U
NIVERSITÀ DI
P
ISA
Dottorato di Ricerca in Ingegneria Industriale
Curriculum in Nucleare e Sicurezza Industriale
Ciclo XXXI
Experimental and numerical activities
for the thermal hydraulic analysis of PbLi eutectic in
breeding-blanket concepts
of nuclear fusion reactors
Author
Alessandro VENTURINI
Supervisors
Prof. Nicola FORGIONE Dott. Ing. Daniele MARTELLI Dott. Ing. Marco UTILI
Coordinator of the PhD Program
Prof. Giovanni MENGALI
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Abstract
This PhD thesis aims to contribute to the thermal hydraulic analyses in support of the development of a Breeding Blanket for nuclear fusion reactors. To achieve this goal, the thesis focused on Lead-Lithium Eutectic (LLE) technologies and leant, as a cathedral, on some pillars: experiments, numerical simulations and, to a lesser extent, design of experimental facilities. This research activity was performed at the Department of Civil and Industrial Engineering of the University of Pisa, for the numerical activities, at ENEA Brasimone RC, to perform experiments in the existing facilities, and in the Fusion Laboratory at UCLA, to install and commission an upgraded experimental facility.
The first chapter of the thesis, the façade of the cathedral, constitutes an attempt to delineate the several open points on the research involving LLE, reviewing the facilities currently in operation in the world, briefly discussing on the exact eutectic point of the lead-lithium alloys and summarizing the many different correlations proposed for the thermophysical properties of this alloy. If the first two points were required to understand the breadth of the research on LLE and the originality of the thesis, the review of thermophysical properties was needed also to select the correlations to be used during the activities and to be implemented in RELAP5/mod3.3.
The first pillar is represented by the experimental activities. Three experimental campaigns were carried out in the facilities IELLLO and THALLIUM at ENEA Brasimone RC. The campaign in IELLLO aimed to qualify components and instrumentation for the use in LLE and, in particular, for the following activities in THALLIUM. The campaigns in THALLIUM, instead, simulated the release of high pressure helium in stagnant LLE, an accidental transient known as In-box LOCA for the HCLL TBS. Eleven injections were performed with different parameters in order to achieve a good comprehension of the involved phenomena. The post-test analyses described how the pressure wave would likely propagate in the LLE loop of the HCLL TBS and highlighted which are the key components to design an effective mitigation strategy.
The experimental data from the three campaigns were used to perform numerical simulations, which represent the second pillar. The experiments on LLE circulation and heat transfer carried out in IELLLO were simulated with the system code RELAP5-3D, validating the nodalization of the facility and contributing to test the code with LLE. The eleven injections of THALLIUM were simulated with RELAP5-3D, using Lead-Bismuth Eutectic for lack of LLE properties above 40 bar, and, for injections 6-11, with RELAP5/mod3.3, after the implementation of LLE properties at the University of Pisa. The use of the system code RELAP5 greatly contributed to delve into the dynamics of the In-box LOCA. The simulations showed a good agreement with the experimental data, with two main discrepancies: the delayed effect of the relief valve and the absence of one of the pressure peaks, likely originated by the elasticity of the structure. The third pillar is represented by the design of experimental facilities. In this thesis, the contribution to the upgrade of MaPLE facility is described. The activity, carried out within the framework of the agreement between EUROfusion and UCLA, implied the realization of the P&ID, the design and installation of two main components, the air cooler and the permanent magnet pump, and the fulfillment of the commissioning tests for the whole facility.
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v
CONTENTS
Abstract ... iii
CONTENTS ... v
LIST OF ACRONYMS ... x
LIST OF FIGURES ... xiii
LIST OF TABLES ... xxi
1 Introduction ... 1
1.1 Research framework ... 1
1.2 Description and objectives of the research activity ... 2
1.3 Structure of the thesis ... 4
1.4 References ... 4
2 State of the art and literature review ... 6
2.1 Introduction ... 6
2.2 Review of experimental facilities working with LLE ... 6
2.3 Note on the eutectic point for LLE ... 20
2.4 Review of the thermophysical properties ... 21
2.4.1 Density ... 23
2.4.2 Specific heat ... 24
2.4.3 Thermal diffusivity ... 26
2.4.4 Thermal conductivity ... 27
2.4.5 Dynamic viscosity ... 28
2.4.6 Volumetric thermal expansion coefficient ... 30
2.4.7 Surface tension ... 31 2.4.8 Electrical resistivity ... 33 2.4.9 Vapour pressure ... 35 2.4.10 Speed of sound... 36 2.5 Main outcomes ... 37 2.6 References ... 38
3 Activities on IELLLO facility ... 43
3.1 Introduction ... 43
3.2 Brief description of the facility ... 43
3.3 Problems solved in order to circulate LLE ... 46
vi
3.4.1 Flow meters performances ... 48
3.4.2 Absolute pressure transducer performances ... 49
3.5 Experimental campaign and RELAP5-3D simulations ... 51
3.5.1 RELAP5-3D nodalisation of IELLLO... 51
3.5.2 Heat transfer in the economizer ... 53
3.5.3 Heat transfer in the air cooler ... 54
3.5.4 Note on pump operation ... 55
3.6 Main outcomes ... 58
3.7 References ... 59
4 First experimental campaign in THALLIUM... 60
4.1 Introduction ... 60
4.2 Brief description of the facility ... 60
4.3 Experimental procedure and test matrix ... 63
4.4 Experimental data ... 65
4.5 Post-test analysis with RELAP5-3D system code ... 71
4.5.1 Nodalisation ... 72
4.5.2 Summary of the pre-test simulations ... 74
4.5.3 Test #1 and #2... 80 4.5.4 Test #3 ... 83 4.5.5 Test #4 ... 86 4.5.6 Test #5 ... 88 4.6 Main outcomes ... 90 4.7 References ... 91
5 Second experimental campaign in THALLIUM ... 92
5.1 Introduction ... 92
5.2 Modifications to the facility and test matrix ... 92
5.2.1 Tests with the new injection valve... 92
5.2.2 Stress dampening system ... 94
5.3 Experimental results ... 95
5.3.1 Discussion of the six tests ... 95
5.3.2 Comparison with the first experimental campaign ... 101
5.4 Post-test analysis with RELAP5-3D and RELAP5mod3.3 system code ... 102
5.4.1 Modification of RELAP5/mod3.3 and discussion over the expected differences with RELAP5-3D ... 102
5.4.2 General considerations on the numerical simulations ... 104
vii 5.4.4 Test VII ... 108 5.4.5 Test VIII ... 111 5.4.6 Test IX ... 114 5.4.7 Test X ... 117 5.4.8 Test XI ... 120 5.5 Main outcomes ... 123 5.6 References ... 124
6 Activities on MHD facility MaPLE ... 125
6.1 Introduction ... 125
6.2 Design of the loop ... 125
6.3 Heat rejection system... 132
6.3.1 Design calculations ... 133
6.3.2 Tube bundle and enclosing box ... 134
6.3.3 Fan and air ducts ... 136
6.4 Pumping system ... 138
6.5 Installation ... 140
6.6 Commissioning tests ... 144
6.6.1 Blank checks ... 145
6.6.2 Pump working checks ... 146
6.6.3 Isothermal mode checks at 300°C ... 147
6.6.4 Loading checks ... 148
6.6.5 Pump circulation checks ... 148
6.7 Main outcomes ... 148
6.8 References ... 149
7 Conclusions and future perspectives ... 150
7.1 Results and future perspectives on IELLLO facility ... 150
7.2 Results and future perspectives on THALLIUM facility ... 151
7.2.1 Phenomenology of the In-box LOCA transient ... 152
7.2.2 Impact of the results on the design of the LLE loop of the HCLL TBS ... 152
7.2.3 Numerical simulations ... 153
7.2.4 Future perspectives ... 154
7.3 Results and future perspectives on MaPLE facility ... 154
8 Appendix A: extensive description of IELLLO facility ... 155
8.1 Instrumentation ... 164
viii
8.3 References ... 171
9 Appendix B: extensive description of THALLIUM facility ... 172
9.1 LLE loop ... 172
9.1.1 TBM mock-up ... 175
9.1.2 Lower leg ... 176
9.1.3 Upper leg ... 177
9.1.4 Expansion tank ... 179
9.2 Automatic Hydraulic Isolation system ... 182
9.3 Gas injection system ... 184
9.4 Gas system of the expansion tank ... 186
9.5 References ... 187
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LIST OF ACRONYMS
AHI Automatic Hydraulic Isolation ARAA Advanced Reduced-Activation Alloy BARC Bhabha Atomic Research Centre
BB Breeding Blanket
CFETR China Fusion Engineering Test Reactor
CIEMAT Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas CLAM China Low Activation Martensitic
CPS Coolant Purification System Cv Řež Centrum výzkumu Řež
DACS Data Acquisition and Control System DCLL Dual Coolant Lithium-Lead
DFLL Dual Functional Lithium-Lead
DICI Department of Industrial and Civil Engineering EAST Experimental Advanced Superconducting Tokamak EBBTF European Breeding Blanket Test Facility
ELLI Experimental Loop for LIquid breeder EMPPIL Electro-Magnetic Pump driven Pb-17Li Loop
EUROfusion European Consortium for Development of Fusion Energy F4E Fusion for Energy
FCI Flow Channel Insert
FDS Frontier Development of Science FPA Framework Partnership Agreement FSN-ING Experimental Engineering Division FSO Full Scale Output
GLC Gas-Liquid Contactor
HCCB Helium Cooled Ceramic Breeder HCCR Helium Cooled Ceramic Reflector HCLL Helium Cooled Lithium-Lead HCML Helium Cooled Molten Lithium HCPB Helium Cooled Pebble Beds HCSB Helium Cooled Solid Breeder HeFUS Helium for FUSion
HLM Heavy Liquid Metal
IELLLO Integrated European Lead Lithium Loop IIT Italian Institute of Technology
INEST Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences IPUL Institute of Physics, University of Latvia
ITER International Thermonuclear Experimental Reactor
JSC Join Stock Company
KAERI Korean Atomic Energy Research Institute KIT Karlsruher Institut für Technologie LBE Lead-Bismuth Eutectic
xi LFR Lead-cooled Fast Reactors
LIFUS LIthium for FUSion
LIMITEF5 LIquid Metal TEst Facility, 5 T LLCB Lead-Lithium cooled Ceramic Breeder LLE Lead-Lithium Eutectic
LOCA Loss Of Coolant Accident
MaPLE Magnetohydrodynamic PbLi Experiment MELILOO MEtal LIquid LOOp
MHD Magnetohydrodynamics
NIFS National Institute for Fusion Science ODS Oxide Dispersion Strengthened
Oroshhi-2 Operational Recovery Of Separated Hydrogen and Heat Inquiry-2 P&ID Piping and Instrumentation Diagram
PAV Permeator Against Vacuum
PbLi Lead-Lithium
PED Pressure Equipment Directive PICOLO PbLi COrrosion LOop
PLD Pulsed Laser Deposition
RAFM Reduced Activation Ferritic Martensitic
RC Research Center
SCADA Supervisory Control And Data Acquisition SCLL Self Cooled Lithium-Lead
SCR Silicon Controlled Rectifier
SG Specific Grant
TBM Test Blanket Module TBS Test Blanket System TES Tritium Extraction System THALLIUM Test HAmmer in Lead LithIUM TRIEX TRItium EXtraction
UCLA University of California, Los Angeles
VST Vacuum Sieve Tray
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LIST OF FIGURES
Figure 1-1: flow chart of the PhD research activity. ... 3
Figure 2-1: layout of TRIEX [2.2]... 8
Figure 2-2: simplified P&ID of TRIEX-II in the configuration for GLC testing [2.3]. ... 9
Figure 2-3: layout of LIFUS2 [2.5]. ... 10
Figure 2-4: P&ID of the new LIFUS2 [2.6]. ... 11
Figure 2-5: one of the test sections of the new LIFUS2 [2.6]. ... 11
Figure 2-6: P&ID of LIFUS5/Mod3 [2.7]. ... 12
Figure 2-7: P&ID of MELILOO [2.11]. ... 13
Figure 2-8: sketch of PICOLO [2.13]. ... 14
Figure 2-9: schematic of LLE loop at IPUL [2.18]. ... 15
Figure 2-10: sketch of MaPLE [2.20]. ... 15
Figure 2-11: picture of DRAGON IV [2.24]. ... 16
Figure 2-12: schematic and picture of DRAGON V [2.27]. ... 17
Figure 2-13: layout of EMPPIL with temperature in the different sections of the loop [2.28]. ... 17
Figure 2-14: picture [2.33] and layout [2.30] of ELLI. ... 18
Figure 2-15: layout and picture of Oroshhi-2, with the LLE loop, the Flinak loop and the superconducting magnet [2.34]. ... 19
Figure 2-16: layout of LIMITEF5 [2.36]. The numbers are explained in the text. ... 20
Figure 2-17: PbLi phase diagram between 0 and 25 at.% Li (taken from [2.38]). ... 21
Figure 2-18: PbLi alloys density Vs temperature according to available references. ... 23
Figure 2-19: PbLi alloys specific heat Vs temperature according to available references. ... 25
Figure 2-20: PbLi thermal diffusivity Vs temperature according to available references. ... 26
Figure 2-21: PbLi alloys thermal conductivity Vs temperature according to available references. ... 27
Figure 2-22: PbLi alloys dynamic viscosity Vs temperature according to available references. ... 29
Figure 2-23: PbLi alloys volumetric thermal expansion coefficient Vs temperature according to available references. ... 30
Figure 2-24: PbLi alloys surface tension Vs temperature according to available references. ... 32
Figure 2-25. PbLi alloys electrical resistivity Vs temperature according to available references. ... 33
Figure 2-26: PbLi alloys vapour pressure Vs temperature according to available references. ... 35
Figure 2-27: PbLi alloys speed of sound Vs temperature according to the available reference and calculated by the authors of this paper. ... 36
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Figure 3-2: pump characteristics vs system pressure drops. ... 47
Figure 3-3: results of the flow meter qualification tests. ... 48
Figure 3-4: device used to test GEFRAN pressure transducer. ... 49
Figure 3-5: measured and corrected pressures at 400°C. ... 51
Figure 3-6: RELAP5-3D nodalisation of IELLLO. ... 52
Figure 3-7: efficiency of the economizer as a function of mass flow rate and temperature. ... 53
Figure 3-8. Air cooler performances as a function of mass flow rate and temperature. ... 54
Figure 3-9: LLE temperatures at the inlet and at the outlet sections of the air cooler. ... 54
Figure 3-10: thermocouples installed on the permanent magnet pump. ... 55
Figure 3-11: initial conditions. ... 55
Figure 3-12: temperature trends with pump speed at 80% of the maximum. ... 56
Figure 3-13: temperatures trends with maximum pump speed. ... 56
Figure 3-14: volumetric flow rate varying the pump rotational speed, with the bypass valve completely open and completely closed. ... 57
Figure 3-15: volumetric flow rate measured at 200 rpm varying the position of the bypass valve. ... 58
Figure 4-1: 3D drawing of THALLIUM facility. ... 61
Figure 4-2: pictures of the mock-up with the flanges of the upper and lower leg and of the injection line. ... 61
Figure 4-3: drawing of the TBM mock-up. From the outside, the mock-up has the shape of a 447x250x200 mm parallelepiped. ... 62
Figure 4-4: main window of THALLIUM DACS. ... 64
Figure 4-5: He mass flow rate injected in the TBM mock-up. ... 65
Figure 4-6: pressure in the TBM mock-up measured by PT10 in the five tests. ... 66
Figure 4-7: pressure in the TBM mock-up in test #1 (with error bar). ... 67
Figure 4-8: pressure in the expansion tank measured by PT21 in the five tests. ... 67
Figure 4-9: pressure in the upper leg downstream of the TBM mock-up measured by PT11 in the five tests.68 Figure 4-10: pressure in the upper leg upstream of the isolation valve measured by PT12 in the five tests. .. 68
Figure 4-11: pressure in the upper leg downstream of the isolation valve measured by PT13 in the five tests. ... 69
Figure 4-12: pressure in the lower leg upstream of the isolation valve measured by PT15 in the five tests. .. 69
Figure 4-13: pressure in the lower leg downstream of the isolation valve measured by PT14 in the five tests. ... 69
Figure 4-14: LLE level in the expansion (test #1). ... 70
Figure 4-15: enlargement of the first peak measured in various locations of the facility (test #1). ... 71
Figure 4-16: RELAP5-3D nodalisation of THALLIUM. ... 72
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Figure 4-18: effect of the breaking time of the rupture disc ... 76
Figure 4-19: effect of the opening pressure of the relief valve on the pressure in the bypass line. ... 77
Figure 4-20: pressure trends in the first 15 s of transient. ... 79
Figure 4-21: LLE level during the injection. ... 79
Figure 4-22: temperature trends in different parts of THALLIUM. ... 80
Figure 4-23: experimental pressure trends in the TBM mock-up and in the expansion tank, ... 81
Figure 4-24: experimental pressure trends in the upper and lower legs upstream of the isolation valves measured by PT11 (a), PT12 (b) and PT15 (c), compared with results from RELAP5-3D (test #1 and #2). ... 82
Figure 4-25: experimental pressure trends in the upper and lower legs downstream of the isolation valves measured by PT13 (a) and PT14 (b), compared with results from RELAP5-3D (test #1 and #2). ... 83
Figure 4-26: experimental pressure trends in the TBM mock-up and in the expansion tank, compared with results from RELAP5-3D (test #3). ... 84
Figure 4-27: experimental pressure trends in the upper and lower legs upstream of the isolation valves measured by PT11 (a), PT12 (b) and PT15 (c), compared with results from RELAP5-3D (test #3). ... 85
Figure 4-28: experimental pressure trends in the upper and lower legs downstream of the isolation valves measured by PT13 (a) and PT14 (b), compared with results from RELAP5-3D (test #3). ... 86
Figure 4-29: experimental pressure trends in the TBM mock-up and in the expansion tank, compared with results from RELAP5-3D (test #4). ... 86
Figure 4-30: experimental pressure trends in the upper and lower legs upstream of the isolation valves measured by PT11 (a), PT12 (b) and PT15 (c), compared with results from RELAP5-3D (test #4). ... 87
Figure 4-31: experimental pressure trends in the upper and lower legs downstream of the isolation valves measured by PT13 (a) and PT14 (b), compared with results from RELAP5-3D (test #4). ... 88
Figure 4-32: experimental pressure trends in the TBM mock-up and in the expansion tank, compared with results from RELAP5-3D (test #5). ... 88
Figure 4-33: experimental pressure trends in the upper and lower legs upstream of the isolation valves measured by PT11 (a), PT12 (b) and PT15 (c), compared with results from RELAP5-3D (test #5). ... 89
Figure 4-34: experimental pressure trends in the upper and lower legs downstream of the isolation valves measured by PT13 (a) and PT14 (b), compared with results from RELAP5-3D (test #5). ... 90
Figure 5-1: figure taken from the Samson datasheets and picture of the valve installed upside down. ... 93
Figure 5-2: drawing of THALLIUM with labels of the main components and of the pressure transducers. .. 94
Figure 5-3: new system to limit the movement of the pipes. ... 95
Figure 5-4: connections of the two springs to limit the oscillation of the pipe upstream of the isolation valve. ... 95
xvi Figure 5-5: pressure measured by the four transducers upstream of the isolation valves (test #6 and #9), with
an enlargement of PT10 for test #6. ... 96
Figure 5-6: pressure measured by the three transducers downstream of the isolation valves (test #6 and #9). ... 97
Figure 5-7: pressure measured by the four transducers upstream of the isolation valves (test #7 and #11). .. 98
Figure 5-8: pressure measured by the three transducers downstream of the isolation valves (test #7 and #11). ... 98
Figure 5-9: test #8: pressure measured by the transducer upstream (shades of red) and downstream of the isolation valves (shades of cyan). ... 99
Figure 5-10: test #10: pressure measured by the transducer upstream (shades of red) and downstream of the isolation valves (shades of cyan). ... 99
Figure 5-11: damages caused by test #11. ... 101
Figure 5-12: density of LLE and LBE as a function of temperature. ... 102
Figure 5-13: speed of sound of LLE and LBE as a function of temperature. ... 103
Figure 5-14: pressure trends in the TBM mock-up (a) and in the expansion tank (b) with LBE and LLE as system fluids. ... 104
Figure 5-15: experimental pressure trends in the TBM mock-up and in the expansion tank, compared with results from RELAP5-3D and RELAP5/mod3.3 (test #6). ... 106
Figure 5-16: zoom of the first peak in the TBM mock-up (test #6). ... 106
Figure 5-17: experimental pressure trends in the upper and lower legs upstream of the isolation valves measured by PT11 (a), PT12 (b) and PT15 (c), compared with results from RELAP5-3D and RELAP5/mod3.3 (test #6)... 107
Figure 5-18: experimental pressure trends in the upper and lower legs downstream of the isolation valves measured by PT13 (a) and PT14 (b), compared with results from RELAP5-3D and RELAP5/mod3.3 (test #6)... 108
Figure 5-19: experimental pressure trends in the TBM mock-up and in the expansion tank, compared with results from RELAP5-3D and RELAP5/mod3.3 (test #5). ... 109
Figure 5-20: zoom of the first peak in the TBM mock-up (test #7). ... 109
Figure 5-21: experimental pressure trends in the upper and lower legs upstream of the isolation valves measured by PT11 (a), PT12 (b) and PT15 (c), compared with results from RELAP5-3D and RELAP5/mod3.3 (test #7)... 110
Figure 5-22: experimental pressure trends in the upper and lower legs downstream of the isolation valves measured by PT13 (a) and PT14 (b), compared with results from RELAP5-3D and RELAP5/mod3.3 (test #7)... 111
Figure 5-23: experimental pressure trends in the TBM mock-up and in the expansion tank, compared with results from RELAP5-3D and RELAP5/mod3.3 (test #8). ... 111
xvii Figure 5-25: experimental pressure trends in the upper and lower legs upstream of the isolation valves
measured by PT11 (a), PT12 (b) and PT15 (c), compared with results from RELAP5-3D and
RELAP5/mod3.3 (test #8)... 113
Figure 5-26: experimental pressure trends in the upper and lower legs downstream of the isolation valves measured by PT13 (a) and PT14 (b), compared with results from RELAP5-3D and RELAP5/mod3.3 (test #8)... 114
Figure 5-27: experimental pressure trends in the TBM mock-up and in the expansion tank, compared with results from RELAP5-3D and RELAP5/mod3.3 (test #9). ... 114
Figure 5-28: zoom of the first peak in the TBM mock-up (test #9). ... 115
Figure 5-29: experimental pressure trends in the upper and lower legs upstream of the isolation valves measured by PT11 (a), PT12 (b) and PT15 (c), compared with results from RELAP5-3D and RELAP5/mod3.3 (test #9)... 116
Figure 5-30: experimental pressure trends in the upper and lower legs downstream of the isolation valves measured by PT13 (a) and PT14 (b), compared with results from RELAP5-3D and RELAP5/mod3.3 (test #9)... 117
Figure 5-31: numerical pressure trend in the TBM mock-up and experimental pressure trend in the expansion tank, compared with results from RELAP5-3D and RELAP5/mod3.3 (test #10). ... 117
Figure 5-32: zoom of the first peak in the TBM mock-up (test #10). ... 118
Figure 5-33: experimental pressure trends in the upper and lower legs upstream of the isolation valves measured by PT11 (a), PT12 (b) and PT15 (c), compared with results from RELAP5-3D and RELAP5/mod3.3 (test #10)... 119
Figure 5-34: experimental pressure trends in the upper and lower legs downstream of the isolation valves measured by PT13 (a) and PT14 (b), compared with results from RELAP5-3D and RELAP5/mod3.3 (test #10)... 120
Figure 5-35: experimental pressure trends in the TBM mock-up and in the expansion tank, compared with results from RELAP5-3D and RELAP5/mod3.3 (test #11). ... 120
Figure 5-36: zoom of the first peak in the TBM mock-up (test #11). ... 121
Figure 5-37: experimental pressure trends in the upper and lower legs upstream of the isolation valves measured by PT11 (a), PT12 (b) and PT15 (c), compared with results from RELAP5-3D and RELAP5/mod3.3 (test #11)... 122
Figure 5-38: experimental pressure trends in the upper and lower legs downstream of the isolation valves measured by PT13 (a) and PT14 (b), compared with results from RELAP5-3D and RELAP5/mod3.3 (test #11)... 123
Figure 6-1: updated P&ID of MaPLE (vertical configuration). ... 128
Figure 6-2: updated P&ID of MaPLE (horizontal configuration). ... 129
Figure 6-3: updated P&ID of MaPLE (any different test section orientation). ... 130
Figure 6-4: P&ID of MaPLE test section. ... 131
Figure 6-5: sketch of the air cooler. ... 132
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Figure 6-7: tube bundle enclosing box. ... 135
Figure 6-8: typical VR assembly. ... 135
Figure 6-9: heating rod to pre-heat the tube bundle (a) and shutter to prevent natural circulation (b). ... 135
Figure 6-10: drawing of the connection flanges. ... 136
Figure 6-11: characteristic curves: static pressure (blue, [Pa]), efficiency (dark grey in the lower part of the graph), sound pressure (green, [dB(A)]) and electrical motor absorbed power (red, [kW]). .... 137
Figure 6-12: sketch of the fan and its motor. The dimensions are expressed in mm. ... 137
Figure 6-13: section view of the permanent magnet pump. ... 138
Figure 6-14: characteristic curves of the permanent magnet pump at different motor rotational speeds. ... 139
Figure 6-15: pressure - flow rate characteristics of the new loop. ... 140
Figure 6-16: the permanent magnet pump installed on the loop. ... 141
Figure 6-17: the air cooler installed in the loop. ... 142
Figure 6-18: the soundproof box for the fan. ... 142
Figure 6-19: pictures of MaPLE at the end of the installation... 143
Figure 6-20: picture of MaPLE in the vertical configuration. ... 143
Figure 6-21: main tab of the DACS (vertical configuration). ... 144
Figure 6-22: electrical cabinet and control system, installed on the facility frame. ... 145
Figure 6-23: temperature trends in the pump channel at 30% of vmax ... 146
Figure 6-24: temperature trends in the pump channel at 50% of vmax and inverter signal (green line). ... 147
Figure 8-1: layout of IELLLO (left) and detail of the lower part of the loop (right)... 155
Figure 8-2: drawing of the permanent magnet pump (M01). ... 156
Figure 8-3: economizer (E01) and air cooler (E02)... 157
Figure 8-4: safety tank (S03), electrical heater (S05) and buffer tank (S04). ... 157
Figure 8-5: technical drawing of the electrical heater S05. ... 157
Figure 8-6: internal view of the air cooler (from below). ... 159
Figure 8-7: four rupture discs inside the expansion tank S03. ... 159
Figure 8-8: layout of the expansion and buffer tanks. ... 160
Figure 8-9: pictures of the storage tank. ... 161
Figure 8-10: storage tank S01, old recirculation tank S02, electrical heater S05, ... 161
Figure 8-11: layout of the gas system. ... 162
Figure 8-12: P&ID of IELLLO (without the Ar system). ... 163
Figure 8-13: picture of a level sensor and position of the level sensors in the tanks... 165
Figure 8-14: design of GEFRAN KE-2 pressure transducer and installation hole. ... 165
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Figure 8-16: Mini-turbine flow meter installed in IELLLO facility. ... 167
Figure 8-17: leakage sensors in the valves. ... 167
Figure 8-18: software architecture. ... 168
Figure 8-19: tab for general facility view. ... 169
Figure 8-20: process tab for the lower part of the loop. ... 170
Figure 8-21: process tab for the air cooler and the economizer... 170
Figure 8-22: process tab for the upper part of the loop. ... 171
Figure 9-1: 3D drawing of THALLIUM facility. ... 172
Figure 9-2: P&ID of THALLIUM. ... 173
Figure 9-3: pictures of THALLIUM. In clockwise order, starting from the top left: the expansion tank; the connection with IELLLO; the bypass line and the last part of the upper leg; a part of the upper and lower legs with the injection valve and the TBM mock-up (in the background). ... 174
Figure 9-4: picture of the whole facility with the thermal insulation. ... 174
Figure 9-5: pictures of the mock-up with the flanges of the upper and lower leg and of the injection line. . 176
Figure 9-6: drawing of the TBM mock-up. From the outside, the mock-up has the shape of a 447x250x200 mm parallelepiped. ... 176
Figure 9-7: lower leg. The red circle shows the position of the GEFRAN pressure transducer. ... 178
Figure 9-8: upper leg. The red circle shows the position of the GEFRAN pressure transducers. ... 178
Figure 9-9: three-way branch. The red circle shows the position of the GEFRAN pressure transducer. ... 179
Figure 9-10: pictures of the expansion tank. ... 180
Figure 9-11: expansion tank and connections to the loop and to IELLLO. ... 180
Figure 9-12: simple sketch of the Automatic Hydraulic Isolation system. ... 182
Figure 9-13: picture of the isolation valve on the lower leg. In the left corner it is possible to see a GEFRAN pressure transducer. ... 183
Figure 9-14: He mass flow rate with valve orifices of 4, 6.4 and 11.1 mm. This calculation was also performed to select the bigger valve of the second experimental campaign, described in the net chapter. ... 184
Figure 9-15: layout of HeFUS3 facility. ... 184
Figure 9-16: gas injection line. ... 185
Figure 9-17: Venturi flow meter. ... 185
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LIST OF TABLES
Table 2-1: list of facilities working with LLE. ... 6
Table 2-2: list of the properties chosen for the analyses and for implementation in RELAP5/mod3.3. ... 22
Table 2-3: list of the authors with Li content, method and temperature range for density. ... 24
Table 2-4: list of the authors with Li content, method and temperature range for specific heat. ... 25
Table 2-5: list of the authors with Li content, method and temperature range for thermal diffusivity. ... 26
Table 2-6: list of the authors with Li content, method and temperature range for thermal conductivity. ... 28
Table 2-7: list of the authors with Li content, method and temperature range for dynamic viscosity. ... 29
Table 2-8: list of the authors with Li content, method and temperature range for volumetric thermal expansion coefficient. ... 31
Table 2-9: list of the authors with Li content, method and temperature range for surface tension. ... 32
Table 2-10: list of the authors with Li content, method and temperature range for electrical resistivity. ... 34
Table 2-11: coefficients for Eq. 2-15. ... 34
Table 2-12: list of the authors with Li content, method and temperature range for vapour pressure. ... 35
Table 2-13: list of the authors with Li content, method and temperature range for speed of sound. ... 36
Table 3-1: instrumentation installed in each component. ... 45
Table 3-2: IELLLO main parameters and pressure drops. ... 46
Table 3-3: pressure drops due to valves and flow-meters. ... 47
Table 3-4: preliminary tests to assure tightness of the device. ... 49
Table 3-5: tests of the GEFRAN pressure transducer. ... 50
Table 3-6: test of the GEFRAN pressure transducer (decreased temperature). ... 50
Table 3-7: mass flow rates as a function of pump speed. ... 52
Table 4-1: test matrix of the first experimental campaign. ... 64
Table 4-2: roughness, friction factors and local pressure drop coefficients for the lines and components of THALLIUM. ... 73
Table 4-3: average discrepancies between RELAP5-3D and the experimental data (test #1 and #2). ... 81
Table 4-4: average discrepancies between RELAP5-3D and the experimental data (test #3). ... 84
Table 4-5: average discrepancies between RELAP5-3D and the experimental data (test #4). ... 87
Table 4-6: average discrepancies between RELAP5-3D and the experimental data (test #5). ... 90
Table 5-1: main parameters of the new injection valve. ... 93
Table 5-2: test matrix with the experiments of the first (1-5) and second (6-11) experimental campaign... 94
Table 5-3: average discrepancies between RELAP5-3D, RELAP5/mod3.3 and the experimental data (test #6). ... 105
xxii Table 5-4: average discrepancies between RELAP5-3D, RELAP5/mod3.3 and the experimental data (test
#7). ... 109 Table 5-5: average discrepancies between RELAP5-3D, RELAP5/mod3.3 and the experimental data (test
#8). ... 112 Table 5-6: average discrepancies between RELAP5-3D, RELAP5/mod3.3 and the experimental data (test
#9). ... 115 Table 5-7: average discrepancies between RELAP5-3D, RELAP5/mod3.3 and the experimental data (test
#10). ... 118 Table 5-8: average discrepancies between RELAP5-3D, RELAP5/mod3.3 and the experimental data (test
#11). ... 121 Table 6-1: operational parameters of MaPLE before and after the upgrade. ... 127 Table 6-2: air cooler characteristics. ... 132 Table 6-3: permanent magnet pump characteristics. ... 138 Table 6-4: commissioning tests performed in MaPLE. ... 144 Table 8-1: characteristics of the economizer and electrical heater. ... 158 Table 8-2: air cooler E02 characteristics. ... 159 Table 8-3: characteristics of the buffer tank S04. ... 160 Table 8-4: main parameters the storage tank S01. ... 161 Table 8-5: instrumentation installed in each component. ... 164 Table 8-6: characteristics of the pressure transducer. ... 166 Table 8-7: characteristics of Foxboro mass flow meter. ... 166 Table 9-1: TBM mock-up main dimensions. ... 175 Table 9-2: upper and lower leg dimensions. ... 177 Table 9-3: expansion tank parameters, compared to the tank of HCLL TBS. ... 180 Table 9-4: main parameters of VEGAFLEX level sensor. ... 181 Table 9-5: distances inside the expansion tank... 181 Table 9-6: operating parameters of the isolation valves supplied by Samson. ... 182 Table 9-7: operating parameters of the isolation pneumatic actuators. ... 183 Table 10-1: list of the facility signals tested during the blank checks. ... 188
xxiii
1
1 Introduction
Lead-Lithium Eutectic (LLE) is considered as a candidate tritium breeder, tritium carrier and neutron multiplier in several concepts of blanket for fusion reactors. In particular, Test Blanket Systems (TBS) employing LLE will be tested in ITER (International Thermonuclear Experimental Reactor) by the European Union in port #16 (HCLL: Helium Cooled Lead or, more likely, WCLL: Water Cooled Lithium-Lead) and by India in port #2 (LLCB: Lead-Lithium cooled Ceramic Breeder) [1.1]. The Indian concept, also supported by the Russian Federation [1.2], uses LLE also as coolant, together with a solid ceramic breeder. Breeding Blankets (BB) for demonstration fusion reactors are being studied and designed all around the world using LLE, in some concepts also as coolant. Different design teams in the European Union are working on the WCLL [1.3], HCLL [1.4] and DCLL [1.5] (Dual Coolant Lithium-Lead) BBs for the European DEMO. DCLL concepts have been considered also by the United States [1.6] and China [1.7] for an American DEMO and for EAST (Experimental Advanced Superconducting Tokamak) or ITER, respectively. Instead, Breeding Blankets using LLE are not currently foreseen in the Chinese CFETR (China Fusion Engineering Test Reactor), the “missing link” between ITER and DEMO [1.8]. China also considered a DFLL (Dual Functional Lithium-Lead) TBS for ITER, with the idea to demonstrate technologies for the DCLL [1.9] and the Self Cooled Lithium-Lead (SCLL). SCLL was studied in the past by different countries, for example by the United States [1.10]. This blanket concept is considered futuristic and its development was stopped because of the unacceptably high pressure drops.
Among the many possibilities, the alloys of lead and lithium with a composition near the eutectic point have drawn the biggest attention, as they represent the best compromise between an acceptable tritium breeding ratio (for the definition see [1.11], for example) and a low lithium activity, having also the lowest melting points, an advantage for both start-up and operation.
1.1 Research framework
In the framework of the development of Breeding Blankets for future fusion reactors, the EU is designing Test Blanket Modules (TBMs) to be tested in the near-term ITER reactor. Two kinds of blanket concepts are under development, the HCLL and the HCPB (Helium Cooled Pebble Beds).
On the way to qualify the TBMs before their installation in ITER, the European Union has planned to test TBMs mock-ups and prototypes in dedicated facilities. For this purpose, ENEA designed and constructed a helium facility (HeFUS3: Helium for FUSion) and a LLE loop (IELLLO: Integrated European Lead Lithium Loop), both installed at ENEA Brasimone Research Center (RC). IELLLO was designed to test:
HCLL TBM mock-up, up to 1:1 scale;
operation of TBM mock-ups in ITER relevant conditions;
instrumentation and components relevant for both HCLL TBM and main TBM ancillary systems (TES: Tritium Extraction System [1.12], CPS: Coolant Purification System [1.13]).
A critical issue for the safety of the HCLL TBM is represented by the In-box LOCA transient [1.14]: injection of helium at high pressure (8 MPa) in the LLE loop following the rupture of the channels of the cooling and/or stiffening plates. To further investigate the consequences of such an event, ENEA designed a loop, named THALLIUM (Test Hammer in Lead Lithium), to be operated together with IELLLO and HeFUS3.
With the aim to support the preliminary design of European TBSs and, in particular, to investigate the consequences of an In-box LOCA, Fusion for Energy (F4E) launched a project, named F4E-FPA-372,
2 divided in several Specific Grants (SG). A part of SG01 [1.15] and SG04 [1.16] dealt with experimental tests and numerical simulations in IELLLO, while SG02 [1.17] backed two experimental campaigns and the related numerical activities in THALLIUM.
The simultaneous presence of an electrically conducting fluid and of a strong magnetic field generates pressure drops and instabilities in the fluid itself. With the objective of further investigating this issue, EUROfusion (European Consortium for Development of Fusion Energy) [1.18] and the team of Professor Abdou at UCLA (University of California, Los Angeles) [1.19] agreed to upgrade the already existing MaPLE (Magnetohydrodynamic PbLi Experiment) facility [1.20]. The EUROfusion team, constituted by ENEA Brasimone RC and its linked third party University of Pisa, was in charge to rethink the loop layout, produce a Data Acquisition and Control System (DACS), design, fabricate and install an heat rejection system and the pumping system.
These activities were carried out within the abiding collaboration between the Department of Industrial and Civil Engineering (DICI) of University of Pisa and the Experimental Engineering Division (FSN-ING) of ENEA Brasimone RC. The FSN-ING supports the development of Heavy Liquid Metal (HLM) technologies, both for fusion and fission reactors. Seven experimental facilities are currently working with lead or LBE (Lead-Bismuth Eutectic) in support of Lead-cooled Fast Reactors (LFR). Instead, eight facilities are performing experiments on helium, LLE or pure lithium for fusion applications, mainly related to the development of Breeding Blankets.
1.2 Description and objectives of the research activity
Within the framework described in the previous section, this PhD activity was carried out at the Department of Civil and Industrial Engineering of the University of Pisa, for the numerical activities, at ENEA Brasimone RC, to take advantage of the existing facilities, and for a short period in the Fusion Laboratory of UCLA, to install and commission the upgraded MaPLE.
The core of the research is represented by the experimental activities of the In-box LOCA in THALLIUM and the related numerical simulations. No experimental data of this kind of transient were available for helium-cooled BBs at the beginning of this activity. However, before to start this investigation, it was necessary to refurbish IELLLO, learning to operate it and using it to qualify the pressure transducers to be used in THALLIUM. For this reason, the first objective of this thesis has been to carry out an experimental campaign in IELLLO, focused on the performances of the main components and on the qualification of the instrumentation. The experimental campaign had also the purpose to validate the nodalization developed for RELAP5-3D, testing the use of LLE in this system code.
The second and main objective of the thesis has been to understand the effects of the release of high pressure He in LLE by experimentally and numerically simulating several In-box LOCA events on the LLE loop of the HCLL TBS. To this end, two injection valves were used, performing two experimental campaigns with different flow areas (1.257∙10-5
m2 and 9.503∙10-5 m2). Moreover, the variation of the injection duration, the He pressure, the actuation of the isolation valves and the opening pressure of the rupture disk created a wide-ranging test matrix that allowed a better comprehension of the involved phenomena. The use of the system code RELAP5 (in the 3D and mod3.3 versions) greatly contributed to delve into the dynamics of the In-box LOCA.
The third objective of the research has been to support the upgrade of MaPLE in order to enhance its experimental capabilities. The upgraded MaPLE will be able to perform experiments of mixed convection with temperature gradients, high magnetic field and the effect of buoyancy. For the purpose of this thesis, the general layout of the facility was established and the design of the heat rejection system and of the pumping
3 system was completed. After the end of the installation, the commissioning tests were carried out, preparing the facility for the experimental campaign.
To summarize, the main objectives of the research have been:
to produce new experimental data on LLE systems and instrumentation in IELLLO, using the data to validate the RELAP5-3D nodalization. The experimental data and the experience with the code were crucial as a basis for the second point of this list;
to understand the effects of an In-box LOCA on the LLE loop of the HCLL TBS, by performing two experimental campaigns in THALLIUM and, then, simulating the results with RELA5-3D and RELAP5/mod3.3;
to contribute to the upgrade of MaPLE, by designing the new layout and two new components and by performing the commissioning of the facility.
Figure 1-1 provides a useful scheme to better comprehend the connections between the different parts of this research activity.
Figure 1-1: flow chart of the PhD research activity. PhD thesis:
Experimental and numerical activities for the thermal hydraulic analysis of PbLi eutectic
in breeding-blanket concepts of nuclear fusion reactors
State of the art and literature review IELLLO Set up of instrumentation in LLE Support to refurbishment Experimental campaign on heat transfer Simulation with RELAP5-3D 1st experimental campaign THALLIUM Simulation with RELAP5-3D
Choice of new testing parameters 2nd experimental campaign Simulation with RELAP5-3D Simulation with RELAP5/mod3.3 Literature review of PbLi thermophysical properties MaPLE Design activities Installation of main components and wiring
of the facility Acceptance and commissioning tests
4
1.3 Structure of the thesis
Beyond this introduction, the thesis is divided in six sections: a chapter dedicated to the state of the art, four main chapters and a final discussion.
The opening chapter summarizes the available correlations for LLE thermophysical properties, also indicating the correlations used in the following chapters, and the state of the art on the research in LLE technologies, mainly describing the existing facilities and their capabilities.
Chapters 3 to 6 describes the activities that constitute the essence of this thesis. Chapter 3 deals with the activities in IELLLO facility: an experimental campaign was carried out with the aim to characterize the facility and its main components. The chapter especially lingers on the instrumentation that was validated for the use in the activities of Chapters 4 and 5. These two chapters detail the two experimental campaigns in the facility THALLIUM and the related post-test analyses performed with the system codes RELAP5-3D and RELAP5/mod3.3. Chapter 6, instead, shows the design, installation and commissioning activities required to upgrade the MHD facility MaPLE at UCLA.
To conclude, the whole research activity is summarized in the final discussion, where also a global interpretation of the results is attempted. This final chapter also outlines some of the future perspectives for three facilities on which this work is centered.
1.4 References
[1.1] B.G. Hong, Overview of ITER TBM program objectives and management, International Journal of Energy Research 42 (2018), 4-8.
[1.2] A.Yu. Hon et al., Lead-lithium facility with superconducting magnet for MHD/HT tests of liquid metal breeder
blanket, Fusion Engineering and Design 124 (2017), 832–836.
[1.3] A. Del Nevo et al., WCLL breeding blanket design and integration for DEMO 2015: status and perspectives, Fusion Engineering and Design 124 (2017), 682-686.
[1.4] G. Aiello et al., Design of the helium cooled lithium lead breeding blanket in CEA: from TBM to DEMO, Nuclear Fusion 57 (2017), number 4, 1-7.
[1.5] D. Rapisarda et al., Conceptual Design of the EU-DEMO Dual Coolant Lithium Lead Equatorial Module, IEEE Transactions on Plasma Science 44 (2016), 1-10.
[1.6] M. Abdou et al., Blanket/first wall challenges and required R&D on the pathway to DEMO, Fusion Engineering and Design 100 (2015), 2-43.
[1.7] Y. Wu et al., Design status and development strategy of China liquid lithium–lead blankets and related material
technology, Journal of Nuclear Materials 367-370 (2007), 1410-1415.
[1.8] Y. Wan et al., Overview of the present progress and activities on the CFETR, Nuclear Fusion 57 (2017), 1-17. [1.9] S. Zheng et al., Neutronics analysis for the test blanket modules proposed for EAST and ITER, Nuclear Fusion 47
(2007), 1053-1056.
[1.10] D.L. Smith et al., Overview of the blanket comparison and selection study, Fusion Technology 8 (1985), 10-113. [1.11] M. Mahdavi et al., Estimates of Tritium Produced Ratio in the Blanket of Fusion Reactors, Open Journal of
Microphysics 3 (2013), 8-11.
[1.12] I. Ricapito et al., Tritium extraction systems for the European HCLL/HCPB TBMs, Fusion Science and Technology 54 (2018),107-112.
[1.13] A. Ciampichetti et al., The coolant purification system of the European test blanket modules: Preliminary design, Fusion Engineering and Design 85(2010),2033-2039.
5
[1.14] ITER D2.3: Final STR_56.A1.LP. (v.2.1 2014/08/07). ITER PbLi loop - final technical report.
[1.15] ENEA website, http://progettiue.enea.it/dett_pdf.asp?id=974.
[1.16] ENEA website, http://progettiue.enea.it/dett_pdf.asp?id=1095.
[1.17] ENEA website, http://progettiue.enea.it/dett_pdf.asp?id=967.
[1.18] EUROfusion website, https://www.euro-fusion.org/.
[1.19] UCLA website, Mechanical and Aerospace Engineering, https://www.mae.ucla.edu/.
[1.20] S. Smolentsev et al., Construction and initial operation of MHD PbLi facility at UCLA, Fusion Engineering and Design 88 (2013) 317-326.
6
2 State of the art and literature review
2.1 Introduction
This chapter constitutes an attempt to delineate the several open points on the research involving LLE (Lead-Lithium Eutectic). For this reason, the chapter has been divided in three sections, trying to summarize the experimental capabilities of the facilities working with LLE worldwide, the discussion on the exact eutectic point of the PbLi alloys and the issue of the copious different correlations for the thermophysical properties. The first paragraph describes (hopefully) every facility currently operating with LLE in the world, with the aim to understand which are the research fields that involve the use of this alloy and how international the interest in LLE is. The idea is also to make clear that the three facilities used during this PhD work are unique and, especially in the case of MaPLE and THALLIUM, trailblazing.
The second paragraph is a short note on the eutectic point of LLE, without claiming to be exhaustive on a very thorny topic.
The third paragraph reports a literature review of the thermophysical properties of LLE. This review was carried out during the PhD period with the objective to answer the call of EUROfusion consortium. A correlation was chosen for each of the ten examined properties. These ten correlations were used in every analysis performed in the PhD activity and were implemented in RELAP5/mod3.3 at the University of Pisa.
In the following, the acronym PbLi has been adopted to refer generally to an alloy of lead and lithium and the acronym LLE only when the cited authors refer to a eutectic alloy, even though a discussion is still going on about the eutectic point (as briefly addressed in the paragraph 2.3). In the cases in which the cited authors stated that they were using LLE, but then also declared the exact composition of their alloy, the notation PbLi has been preferred with the aim to not create confusion on the eutectic point. Sometimes the chemical compound Pb83Li17
has been used to better specify the composition of the alloy.
2.2 Review of experimental facilities working with LLE
Several facilities are involved in different areas of the research on LLE technology. Table 2-1 summarizes the facilities that are, omissions excepted, in operation in the world, providing some details on the location and on the type of research carried out. Moreover, the volume of LLE used for the experiments is provided in order to give a rough idea of the dimension of each facility. Hereafter, a brief description of the facilities and of their capabilities is provided. The facilities IELLLO and THALLIUM are not illustrated here, as they are described in detail in chapter 3 and 4, respectively. A facility, named CLIPPER, to study tritium extraction from LLE is under construction at CIEMAT (Madrid), but nothing has been published at the time of writing. For this reason, the facility was not included in Table 2-1.
Table 2-1: list of facilities working with LLE.
Name Organization Country Location Main research fields LLE volume [m3]
IELLLO ENEA Italy Brasimone Heat exchange 0.5
7
THALLIUM ENEA Italy Brasimone In-box LOCA (helium) 0.15
TRIEX/TRIEX-II ENEA Italy Brasimone Tritium extraction 0.25/0.15
LIFUS2 (old/new) ENEA Italy Brasimone Corrosion 0.1/0.18
LIFUS5/Mod3 ENEA Italy Brasimone In-box LOCA (water) 0.03
MELILOO Cv Řež Czech
Republic Husinec-Řež
Purification
0.01 Instrumentation testing
PICOLO KIT Germany Karlsruhe Corrosion 0.01
Unnamed facility IPUL Latvia Salaspils MHD 0.01
MaPLE (old/new) UCLA USA Los Angeles MHD 0.02/0.03
DRAGON IV INEST China Hefei
MHD
0.2 TMB mock-up testing
Purification Corrosion
DRAGON V INEST China Hefei MHD 0.3
Corrosion
EMPPIL BARC India Mumbai Corrosion 0.002
ELLI KAERI South
Korea Daejeon
MHD
0.01 Corrosion
Oroshhi-2 NIFS Japan Toki
MHD
0.1 Corrosion
Hydrogen recovery S-CO2 cycle
LIMITEF5 JSC “NIIEFA” Russia St. Petersburg MHD 0.08
Heat transfer
TRIEX (TRItium EXtraction) is a facility dedicated to the testing of the technologies to extract tritium from LLE. In particular, TRIEX was dealing with optimization and testing of the performances of packed columns, which were considered the most interesting configuration in the family of Gas-Liquid Contactors (GLC) [2.1]. TRIEX used hydrogen to simulate the behavior of tritium in LLE. TRIEX was a closed loop mainly constituted by three tanks: a recirculation tank, which hosted the mechanical pump and served also as draining tank, the hydrogen saturator, which had the objective to inject hydrogen in LLE eventually reaching the saturation, and the extractor column, used to remove hydrogen from LLE. A mixture of molecular hydrogen and argon was injected from the bottom of the saturation tank by means of a gas distributor, which forced bubbles to enter LLE in countercurrent. The extractor column used the same principle, with the stripping gas (pure argon) entering through an appropriate distribution system from the bottom and LLE entering from the top. The extractor was conceived to test packed columns of different heights. Figure 2-1 shows a picture of the Data Acquisition and Control System (DACS) of TRIEX with the three tanks and the LLE and gas pipes. In the experiments, the concentration of hydrogen in LLE and the flow rate of both the stripping gas and LLE were varied, in order to evaluate the extraction efficiency and to have a set of data to be used in modeling [2.2]. TRIEX handled 0.1-0.35 kg/s of LLE at 450°C and 5-150 Nl/h of argon, while partial pressures in the range 8000-14300 Pa were used in the experiments [2.2]. The range of LLE mass flow rate was chosen to be representative of the working conditions of the LLE loop of the HCLL TBS (Helium Cooled Lithium Lead Test Blanket System).
8 Hydrogen concentration was measured by two sensors, installed at the inlet and outlet of the extraction column. These sensors were based on the permeation of hydrogen in an empty capsule. Pressure in the capsule is measured by an external pressure gauge. The hydrogen partial pressure can be correlated with the concentration in LLE by means of the Sieverts’ law, which for an H-LLE system is:
√ Eq. 2-1
where C is the concentration, Ks is the Sieverts’ constant and Peq is the equilibrium hydrogen partial pressure. A vacuum pump is used to create vacuum in the capsule at the beginning of each experiment [2.2].
Figure 2-1: layout of TRIEX [2.2].
TRIEX was upgraded to TRIEX-II, taking advantage of the experience to optimize the design of the key components. TRIEX-II was designed to test three extraction technologies by installing mock-ups of a packed column (GLC), of a Permeator Against Vacuum (PAV) and of a Vacuum Sieve Tray (VST). TRIEX-II will have two operational phases, distinguished by the use of hydrogen or deuterium as solute (solubilized as He+H2 or
He+D2) and by pure helium or helium plus molecular hydrogen as stripping gas. The facility will work at 450°C,
with a LLE mass flow rate in the range 0.2-4.0 kg/s, a hydrogen (or deuterium) partial pressure of 100-5000 Pa. The range of LLE mass flow rate was chosen to test these technologies for the HCLL TBS, but also for the HCLL BB and WCLL BB (Water Cooled Lithium Lead Breeding Blanket). The layout of TRIEX-II is similar to the one of TRIEX, with the main differences being the storage tank, which can be isolated from the rest of the loop by means of a valve, and the permanent magnet pump, which does not require a dedicated tank to work (Figure 2-2).
The design principles used for TRIEX are described in detail in [2.1], while a description of the experiments and of the results can found in [2.2]. The details of TRIEX-II were found in the ENEA internal report [2.3].
9 Figure 2-2: simplified P&ID of TRIEX-II in the configuration for GLC testing [2.3].
LIFUS2 (LIthium for FUSion) was designed to characterize the behavior of structural materials in flowing LLE, especially understanding the degradation of mechanical properties and the compatibility. The loop was a figure of eight with the cold part of the loop at 300-400°C and the hot one at 450-480°C. The cold part was constituted by a storage tank, isolated from the rest of the loop during the operation phases, a recirculation tank, a mechanical pump and an air cooler. A bypass line (L3 in Figure 2-3) was used to have a finer control on the flow rate driven to the test sections. The hot part, instead, was constituted by two electrical heaters and two test sections. Between the hot and the cold part, an economizer helped to save some power in cooling/heating the alloy. The LLE flow rates were measured by electromagnetic flow meters. The cold part of the facility was made of AISI 316L, while the hot part of ferritic steel 2Cr1/4Mo. The test sections could be equipped with different devices, such as the fatigue machines of [2.4] or the tensile and corrosion specimens of [2.5], depending on the objectives of each experimental campaign. The LLE velocity in test sections was about 10-2 m/s, simulating the velocity of the reference design of WCLL.
10 Figure 2-3: layout of LIFUS2 [2.5].
LIFUS2 is under upgrade, as described in [2.6]. The new facility aims to investigate the corrosion of EUROFER at 550°C with and without Al2O3 coatings. Different velocities and exposure times are foreseen with the aim to
achieve a good comprehension of the corrosion phenomena. The new LIFUS2 design kept the global loop configuration (Figure 2-4), but added an expansion tank, to accommodate the LLE volume expansion following a temperature change, and two cold traps, to purify LLE from corrosion products. Moreover, the test sections were drastically modified. The cold traps, which also help to cool down the alloy, will be useful to improve the knowledge on the purification of LLE. The cold part of the loop will operate at 400°C, while the hot one at 550°C. The maximum mass flow rate, measured by an induction mass flow meter, is about 4.6 kg/s. The two test sections are installed vertically and in series and are equipped with a removable glove box, to avoid contamination of LLE during the extraction of specimens. Each test section haa three internal diameters (1″, 3″ and 10″, as shown in Figure 2-5) with the aim to expose the specimens at different LLE velocities (1.0, 0.1 and 0.01 m/s). The specimens are installed on a rod located in the center of the test section: 3 coated and 3 non-coated specimens are installed in each segment of the test section with a constant cross section. Aluminum based coatings consisting of an amorphous matrix of Al2O3 with nano-crystalline inclusions will be prepared at IIT
11 Figure 2-4: P&ID of the new LIFUS2 [2.6].
Figure 2-5: one of the test sections of the new LIFUS2 [2.6].
The description of LIFUS2 and the results of experimental campaigns with AISI 316L and EUROFER 97 steels can be found in [2.4] and [2.5], while the design of the new loop is described in [2.6].
12 LIFUS5/Mod3 aims to analyze the interaction and chemical reaction between high-pressure (155 bar) water and LLE following an In-box LOCA in the WCLL BB [2.7]. The experimental campaign will also be dedicated to validate SIMMER code, previously modified to include the water-LLE reaction [2.8]. The facility is an upgrade of the LBE (Lead-Bismuth Eutectic) facility LIFUS5/Mod 2, described in [2.9]. Figure 2-6 shows the P&ID of the LIFUS5/Mod3.
Figure 2-6: P&ID of LIFUS5/Mod3 [2.7].
The facility is composed by the water injection system and by four tanks: the reaction tank (S1_B in Figure 2-6), an expansion tank connected to it by means of two rupture disks (designed for 200 bar) and two storage tanks for fresh and depleted LLE. The reaction tank is equipped with fast, differential and absolute pressure transducers, thermocouples and three strain gauges on the external surface. A Coriolis mass flow meter and four differential pressure transducers are installed on the water injection line to obtain reliable data on the reaction that occurs in the reaction tank. A brass cap, calibrated for the desire breaking pressure and sized for the desired flow rate, covers the injector orifice on the bottom of the reaction tank. This cap breaks in each test, thus it has to be changed before being able to start a new injection. The test section is equipped with a holed plate that breaks the water jet and forces it to interact with LLE, while the holes allow vapors and hydrogen to escape towards the upper plenum. 74 thermocouples are installed in the test section to map the heat generated by the water-LLE reaction. Instead, a gas analyzer measures the amount of hydrogen generated by the reaction. At the end of each injection, the gas mixture flows from the upper plenum to the gas analyzer through a dedicated valve. The instrument is protected from overpressures by a relief valve. A different sampling point is provided in case one
13 of the two rupture disks which protect the reaction tank should break, releasing the gas mixture towards the expansion tank.
MELILOO (MEtal LIquid LOOp) is a facility primarily designed to investigate the purification of LLE from corrosion products and impurities. Secondly, MELILOO is used to test instrumentation in LLE. The only references on this facility that were found are the website of Cv Řež [2.10] and an internal deliverable of Fusion for Energy (F4E) [2.11]. The loop, shown in Figure 2-7, is composed by a storage tank, connected to the loop by means of a dedicated pipeline, a centrifugal pump and the test section. A sintered filter is installed on the filling pipeline to avoid impurities from LLE ingots to be injected in the loop. The test section includes an electromagnetic flywheel flow meter, a liquid level control and an air-cooled cold trap, equipped with thermocouples. The air to cool the cold trap is provided by a circulator installed on a separate circuit, equipped with instrumentation for measurement of air flow rate and temperature. Impurities of Fe, Mn, Ni and Cr are injected in dosed amounts (traces) in order to simulate the typical products of corrosion of stainless steels. The efficiency of cold trap is tested in the ranges 0.09-0.64 kg/s and 250-420°C, while the rest of the loop is normally kept at about 300°C. The loop has the capability to reach 550°C in the test section.
Figure 2-7: P&ID of MELILOO [2.11].
PICOLO (PbLi COrrosion LOop) was designed to perform experiments on corrosion and transport of corrosion products at LLE temperatures and velocities higher than the previous loop installed at KIT (Karlsruher Institut für Technologie) [2.12]. Figure 2-8 shows a sketch of the loop. The loop is divided in a hot leg (with maximum temperature of 550°C) and a cold leg (with minimum temperature of 350°C) by the central heat exchanger. The electromagnetic pump (able to supply 120 l/h), the magnetic flow meter and the magnetic trap constitute the cold leg, while the hot leg is composed by the electrical heater, the test section and the air cooler. The loop comprises also a dump tank and an expansion vessel. The entire cold leg was made of austenitic steel AISI346 Ti, while the hot leg of ferritic steel X10CrAl17. The loop has a total length of about 12 m [2.13]. The facility is equipped with an argon glove box to avoid LLE oxidation when handling the specimens. The glove box is connected to the test section through the expansion vessel. The specimens are installed in series on a rod in the middle of the 440 mm long cylindrical tube constituting the test section (16 mm of internal diameter). The LLE velocity in the test section can vary roughly in the range 0.01-1 m/s [2.14]. The testing of martensitic steel X 18 CrMoVNb 12 1 and a discussion on the results are reported in [2.12]. Recent experimental campaigns have been carried out on
14 transport and precipitation of corrosion products [2.13], on a comparison of corrosion resistance between EUROFER and CLAM (China Low Activation Martensitic), on long-term corrosion behavior of ODS-EUROFER (Oxide Dispersion Strengthened) [2.15] and on corrosion of Al-based coatings [2.16].
Figure 2-8: sketch of PICOLO [2.13].
The Institute of Physics, University of Latvia (IPUL) built a small experimental loop aiming to study heat and mass transfer in a strong magnetic field [2.17]. Moreover, the loop aimed also to investigate the processes in a BB channel when using Flow Channel Inserts (FCI). The isothermal loop (350°C), shown in Figure 2-9, is composed by a dump tank, an electromagnetic pump, able to supply 0.5 l/s when the magnet is working and 2.0 l/s when it is not working, seven expansion tanks and a solenoidal super conducting magnet. The loop is made by pipes with an internal diameter of 27.3 mm. The total flow length is about 6.5 m [2.18]. A DC electromagnetic flow meter is installed on the loop. It allows to estimate the potential difference across the channel width by means of a linear correlation with the flow rate [2.19]. Argon is used to fill the loop by pressurizing the dump tank, but also as cover gas in the expansion tanks. The pressure in each tank is measured by gas manometers and it is used to evaluate pressure drops in the test section (details on the methodology are provided in [2.17]). The superconducting magnet, generating up to 5 T, uses a cryocooler to obtain temperatures of about 4.2 K on the winding. The hole in the magnet, maintained at room temperature, is about 1000 mm long and has a diameter of about 300 mm. The magnet can rotate from horizontal to vertical position to include the effect of buoyancy in the study of liquid metal flow. Experiments on geometries relevant for the Indian LLCB (Lead Lithium cooled Ceramic Breeder) have been carried out in collaboration with the Institute of Plasma Research (Gandhinagar) and the Bhabha Atomic Research Center (Mumbai) [2.18]. Recent experiments on a multi-channel test section, simulating the flow path foreseen in several BB, are reported in [2.19].
15 Figure 2-9: schematic of LLE loop at IPUL [2.18].
MaPLE (Magnetohydrodynamic PbLi Experiment) is a facility conceived with the goal to study the effect of a strong magnetic field on all the aspects of LLE flows [2.20]. In particular, MaPLE aims at investigating MHD effects and the use of FCI to mitigate magnetic pressure drop issues in liquid metal breeder blankets. The construction of the loop started in UCLA (University of California, Los Angeles) in 2010. The facility was built under the US base fusion program and the US–Japan “TITAN” program. The loop was first operated with LLE in 2011, but it underwent two consecutive upgrades to increase the capabilities of the magnet and the LLE inventory (up to 200 kg) and to fabricate two test sections, with a circular and rectangular cross sections. Figure 2-10 shows a sketch of the third version of the loop (2013). The loop operational parameters were: maximum magnetic field of 1.8 T, temperature up to 350°C, maximum LLE flow rate with/without a magnetic field of 15/50 l/min, maximum pressure head 1.5 bar.
16 The version of the facility upgraded in 2018 is not described here, as the upgrade constitutes the subject of chapter 6. Besides of enhancing the testing parameters, a major part of the new upgrade consisted in the possibility of changing the inclination of the test section, with the aim to address the combined effects of gravity, magnetic field and heating on the LLE flow. Experimental results of the old version of MaPLE have been documented in [2.21] and [2.22], while [2.20] mainly describes the operation procedures and the development of diagnostics.
Several DRAGON loops were built and are being designed by FDS (Frontier Development of Science) team in INEST (The Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences). An overview of the facilities built, designed and proposed is presented in [2.23]. At the time of writing, only DRAGON IV and DRAGON V are in operation. Thus, only these two facilities will be briefly described in the following.
DRAGON IV (Multi-functional Liquid PbLi Loop) was designed as a multi-purpose facility, aiming to study MHD effects, material compatibility, thermal-hydraulics of DFLL (Dual Functional Lithium-Lead) TBM mock-ups and purification of LLE. The facility, built in 2009, has a maximum temperature of 800°C, a magnetic field of 2 T and can supply a maximum LLE velocity of 2 m/s [2.23]. The loop, shown in Figure 2-11, is divided in a main and an auxiliary loop. The loop is composed by a dump tank, an expansion tank, a calibration tank, an electromagnetic pump, an electromagnetic flow meter, a purification system (cold traps), two coolers and a concentric tube heat exchangers. A bypass is used to adjust the flow rate. The facility has five experimental sections [2.24]: high temperature corrosion section, stress corrosion section, MHD test section, TBM mock-up test section and purification system. DRAGON IV has conducted corrosion tests for CLAM steel under magnetic field for more than 800 h [2.23]. The magnet is 400 mm long and the space between the magnetic poles is 80 mm [2.25]. The design of a 50x50 mm square experimental duct is detailed in [2.25], together with the program of the experiments.
17 DRAGON V (Dual Coolant Thermal Hydraulic Integrated Experimental Pb-Li Loop) was built in 2017 to perform multi-physics experiments in support of the design of the Chinese TBMs (DFLL and HCCB: Helium Cooled Ceramic Breeder) and the blanket for Chinese DEMO. DRAGON V is composed by a LLE loop, with a maximum temperature of 550°C in the loop and of 1100°C in the test section, a maximum LLE mass flow rate of 40 kg/s and a magnetic field of 5 T, and a helium loop, with a maximum pressure of 105 bar [2.26]. The design of the recuperator is described in detail in [2.27].
Figure 2-12: schematic and picture of DRAGON V [2.27].
