Dynamic Simulation of Sodium Cooled Fast Reactors

273 Pages·2022·24.342 MB·English

by  G Vaidyanathan

Dynamic Simulation of Sodium
Cooled Fast Reactors
This book provides the basis of simulating a nuclear plant, in understanding
the knowledge of how such simulations help in assuring the safety of the
plants, thereby protecting the public from accidents. It provides the reader
with an in- depth knowledge about modeling the thermal and flow processes
in a fast reactor and gives an idea about the different numerical solution
methods. The text highlights the application of the simulation to typical
sodium- cooled fast reactor.
The book
• Discusses mathematical modeling of the heat transfer process in a fast
reactor cooled by sodium.
• Compares different numerical techniques and brings out the best one
for the solution of the models.
• Provides a methodology of validation based on experiments.
• Examines modeling and simulation aspects necessary for the safe
design of a fast reactor.
• Emphasizes plant dynamics aspects, which is important for relating
the interaction between the components in the heat transport systems.
• Discusses the application of the models to the design of a sodium-
cooled fast reactor
It will serve as an ideal reference text for senior undergraduate, graduate
students, and academic researchers in the fields of nuclear engineering,
mechanical engineering, and power cycle engineering.

Dynamic Simulation of
Sodium Cooled Fast
Reactors
G. Vaidyanathan
Cover image: snvv18870020330/Shutterstock
First edition published 2023
by CRC Press
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and by CRC Press
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CRC Press is an imprint of Taylor & Francis Group, LLC
© 2023 G. Vaidyanathan
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ISBN: 978-1-032-25435-7 (hbk)
ISBN: 978-1-032-25437-1 (pbk)
ISBN: 978-1-003-28318-8 (ebk)
DOI: 10.1201/9781003283188
Typeset in Sabon
by SPi Technologies India Pvt Ltd (Straive)
Contents
Preface xiii
About the Author xv
1 Introduction 1
1.1 General 1
1.2 Basics of Breeding 1
1.3 Uranium Utilization 2
1.4 Components of Fast Reactors 5
1.5 Overview of Fast Reactor Programs 6
1.6 Need for Dynamic Simulation 9
1.7 Design Basis 10
1.8 Plant Protection System 12
1.9 Sensors and Response Time 14
1.10 Scope of Dynamic Studies 15
1.11 Modeling Development 16
Assignment 17
References 17
2 Description of Fast Reactors 19
2.1 Introduction 19
2.2 Fast Breeder Test Reactor (FBTR) 19
2.2.1 Reactor Core 21
2.2.2 Reactor Assembly 23
2.2.3 Sodium Systems 24
2.2.4 Decay Heat Removal 27
2.2.5 Generating Plant 28
2.2.6 Instrumentation and Control 28
2.2.7 Safety 29
v
vi Contents
2.3 Prototype Fast Breeder Reactor 31
2.3.1 Reactor Core 32
2.3.2 Reactor Assembly 33
2.3.3 Main Heat Transport System 35
2.3.4 Steam Water System 35
2.3.5 Instrumentation and Control 36
2.3.6 Safety 37
2.4 Neutronic Characteristics of SFRs 38
2.5 Thermal-Hydraulic Characteristics of SFR 40
Assignment 41
References 41
3 Reactor Heat Transfer 43
3.1 Introduction 43
3.2 Reactor Core 43
3.2.1 Core Description 44
3.2.2 Fuel Pin 45
3.2.3 Subassembly 47
3.3 Coolant Selection 47
3.4 Control Material Selection 48
3.5 Structural Material Selection 48
3.6 Heat Generation 49
3.7 Reactivity Feedback 51
3.7.1 Doppler Effect 52
3.7.2 Sodium Density and Void Effects 53
3.7.3 Fuel Axial Expansion Effect 53
3.7.4 Structural Expansion 54
3.7.5 Bowing 54
3.8 Decay Heat 56
3.9 Solution Methods 57
3.9.1 Prompt Jump Approximation 57
3.9.2 Runge Kutta Method 58
3.9.3 Kaganove Method 58
3.9.4 Comparison of the Different Methods 58
3.9.5 Solution Methodology 59
3.10 Heat Transfer in Primary System 61
3.10.1 Core Thermal Model 61
3.10.2 Fuel Restructuring 62
3.10.3 Gap Conductance 63
3.10.4 Fuel Thermal Model 63
3.10.5 Solution Technique 64
Contents vii
3.11 Determination of Peak Temperatures: Hot Spot Analysis 64
3.12 Core Thermal Model Validation in FBTR and SUPER
PHENIX 65
3.13 Mixing of Coolant Streams in Upper Plenum 66
3.13.1 Solution Technique 69
3.14 Lower Plenum/Cold Pool 70
3.15 Grid Plate 74
3.16 Heat Transfer Correlations for Fuel Rod Bundle 75
Assignment 76
References 77
4 IHX Thermal Model 79
4.1 Introduction 79
4.2 Experience in PHENIX 79
4.3 Thermal Model 82
4.4 Solution Techniques 83
4.4.1 Nodal Heat Balance Scheme 83
4.4.2 Finite Differencing Scheme 84
4.5 Choice of Numerical Scheme 85
4.5.1 Nodal Heat Balance for Unbalanced Flows 85
4.5.2 Modified Nodal Heat Balance Scheme (MNHB) 86
4.6 Heat Transfer Correlations 89
4.7 Validation 90
Assignment 91
References 92
5 Thermal Model of Piping 95
5.1 Introduction 95
5.2 Thermal Model 96
5.3 Solution Methods 97
5.4 Comparison of Piping Models 98
Assignment 100
References 100
6 Sodium Pump 101
6.1 Introduction 101
6.2 Electromagnetic Pumps 101
6.3 Centrifugal Pump 102
6.3.1 Pump Hydraulic Model 104
6.3.2 Pump Dynamic Model 104
viii Contents
6.3.3 Pump Thermal Model 108
Assignment 109
References 109
7 Transient Hydraulics Simulation 111
7.1 Introduction 111
7.2 Momentum Equations 111
7.3 Free Level Equations 113
7.4 Core Coolant Flow Distribution 113
7.5 IHX Pressure Drop Correlations 116
7.5.1 Resistance Coefficient for Cross-Flow 117
7.5.2 Resistance Coefficient for Axial Flow 118
7.6 Pump Characteristics 118
7.7 Computational Model 118
7.8 Validation Studies 119
7.9 Secondary Circuit Hydraulics 120
7.9.1 Secondary Hydraulics Model 121
7.9.2 Natural Convection Flow in Sodium Validation
Studies 122
Assignment 123
References 123
8 Steam Generator 125
8.1 Introduction 125
8.2 Heat Transfer Mechanisms 125
8.3 Steam Generator Designs 127
8.3.1 Conventional Fossil-Fueled Boilers 127
8.3.1.1 Drum Type 127
8.3.1.2 Once Through Steam Generators
(OTSG) 128
8.3.2 Sodium-Heated Steam Generators 129
8.4 Thermodynamic Models 133
8.5 Mathematical Model 138
8.6 Heat Transfer Correlations 139
8.6.1 Single-Phase Liquid Region 139
8.6.2 Nucleate Boiling 139
8.6.3 Dry-Out 141
8.6.4 Post Dry-Out 142
8.6.5 Superheated Region 142
8.6.6 Sodium Side Heat Transfer 142
Contents ix
8.7 Pressure Drop 142
8.8 Computational Model 144
8.8.1 Solution of Water/Steam Side Equations 144
8.8.2 Solution of Sodium, Shell, and Tube Wall
Equations 145
8.9 Steam Generator Model Validation 146
Assignment 149
References 149
9 Computer Code Development 151
9.1 Introduction 151
9.2 Organization of DYNAM 151
9.3 Axisymmetric Code STITH-2D 154
9.4 One-dimensional CFD-coupled Dynamics Tool 155
9.5 Comparison of Predictions of DYANA-P and
DYANA-HM 156
References 162
10 Specifying Sodium Pumps Coast-Down Time 163
10.1 Introduction 163
10.2 Impact of Coast-Down Time in Loop-Type SFR 163
10.3 Impact of Coast-Down Time in Pool-Type SFR 165
10.4 Considerations for Determining Flow Coast-Down Time 166
10.5 SCRAM Threshold versus Coast-Down Time 169
10.5.1 FHT Effect on Maximum Temperatures 170
10.5.2 FHT to Avoid SCRAM for Short Power Failure 171
10.6 Secondary Pump FHT 171
10.7 Primary FHT for Unprotected Loss of Flow 172
Assignment 174
References 174
11 Plant Protection System 177
11.1 Introduction 177
11.2 Limiting Safety System Settings (LSSS) for FBTR 177
11.2.1 Safety Signals and Settings 178
11.2.2 Limiting Safety System Settings (LSSS) Adequacy 178
11.3 Limiting Safety System Settings for PFBR 180
11.3.1 Design Basis Events 181
11.3.2 Core Design Safety Limits 181
11.3.3 Selection of SCRAM Parameters 182