 1-11 gives the I general characteristics of the two typss of transients observed. -
The heatup cooldown transient labels have the following logic:
- 1. Transients H1 through H12 correspond to insurge or outsurge transients postulatedduringheatups(H). ,
i se .mmes in 1 34 i
1
- 2. Transients HFIA through HF3 correspond to fluctuation transients postulated during heatups (HF).
- 3. Transients C1 through C9 correspond to insurge or outsurge transients -
, postulated during cooldown (C).
- 4. Transient CF1 represents the fluctuation transients postulated for cooldowns(CF).
1.2.9.1 [ la c.e Transients i 1
A) Monitoring Transient Summarv !
For a given monitored location, plots of temperature difference versus time were generated (figures 1-33,1-34,and1-35). Two parameters were plotted, the pipe top to bottom temperature difference (labeled " surge line") and the pressurizer to hot leg temperature difference (labeled " system"). l It is clear from figures 1-33, 1-34 and 1-35 that for the observed heatups,
[ ja c.e
. while Vogtle Unit 2 (figure 1-33) had very little thermal transient activity.
For conservatism, the envelope from measured transients in all plants is ;
applied to define the transients, even though there was only a minimal number f of these transients observed at Vogtle Unit 2.
Figures 1-36 through 1-46 show some actual RTD readings top and bottom for the Vogtle surge line during the power ascension test. The figures are typical of the data obtained by the Vogtle Unit 2 monitoring program.
B) Faticue Cycles
,. The fatigue cycles were obtained using the technique illustrated on figure 1-47, which reduces each transient to its temperature range, rather than its
, absolute magnitude. Table 1-12 is a summary of the approximate magnitude of s .misse in 1-15 1
1 each cycle shown in figure 1-47. The heatup and cooldown design transients with stratification used in the piping qualification conservatively accounts ,
,)
for the mean stress effect. Figure 1-48 provides a single heatup interpretation of the design transients. Note the relative severity of the -
design transients by comparing them with the actual thermal activity observed at Vogtle Unit 2 (figure 1-33) and the worst case plant (figure 1-34). [
l l
']a,c.e p$gure 1-49 illustrates the difference between the design transients and the transients observed at plant A (which envelope the Vogtle transients).
C) Strength of Stratification Plant monitoring data indicate that for the various transients observed the AT in'the pipe (top to bottom) is not as large as the AT in the system (pressurizer to hot. leg). The ratio of AT in the pipe to AT in the system .
will be referred to as " strength of stratification".
- j I
)a,c.e D) Number of Stratification Cycles (table 1-14)
Plant monitoring data indicated the significant events which could occur {
during a given heatup. [
nu.mine in 1-16 I
^
.. .. . . . )
[
ja,c.e E) Maximum Temperature Potential The key factor in thermal stratification of the surge line is the temperature .
difference between the pressurizer and hot leg (section 1.2). This tempera-ture difference is clearly maximized during the heatup and cooldown, when the plant.is in mode 5 cold shutdown (hot leg less than 200'F) and the pressurizer bubble has been drawn with the reactor coolant pump running (pressurizer temperature larger than 425'F). [ -
1
- l. ja.c.e
.- F) Final Cycles and Stratification Ranges t
ja,c.e nu. mum in 1-17
[
e o
e e
4 e
O ja,c e 1
J aw.mine in 1-18 I
Example:
p [ !
l ja,c.e G) Cooldown Transients The procedure used in heatup is applied to develop transients for plant cooldown. [
ja,c.e
~
1.2.9.2 [ Ja,c.e Transients
[
ja,c.e
-1.2.10 Striping Transients Mean stress effects are included in determining the usage factor contributed by thermal striping. Fatigue cycles like those shown in figure 1-47 were not used in the development of the striping design transients. [
3a,c.e
= =.m u m io .
1 3g O
l
[ .
Ja,c.e It should be noted that each striping transient cycle is assumed to initiate a discrete hot ,
~
to cold fluid interface that will be attenuated with time (see section 2.3 for l discussion). Figure 1-50 shows the relative magnitude and frequency of the -
striping transients for one heatup or cooldown with respect to the system AT (PRZT-RCST). The highest pipe AT (pipe TTop pipe Tbot) bserved during heatup never exceeded [ ].a,c.e However, the design striping transients consider [ ]a,c.e transients at pipe AT's greater than g 3a,c.e Striping transients use the labels HST and CST denoting striping transients (ST). [
3a,c.e 1.3 Conclusions Design transients were updated to incorporate stratification. The transients ~
were developed to conservatively represent the cyclic effects of ,
stratification. To illustrate the margin included in the development of heatup transients, a simplified fatigue factor calculation is provided in figures 1-51 and 1-52. This comparison indicates that the design transients have a factor of conservatism of approximately [
ja,c.e l
me,m3= ie 1-20
_ __ __ _ _ _ - - - - - _ _ _ _ - - - - . - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -~--
1 I
TABLE 1-1 l IMPORTANT DIMENSIONLESS GROUPS FOR SIMILITUDE I* ,
IN HYDRODYNAMIC TESTING I
)
(
l l
Peremeter Symmel Dennmen
.. w omenee ,
Weoosenfrcion. t 04P 2eV'L P'veaure t>rce, cone force rector 2 Coveenon nurreer e se, .7,ta v' beneure of'orencemome torce 3 Reynees numeer me pVD .
ineme forcevecous W 4 Sueuner nurmer Sr 4V vonos sneanng trumancy come tree 5 weeer nummer we pOV8 e reme tweeeurmeeensen mne 6 Feme nurneer Fr V8 pD morse so rcegrerey toree
- 7 Asterceon nummer Re AsgD'aV' Sevency toramenene force theastec Prowse nurreer) 8 Euser nummer Eu AP'a V' preneure forcemeros force
, 8 Prense nummer Pr pCA Momerewn eewaarey'tnormel e#usarey to Pecses nummer Pe pVDCS Corevectres near renosor-(Ae a Pr) cono6came mass wireses 11 Greenaf awreer Gr L 8a'pSATim 8 Suoyancy torcervasous force 12 Reytogn nurreer Me 188s CgAar,,4 -
(Gr a Pr)
@ ENCLATUfE.
C = spacec nees p = acceeremon of yovey a = conomy P = prenews a a setece tensen P. = sets #tue preenwo a a merme consacovey 7, = Aus venor preneure
- = voswnstne esonneen asemcent LD = charecenets omeneers AT = nual tempersaare snenge V = Rue wesocoy a'
.cnon snocong treassicy as = vousesy O
m..mius io 1-21
TABLE 1-2 [ '
STRATIFICATION POTENTIAL BASED ON RICHARDSON NUMBER ,
e Stratification potential exists if Ri > 1 a,c.e l
. .i 3542s-01268910 1-22
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ .- J
WLSTINGHEUSE PR!PRIETARY CLASS 2 TABLE 1-3 SURGELINE TRANSIENTS WITH STRATIFICATION HEATUP (H) AND COOLDOWN (C) - 200 PLANT CYCLES TOTAL a.c,e s
t O
' f l
e e
i 3004s/0320ee 10 g.g l
. 1
- , - - - - - - . - - , - - , - . - - - - - - - - - - , , - - - . - - , - - - -r---.- -
O # Mef g .) g gg g g TABLE 1-4 SURGE LINE TRANSfENTS WTTH STRATIF2 CAT 20N NORMAL AND UPSET TRANS]ENT LIST a,C,e r
O 4
W 9
e e
b O
l O
S 1
l u
TABLE 1-4 (CO- 1, )
SURGE LINE TRANSIENTS WITe STRATIFICATION NORMAL AND UPSET TRANSIENT LIST a,C,e e
4 a
G e
e W
9 I e
==.asme in 1-25 r
g -__ - - _ . _ . _ _ _
TABLE 1-5 STRATIFICATION PROFILES
[
p 3a.c.e ,
~
4 i
l 3664s/031*As.* 0 1
TABLE 1-6
, HEATUP - C00LDOWN TRANSIENTS o Transients Were Developed Based On:
Typical Heatup Cooldown Curves Envelope (Plus Margin) of Events (Transients) Monitored Historical Data on Temperature Plateaus
[
O O
O O
, ja,c.e e
e e
m wo - o 1-27
1 4
TABLE 1-7 DESIGN TRANSIENTS WITH STRATIFICATION o Heatup and Cooldown Combined With Other Events e
o Design Transient Criteria
[
I ja c,e o Input for Local and Structural Analysis Defined - Plus Nozzle 4
o Striping Transients Defined to Consider Maximum Stratification Cycles Regardless of Range .
-. 1 I
mu.mim in 1-28
l TABLE 1-8
. OPERATIONS SURVEY I
o Summarj of Plants Surveyed NO. OF YEARS OF OPERATION PLANT LOOPS (MAXIMUM) 1
, [
1 ja,c.e o Reviewed Typical Heatup Cooldown Process o Reviewed Administrative / Tech Spec Limitations
'o Reviewed Historical Events and Time Durations o Developed Heatup - Cooldown Profiles
]
m.mim.io 1-29
l) 1Ill l
I e.
c.
a 9
E S
A H
P H
C A
E R
O F
N O
I T
A R
U D
Y
- R E AW l
l ,
l eT l
9 U
- S D 1 N A A
- E T ,
L A E B D C A N T P E U R T E A F E F H I D
P ll l
E T
)
G E
L T
O H
R Z
P
(
0 1
9 8
5 1
3 a 0
s 4
6 6
3 a
e 9ao t
l llllllllll l llll
- liIjlIllli1 -
i!l l i l I
)
u O.
C.
- a h
E S
A H
P H
C A
E R
O F
N O
I T
A R
U Y D R
, A E M N u I I n
0 uT 1 S
- - D 1 A N T A E A L D E B C A N N T W E O R D E L F O F O I C D P
N I
E T 4
)
G E
L T
O H
R Z
P
(
0 1
9 8
5 1
3 0
s 4
6 6
3 A
w9 (Dw
~
TABLE 1-11 TRANSIENT TYPES s
ja.c.e l e
e i
ein ww.-ema io 1-32 l
TABLE 1-12
SUMMARY
.0F FATIGUE CYCLES FROM [ Ja,c.e Cycle DeltaRange(*F) Cycle Delta Range (*F) a,c,e NOTE: The delta range represents the relative severity (AT) of each transient following the fatigue cycle approach.
e
+
. m.-osim io 1-33
WESTINGHOUSE PROPRIETARY class 2 TABLE 1-13
SUMMARY
OF PLANT MONITORING HEATUP/C00LDOWN TRANSIENTS WITH STRENGTH OF STRATIFICATION (RSS) t ja,c.e t ja,c.e t 3a c.e 00 served Observed 00 served <
Cycles RSS(1) Cycles RSS (1) Cycles RSS (1) a,c.e l
l l
OBSERVED TRANSIENTS GROUPED .
BY SIRENGTH OF STRATIFICATION (RSS) INTERVALS No. Observed % of RSS Cycles Total
__ _. a,c.e Note: The No. of groups is reduced by combining the intervals .70 < x .
< .8 and .60 < x < .70 % of total = 3.4% for the interval-
~
.60 < x < .80-w,m=A in 1 34
WESTIN!H3USE PROPRIETARY CLASS 2 -
TABLE 1-13 (cont.)
SUMMARY
OF PLANT MONITORING HEATUP/C00LDOWN TRANSIENTS WITH STRENGTH OF STRATIFICATION (RSS)
RSS J % of Transients
- a,c.e RELATIVE NUMBER OF CYCLES OF STRENGTH OF STRATIFICATION (RNSSj)
AFTER GROUPING RSSj RNSSj .
Strength of
% Transients (2) j Stratification (1) a,c.e Nomenclature:
(1) Strength of Stratification (RSS)
(2) Relative Number of Cycles of Strength of Stratification (RNSS) e*
m .mne in 1-35
i
. TABLE 1-14
SUMMARY
OF MONITORED TRANSIENT CYCLES (ONE HEATUP) ,
Plant No. of Cycles I
a,c.e l
Avg. Monitored Cycles: 15.75 = x; Selected No. of Design Cycles: 36.5 (added 30% to observed maximum number of-cycles, plant A)
DESIGN DISTRIBUTION APPLIED TO MAX NUMBER OF -
TRANSIENTS EXCEPTED MULTIPLIED BY 200 HEATUP OR C00LDOWN CYCLES No. of Transients RSS a,c.e i
Total .\
{
seu.mairw ie 1-36 -
l TABLE 1-15,
SUMMARY
OF % TIMES AT
,. MAXIMUM TEMPERATURE POTENTIAL RMTP g l
, _ HEATUP l'
8.C,9 l
.4 9
e e
ee u m.-on e in 1-37
TABLE 1-16 SURGE LINE TRANSIENTS - STRIPING FOR HEATUP (H) and C00LDOWN (C) .,
Label Cycles AT,,x (*F) ,
a,c.e I-4 m
9 m
a e
e I
m.-nwo 1-38
M M o o ,
u o tQ ,
I
&s
\
i, M
w
~ -
M
- Y - G
@~ '
b
,s s.
D v '
v terv Sw/gy V a w
w w
- Simplified o'*9 Yam of the RCS I'9UGO1~1.
m-eum io 1-39 f i
_ _ - _ - _ - _ _ - - _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ .1
e, g
- y 3
E',
- )
p F o
=hg] o c '
e L o
n l a
t c s i sM n p y
eR T oq H, : (
e e m e
3 I
e s*
- wL a r
e*
d ee g e c s.
e a t
O ne i F l S* (, m o
n D
w s )
o l
yS F
eC r > [ )
s oV h c m MSC
- t
( ~ v e ,
c t s
a
= s MMN L
J f
1 t
,t o m
w S t
y u n o a s
e l
o
)
S e o
' .R L C g
o c
,o 'R H
' r o
t e s,
- en (h t
"*Rs oy e c Ht( .e a esy e
=, Hs R r
o ese t 2 c
e c oe J_ - - 1
=$
- nv k e r
u g
gg i oo . F tc o w ,y o
CtT e
%tM 4
k -
- e 3
'i
- 8 .
!l l I
Aux. Spray
- it ,
. 6 '
1 N$
+- Spray From l
Loop CL V,e,
- _: +- Spray From Loop CL Surge Line Connecting
-
- to Loop HL 1
.- l l,
Figure 1-3. RCS Pressurizer
.. . , - n 1-41
e.
c, a]
i
[
= '
P y
e.
t i
c o
n d d
l _ U c, e ._ _
i u3 a V _
l F
]
__ __ ob d b 7
l l
E
{
/
/ C" t
i n
= ndl a
n r
y _ . n o g c t e
t t i
_ _ aT a c t P
o _ _
._~S l
- e _ _ - n o
. V i r= t a
- e. .
i za u
r y k ' 's i
f i
c t
s / - a r
e ' t P
f s]Ov.ItI889 r
m[
o-r ,
IIeI8{
II tI 8 { \
l F
f S
w o
o l
F t
w %OWIItI8I o1 I' t i
e a
m o t s
H E 4
1 e
r u
g i
F
'0 t 1
l
- 1) :)l ]1l1 m
a
. r
- g o
r P
n o s . o yt r e i i s l e t c
l ui n i
a t aWssm n sAe r c nAeeieh e r e nwpsDT i
f mg ei i
l Ce- s
- - . - a u
D Q d
n a
I I
I s E W M W S s
s st e A n se t a nr es tr p n
o eT r i 5u i r
ug n Et r t Ci s Mo sp a
c e Ae i D e e f f
e i t
s a a c, n r r I t T" S t
- a. c
. e _- e H n
' i s
s n -
L n s f e e gr e o n e on n g .
r n o o Q',
~
sf est Dt na oi t s si s ey I
I I i Et n op i s a i
t . W e
a S
r u
dek wist i
- u. nl ia t n I
Mso 5kc ek ti I s l i c r one
- dar eA Al a i
l a - n e g ai u _ a z ue M s f
I yTsr t s
e w Qws y
s
.Q _
p y
o r
i u
s r
nk s on = e r
it e ah P i
I d 2 kw i
t a
=
n t t
rd i kn i n
sm o U C
e W
t e
e l
t
- r f s
9 S O 9 R V t
W
. f 5 S
1
. e
- r u
g i e s F
a
,m e
w m
1
$YSTEM Of SIGN MONITORED INF0aMAfl0N DATA III (I) w STRAfiflCAfl0N WEAT TRANSFER IPPECT5 CRifthA 3Taall A4&Lv115 (Il (4)
I BrCoe
~
MI570aJCAL ~
DATA l
l l
TaAmsasNTs (10) e Svent.Desegn e cydm.Ds ,a . men.w w e Trent.entType*Strwtwos e Dn.,a . men,ww l trea ec.w l
Figure 1-6. Transient Development Flow Chart -
M **e'01244010 1-44 l
l l
i 1
1
~ - \
ace o s l l
l l
y
. Figura 1-7. Vogtle Unit 2 Pressurizer Surge Line Monitoring Locations l
l w..mme in 1-45 L-__-______-_-_-_---_-_-- --
- - - . - - - , - - . - . - - - - - - - - - - , . - - - - - , - - - - - - - - - - - - - - - , , - - - , - . - . - - - . .- - - --- - - - - - - - - - - - - , - - - - - - - - - - - - - , --.----,---,-------------------------------.r----,.- - - - ----,- - - - - ---- -----------------7-----w,- - , - -
O.
O.
C .
O V
N C
O se-abh 80 8,
C ops b
.O a.e ore C
O E
c
.e L
3 M
L
.N ,-
b
- 3 e
O .
6 CL,. .
U.
N m
f w
6 s
e=4 O 1
% \
3
.O -
b
$
- i l
\ ~
e
- R
- A E
1-46
-)
ll l1 l1. iii 1 ilji i! .IIIl4 i llJ e,
, c, a
s n
o i
t a
c o
L g
n i
r o
t i
n o
M e
n i
L e
g r
u S
r e
. z i
r u
s -
. s
- e r
P e,
c, a
J
[
9 1
e r
u g
i F
9 1
9 9
7
. 2 14 s
2 6
9 3
weAM l;l ll l
.0 U.
0 GO C
O ee-d=0 85 8
.c-b O
s*
er=
C c
ac=
A b
3 Vb b
W N .
er-b
- 3 en so W
- b
- A We U.
Y m
W e
O M
i W
W b
3 e
m b
?
I t
1-48
- o. ..
c, -
a -
s t
n d m e n i E s -
n e a f r a T S f
f l e
o z
- z t o u N C
L p C m R u
P m o
t r n F a
l o '0
- o1 C
y r l o e t t
- c a a m e i R x o
. p r
1 p 1 A 1 n o
e i r t u
g c a
i o F L 7$
U.
U 9
T C
LJ B
4 Vb W
N
, N O
2; s
U CE
.ee C
up N
C C
L
>=
W W
O e
and 3
U .
e b
ou
- C 9
O o
U L
O
.e.a U
m C
CK O
.N e i
1 1
L 3
b f
~
.t J:
E .
1 1-50 i
l l
l
a,c.e
-9 3
9 1
e l
l l
l l
l
- Figure 1-13. Transient Typical of RC Pump Cut-off 1-51
i! 1Illi e,
C, 3
)
e p
i P
) D s I e h c
e r i n
g 5 e 6
(
D
( l e
i f
0 o r
l e P e
. g r u
n t a
A r e
p m
T e
) .
F 4 1
( 1 e e r
r g u
t u i F
a r
e p
m e -
T i,
n o
r m
h l liI( 1l
0 O
,* ~
A I
C e w c Y
m
.E.
T 6- O CL 2 E i
@ r H e m h m %
e E' C -
E
.C C 2 e 8
~
to E T, c
.R g O 8
e s V.
a
=
. ee-g emm.
u.
C
. 9 I
=
R 3
E 1-53
a e
I 99 Z I 8
'7 3
C 000 m
5 J
e j h ;
m o \
e 1 4.
E ,
T C E \ J /
N O. ) i
}
l 2 ,
=
R R
E 1-54
I
- a,c,e i,
1 e Figure 2-17. Surge Line Hot-Cold Interface Locations 3M24/012400 to 1-55
W U.
l N
oa C
,b, 4
h E
u 6
8 4
8 '
a -
u u -
ee k
2O U-S O
Z Y
G b,
a E
I l e .
i, E
l 1-56 L.
9 a,c,e d
9
. Figure 1-19. Typical [. Ja,c.e Temperature Profiles wu.m- in 1-57
a,c,e I
. 4 I
1
" 4
.\
Figure 1-20. Inadvertent RCS Depressurization (AT = 260*F in Surge Line) l 4
m..mism in 1-58 l
iIl1 e,
c, a
p u
t a
e H
) e s
r d
M o _
u e o l b
. H
(
b B
u e m a
e i
m t S
T .
1 2
1 e
r u
g i
F
)
F
(
e r
t u
a r
e p
m e o i
T- m i
m.
m TlB l llllllI
l ll l
l]
e, c, -
a i
n w
o dl o
o C
e d
o
) M s
r e u l b -
o b u .
H
(
B m
a e e -
t .
S i
m .
T 2 2
1 e
r u
g i
F
)
F
(
e r
t u
a r
e p 10 9 .
m 8 5
1 e 3 0
/
T 4 6
6 3
s
- 8 i
1lj 1 1 e.
c, a
s 2
e.
c, a ,
1
[
p u
- t a
e H
3 2
1 e
r u
g i
F o
0 1
_ . 9 8
5 1
3 0
/
s 4
6 8
3
~ . o, ea-
e h
J.
O
\
C.
U.
N m
e 0
1 O
E .
O *
"O O
O U
Y N
t M
C
. L 3
.C1 b
e l
l
? .
I i
1-62
1 1 l ll lllIi i ,:
lI o -
m m
e, -
c, a
g l e K
g l i g l I J
g l J e, I
c, a
]
Eg a! e GH I ' ~
M F
[
I p T u t
a e
H e! I F
5 2 _
1 _.
e _
r u
g _
i F
l 8 C,E.
BD
.. - g l l A
O w
y 0
0 4 m2% 0 0
0 1
0 1
9 i
- t. lr545(Ioh a
te L t 8
5 1
3 0
/
s 4
6 8
3 iO
}jl( l!!ll ii
l ;! 1 1ljl1l lll 1
e, c,
a l l H l l
'"o FF e,
c, a
l E
I
[
n T w ,
o d
l o
o
- C ,
6 2
1 e
r u
g i
F l l F
1 l CDE 1
1 i
l B A
M6 0 0
0 0
4 -
0 0
2 0
0 1
O k.
o s
m s
e ms e
m T
)
l 11 j
))1' l)l' fi l il' l[
j
,i, w
6 4
er -
C r
B I 8 e.
E j c,
aj D g 8
' e T g
[
p u
t i f I a -
l f e
' i l
t f
H f I '
E .
7 2
I 1 e
r u
g i
F i
BC 4
- eg I A
0 0 0 0 _
0 7
- 0 4
0 3 y1 0 0
- k. WE344EsLIla~
- a tI tf s
n
- a e
s a
wAnu Ill i lllft1il
i' 'l ifl fl\ lfi JlIl'll>
e, c,
a
- I i '
H 8 I '
G gf' F e, gI' '
F c, aj I
E T
[ .
n .
w o
d l
8 l , F o .
1 l ,
E o . -
C 8
2 1
e r
u g
i F
s! ' CD e! '
B s! '
A 0 0 0 0 0 0 0 O 0 0 0 0 0 0 0 7 6 5 4 3 2 1 oE3D<EdEINb k~ t I I is m,
m wEm I1 lll'II iIil1,l,')Il)l lf i II1)Ill 1lll IlI i l lI -l' .
,I iIl'l Ill, cy C
r G
s i l g I l n,; .
. 01 I l r
e, e iii E c.
E ay M
I T
eei o
8 'i c [
p u
t a ,
. e
- H 9
2 1
l I B
e r
u g
i F
l i
^
O 0 0 0 0 0 0 0 0 0 0 0 0 7 6 4 3 2 #
. r3E4 E
aIa n
_ o i
e s
i m.
m a
w.O l}llII(llI ! l'
l l ill!l!l1: i! i ,l er C r r
B e.
c, a
l E i i H
I T
[
n a w
o ,
d l
o o -
C .
0 3
I I I FG 1 e
r u
g I I I E i
' F I I I D
I I I BC I I I A
o 0 0 0 o O o 0 0 0 o s 4 3 2 i l
L. oraF<$n.IoF it t 0
1 8
8 S
t3 0
/
4 s
6 6
3 J. _
illl 1l llJ e.
c, a
I 1 K
I l i J I l I l
I I i Gi C 1
t 8! e F p e
t a
E i t
e lI i D
1 3
I i C 1 e
r u
g i
r i I D
I I I A
0 0 0 0 0 O 0
7 0
6 0
4 0
3 g1 0
- k. tt d
dr3F46 ieF .
rm*
1 ;:!l l ll il1;)l ll;Illl lilll I i4 t
e.
c, a
e, c,
a J
e it i H
E I M n '
I w
T o ,
d l
o o
- C .
2 3
i I FG 1 e
r l I E u g
i F
i I CD I I B
I i A
0 o 0 0 0 0 0 O 0 o s
0 0 0 3
0 2
0 7 5 4 1 g' wra6<6eId-t*
0 1
9 8
4 2 '
1 0
/
s 2
6 5
3
-4o ll
_ - _ - = - _ - - - - - - - - - - - - - - - - - - - - - _ - - - - _ - - - - . -- - - - .
u.
m I
I t
8.
2 CD .
oo a hN
- E a #
%=
O 4E r !
w I
~
~
H i
o b
e in c
l
.. i i
?
l [
l 9 .
d 930 BJN3HBddIO dWB1 i I 1-71
e, c,
a .
8, r
)
. s y
a D
7
(
p u
t a
e H
1 n
) i o
S t a
R c ,
U
]
o L
(
M e E
- l I
T
[
4 3
1 e
r u
g i
F I'
000000 0 0
_ 0 1
e 006420 3 2 5 0 0 5
O 9 8
S t
i 3 0
/
s Y 3 4 5 a. f 4 F d o 4 6
9 3
TM
I i
i a,c a e 325 300 27'5 F 2tio 225 200 4 175
. CC 1
f$ 150 125 W 100 50 25 0
~
TIME (HOL: )
. Figure 1-35. [ Ja,c e Location 1 - Heatup (4 Days) w.mine io ,
______ _ _ _ , _ _ _ _ , - - - - - ' ' ' ' ' ' " ~
O
.U.
e OE 8
M 4
.m W
.Nm 4
L a
M
.c-8, .
L 3 .
M N
u
- ep
- C D
m 0")
i m
L 3
On e
b S
u osa) suramens.t l
1-74
i !I]iIlill I
e.
c, a
n i
o t
a c
i f
i t
a t
r S
e n
i L
~ e g
r
, u S
2 t
i n
U l
e t
g o
V 7
3 1
e r
u g
i F
C iUv wrM$n.2N t
7M -
if i!lj!
t.o ~
4 W
t C
C-M U
N w
+0 L
a W
c O
L .
D N
op
- C
- 3 m
e e-4 G
L 3
Da b
E Cd '030) 3WruYW3dW21 1-76
- e e
m e
e o
C O
U e
U h
=e M
4
.L a
M
.cm O
' O L
- D M
N
- a G se C
D C
. M I
M
@ j L
3 D
op b
- E
. u cao) zuruwunn g 1-77 i
U e
M e
4 4
e C
O M
U ope M
er=
abJ M
L
.be M
S ep c
u .
3 .
W N
a s em ,
C 3
e ebO O
v 4
M G
L 3
CM b
l E s Ia G oaa) suruvwsdnal l
1-78
0 O
e l e*
f'
- e. . .
C O
80
.U-
.Nm abb 85 L
a M
W c
en O
u 4 3 M
N e
- . a
,, w C
3 e
etel M
V i
e=0 L
3 O
b w
e t I
G '030) swruvwadn..u i l
1-79
N e'
U.
o O
4 l
c O
M U *
- e
.Me M
4 L
a M
W
.c-u-
3 +
W N
a era s c
3 W
abd N
v 0
- A W
L 3
m
.e b
E s I
a Cd oso) awruvwadnaa.
l 1-80
we U ,
e e
e W '
r C
C ehmI 4
U e-
.N.
c ehm3 40 L
.s a M
W
'1
.C- j A
- E"
=
. M N
.se
- er=
C ll2 G
".s.a ll>
O v
l e=4 G
L 3
CD b
l s=
l O G oxo suruvp.mn l 1-81 l J
F 0
U.
N 4
s C
O abJ N
.U -
N
.c=
abJ N
b a
M
.b -
A u
3 '
M N 1
.O -
C
- 3 .
W M
T T
l M
W L
7 b
O l
f:: s o Q 'D30) 3WfuYW3dW21 1-82 I
i
jlllll:l1 ll' 1i1 4i llil e.
c, a
~
s n
i o
t a
i c
f i
t a
t r
S e
n i
L e
g r
. u S
2 t
. i n
U l
e m
t g
o V
5 4
1 e
r u
g i
F e
- w 0 C.OwOvWcU go.2N m.
e m
To,w
, l ll
U e
C O
a C
,.e O.
8tf U
er=
M ew 00 L
a c
em A
b u .
3 M ..
N ew C -
C W I a i
> l j
T I
M i L
3 h
I .
I I
I E i I
1 1-84
e.
c, a
~
5
)
s y
a D
1 1
(
p u
t a
e H
s l
e R c y
E C O
D e
u U g N i t
a T F
. N 1 E n -
V o -
E i
t '
a c
o L _
8' _
]
[
7 4
1 _
e r
u g _
i F
-. p d a a.
. s k .==. I$t4Et8Id-e9 <pd0 '
0 1
9 -
. 8 5
1 3
0
/
s 4
6 6
3 Tc*
o
e.
c.
a e
l c
y C
p t
u a
e H
e n
O r
o f
d e
m u
s s
A n
o .
i t .
u b
i r .
t s ,
i D
l e
c y
C l
a m
r
- e h
T 8
4 1
e r
u g
i
- F T
- E i(ll
,_,____.__..._-r,__-____ - _ _ _ _ _ , _ , _ - _ _ , . _ - _ _ _ _ _ _ _ - _ , _ _ _ _ _ _ _ _
e 1
e as 4
Q L
Y L.
- Asstag a .s- a - ,
- NIMO Td%Q s i
1-87
e.
c, a
t
. H O
f d
s s
A s
l c
C l
a h
T g
n i
p i
r t
S f
o n
i o
t a
i t
i I
n 0
5 1
e r
u g
i F
T8
l a,c,e e
i f
Figure 1-51. Comparison of Design to Monitored Transients l
i se .emeio i 1-89
i
" ~
a r c,e 1
e 1 I
i 4
l 1
1 l
l l
l 1
Figure 1-52. Comparison of Design to Monitored Transients '
=4.m " "
1-90
t 1
I SECTION 2.0
. STRESS ANALYSES Flow diagram figure 2-1 describes the procedure to determine the effects of '
thermal stratification on the pressurizer surge line based on transients developed in section 1.0. [
ja,c.e Section 2.1 Addresses the structural or global effect of stratification Section 2.2 Addresses the local stress effects due to the nonlinear portion of the temperature profile Section 2.3 Addresses the total stress effects due to the oscillation
, of the hot-to-cold boundary layer (striping) plus the thermal stratificatic stress
~
2.1 Piping System Structural Analysis 2.1.1 Introduction The thermal stratification computer analysis of the piping system to determine the pipe displacement, support reaction loads as well as moment and force loads in the piping is referred to as the piping system structural analysis.
These loads are used as input to the leak-before-break, fatigue, and fatigue crack growth evaluations. The thermal stratification condition consists of both axial and radial variations in the pipe metal temperature, as described in section 1.0. The model consists of straight pipe and elbow elements for I the ANSYS comouter code. [
la,c.e These studies verified the suitability of the nn.mincio 2-1 A
l ANSYS computer code for the thermal stratification analysis. [- i:
l
.s .
ja,c.e 2.1.2 Discussion The piping layout for a typical surgeline is shown .in figure 2-3. The rigid support, Ril, originally installed to reduce deadweight and seismic loads provides resistance to the displacements caused by thermal stratification.
[-
e er o
ja,c,e {
\
- * *
- 2-2 l
l
(-.---_____
l i e e
to
- e e
e e
. ja,c,e h
e
)
368Ss/031549 10 2-3
(
[ -- .
)a,c,e Based on the above discussion, the ANSYS computer Code is suitable for the
. thermal stratification analysis. [
Ja,C,8
[ .
3a,c,e seenvosites:10 p.4
[ .
ja.c.e
.2.1.3 Results.
The rigid vertical support (H006) at node 2260 in Figure 2-22 is replaced with-a snuboer and spring hanger from the design basis to prevent support overload. The remaining-rigid support, H002 (node 2620), as well as'the pressurizer and hot leg branch nozzle, are acceptable for all _ the design loadings including thermal stratification.
The calculated piping stress due to thermal stratification is reviewed to ensure that the system will not collapse in a " hinge moment" mechanism. The primary plus secondary stress limit for this piping stress is'given by ASME III, Section NB 3600, Equation 12 as 3.0 Sm. The calculated stress intensity range was determined from the methodology in ASME III, Section NB-3685. The maximum stress intensity range, which occurs at the 16 in. x 14 in, reducer, f is 50.7 ksi this is less than the Code allowable value of 51.3 ksi. This
. corresponds to a bounding thermal stratification case with AT = 320*F. It should be noted that, in qualifying this reducer component, the Vogtle specific temperature profile from section 1.2.5 was used. The stress indices C1 and C2 in equation 12 were developed from finite element analysis of the reducer.
1 A study was also made by elastic plastic system analysis of the surge line.
In this study, the stress-strain relation adjusted to the Code minimum yield stress was used in conjunction with the kinematic hardening rule. Three !
stress cycles were calculated by the ANSYS code from a conservatively
{
enveloped temperature profile along the pipe. The limited results provided an
, indication that the incremental axial total strain (elastic and plastic) at the worst location is bounded. Due to the high costs associated with the
, computer runs for additional stress cycles, the study was terminated. This does not have any effect on the qualification of the line since all ASME Code qualification requirements are satisfied per previous discussions.
~
2-5 l
2.1.4 Additional Information on Linear Equivalent Techniques
~
l 2.1.4.1 Introduction -
A review of the pressurizer surge line thermal stratification for several ~
plants indicated that the actual stratification temperature profiles are better described by nonlinear cross-sectional temperature distributions.
These temperature profiles will have effects on the global structural behavior of the surge lines in terms of loads and displacements. The use of isopara-metric solid elements has made possible the study of nonlinear cross-sectional temperature profiles, such as step change of temperatures at mid plane. This study was performed using a model developed for the WECAN computer code. In order to achieve a less costly analytical solution, an alternative model using pipe and elbow elements was developed for the ANSYS computer code. These elements can only be loaded with a constant cross-section temperature or a linear top-to-bottom cross-section temperature. It, therefore, becomes necessary to establish an equivalent linear temperature profile which will result in the same deflections and loads in the piping system, as would a nonlinear temperature profile. It should be noted that there are differences '. l in the WECAN and ANSYS models as described in section 2.1.2. These modeling differences will contribute to minor differences when results obtained from '.
the analyses are compared. A comparison of calculated and measured displace-ments both from power acension test showed that displacements calculated from the equivalent linear temperature profile compare reasonably well with the measured displacements as summarized in figure 2-22. The purpose of the study and the comparison with the measured displacements is to verify the suitability of the ANSYS code for the thermal stratification global analysis.
The theoretical basis for the equivalent linear temperature profile is based on a cantilever beam model and is summarized below.
2.1.4.2 Theory The closed form solution is determined for the free-end vertical and axial .
displacements of a cantilever cylindrical beam subject to two types of stratification temperature profiles: .
ms.mme in 2-6
a) linear equival,ent variation from top to bottom;
, b) step change at distance Y, below the beam centerline.
The axis of the beam (x-axis) lies in a horizontal plane. The solution is
~
based on the following principles:
[
ja,c.e
- 5. For a cantilever beam subject to thermal stratification, the axial force (F) and bending moment (M) are zero at each cross section (A),
thus, F=IA o dA = 0 (2.1-5)
M=/A o y dA = 0 (2.1-6)
The above equations are solved in closed form with the following results:
" " 2-7
( -
l
[
Ja,c.e The solution for the equivalent linear temperature in the form of coefficients J
ik is obtained by equating (2.1-7) with (2.1-9) and (2.1-8) with (2.1-10).
[
3 '
8 (2.1-12) m.*"
- 2-8
l where ,
. 1
.' I ja,c e 2.1.4.3 Application The deflections and loads in the surge line for case 3 (step at mid plane)
, have been calculated by WECAN. The same step change temperature profile is converted to an equivalent linear temperature profile (case 3L) for ANSYS
, using the Jik coefficients with Y, = 0 (table 2-4). The case 3 and case 3L temperature profiles used in the analyses are shown in figure 2-23c and 2-23d. The results are presented in table 2-2.
2.1.4.4 Discussion The suitability of the ANSYS computer code for the thermal stratification global analysis is demonstrated by the comparisons between case 3 and case 3L. Measured and calculated pipe displacements on table 2-2 also confirm this. In addition, casa 3L is representative of the eleven analysis cases which represent various step temperature profiles along the pipe axis.
1 2.1.5 Conclusions '
.~
Analytical studies with the ANSYS and WECAN computer codes have confirmed the validity of using an equivalent linear radial temperature profile to represent
- 2-9
= - ____ ___ _______ ____ ___ - - _ _ __ __ -
)
i i
the thermal stratification for dispiscement and loads. Good agreement was obtained between the ANSYS results and the measured displacements with thermal
- stratification. Eleven cases of thermal stratification were analyzed using the ANSYS code for the Vogtle Unit 2 rurgeline. Results for all other cases - -
of stratification were obtained by interpolation. The resulting loads on the pressurizer and hot leg nozzles P,re acceptable. The surge line pipe stress satisfies the ASME III NB-3600 Code Equation 1.2 limits. The resulting load on rigid support H002 is acceptable.
2.2 Local Stress Due to Non-Linear Thermal Gradient 2.2.1 Explanation of Local Stress Figure 2-24 depicts the local axial stress components in a beam with a sharply
- nonlinear metal temperature gradient. Local axial stresses develop due to the restraint of axial expansion or contraction. This restraint is provided by the material in the adjacent beam cross section. For a linear top-to-bottom temperature gradient, the local axial stress would not exist. i
- 3a,c.e 2.2.2 Superposition of Local and Structural Stresses For the purpose of this discussion, the stress resulting from the gicbal structural analysis (section 2.1) will be referred tu as " structural stress."
[
la,c.e Local and structural stresses may be superimposed to obtain tha total stress. This is true because linear elastic analyses are performed and the two stresses are independent of each other as summarized in figure 2-25.
m wo:i m to 2-10 -
Figure 2-26 presents the results of a test case that was performed to
~ demonstrate the validity of superposition. As shown in_the figure, the super- !
~
position of local and structural stress is valid. [
~
3a,c.e 2.2.3 Finite Element Model of Pipe for Local Stress A short description of the pipe finite element model is shown in figure 2-27.
The model with thermal boundary conditions is shown in figure 2-28. Due to symmetry of the geometry and thermal loading, only half of the cross section was required for modeling and analysis. [.
ja.c e 2.2.4 Pipe Local Stress Results Figure 2-29 shows the temperature distributions through the 14 in.. schedule 160 pipe wall [
S ya c.e m.wmu nn,o 2-11
L ja,c.e 2.2.5 Unit Structural Load Analyses For Pipe In order to accurately superimpose local and global structural stresses, several additional stress analyses were performed using the 2-D pipe model.
[
4
. j a , c . e, 2.2.6 RCL Hot Leg Nozzle Analysis Two RCL surge line nozzle models were developed to evaluate the effects of thermal stratification. These two models are shown in figures 2-43 and 2-44.
[
ja,c.e Figures 2-45 thru 2-53 present color contour plots of temperature and stress distributions in the surge line RCL nozzle. A summary of local stresses in ,
the RCL nozzle due to thermal stratification is given in table 2-6. A summary
' of stresses for unit loading applied is shown in table 2-7.
mm.amo 2-12 ;
2.2.7 Reducer Analysis-A model of the 16 x 14 reducer was developed to evaluate detailed stress
, distributions due to pressure, bending, and stratification loading. The reducer model is shown in figure 2-54.
2.2.8 Conservatism
-Conservatism in the local stress analysis are listed below:
1.
The hot / cold fluid interface is assumed to have zero width. A more gradual change from hot to cold would significantly decrease local stresses.
- 2. Stresses are based on linear elastic analysis even though stress levels exceed the material yield point.
. 2.3 Thermal Striping 2.3.1 Background ~
At the time when the feedwater line cracking problems in PWR's were first discovered, it was postulated that thermal oscillations (striping) may significantly contribute to the fatigue cracking problems. These oscillations were thought to be due to either mixing of hot and cold fluid, or turbulence in the hot-to-cold stratification layer from strong buoyancy forces during low flow rate conditions. (See figure 2-55 which shows the thermal striping fluctuation in a pipe). Thermal striping was verified to occur during subsequent flow model tests. Results of the flow model tests were used to establish boundary conditions for the stratification analysis and to provide striping oscillation data for evaluating high cycle fatigue.
Thermal striping was also examined during water model flow tests performed for the Liquid Metal Fast Breeder Reactor primary pipe loop. The stratified flow was observed to have a dynamic interface region which oscillated in a wave f
2-13
pattern. (See figure 2-56 for test pipe sizes, thermocouple locations, and
{
table 2-8 for typical frequency of striping oscillations.) These dynamic
,{
oscillations were shown to produce significant fatigue damage (primary crack (
initiation). The same interface oscillations were observed in experimental
)
studies of thermal striping which were performed in Japan by Mitsubishi Heavy Industries. f 203.2 Additional Background Information Thermal striping was examined during 1/5 scale water model flow tests performed for the Liquid Metal Fast Breeder Reactor primary pipe loop. These tests were performed by Westinghouse at the Waltz Mills test facility. In order to measure striping, thermocouple were positioned at 5 locations in the hot leg piping system (three in the small diameter pipe and two in the large diameterpipe.) The inside diameters of the large and small pipes were 6-1/2 and 4 inches, respectively. Figure 2-57 shows the test setup and locations of j
the thermocouple. (Figure 2-56 shows test pipe sizes with circumferential I
positionofthermocouples.) Thermocouple locations were selected [ -
ja,c,e The '
thermocouple extended [ Ja.c,e into the fluid. The flow rates and .
corresponding Richardson numbers for each pipe size are shown in table 2-9. "
A total of [' la.c.e tests were performed and evaluated. Three parameters were measured during the water tests which help define thermal striping: frequency of fluctuations, duration, and amplitude of delta fluid temperature. The [
]a c.e were recorded in the discussion of test results and are presented in table 2-10.
The frequencies of the temperature fluctuations from these test results were reported to be in the range of [
]a,c.e As shown in table 2-10,the[
ja,c.e mm.mma 2-14
E Ja,c.e In order to use the water test data for the surge line striping analysis, the test data with a ['
Ja,c.e was chosen to be used in tho evaluation. From table 2-9, the [. Ja,c.e inch I.D. pipe with flow rates of (
ja c.e for the pressurizer surge line.
When all other factors are equal, it has been shown that the thermal striping stress is [. Ja,c e A typical value of usage factor was calculated with the [
,' Ja,c,e as follows:
.' [
3a,c.e This distribution corresponded to [ . Ja,c.e considt. red to occur at a stress level calculated with frequencies of [
),a,c.e respectively. Calculations revealed that there was [
Ja c.e in the usage factor when a [
Jac.e Therefore,[ Ja,c.e was assumed in all usage factor calculations.
9
- me..,om in 2-15
For the Vogtle Unit 2 Pressurizer surge line, the frequency of [ Ja,c.e was used in the [ "
3a,c.e As shown in table 2-10, the amplitude of AT varies from [
Ja,c.e of the full AT between the hot and cold fluid temperatures.
For the Vogtle Unit 2 Surge line, the amplitude was assumed to be at [
3a,c.e as shown by the curve in figure 2-58. This is conservative since a higher AT results in higher stress.
The maximum duration of thermal striping from table 2-10 shows that thermal striping occurred for [ Ja,c.e For the Vogtle Unit 2 pressurizer surge line, thermal striping was considered to occur [
ya,c e 2.3.3 Thermal Striping Stresses ,
Thermal striping stresses are a result of differences between the pipe inside surface wall and the average through wall temperatures which occur with time, -
due to the oscillation of the hot and cold stratified boundary. (See figure 2-59 which shows the typical temperature distribution through the pipe wall).
[
,)a,c.e The peak stress range and stress intensity is calculated from a 2-D finite element analysis. (See figure 2-60 for a description of the model.) ['
Ja,c.e The methods used to determine alternating stress intensity .
~
mm.mm io 2-16
l are defined in the ASME, code. Several locations were evaluated in order to determine the location where stress intensity was a maximum.
Stresses were intensified by K3 to account for the worst stress concentra-
~
tion for all piping element in the surge line. The worst piping elements were the butt weld and the tapered transition.
[
ja,c.e 2.3.4 Summary of Striping Stress Considerations
[1.
4 0
e 2.
6 e
O Ja,C,e o
me..mm in 2-17
[ -
l P
en ja,c.e 2.3.5 Thermal Striping Total Fluctuations and Usage Factor Thermal striping transients are shown at a AT level and number of cycles.
[
l Ja,C,9 mi. muss in 2-18 l
I I
L l
i
[
4
.)a,c.e 2.3.6 Conservatism The conservatism in the striping analysis are: striping occurs at one location; surface film coefficients assume high values with constant flow; and conservative design transients are used. The major conservatism involves the combination of maximum striping usage factor with fatigue usage factor from all other stratification considerations. The [
ja,c.e O
m.a +$ io 2-19 i
TABLE 2-1
, COMPARISON OF.WECAN AND ANSYS RESULTS FOR .-
LINEAR STRATIFICATION - Case 2 -
(Displacements.in Inches). --
ANSY5/.!ECAN (JOBANSF)WECAN (AGJAQLM)ANSYS (PERCENTAGE) 1' 8,C,e 1
(,.
9 4
e l
4 sees.a m io 2-20
TABLE 2-2
~ COMPARiSONOFWECAN[. Ja,c.e AND
~
ANSYS[' Ja,c,e RESULTS FOR CASE 3 -
~
Case 3L/ Case 3 Location Direction- WECAN Case 3 ANSYS Case 3L (Percentage)
-t a,c.e I
t Case 3L ANSYS: DCISKXY, 11/12/88 e
um.mine se 2-21
._a . _ .' ' ' -._:::._,_ ' ' ' ' ' ' " ' ' ' ' ' ' ' " ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' '
i
v.m__m,-_______.___.---,------__.m_____ _ . --_.._---,,s. . . _ _ _ .. _ _ _ , . _ . _ --.._,-,___--.---.,--_.__.__----,.-...m____.--__,. , _ , - _ __. ___ - - - _ - - - . _ _ _ _ _ . _ _ _ _ . _ _ . , - - . _
' TABLE 2-3 TEMPERATUREblSTRIBUTIONSINPRESSURIZERSURGELINE se 8,C,9 J
W e
t 4
e e
mm.mim in 2-22
h-I
. TABLE 2-4 THE EQUIVALENT LINEAR COEFFICIENTS J
, ik (14 inch - Schedule'140 Pipe)'
i
~ Y, J J U J hh hc ch cc 1
~
a,c,.
4 e
O e
nn.* *" "
2-23 I
l
l- -1
]
l I
TABLE 2-5 ,
' i V0GTLE UNIT 2 SURGE LINE MAXIMUM LOCAL AXIAL STRESSES AT [ la.c.e ~
f 16 in. SCHEDULE 160 Local Axial Stress (psi)
Location Surface Maximum Tensile Maximum Compressive a,c.e
~
~
"14 in. schedule 160 portion Note: Local thermal shown are for a AT = 260*F.
b s
um.mnwas '
2-24
1 WESTINfH3USE PROPRIETARY CLASE 2 TABLE 2-6
SUMMARY
OF LOCAL STRATIFICATION STRESSES IN THE SURGE LINE AT THE RCL N0ZZLE.
All Stress in psi Linearized Stress Peak Stress Intensity Range Intensity Range Diametral Location Location Inside Outside Inside Outside
-la.c.e W
9 O
O lumsmo o
e i 10 2 25
l l
l l
TABLE 2-7
SUMMARY
OF PRESSURE AND BENDING INDUCED STRESSES IN THE SURGE LINE RCL N0ZZLE FOR UNIT LOAD CASES All Stress in psi Linearized Stress Peak Stress Intensity Range Intensity Range -
Diametral Unit Loading Location Location Condition Inside Outside Inside Outside Nozzle-Hot Leg Bottom a,c.e Crotch Region Nozzle-Hot Leg 45' Crotch Region Nozzle-Hot Leg Side Crotch Region Nozzle-Hot Leg 135' Crotch Region Nozzle-Hot Leg Top .
Crotch Region .
~
Nozzle-Hot Leg Bottom .
Crotch Region Nozzle-Hot Leg 45' Crotch Region Nozzle-Hot Leg Side Crotch Region Nozzle-Hot Leg 135' Crotch Region Nozzle-Hot Leg Top Crotch Region Nozzle-Hot Leg Bottom /
Crotch Region Top Nozzle-Hot Leg 45*/135' -
Crotch Region Nozzle' Hot Leg Side -
Crotch Region an.m= in 2-26
A 4
TABLE 2-8 4 STRIPING FREQUENCY AT 2 MAXIMUM LOCATIONS FROM-15 TEST RUNS
e 1.
im 8,C,9
.a e
4
'o G
.uumune -
a0
+
- j IS88s41 Hep.10 i
2-27 j
.~ TABLE-2-9
. FLOW RATES AND RICHARDSON NUMBER FOR WATER MODEL FLOW TESTS .,
. Cold Water .
Flow Rate-Pipe Section (GPM) Ri 4.0 inch I.D.. a,c.e i
6.5 inch I.D.
6
'O e
O, nm.mine ie 2-28 a
. . . . . . . . . . . - l
Y C
(
) G L V A A I
4 T )
N S E E T L O %C P Y C
F (
O
% X
( A M
E D )
U S T E I L
. L %C P Y M C A (
S N
O N.
I I T M A
C )
O / C L N S E O E N S .)
E I L I (
) 1 L L T C P A A Y H E 1 U T R C T M 2 O O U G I 2 C T D # L T 2 O 2 M )
0 R N e r 1 E O r u g u
- H I
2 T %T gi A i f E T R f L S U
. B E D e e A H ( e s T G s(
I . (
H G 5 V 2 #
O A s
. W n o T )
- N oi M O i t O I t R %T a c F ) A c o Z R oL S H U L T ( D t t
L (
U Y a S C E N X. n u R E A u r
r U M Q s t E )
R N t F O s e I et
%T t A
R mo o r U r f D f
(
n n e N. ek I k a M at t
s s g g n n i i d d a
- a e e e r p r i e
- c P el p
lp u u o ia oc D c o o m
. l m r l r e a eh m h T T
S * "
Y0
DETERMINATION OF THE EFFECTS OF THERMAL STRATIFICATION a,c.e ,
l Figure 2-1. Determination of the Effects of Thermal Stratification .
Seets/12108810 2-30
1 a .c .e Figure 2-2. Stress Analysis i
3686s431548 to 2-31 I -
l . _ _ _ _ . . _ . . _ _ _ _ _ _ _ _ _ _
Z o
I PRESSURIZER D'
/
() <
p p Sp2 6 FT i
3 FT 27 FT -
u SNUBBER -
l
]
\
SNUBBER RIl l %s 21 FT RCL i HOT LEG I l 10 FT Figure 2-3. Typical Pressurizer Surge Line Layout .
1 sesumunes to j
2-32 l
l
. i
, J l
, . a a c,e k
Figure 2-4. Cases 1 to 4: Radial Temperature Profiles 1
2-33 F
a a c,e
~
S.
4 Figure 2-5. Case 5: Radial and Axial Temperature Profile M016/131PN 10 2-34
.r -
l a,c.e-1
- Figure 2-6. Finite Element Model of the Pressurizer. Surge Line Piping General View DettoAtlete 10 2-35
a,c.e i
I I
1 4
Figure 2-7. Finite Element Model of the Pressurizer Surge Line Piping Hot leg Nozzle Detail .
sesi.yisesse 2-36
p 1 l .
'I
(- - a,c.e f
1 l.
(
I.
I l . .j e'
e Figure 2-8. Thermal Expansion of the Pressurizer Surge Line Under Uniform l
- Temperature j 1
1
.mi .
2-37
1
\
a,c.e i
1 l
\
Figure 2-9. Case 2 (linear) Temperature Profils. at Hot leg Nozzle l
maw im .. 2-33
.t :
t a,c.e
+ -
4
. Figure 2-10. Case 2 (linear) Temperature Profile at Pr==surizer Elbow s u s. m a n i.
2-39
n
.a.c.e l
A-l l.
l l
l l
~
FiNre2-11. Thermal Expansion of Pressurizer surge Line Under Linear Temperature Gradient M9ts/12198210 2-40
{
A a,c.e Figure 2-12. Bowing of Beams Subject to Top-to-Bottom Temperature Gradient wei.mius in 2-41
a,C.t e
O O
N N
a F
S O
o L
A 9
h 4
L e b E
O c
e 5*
T' e
E w
O s
W M
. ?
N 9
h, o
E E
e I
I I
2-42
l^
O l a,c.e
.. l 1
l' e N
N O
, E-L N
- e=
b 3
en te b
A
.se 4
9 eps b
O 6
A 3
- w 4
. 'b O
V5 k.
e
- C X
w O
O e4 4
4.J T
e4 i
N O
L
.- g b
I
. I ,
I I
2-43
U j-8 s C ,8 A
W.
N N
O E
a F-4 9
- P' M
O L
Ch.
9 b ,
4 L.
>=
i e
M 4
E h
w T
S em 4
U N
e4 i
! N e
L b
l l
l 2-44 1.
i l l a,c.e .
5 L
N es=
b 3
- a Vi e
L
<ed 4
9 m
ese b
O b
G L
3 a
- 4 b
A k
b m
w w
Z w
T M
4 v
U N
m i
N L
3 llD g
a ?
I s e
R R
I 2-45
w-I l B eC et eW N
O i 6
S.
- 9 6
3 e
4 L
O T
a e M
c M
ew 4
en 4
O b
M i
N O
h
.P S
9 I e
_I I
a 2-46
l 1
1
- l l l,,c,,
i l
e N
N O
E
- a. -
M C
Z w
4 9
e99 M
C 6
L 9
6 3
a L
i e
e e
E E
er=
M 4
l' i
e M
4 l
.Ee i
N
. 9 6
3 tlD
- S
- I i g i
2-47
L i
9 '
O y
en
[a,C,e 1
I T
C W
En E
b 4J 4
- G !
W l e
M O
L CL.
W L
3 a
4 L
N
- e
,e e E
T c
4 w
O M
4 so 4
0 O
m i
N du 6
3 l
?
I i
2 E
2-48
4 4
, ; a,c.e
\
. LM L
N
- p.
b 3
m H
L
.a 9
~
W ecup h
O
-L 9
6 3
.w 4
L e
e w
e E
T.
w 4
N 4
m W
4 Y
O N
e N
G L
8,
. b l l I
i R
I 2-49
i 1
a,c.e I
r Figure 2-21. [ 3a,c.e Profile
. miens.ie 2-50
-_ . = _
ConrantscN or vtaficAL ogsPtacIntNis (tN)
LANYAA0 ntA5URED POWER CALCULATED toUIVAltNT LOCATION A5CENSION itMPERATURE PROFILE (NODE) itsTING (suRGETN)
. riso ..is . 323 Patssuntzta j
l, erso . 46 ..es,
,g l, rero ..se . .en ,, ,
rito .to .en rs30 78 azi i OTm1 ,
n00g ra
,,A ":;M P Th1 ~
2620 s
100 ip 7,4' 2160 Th1 Tg!,
2480 2340 24W 2260 26.0
, 2200 4.
1-l Figure 2-22. Comparison of Measured and Calculated Pipe Displacements m s. m is i.
2-51
i a,c.e
~
t I
,1 Figure 2-23. Equivalent Linear Temperature man.eims i.
2-52
m ._._ _ _ __ _ _ _ _ _ _ - _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ - _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ - - _ , . _ _ _ _ _ _ , . - , _ _ _ _ _ _ _ _ - - _ _ _ _ , _ _ _ _ ,
$.3 U.
N 7
i e 1
W C
O e
ab.A
- 4 U
ee=
b
.c=
abJ 4
- L
+J M
.8 O
a
. E o
O C
<e=
- .b
.9 C
.e.
N e
G L
e M
O 8
a T l' N
s N
9 L -
3 e
b I
e I 8 l =
e I
2-53
l I I i
a ,c.e -
I 4
i .
Figure 2-25. Independence of Local and Structural Thermal Stratification Stresses Permitting Combination by Superposition m w eim m to 2-54 .
a,c,e e9 A
I 4
s.
1 I
- 1
)
Figure 2-26. Test Case for Superposition of Local and Structural Stresses Ms41240010 2-55
I
- e ,c .e i
4 4
l Figure 2-27. Local Stress - Finite Element Models/ Loading
- I l
I neuman io 2-56
a a,c.e
-I i
i 1
I r \
i l
l l
Figure 2-28. Piping Local Stress Model and Thermal Boundary Conditions l
" ' * " ' ' 2-s7 I
a,c a e ,
. l l
s l
1
~
Figure 2-29. Surge Line Temperature Distribution at [ ]a,c.e Axial '
Locations n u.m u m io 2-58
a r c,a l-l 4
t Figure 2-30. Surge Line Local Axial Stress Distribution at ( Ja,c.e Axial Locations usi.mim in 2-59
I i
a o c,e j 1
- i i
Figure 2-31. Surge Line Local Axial Stress on Inside Surface at '
[ Ja,c.e Axial Locations mei.n a so 2-60
te a r c,e t
eP I
figure 2-32. Surge Line Local Axial Stress on Outside Surface at
[ )"'C Axial Locations wi.mim in 2-61
- , - . - . - . - . - . - - . - - , - - - - - - - - - - - , - , . - , . - - - - - - - , - - . - - , . - - . - - , - - - ------------..--r...r--,-.--- , - - - - . - - - - - - - - - --------- - - - - - -- - -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - . - - - . - - , - , - - - - - - . , - - - - , - , - , - , - - - - , - - - - , - - - - - , - . - - - - - - - - - - - , - - - , . - - . - . - - - - - -
N i 8,Cie s, l l
U.
4 M
c C
4 a
a 4
C O
e a
3 O
. b a
M.
. C 3
a 4
L 1
e c
u 3
M O
M t
N e
L 3
.tlM e
g.
I i
a 2-62
-- .y - - - - - - - , . _ _ . _ . . . - ,
- , - - .m-.. ----, ..-------,---,.-,----------_-- - - , - -- . , - . - - - . - - - - - - , - . - - - . - . - . - . - - - - - . - - . , -
e-l ga .c .e 1
l e.
U
=
e m
Put W
C C
.e M
4 8,
a 4
.e 8
'M 3
.O
.e b
a ..
80
.e b
- so so W
L
- a M
e M
E ee M
4 8
a 9
C 6
3 M
Y M
e N
6 3
CD g L I I E
e I
i A
I 2-63
.g 8,C,e o
e We m
M W
C
.C-ebO 9
a a
4 8
aks 3
g S b
- a 1/.3 .
g .
W L
3 a
4 L
c u
3 M
4 N
m a
N L
3 On A
l 2 I
e t
.R E
2-64
'i
.2
. 8.C ,e l'
i e.
U.
O m
M W
C 0
M U
C I
a 9
C C-b a
e es-N M
- 6 M
~
M 4
8, c
OpBD Y
u 3
M m
o N
O i
e e I
a A
I 2-65
-.'wwW -rm'------- vv-r.------- - - _ _ . . _ _ , _ _ , _ _ _ _ _ _ _ _ _ _
a ,a ,c .e d.
M m
W C
C
'O
=
8 a
me s
C O
en j j
b
. es ca 4
W
=
h.
4 L
h m
N 7
N S
L l 3 i w
.e l
I 1 I e I I t i l
i i
2-66 I
,mv - - , - - , - - . - , - , , _ - . . , _ __ , , _ _ _
a,c.e G
e U
e N
m M
hues C
O almul 4
a a
4 C
C -
3 D
b a
M
' e .P S
N M
G e L
. . W
.S-M C
a W
.c -
M u
- J M
M t
N L
3 O -
b e
i 2-67
i
~
e-4 s .c .e l ,
U.
N m
M W
C O
9 a
a 4
C C
3 O
b
- a G4 es-cm
- l. ,
e L
3 a
9 L
c span M
L 3
VJ h
m e
l- N e
L 3
.Ch
./s I _ __ __.__.__._.______ _ _ _ _ _ i ,
1 I
1
_e K
l.
2-68
.N s
o 8 ,C i e I
, I l
.( l U.
N M
bamme C
O M
4 8
a a
4 8
asma
.Lma
.,M=
h s
an in G
L
.ma N
e M
ew W
C 8
a c
b m
O w
I N
L 3
.Ch Og I I t
!'* g a
R E
2-69
--r---,.- - - . - - - - - , - - - - - , - - - - - - - - - - - - - - - - . - - - - - - - - - - - . , - - - - , , - - . - - - .- - - - - - - - - - - - - - - - - - - - - - - - - - - _ - - - - - - _ - - - - - - - - -
0 4
i a
, j g .c ,e e.
U.
N M
M C
C M
U C
a
+4 4
C O
e M
3 e =O.
.e b
s a e,M-b W
L 3
a 4
L c
.e.
!s th M
T I
N e
L.
D
, 1 _
l .
I i
2-70
fi e'
i e
a ,c .e .
j U.
E m
amme hemd E
4 8,
8 dimi 3
.Q e
M
.=
b M
M
- S 6
- a
~
N e
W 4
S U
O
.,m8 .
S
- c U
u 3
M N
v i
N 6
- P D l .-
La.
0 2
I E
2-71 J
i! li I 1 lllI(!i )
, e, c,
s a
5 1
. l e
d o
M N
A C
E W
D 3
l e
z z
< o N
L C
R e
n i
L e
g r
u S
3 4
2 e
r u
g i
F m,
m _
'? ~ N
i liiI ll l i I 1l I j 11\l llll1!lli1II!!1! '
e.
c, a
5 2
l e
. d _
o _
M _
N A
C E
W D
3 _
l e
. z z
o N
L
, C R
e n _
i _
L _
e g _
r u
S _
4 _
4 _
2 e
r u
g i
F _
S e
s s
e s
i m,
- i m
NgNw
B eC et e
J 8'
O C
0 C; i
.s 8
=
w C
2 a-
' 3
, g i
0 E
3 8,
h m
N W
> h, a
I.
I
, i 2-74
, _ = . . _ . . _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . - _ _ _ . _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ - - . _ . _ _ _ . . _ _ _ . _ . _ _ _ _ _ _ _ . _ _
l l
I - 8 ,C .e l
i e2 '
l
. g M
4 I
u
.Ne=
M 9
i i
L M
l W
.s O
a C
A a
som M
C
- a C
=
N N
- G L
a M
N N
O E
c O
8, u
3 i M l e
e N
@ l b I 3
On t ,
e I
I
- R I
E 2-75
a*n.o
_ 3 b
os ria
1
)
l l
4
, l- 8.C e W
L 3
M M
W
- L CL Q
w E
e A
a en M'
C' w
W C
e e a M
M e W L
a W
N N
O E
W C
l u
3
. M v
I N
W L
3 C) !
ew !
E i i
4
.s
__ l t
A I
2-77 w_
h
- . 8 .C ,e I
1
/
t W
L 3
m M
L CL O
. .a 8
m A
a som M
C w
e.C =
N
- W a b d
M e
N N
O E
c e
A u
3 W
w I
N L
3 On b
2 I
e e
l I
- E 2-78 1
8 ,C .B 4
.} ,
l
( '.
.=
c c
W CC O
- e 3
C h
a em ,
N c
sa c
m M
N
- G b
ea e
W N
N O
E W
c em b
m N
L 3
.a
- 2 E
=
t l Jl i
l E 2-79
jl. l , !l l I ii
.o *m s
g -
i n
w o
h S
g i
n d
n e
B t
o e
u D
e n
i L
e g
r u
S t
o l
i a
- x A
n
. i o
t c
e r
i D
i n
s s
e t r n t e S m e
e c l a z l z p o s N i D
e n d i e L i f
ei g ar r g u a S M 4
1 5
2
e*
r u
g""*
i F "
7mO jLlllllll! ll l,
i l I )a,c.e M
C 3- p U
80 m
b e
T i
t C.
C D
O, E
.e M
F
.c W
D
=c g
- O
.6.e 8
e a
~
m C
b 2
M G
N N
O 2
b O
O 6
3 W
m l I h2 u . I al CE 2-81
- _ - _ . - - . . - - . _ . , . . . -.--.-_-_,----r-
}
'.I ,
a,c,e i
c C
CD O
w 8
o A
w.
ev=
c w
C w
M e N e
6 e
u m,.
e W
. "N N
O 2:
c ee=
!s m
O m o N
b 3
.e b
I
- A E
2-82
i 1,
i l
's ne
'saa 4
.s.
l.-
Figure 2-54. Finite Element Model of the Reducer
(
l ms.mim in 2-83
_ _ _ _ __ _ __ _ _ _ _ _ _ - _ _ _ _ _ - _ _ _ _ _ b
i l
- I
- l .
. l l
.__ _ *- )
a,c.e ( ;
l 1
I
)
i i,
Figure 2-55. Thermal Striping Fluctuation 2-84 nn.mu.e in l _ _ - _--_-_ -_
,, . _ _ _ - - - - - _ - - - . . - _ . _ , , - , - - - - - _ , , - . ---.___,-,._n-,. , _ . - , , _ , , . - . , - - , . - , - - - _ _ , - , . , , _ _ _ , , _
~
e 4
e @
e
- U. -
1 1
'o' ..
M 3
a M
CD c
.- 1 l
.CL b
a m
- C c'
4 c
C e-4
" U h
e-a 4
L a
m t
N L
3 tlD b
4 2
- 5 l R A
E 2-85
4 s
VititCALatse.L F%7 3 g l
y l roe LOCAT14e 4 meg it.pr*
. : -r
/
[ ; .,, t--. . , 1,
[
()
MpelP (){ j t t jf
< .. . oi ... . ..,s
.{UTLET ggggggge 3 v'a= '
ggggggge g VI.fl&AL 4 8 .tL F%r a M agygg si c ie v vess6 aw -
m-
" * ' r ,
. A. _
l Figure 2-57. Water Model of LMFBR Primary Hot Leg 3543s 1 12449 10 2-86
t o
a,c.e l l
l Figure 2-58. Attenuation of Thermal Striping Potential by Molecular Conduction (Interface Wave Height of [ ]a,c.e 3963s412749 to 2-87 L _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ - _ _ _ _ _ _ _ _ .i
1 aoc,e 4
1 Figure 2-59. Thermal Striping Temperature Distribution ,
nn. min. io 2-88 ,
-_.,._,4. _ ---- .- _- -- . - - - . _ - - . - , - _ , . - - - - - - - - . . - - . - _ - . - . - , , . - - - - - - - , . - . .---------,---.,--,--,,---,r. -- --,-.---,.---:-- , . - - - - - - - . - -
0 We U.
P C
O G
a er=
C em I b
- .C g
b a
M 8,
N L.
2 C'
e b
l l
, g 7.
e
,1; E
2-89
SECTION 3.0
.- ASME SECTION III FATIGUE USAGE FACTOR EVALUATION 3.1 Code and Criteria Fatigue usage factors for the Vogtle Unit 2 surge line were evaluated based on the r. , irements of the ASME B & PV Code,Section III (reference 3-1),
Subsection NB-3600, for piping components. The more detailed ter!.aiques of NB-3200 were employed, as allowed by NB-3611.2. The fa % ue evaluatior, required for level A and B' service limits in NB-3653 is summarized in page 146. ASME III fatigue usage factors were calcuhted for [
Ja,c.e points in the surge line piping usirg program WECEVAL (reference 3-2).
3.2 Previous Design Methods Previous evaluations of surge line piping fatigue used the NB-3653 techniques but with thermal transients defined by W_ SSDC 1.3 F(3-3] and 1.3.X (3-4],
assuming the fluid surges to sweep the surge line piping with an axisymmetric temperature loading on the pipe inside wall. These evaluations produced typical usage factors of approximately [ Ja,c.e at girth butt welds,
[ ]a,c.e at elbows and bends, and [ ]a,c.e at the RCL hot leg nozzle crotch region. Effects of stratification were not included in previous design analyses.
It must be noted that these usage factors are conservative since, in the design process, calculations are carried to the point where results meet code requirements, and are not further refined to reduce the usage factor.
3.3 Analysis for Thermal Stratification l
With thermal transients redefined to account for thermal stratification as described in section 1.0, the stresses in the piping components were
- established (sect . 0) and new fatigue usage factors were calculated. Due to the non-axisymmetric nature of the stratification loading, stresses due to all loadings were obtained from finite element analysis and then combined on a stress component basis.
'*"'"*"" 3-1
3.3.1 Stress Input l Stresses in the pipe wall due to internal pressure, moments and thermal stratification loadings were obtained from the WECAN 2-D analyses of both 14 -
inch and 16 inen, schedule 160 pipes. [
ja,c.e E
3a,c.e 3.3.2 Classification and Combination of Stresses 1
As described in 3.3.1 the total stress in the pipo wall was determined for '
each transient load case. Two types of stress were calculated ' Sn (Eq 10),
to determine elastic plastic penalty factors, K,, and Sp (Eq 11) peak stress. For most components in the surge line (girth butt welds, elbows, bends) no gross structural discontinuities are present. As a result, the code-defined "0" stress (NB-3200), or C 3ElaaT, abTb lin Eq (10) of NB-3600 is zero. Therefore, for these components, the Eq. (10) stresses are due to pressure and moment. !
For the RCL hot leg nozzle, the results of the 3-D finite element WECAN analysis of the nozzle were used to determine "Q" stress for transients with stratification in the razzle. Note also that the Eq. (10) stresses included j appropriate stress intensification using the secondary stress indices from ,,
l NB-3681. The pressurizer nozzlo load was also specially qualified by finite l element analysis technique. .\
l l
. m .. 3-2 L
Peak stresses, including the total surface stress from all loadings -
pressure, moment, stratification - were then calculated for each transient.
[
3a,c.e 3.3.3 Cumulative Fatigue Usage Factor Evaluation Program WECEVAL uses the n S and p
S stresses calculated for each transient to determine usage factors at selected locations in the pipe cross section.
Using a standard ASME method, the cumulative damage calculation is performed accurding to NB-3222.4(e')(5). The inside and outside pipe wall usage factors were evaluated at [ la,c.e through the pipe wall of the 2-D WECAN model.
This includes:
- 1) Calculating the Snand Spranges, K , and Salt f r every possible combination of the [ ]a, ,e transient load sets.
~
- 2) For each value of Salt, use the design fatigue curve to determine the maximum number of cycles which would be allowable if this type of cycle were the only one acting. These values, N1 , N 2 ...N n '
were determined from Code figures I-9.2.1 and I-9.2.2, curve C, for austenitic stainless steels.
- 3) Using the actual cycles of each transient loadset supplied to WECEVAL, ny,n2 '***"n, calculate the usage factors V '
1 U
2
- U n fr m U$ = ng /N
$ . This is done for all possible 11 combinations. If N $is greater than 10 cycles, the value of Ug is taken as zero.
l .-
! [
i 3a,c.e I
I l
l
.....m...
l 33 J
l l-ja,c.e
- 4) The cumulative usage factor, Ucum, is calculated as U cum =U1+
U2+".+U.n The code allowable value is 1.0.
3.3.4 Simplified Elastic-Plastic Analysis.
When code Eq. (10),nS , exceeded the 3Sm limit, a simplified elastic plastic analysis was performed per NB-3653.6. This requires separate checks of expansion stress, Eq. (12), and Primary Plus Secondary Excluding Thermal B:nding Stress, Eq. (13), and Thermal Stress Ratchet, and calculation of the '
elastic plastic penalty factor, Ke, which affects the alternating stress by S
alt
- K e Sp /2. The K, values for all combinations were automatically calculated by WECEVAL. Thermal stress ratchet is also checked by WECEVAL.
Eq. (13) is not affected by thermal stratification in the pipe where no gross structural discontinuities exist, but required to be verified at the nozzle. .
Eq. (12) was evaluated in the Global ANSYS analysis by checking the worst .
possible range of stress due to the expansion bending moments (section 2). .
3.3.5 Fatigue Usage Results The maximum Usage factors were [ ]a,c e at the reducer (node 2720, figure 1-7) and [ ]a,c.e at the RCL nozzle safe end (node 10eC, figure 1-7).
The above usage factors do not include the effects of striping. Because the l
nature of striping damage is at a much higher frequency, varies in location due to fluid level changes and is maximized at a different location than the ASME usage factor, it was determined to be more appropriate to calculate a l
total usage factor by conservatively adding the above calculated and striping
! usage factors. This results in a total maximum U cum II
! Ja,c.e which is less than the Code allowable of 1.0. -
l m ..ome io 34
3.4 Conservatism in Fatigue Usage Calculation
.~
The above calculated ASME usage factors contain the inherent conservatism
> known to be in the ASME Code methods. These ir.clude the conservatism in the elastic plastic penalty factor, K,, the method of combining loadsets based on descending Salt, and the fr: tor of 2 on stress and 20 on cycles in the design fatigue curve.
Also, due to input limitations in program WECEVAL, the maximum value of peak stress intensification for all loading types was used. This was conservative at girth butt welds, since K1 = 1.2, K2 = 1.8, K3 = 1.7 in NB-3681 and K=1.8 was used in WECEVAL for all stresses.
3.5 References 3-1. ASME Boiler and Pressure Vessel Code Section III, 1986 Edition.
3-2. WCAP-9376, WECEVAL, A Computer Code to Perform ASME BPVC Evaluations Using Finite Element Model Generated Strees States, April,1985.
[ Proprietary]
4 3-3. W Systems Standard 1.3.F, Rev. O. (Proprietary) 3-4. W Systems Standard 1.3.X, Rev. 0 (Proprietary) 3666s-03'589 10 3-5
SECTION 4.0 FATIGUE CRACK GROWTH 4.1 Introduction To determine the sensitivity of the pressurizer surge line to the presence of small cracks when subjected to the transients discussed in section 1, fatigue crack growth analyses were performed. This section summarizes the analyses and results.
Figure 4-1 presents a general flow diagram of the overall process. The methodology consists of seven basic steps as shown in figure 4-2. Steps 1 thru 4 are discussed in sections 1 and 2 of this report. Steps 5 thru 7 are specific to fatigue crack growth and are discussed in this section.
There is presently no fatigue crack growth rate curve in the ASME Code for austenitic stainless steels in a water environment. However, a great deal of work has been done rectntly which tupports the development of such a curve.
- An extensive study was performed by the Materials Property Council Working Group on Reference Fetigue Crack Growth concerning the crack growth behavior of these steels in air environments, published in reference 4-1. A reference curve for stainless steels in air environments, based on this work, will appear in the 1988 Addenda of Section XI. This curve is shown in figure 4-3.
A compilation of data for austenitic stainless steels in a PWR water environment was made by Bamford (reference 4-2), and it was found that the effect of the environment on the crack growth rate was very small. For this reason it was estimated that the environmental factor should be set at 1.0 in the crack growth rate equation from reference 4-1. Based on these works (references 4-1 ano 4-2) the fatigue crack growth law used in the analyses is as shown in figure 4-4.
m.-oma. io 41 1
- - _ _ _ _ - - - - _ _ _ - _ _ _ _ _ _ _ 1
i i
4.2 Initial Flaw Size
. 1 Various initial surface flaws were assumed to exist. The flaws were assumed to be semi-elliptical with a six-to one aspect ratio. The smallest flaw size .,
assumed was one having one-fourth the depth of a surface flaw found acceptable by paragraph IWB 3514.3, Allowable Flaw Standards for Austenitic Piping of the )
ASME Code. The largest initial flaw assumed to exist was one with a depth equal to 10% of the wall thickness.
t-3 Critical locations for FCG All [: Ja,c.e locations (as shown in figure 1-18), representing all cross sections of the surge line where thermal stratification could occur, were checked for fatigue crack growth. Figure 4-5 identifies [
]a,c,e locations (locations [ la,c.e) as sections along the length of the surge line. Figure 4-6 identifies the positions at each location where fatigue crack growth vis checked. These positions ([
]a,c.e) are controlling positions because the global structural bending .
stress is maximum at positions [ la,c.e while the local axial stress on -
the inside surface is maximum at positions ( ).a.c.e ,
9 Location [ la,c.e (as shown in figure 1-18) is not shown on figures 4-5 and 4-6. The location [ Ja,c.e stratification profile exists at the surge line RCL nozzle when the RCP pump is not running and, therefore, turbulent mixing caused by flow in the main RCL piping is not occurring. This effect was observed in the surge line monitoring programs.
The location [ la c.e temperature profile develops a lower inside-wall local axial tensile stress than developed at other locations.
Based upon the above discussion, location [ Ja,c.e is not a critical location for fatigue crack growth. For completeness, however, fatigue crack growth calculations were performed at location [ la,c,e for positions (
3,a,c,e aen,-cm . in 4-2
4.4 Results of FCG Analysis
,=
Results of the fatigue crack growth analysis are presented in table 4-1 for a
~
10% wall initial flaw. -
Conservatism existing in the fatigue crack growth analysis are listed below.
- 1. Plant operational transient data has shown that the conventional design transients contain significant conservatism
- 2. Monitored data from STP indicated the least amount of transient activity of all plants considered
[
)a,c.e
- 5. Fatigue crack growth calculations based conservatively on elastic stresses
- 6. FCG neglects fatigue life prior to initiation 4.5 References 4-1. James, L. A. and Jones, D. P., " Fatigue Crack Growth Correlations for Austenitic Stainle:s Steel in Air," in Predictive Capabilities in Environmentally Assisted Cracking, ASME publication PVP-99, December 1985.
4-2. Bamford, W. H., " Fatigue Crack Growth of Stainless Steel Reactor Coolant Piping in a Pressurized Water Reactor Enviornment," ASME Trans. Journal of Pressure Vessel Technology, Feb. 1979.
.-omme.io 3
43
TABLE 4-1
!. FATIGUE CRACK GROWTH RESULTS FOR 10% WALL INITIAL FLAW SIZE Initial Initial Final (40 yr) Final Flaw Location Position Siza(in) (% Wall) Size (in)' (% Wall) a,c.e 9
e 4
9 a
O m e.-a m io i 44
1 s.
b, t.
a,c.e
. El l
l
.' Figure 4-1. Determinination of the Effects of Thermal Stratification on Fatigue Crack Growth as43e-12194810 4-5
)
_. 1
--,-,---,-_-,.7, e
49 e
8,C,e O
O 1
1 figure 4-2. Fatigue Crack Growth Methodology .
f u
l I
l 1
I I
I i
so.a.
/i .
- e. ; Men;1s% ).: .(l(l> '.
. = _ . f ' _ :: . .:' ;';"*'.. .
. y .. ..
,...y..,f.3-
_f. '
- a. : : - -- . . .., ./ ./.
. rs= < . - - <- i- .s.; ,
la e c.7s . - ,-.
-4 ,
. w _ .
} -
j; ,
j
,r
. 7-
\ fi, //
s'l .
.;f... ."'f:. ./.. ..._ "' -
1,2".. t";".'::
a e o.og. -
[..
,jj g e - .=.
/ /.'
T ._ .......' .
// ./
/ / 1
. /* l'l'.
c,A>W W W 4R bal/in.)
Figure 4-3. Fatigue Crack Growth P.sie Curve for Austenitic Stainless Steel l
3564s-J t 258910 l
1 da 3 .
dT = C F s y gg .30 where
= Crack Growth Rate in micro-inches / cycle d
-0 C= 2.42 x 10 I F = frequency factor (F = 1.0 for temperature below 800*F) .
S= R ratio correction (S = 1.0 for R = 0; S = 1 + 1.8R for .
O < R < .8; and S = -43.35 + 57.97R for R >
0.8)
=
E Environmental Factor (E = 1.0 for PWR) 4K = range of stress intensity factor, in psi /in and R is the ratio of the minimumy K (y,,,) to the maximum Ky (K, ).
Figure 4-4. Fatigue Crack Growth Equation for Austenitic Stainless Steel I
m 4..ousu io 4-8 j
)
+ - ,
c, ie I l
l l
SECTION 5.0 REASSESSMENT OF LEAK-BEFORE-BREAK 5.1 Introduction Leak-before-break evaluations were performed for the pressurizer surge line of l the Vogtle Unit 2 nuclear power plant in July,1987 (reference 5-1).
Following submittal to the Nuclear Regulatory Commission (NRC) in 1987, the NRC requested additional information which was supplied in references 5-2 and 5-3. Subsequently the NRC approved the request by Georgia Power Company which was technically supported by the leak-before-break reports.
The ingredients of the leak-before-break methodology are reviewed in table 5-1. Items 2, 3 and 8 are addressed in sections 2.0,1.0 and 4.0 of this report, respectively. This section addresses the remaining items. The conservatism used in this section are listed in table 5-2.
5.2 Material Properties Applicable material properties were developed from those in the Certified Materials Test Report as given in table 5-3 taken from reference' 5-1. The ASME code minimum properties are also given in table 5-3. It is seen that the measured properties well exceed those of the code. As seen later properties at 653*F and 455'F are required for the leak rate and stability analyses.
Industry data at 650'F were used as a basis for determining tensile properties at the required temperatures similar to the method described in reference 5-1. The required average and minimum properties are given in table 5-4. The 6 6 moduli of elasticity are 26.1 x 10 psi and 25.1 x 10 psi at 455'F and 653*F, respectively. The stress strain curves required for the leakage and stability analyses are shown in figures 5-1 through 5-3 as obtained bj application of the Nuclear Systems Materials Handbook (reference 5-4).
O m e.,o m asio 5-1
5.3 Loading Conditions
~
Because thermal stratification can cause large stresses at hcatup and cooldown temperatures in the range of 455'F, a review of stresses was used to identify the worst situations for LBB applications. The loading states so identified are given in table 5-5. The procedure for determining the worst loading situations is explained in section 5.6. Two locations, nodes 2060 and 2720, as shown in figure 5-4, were found to be the most critical for the LBB evaluation. At node 2050 there is a SMAW field weld. At node 2720 there is a GTAW (TIG) weld. The weld types at other locations are also indicated.
Five loading cases were identified for LBB evaluation as given in table 5-6.
CasesAandBarecasesforieakratecalculationswiththeremainingcases the corresponding faulted situations for stability evaluations. The loads at the critical locations for the five cases are given in table 5-7. The four case combinations for the leakage and stability evaluations are listed in table 5-8. Details of the evaluations for the four cases are given in table 5-9. .
5.4 Leak Rate Calculation .
Leakage through postulated cracks were calculated using the procedure discussed in reference 5-1. The resulting leakage flaws (i.e., the flaw sizes giving 10 gpm) are given in table 5-10. The normal loads for cases A and B were used noting that the temperature was [ Ja,c.e Actucily the .
laakage flaws associated with case A are of little relevarce since the normal operating stratification surges would lead to leakage datection for the associated leakage flaw (i.e., [
Ja c.e). This is particularly noteworthy at Node 2720 where the normal operating stress, without stratification, is low.
I
- =,
3sses/0315ee 10 5-2
5.5 Reactor Coolant System (RCS) Cooldown Stratification Temperature Considerations This section provides additional information for the postulated leak-before-break (LBB) case { ]a,c e This is a case in which (-
. 1 Ja,c.e The specific area of
. interest is the maximum pipe AT (Pipe Top-to-Bottom Temperature) that is postulated to occur during the cooldown. Two factors are used to predict the pipe AT; the system AT (pressurizer temperature minus hot leg tempera-ture), and the ratio of pipe AT to syr, tem AT (measured during testing).
5.5.1 Reactor Coolant System Temperature:
The postulated leak rate for [ la,c.e would not be expected to cause the activation of any safe'ty injection systems. Therefore, the generic Westinghouse procedure " Plant Shutdown from Minimum Load to Cold Shutdown" would apply. This procedure is the basis for the discussion which follows.
. Information from Vogtle Unit 2 procedures will be inserted as appropria N.
A plot of the pressurizer water temperature and the reactor coolant water
~
temperature during a typical normal cooldown is illustrated in figure 5-5.
The curves shown depict the band of temperatures possible per Vogtle Unit 2 procedures and the temperatures expected for F r cooldown following tiscovery of a leak in the RCS. Initially, the pressurizer contains a steam buoble with the water level at 25% of level span (no lead conditions). Early during the cooldown procedure, all but one (two pumps for Vogtle Unit 2) of the reactor coolant pumps are stopped. The operating pump is in the loop to which the i pressurizer surge line and a spray line are connected.
In general, the process can be divided into three phases; first from 0 to 4 j hours, the pressurizer water and reactor coolant system water are cooled down
.. together with the reactor coolant temperature maintained approximately 50 to mweme. io 5-3
100*F below the pressurizer saturation temperature. This temperature differ-Snee is mandated by subcooling requirements of the RCS. At 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, when the reactor coolant pressure and temperature have decreased to approximately 250 .
psig (225 to 275 psig range for Vogtle Unit 2) and 350'F, the residual heat removal system is placed in operation. From approximately 4 to 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />, the l pressurizer pressure remains constant at the pressure required to operate the reactor ecolant pumps while the reactor coolant temperature continues to dscrease to 160*F. When the reactor coolant system temperature has deceased !
to 160'F (110*F for Vogtle Unit 2), the operating reactor coolant pump is stopped. From 16 to 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />, the system is depressurized using auxiliary spray. The steam bubble in the pressurizer is collapsed when the pressure has been decreased to 25 psig. -
Based on the above discussion, the maximum temperature difference between pressurizer water and hot leg water is 314*F, that is, the difference between the saturation temperature of 414*F corresponding to 275 psig and the reactor coolant system temperature of 100*F. This temperature difference is the maximum potential temperature difference and is considered (when corrected to pipe versus system AT) in the stress and fatigue analysis. -
The case under question is (the postulated scenario of a 1 gpm leak being -
detected at full power and the subsequent cooldown to locate and repair the ieak ( )]a,c.e For this case a more realistic postulation of RCS conditions is assumed.
Per Vogtle Unit 2 procedures, the leak will be located while the plant is in mode 3, or time 0-4 hours on figure 5-5. Based on Vogtle operating proce-dures, if a leak in the RCS was detseted the first priority would be to depressurize the system. This depressurization would most likely occur when the RCS is at approximately 180*F as illustrated in figure 5-5 at time 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Therefore, the maximum expected system temperature difference would be between [ Ja.c.e For the analysis l
of case B/F the system temperature difference is assumed to be [ Ja.c,e O
3666s/031589 10 5-4 i
5.5.2 Pipe Versus System Temperature Difference The maximum expected pipe AT (Pipe T - Pipe TBottom) is a function of Top the system AT.
Thermal hydraulic considerations and actual monitoring data indicate that, for the phase of the cooldown considered herein, the pipe AT will always be less than the system AT. The phase of cooldown under investigation occurs after the reactor has achieved cold shutdown status. Data from the entire plant cycle (as available) was considered even though there was significantly less thermal activity observed during plant cooldowns. This investigation is based on monitored thermal transient information from : Ja,c.e plants. The number of thermal transients considered significant in this investigation was
[ Ja,c.e These transients are provided in table 5-11.
The mean (x) of the ratio of pipe AT to system AT was determined to be
[ la,c.e The maximum range of the data showed that the ratio of pipe AT to system AT varied from (
Ja,c.e It should be noted that a significant number of thermal transients were observed with pipe AT to system AT ratios much lower than
[ la'C These transients were excluded from consideration for conservatism.
5.5.3 C_onclusions The pipe AT is determined from the system AT in section 5.5.1 and the ratio of the pipe to system aT in section 5.5.2. The maximum system AT is
( Ja,c.e based on the arguments of section 5.5.1. The ratios of pipe to system AT were between [ Ja,c,e j i
I Therefore, the magnitude of pipe AT's expected for ['
]a,c.e The pipe aT used in the analysis of ( Ja.c.e m e,.,e m ,o s.5 I
Additional data obtained to date from actual plant cooldown supports the above position. Figure 5-6 (reference [ ' .)]"'C shows the pressurizer and
.RCS hot leg temperatures vs. time for two consecutive cooldowns. The maximum .
system AT was [ ]a,c.e; the pipe AT was not monitored during this cooldown. The first cooldown was due to a weld leak on the seal injection
- line and is typical of the type of response expected for a small leak that did not require a safeiv bjection. The second cooldown was for repairs on the secondary side of a steam generator manway gasket (also detected as a leak in containment).
Figure 5-7 (reference ( )]a,c.e illustrates the system temperatures from another actual plant cooldown. The maximum system aT obtained was
[ la,c,e Pipe AT's were also obtained for this period and are shown in figure 5-8 along with the system AT. The maximum pipe AT's for this cooldown was less than [ Ja,c.e Figure 5-9 illustrates the system versus pipe AT during HFT cooldown at Vogtle Unit 2. The maximum pipe AT was approximately 227'F while system aT was approximately 305'F. This cooldown is not considered as typical of those expected per Vogtle procedures. However, even with a high system AT, the pipe AT remained below the [
3a,c,e 5.6 Evaluation of Flux Welds The stability evaluations were performed using the ASME Section XI IWB 3640 procedure (reference 5.5). This procedure uses the limit load methodology with a correction factor related to the type of weld. This procedure was applied at all weld locations in establishing the critical locations to be node 2060 and node 2720. The flaw sizes for instability are also given in table 5-10.
5.7 Results t The leakage flaws and instability flaws are given in table 5-10. The margins .
(ratio of instability flaw to leakage flaw) are also given. The margins for analyses at 653*F (cases A/D and [ la,c,e) well exceed the factor of 2.
l l
ms,nma, ,a 9.s m_ .
j
The margin for the stratification during forced cooldown [ ]"'C
. is [
Ja,c.e As previously discussed, the case A (in this instance case
, [ ]a,c.e) is of little relevance since leakage would be detected for the leakage flaw size of case [ ]a,c.e Thus conclusions of the evaluations of this section are:
- 1. LBB exists at operating temperature without stratification
- 2. LBB exists at operating temperature with stratification
- 3. LBB exists for forced cooldown due to leakage In summary, LBB is reconfirmed for the surge line subjected to thermal stratification.
5.8 References ,
. 5-1 Swamy, S. A., et al., Technical Bases for Eliminating Pressurizer Surge
. Line Rupture as the Structural Design Basis for Vogtle Unit 2, WCAP-11531, July 1987 (Westinghouse Proprietary Class 2).
5-2 Swamy, S. A., et al., Additional Information in Support of the Elimination of Postulated Pipe Ruptures in the Pressurizer Surge Line of Vogtle Unit 2, WCAP-11531, Addendum 1, August 1987 (Westinghouse Proprietary Class 2.)
5-3 S. A. Swamy, Additional Information in Support of the Elimination of Postulated Pipe Ruptures in the Pressurizer Surge Line of Vogtle Unit 2, WCAP-11531, Addendum 2, September 1987 (Westinghouse Proprietary Class 2).
5-4 Nuclear Systems Materials Handbook, Part I - Structural Materials, Group 1 - High Alloy Steels, Section 2, ERDA Report TID 26666, November 1975 ;
e Revision.
l
- 5-5 ASME Code Section XI, Winter 1985 Addendum, Article IWB-3640.
mwomse so 5-7
TABLE 5-1 STEPS IN A LEAK-BEFORE-BREAK ANALYSIS (1) Establish material properties including fracture toughness values '
1 (2) Perform stress analysis of the siructure (3) Review operating history of the plant (4) Select locations for postulating flaws (5) Determine a flaw size giving a detectable leak rate (6) Establish stability of the selected flaw (7) Establish adequate margins in terms of leak rate detection, flaw size and load.
(8) Show that a flaw indication acceptable by inspection remains small throughout service life.
G 4
0
)
4 a womaein 5-8
_ _ _- u
1 TABLE 5-2 LBB CONSERVATISM
. i o Factor of 10 on Leak Rate o Factor of 2 on Leakage Flaw ,
o Algebraic Sum of Loads for Leakage o Absolute Sum of Loads for Stability o' Average Material Properties for Leakage o Minimum Material Properties for Stability 5
0 9
E o
an.mn.. io 5-9
n o
ia t e 5 5 4 6 0 1 3 2 cr A A A 3
uA 2 3 0 8 ///4 8 6 d 7 6 7 6 N N N 5 4 7 6 _
en _
Ri _
n o
ih <
t c an gI 8 5 7 6 0 0 0 0 5 5 n 3 2 6 0 1 6 0 1 9 2 0 or 5 5 5 5 4 3 4 4 4 6 5 l e EP F
O %
E SH ET I s 0 0 0 0 0 0 TF ws 5 0 0 0 0 0 9 t n
RO oe 4, 8, 4, 0, 5, 4, 7 6 -
E l r A A A e -
PS Ft 2 1 1 7 / / / 9 1 7 6 m -
OD S 6 6 6 6 N N N 7 7 5 6 e RLT r PEN i WA u q
L L ADP eh e .
3CN tt R
- I A2 ag 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 5N mn 0 0 0 0 0 0 0 0 0 3 8 m u
0 0 0 0 AST EHLI i e t r 7, 4, 9, 6, 5, 9, 5, 5, 5, 6, 2, m 0, 0, 0, 0, LCAN l t 2 1 9 7 2 2 1 1 3 2 0 i 5 5 0 0 BEIU US 8 8 7 8 9 9 9 9 9 8 9 n 7 7 6 8 .
AMR i T EE M ETL s RAT s e UMG t e d T 0 er o AEV st 0 0 0 0 0 0 0 0 C 0 0 0 RN fS 0 0 0 0 0 0 4 2 0 0 0 EI PL f
Od 2, 2, 9, 4, A A A 5, 3, 9, 9, E M 0, 0, -
0, M l 2 2 2 6 / / / 7 9 6 2 S 0 0 5 EE %e 4 4 4 4 N N N 6 4 3 4 A 3 3 3 TG 2i R Y MU 8 8 OS 6 6 6 6 0 8 0 4 N 6 4 N O 1 1 1 1 3 0 3 0 6 1 0 6 R 3 3 3 3 R 8 3 8 R 3 1 3 3 1 l P P P P E 0 E 0 E P 3 P P 3 a T T T l 3 - W F T W F i - - - - 9 E 4 E 9 - -
r 6 6 6 6 - - 3 2 6 3 2 e 7 7 7 7 5 4 5 4 S 0 8 7 0 8 8 t 3 3 3 3 A A A 4 1 3 4 0 1 a A A A A F 5 F S F A A A A 3 A M S S S S S A S A S S S S S E S A H A 4 H 1 7 e 6 6 6 0 9 5 0 2 6 7 3 l r 1 1 1 7 5 1 4 7 4 0 4 b a
t e 0 0 0 5 8 6 9 1 0 1 4 ab 4 4 4 6 5 0 1 2 - 4 6 l l
emu L L L J 7 5 1 S 1 6 n 6 J D 5 C 0 2 . 3 i a r l N i v e e e e A p p p p 4 i i i i 1 t O p p p p x o I t r r N 9 8 .
c . , . . e . le e e S dr um n n n n i i i i d d d d d ul i lz l c n c e u d z l
t 3
0
/
oo l l d z p d l z A 6 s
rF 6 6 6 4 e e e e e e 6 o i e e o / 6 6
P 1 1 1 1 W W W W W R 1 N P R W N N 3 uf
2 1
TABLE 5-4 TENSILE PROPERTIES FOR'THE SURGE LINE MATERIAL AT [ Ja,c.e and 653*F Temperature YieldStress(psi) Ultimate Strength
('F) Average Minimum Average Minimum
-- [ ya.c.e
- 653 [ .)a,c.e s
i i
l t
no minno 5-11
-_. .l
v' .;
TABLE 5-5 TYPES OF LOADINGS ,
Pressure (P) ,
- i -
l- Deadweight (DW)
Normal Operating Thermal Expansion (TH)
Safe Shutdown Earthquake and Seismic Anchor Motion (SSE)a
[
ja,c.e aSSE is used to refer to the absolute sum of these loadings. ,
e 09 w
n mine io 5-12
e TABLE 5-6
, NORMAL AND Ft.ULTED LOADING CASES FOR LBB EVALUATIONS
/ CASE A: This is the normal operating case at 653*F consisting of the algebraic sum of the loading components due to P, DW and TH.
[
ja,c.e CASE D: This is the faulted operating case at 653'F consisting of the absolute sum (every component load is taken as positive) of P, DW, TH and SSE.
[
ja,c,e
[
. ja,c.e 4
e 3 = .m i m in 5-13
l TABLE 5-7 ,
SUMMARY
OF LOADS AND STRESSES AT THE CRITICAL LOCATIONS s
Force Stress Moment Stress Total Node Case F(lbs) r5 7(psi) M(in-lbs) ch(psi) Stress (psi) 2060* A 327870 5057 3721112 17109 22165 2060 ( la.c.e 2060 0 333810 5148 6189649 28458 33606 2060 .[ Ja.c e b 2442 6786 2720 A 214374 4344 354061 2720 [ Ja,c.e e 3a,c.e 2720 [
t I
a Dimensions: 0.D. = 16 in., minmum wall thickness = 1.415 in. .
b 0.D. = 14 in., minimum wall thickness = 1.23 in, Dimensions:
stratification AT is [ ]C
l S
no m m io 5-14
TABLE 5-8 ASSOCIATED LOAD CASES FOR ANALYSES A/D This is here-to-fore standard leak-before-break evaluation.
[ .
ja,c.e
[:
ja,c.e
[-
ja.c.e O
8 i
i l
l 0
f 3666s/0315as to 5-15 l l t u
TABLE 5-9 LOAD CASES, LOCATION AND TEMPERATURES CONSIDERED FOR LEAK-BEFORE-BREAK EVALUATIONS '.
Temperature (*F) %
Case Node Leak Rate Stability A/D 2060 653 653
( ja.c.e
( 3a.c.e
[ 3a c.e
'9 e
b 4
e b
n 4m e in 5-16
TABLE 5-10 i LEAKAGE FLAW SIZES, CRITICAL FLAW SIZES AND MARGINS
. I
/ Location of Smallest Critical Flaw Load Critical Flaw Size Size Based On Case Based on IWB-3640 Calc. IWB-3640 Leakage Flaw Margin i
A/D 2060a 7.96 2.30 2.7
[ 3a,c.e
[- ja.c,e
[ ja,c.e aSMAW Weld
. b l
GTAW Weld e
h a
mwem . io 5-17
TABLE 5-11 SIGNIFICANT THERMAL TRANSIENTS
- PLANT D Pipe AT System AT %
a,c.e
[ ja,c.e .
Pipe AT System AT %
- a,c,e newesisa in 5-18
I TABLE 5-11 (cont.)
SIGNIFICANT THERMAL TRANSIENTS
[ ja.c.e Pipe AT System AT %
a,c.e
)
}
[ ja,c e Pipe AT System AT %
a,c.e l
e 3seos/03154010
i
~,
.. a,c.e Figure 5-1. Average True Stress-True Strain Curve for SA316 TF316 -
Stainless Steel at 653*F l _ _ . ,.
L_ _._
n l
l
- - a,c.e i
i l
1 Figure 5-2. Minimum True Stress-True Strain Curve for SA316 TPM6 Stainless Steel at 653*F no eu io 5-21 f
J
F.
[ j.
a,c.e Figure 5-3. Minimum True Stress-True Strain Curve for SA316 TP316
- Stainless Steel at ( Ja c.e me ma ie 5-22
e .
A: Critical Locations PRESSURIZER e: GTAW Weld
- g
,: SMAW Weld e
^
4 O: SAW Weld o
Hot eg Aa 2060 b eA a
(
O e
a Figure 5-4. Sketch r f Analysis Model for Vogtle Unit 2 Pressurizer Surge Line Showing Node Points, Critical Locations, Weld Locations and Type of Welds a minio 5-23 l
W.
S 4
,5 8
U .
M U
- CK I L
3
?
6
! t E
i 5-24
ll1 I :1 IlI. lll 11l
(
- e.
c, a .
k a
e L
S C
R n
a o
t e
u D
n w
o d
l e
I.
, l a
- t u
c A
e.
- c, a]
[
6 5
e r
u g
i F
e i
e w
. u e - _
3 Ttw o _
r l t lllli i
0 0
U.
N w a
I
+
e o
8 3
a O
4 ee O.
M 4 m
n 9
P W
e b
e LO W
L.
3 CD e
b i
'I 2 )
a b-26 .
j l l!!! I l! lIl>
' e, C,
8 I
_ e i
m T
s v
T a
e p
i P
d n
a T
A m
t e
s y
S n
g w o
- l a
o o
C 1
n i
o t
a c
o l
e.
c, a
J
[
8 5
e r
u g
A i F
e i.
9 e 8 15 3
6 -
s 0
8 _
0 _
3 1
JeNN
(
e Df ,'
n9 p
.n t
2 TE
=
M F
3 P:
8 e q 8
O S
c b
w 2
J" l
l 4
s s '
g F GED ECNEREFFID ERUTAREPMET i 9-28
1 SECTION
6.0 CONCLUSION
S y
Based on the monitoring and analysis results presented in the report the following conclusions are reached:
(a) Based on plant monitoring results from ( Ja.c.e Westinghouse PWR's including Vogtle Unit 2 and flow stratification test data, the thermal design transients for the surge line have been updated to incorporate the effects of stratification conservatively.
(b) The global structural and local stresses in the surge line piping and support system meet ASME III Code allowables, with support H006 replaced by snubber and spring hanger. The maximum cumulative fatigue usage factor is [ Ja.c.e for 40 year design life, comparad to the Code allowable of 1.0.
(c) Fatigue crack growth (FCG) analyses show that a postulated 10% initial crack will not propagate beyond 35% of the pipe wall in the 40 years design life.
4 (d) Leak-Before-Break (LBB) is confirmed for all loading combinations, including maximum postulated stratification.
In summary, based on the current understanding of the thermal stratification phenomenon, it is concluded that thermal stratification has very limited impact on integrity of the pressurizer surge line of the Vogtle Unit 2 nuclear power plant. The forty year design life is not impacted.
o me.an=in 6-1
1 APPENDIX A y LIST OF COMPUTER PROGRAMS
,j This appendix lists and summarizes the computer codes used in the analysis of stratification in the Vogtle Unit 2 pressurized surge line. The codes are:
- 1. WECAN
- 2. WECEVAL
- 3. STRFAT2
- 4. ANSYS
- 5. FCG A.1 WECAN A.1.1 Description WECAN is a Westinghouse-developed, general purpose finite element program. It
- contains universally accepted two-dimensional and three-dimensional s isoparametric elements that can be used in many different types of finite e element analyses. Quadrilateral and triangular structural elements are used i for plane strain, plane stress, and axisymmetric analyses. Brick and wedge structural elements are used for three-dimensional analyses. Companion heat conduction elements are used for steady state heat conduction analyses and transient heat conduction analyses.
A.1.2 Feature Used The temperatures obtained from a static heat conduction analysis, or at a specific time in a transient heat conduction analysis, can be automatically input to a static structural analysis where the heat conduction elements are replaced by corresponding structural elements. Pressure and external loads can also be include in the WECAN structural analysis. Such coupled
+ thermal-stress analyses are a standard application used extensively on an industry wide basis.
n -esme,o A-1
i A.1.3 Program Verification v,
Beth tha WECAN prograra and input for the WECAN verification problems, currently numbering over four hundred, are maintained under configuration 4 control. Verification problems include coupled thermal-stress analyses for the quadrilateral, triangular, brick, and wedge isoparametric elements. These problems tre an integral part of the WECAN quality assurance procedures. When '
a change is made to WECAN, as part of the reverification process, the configured inputs for the coupled thermal-stress verification problems are used to reverify WECAN for coupled thermal-stress analyses.
A.2 WECEVAL A.2.1 Description WECEVAL is a multi purpose program which processes stress input to calculate ASME Section III, Subsection NB equations and usage factors. Specifically, the program performs primary stress evaluations, primary plus secondary stress .
intensity range analysis, and fatigue analysis for finite element models , i generated and run using the WECAN computer program. Input to WECEVAL consists >
of card image data and data extracted from the output TAPE 12's generated by .
WECAN's stress elements. The program reads the input data, performs the
! necessary calculations, and produces summary sheets of the results.
The required stresses are read from the WECAN TAPE 12's and placed onto intertnediate or restart files. The user may then catalog thase files for use in later evaluations. The stress state for a particular loading condition is obthined by a ratio-superposition technique. This optimal stress state is formed by manipulating the signs of the applied loads to generate the largest postible stress magnitude.
1 A.2.2 Feature Used '
WECEVAL has many options and features which enhance its versatility. Among those used for this evaluation were: -1 me.-ovmo A-2
- 1. The ability to perform simplified elastic plastic analysis per NB-3228.5,
" including the automatic calculation of Ke factors and removal of thermal bending stresses from the maximum range of stress intensity evaluations.
4
- 2. Built-in ASME fatigue curves plus provisions for accepting user-defined fatigue curves.
- 3. Equivalent moment linearization technique, along with the ability to correct for the radius effects in cylindrical and spherical geometries,
- 4. The ability to limit the interactions among load conditions during the-fatigue analysis,
- 5. Generating input for the fatigue crack growth program FCG.
A.2.3 Program Verification
- WECEVAL is verified to Westinghouse procedures by independent calculations of 5
ASME III NB Code equations and comparison to WECEVAL results.
e
' A.3 STRFAT2 i
A.3.1 Description STRFAT2 is a program which computes the alternating peak stress on the inside surface of a flat plate and the usage factor due to striping on the rurface.
The program is applicable to be used for striping on the inside surface of a pipe if the program assumptions are considered to apply for the particular pipe being evaluated.
for striping the flu'i temperature is a sinusoidal variation with numerous cycles.
d The frequency, convection film coefficient, and pipe material properties are input.
I ami-osius to A-3
L The program computes maximum alternating' stress based on the maximum difference between inside surface skin temperature and the average through t wall temperature.
k
.A.3.2 Feature Used The program is used to calculate striping usage factor based on a ratio of actual cycles of stress for a specified length of time divided by allowable cycles of stress at maximum the alternating stress level. Design fatigue curves for several materials are contained into the program. However, the user has the option to input any other fatigue design curve, by designating
-that the fatigue curve is to be user defined.
A.3.3 Program Verification STRFAT2 is verified to Westinghouse procedures by independent review of the atress equations and calculations.
A.4 ANSYS A.4.1 Description ANSYS is a public domain, general purpose finite element code.
A.4.2 Feature Used The ANSYS elements used for the analysis of stratification effects in the surge and RHR lines are STIF 20 (straight pipe), STIF 60 (elbow and bends) and STIF14 (spring-damper for supports).
A.4.3 Program Verification g
As described in section 2.1, the application of ANSYS for stratification has been independently ~ verified by comparison to WESTDYN (Westinghouse piping] ,
e no -onme in A-4
r analysis code) and WECAN (finite element code, section 8.1). The results from l(
ANSYS are also verified against closed form solutions for simple beam configurations.
J A.5 FCG A.5.1 Description The FCG computer program models fatigue crack growth using linear elastic fracture mechanics methods. In order to provide a realistic model of crack growth the design transients which are input are automatically scheduled evenly over the life of the system or component.
A.5.2 Features Used The program options enable calculation of crack tip stress intensity factors (Ky ) for surface flaws and embedded flaws in a large. number of geometries, 6 under any loading condition. Crack growth results are determined for each i year of operation, and summarized in tabular form at the end of the output, at i 10 year intervals.
f.
A.5.3 Program Verification The program has been verified by performing alternate calculations and placed under Westinghouse configure. tion control. The c=1culations using this program were presented and approved by the NRC staff in connection with several l applications.
t o
J nu.e u.." A-5
_ . . . . . _ . _ . _ _ _ . . .