[표제지 등]
제출문
Summary
요약문
Contents
Development of Regulatory Assessment Technology for the Prediction of Local Areas Susceptible to FAC-Caused Wall Thinning in Carbon-Steel Pipes 20
1. Introduction 22
2. Prediction of the Local Areas Susceptible to the Wall Thinning due to Flow-Accelerated Corrosion on the Feeder Pipes Conveying Single-Phase Coolant 28
2.1. Validation of CFD Approach 28
2.2. Evaluation of turbulence models 29
2.3. Feeder pipe models for CFD Analysis 30
2.4. CFD Calculations 32
2.5. Results and discussion 35
2.6. Conclusions 36
3. Numerical Calculation of Shear Stress Distribution on the Inner Wall Surface of CANDU Reactor Feeder Pipe Conveying Two-Phase Coolant 64
3.1. Mathematical formulation 64
3.2. CFD Calculations 65
3.3. Results and discussion 68
3.4. Conclusions 69
4. Prediction of the Structurally Weakest Local Region of Branch Pipes Subjected to Flow-Accelerated Corrosion Degradation 84
4.1. Background 84
4.2. CFD Calculations 85
4.3. Results and discussion 89
4.4. Conclusions 89
Reference 110
Table 2.1. Specification of feeder pipes 37
Table 2.2. Classification according to the type of outlet lower feeder pipe 38
Table 2.3. Major parameters of CFD analysis 39
Table 4.1. Examples of wall thinning failure 91
Table 4.2. Major parameters of CFD analysis 92
Figure 1.1. Geometry and dimensions of a typical feeder pipe connected to pressure tube 25
Figure 1.2. Present monitoring points of feeder pipes 26
Figure 2.1. Schematic result of Surry unit 2 wall thinning failure 40
Figure 2.2. System modeling of Surry unit 2 wall thinning failure 41
Figure 2.3. Velocity vectors for Surry unit 2 wall thinning failure (on z=0 plane) 42
Figure 2.4. Wall shear distribution on the inner surface area for Surry unit 2 wall thinning failure 42
Figure 2.5. Comparison of velocity vectors for the SST and k-ε model on z=0 plane 43
Figure 2.6. Comparison of wall shear distribution for the SST and k-ε model 44
Figure 2.7. Two categories by the direction of the 1st bend outlet(이미지참조) 47
Figure 2.8. System modelings of selected feeder pipes 48
Figure 2.9. Comparison of wall shear distribution between a real feeder pipe model and its simplified model for type 4B feeder pipe 49
Figure 2.10. Comparison of wall shear distribution between a real feeder pipe model and its simplified model for type 5A feeder pipe 50
Figure 2.11. Comparison of wall shear distribution between a real feeder pipe model and its simplified model for type 10A feeder pipe 51
Figure 2.12. Comparison of wall shear distribution between a real feeder pipe model and its simplified model for type 11B feeder pipe 52
Figure 2.13. Effects of the bend angle of type A feeder pipe on the pressure drop and maximum wall shear 53
Figure 2.14. Effects of the bend angle of type A feeder pipe on the location subjected to the maximum wall shear 54
Figure 2.15. Effects of the 2nd(이미지참조) straight span length of type A feeder pipe on the pressure drop and maximum wall shear 55
Figure 2.16. Effects of the 2nd(이미지참조) straight span length of type A feeder pipe on the location subjected to the maximum wall shear 56
Figure 2.17. Effects of the 1st(이미지참조) straight span length of type A feeder pipe on the pressure drop and maximum wall shear 57
Figure 2.18. Effects of the 1st(이미지참조) straight span length of type A feeder pipe on the location subjected to the maximum wall shear 58
Figure 2.19. Effects of the bend angle of type B feeder pipe on the pressure drop and maximum wall shear 59
Figure 2.20. Effects of the bend angle of type B feeder pipe on the location subjected to the maximum wall shear 60
Figure 2.21. Effects of the 1st(이미지참조) straight span length of type B feeder pipe on the pressure drop and maximum wall shear 61
Figure 2.22. Effects of the 1st(이미지참조) straight span length of type B feeder pipe on the location subjected to the maximum wall shear 62
Figure 2.23. Weak region due to FAC in case where the 1st(이미지참조) bend winds in the upstream direction of pressure tube 63
Figure 2.24. Weak region due to FAC in case where the 1st(이미지참조) bend winds in the downstream direction of pressure tube 63
Figure 3.1. Void fraction distributions on the symmetry plane Z=0 of the feeder pipe type A 71
Figure 3.2. Void fraction distributions at the wall cross sections of the feeder pipe type A (α=0.2) 72
Figure 3.3. Effects of the void fraction of type A feeder pipe on the pressure drop and maximum wall shear 73
Figure 3.4. Fluid shear stress distribution on the inner wall surface of the feeder pipe type A 74
Figure 3.5. Effects of the void fraction on the local positions of the feeder pipe A inner wall surface subjected to the maximum fluid shear stress 75
Figure 3.6. Void fraction distributions on the symmetry plane Z=0 of the feeder pipe type B 76
Figure 3.7. Void fraction distributions at the wall cross sections of the feeder pipe type B (α=0.2) 77
Figure 3.8. Effects of the void fraction of type B feeder pipe on the pressure drop and maximum wall shear 78
Figure 3.9. Fluid shear stress distribution on the inner wall surface of the feeder pipe type B 79
Figure 3.10. Effects of the void fraction on the local positions of the feeder pipe B inner wall surface subjected to the maximum fluid shear stress 81
Figure 3.11. Weak region due to FAC in case where the 1st(이미지참조) bend winds in the upstream direction of pressure tube 82
Figure 3.12. Weak region due to FAC in case where the 1st(이미지참조) bend winds in the upstream direction of pressure tube 82
Figure 4.1. Geometry and dimensions of a branch pipe having two bends connected to the straight pipe 93
Figure 4.2. Two categories by the direction of the main flow 94
Figure 4.3. Effects of the L₃ length of type A branch pipe on the location subjected to the maximum wall shear 95
Figure 4.4. Wall shear distributions on the line of θ=45˚, 135˚, 225˚ or 315˚ according to the L₃ length 96
Figure 4.5. Effects of the L₁ & L₂ length of type A branch pipe on the location subjected to the maximum wall shear(L₁=9 [in]) 97
Figure 4.6. Effects of the L₁ & L₂ length of type A branch pipe on the location subjected to the maximum wall shear(L₁=18 [in]) 98
Figure 4.7. Effects of the L₁ & L₂ length of type A branch pipe on the location subjected to the maximum wall shear(L₁=27 [in]) 99
Figure 4.8. Effects of the L₁ & L₂ length of type A branch pipe on the magnitude of the maximum wall shear 100
Figure 4.9. Effects of the inlet mass flow rates of type A branch pipe on the location subjected to the maximum wall shear(L₁=L₂=18 [in]) 101
Figure 4.10. Effects of the inlet mass flow rates of type A branch pipe on the magnitude of the maximum wall shear (L₁=L₂=18 [in]) 102
Figure 4.11. Effects of the L₁ & L₂ length of type B branch pipe on the location subjected to the maximum wall shear(L₁=9 [in]) 103
Figure 4.12. Effects of the L₁ & L₂ length of type B branch pipe on the location subjected to the maximum wall shear(L₁=18 [in]) 104
Figure 4.13. Effects of the L₁ & L₂ length of type B branch pipe on the location subjected to the maximum wall shear(L₁=27 [in]) 105
Figure 4.14. Effects of the L₁ & L₂ length of type B branch pipe on the magnitude of the maximum wall shear 106
Figure 4.15. Effects of the inlet mass flow rates of type B branch pipe on the location subjected to the maximum wall shear(L₁=L₂=18 [in]) 107
Figure 4.16. Effects of the inlet mass flow rates of type B branch pipe on the magnitude of the maximum wall shear(L₁=L₂=18 [in]) 108
Figure 4.17. Weak region due to FAC in case where the main flow has an identical direction to the 1st(이미지참조) bend outlet of branch pipe 109
Figure 4.18. Weak region due to FAC in case where the main flow has an opposite direction to the 1st(이미지참조) bend outlet of branch pipe 109