VVER-1000 Coolant Transient Benchmark - OECD Nuclear Energy ...

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COARSE MESH RESULTS Figure 5.53 shows the time history of pressure above the core. Figure 5.54 shows the time history of SG-1 pressure. Generally good agreement with plant data and code-to-code is displayed, with the exception of loop flow rates in the ORNL results and pressure above the core in the KU simulation. 5.4 Discussion Computationally efficient coarse-mesh vessel TH models were tested in flow mixing calculations. Code-to-experiment, code-to-CFD and coarse-mesh code-to-code comparisons were performed. The detailed evaluation of the differences to plant data shows that the coarse-mesh vessel TH models can reasonably well reproduce the main flow features and the assembly inlet temperatures in asymmetric flow mixing transients, characterised by sector formation. For this type of coolant transient, coarse-3-D models do not perform noticeably better than multi-1-D. The resolution improves with the mesh refinement. The solutions are sensitive to the azimuth meshing. The available results suggest that for an acceptable accuracy in core inlet distributions at least 16-18 azimuth sectors are necessary. The deviations in assembly inlet temperatures are within 1-8 K which is significantly larger than the observed CFD error range. Some of the discrepancies between different coarse-mesh results can be explained by the modelling differences summarised in Table 5.1 and the participants’ provided calculation details given in Appendix D. 64 V1000CT-2: SUMMARY RESULTS OF EXERCISE 1 ON VESSEL MIXING SIMULATION – © OECD/NEA 2010
Table 5.2: Initial state results INRNE GRS/KI KU ORNL PSU Parameter Plant data Uncertainty CATHARE 2.5 ATHLET/BIPR8 RELAP3D RELAP3D TRACE Core power, MW 281 281 295 281 281 – ±60 Pressure above the core, MPa 15.59 15.605 15.595 15.593 15.6 – ±0.3 MPa Cold leg #1 temperature, K 541.75 541.75 (BC) 541.74 541.74 541.62 – ±1.5 K Cold leg #2 temperature, K 541.85 541.85 (BC) 541.83 541.7 541.64 – ±1.5 K Cold leg #3 temperature, K 541.75 541.75 (BC) 541.95 541.73 541.62 – ±1.5 K Cold leg #4 temperature, K 541.75 541.75 (BC) 541.76 541.7 541.64 – ±1.5 K Hot leg #1 temperature, K 545 544.65 544.85 544.73 544.8 – ±1.5 K Hot leg #2 temperature, K 545.09 544.68 544.91 544.59 544.9 – ±1.5 K Hot leg #3 temperature, K 545.09 544.71 545 544.7 544.8 – ±1.5 K Hot leg #4 temperature, K 545 544.83 544.88 544.61 544.9 – ±1.5 K Loop #1 flow rate, kg/s 4 737 4 737.0 4 738.4 4635.4 4 245 – ±110 kg/s Loop #2 flow rate, kg/s 4 718 4 718.0 4 720.4 4 636.1 4 275 – ±110 kg/s Loop #3 flow rate, kg/s 4 682 4 682.0 4 684.1 4 635.4 4 245 – ±110 kg/s Loop #4 flow rate, kg/s 4 834 4 833.9 4 831.5 4 636.1 4 275 – ±110 kg/s Core flow rate, kg/s 18 971 18 970.9 18 699.7 18 543 16 762 – ±490 kg/s Reactor pressure drop, MPa 0.418 0.418 0.4132 0.407 0.409 – ±0.043 MPa Pressure in SG 1, MPa 5.11 5.1344 5.131 – – ±0.2 MPa Pressure in SG 2, MPa 5.13 5.1344 5.131 – – ±0.2 MPa Pressure in SG 3, MPa 5.15 5.1344 5.131 – – ±0.2 MPa Pressure in SG 4, MPa 5.13 5.1344 5.131 – – ±0.2 MPa MSH pressure, MPa 5.07 5.13 5.129 5.12 – ±0.2 MPa CFD RESULTS AND DISCUSSION V1000CT-2: SUMMARY RESULTS OF EXERCISE 1 ON VESSEL MIXING SIMULATION – © OECD/NEA 2010 65
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Nuclear Science ISBN 978-92-64-9915
Page 3 and 4:
Foreword FOREWORD The Nuclear Energ
Page 5 and 6:
Table of contents TABLE OF CONTENTS
Page 7 and 8:
List of tables LIST OF TABLES 1.1 L
Page 9 and 10:
LIST OF FIGURES 4.34 CEA TRIO_U and
Page 11:
List of abbreviations ANS American
Page 14 and 15: INTRODUCTION 1.2 Exercise 2 - Compu
Page 16 and 17: THE INVESTIGATED MIXING PROBLEM •
Page 18 and 19: THE INVESTIGATED MIXING PROBLEM Fig
Page 25 and 26: Chapter 3: Methodology of compariso
Page 27 and 28: Chapter 4: CFD results and discussi
Page 29 and 30: Temperature, K Temperature, K Figur
Page 31 and 32: CFD RESULTS AND DISCUSSION Figure 4
Page 33 and 34: 4.4.3 Radial distributions at the c
Page 35 and 36: Temperature, K Figure 4.4: Downcome
Page 37 and 38: Velocity at 5 800 mm (m/s) Figure 4
Page 41 and 42: Figure 4.10: EREC REMIX results - a
Page 43 and 44: Figure 4.14: FZK CFX 5 results - an
Page 45 and 46: Figure 4.18: BUTE CFX 10 results -
Page 47 and 48: Figure 4.22: Assembly-by-assembly c
Page 49 and 50: Temperature deviations, K Temperatu
Page 59: Velocity, m/s Velocity, m/s Figure
Page 62 and 63: COARSE MESH RESULTS 5.2 Final state
Page 66 and 67: CFD RESULTS AND DISCUSSION Table 5.
Page 68 and 69: COARSE MESH RESULTS Velocity at 5 8
Page 70 and 71: COARSE MESH RESULTS Figure 5.6: INR
Page 72 and 73: COARSE MESH RESULTS Figure 5.10: KU
Page 74 and 75: COARSE MESH RESULTS Figure 5.14: UN
Page 76 and 77: COARSE MESH RESULTS Figure 5.17: De
Page 78 and 79: COARSE MESH RESULTS Temperature dev
Page 88 and 89: COARSE MESH RESULTS Figure 5.40: As
Page 90 and 91: COARSE MESH RESULTS Temperature, K
Page 98 and 99: COARSE MESH RESULTS Flow rate, kg/s
Page 101 and 102: Chapter 6: Summary and conclusions
Page 103 and 104: References REFERENCES ANSYS (2010a)
Page 105 and 106: CFX 10 (FZK, FZD, BUTE, UNIPI) Appe
Page 107 and 108: DESCRIPTION OF CFD CODES millions o
Page 109 and 110: CATHARE2 (INRNE) Appendix B: Descri
Page 111: DESCRIPTION OF SYSTEM CODES The rea
Page 114 and 115:
PARTICIPANT-PROVIDED COMPUTATION DE
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INRNE (CATHARE 2.5) I. Vessel therm
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PSU (TRACE) I. Vessel thermal-hydra
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II. Core thermal-hydraulic model 1.
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DEVIATIONS OF CFD COMPUTED-TO-EXPER
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*89 1.00 *62 2.84 103 0.33 76 2.06
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*89 -0.38 *62 3.46 103 -0.40 76 4.3
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*89 -0.98 *62 7.73 103 -0.84 76 8.9
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