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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 1
Manfred Glugla
Fuel Cycle Engineering DivisionCentral Engineering Department
ITER Organization
Tritium in ITER
Presented by Scott Willms
ITER Fuel Cycle Integrated Product Team Co-LeadLos Alamos National Laboratory
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 2
Outline of the Lecture
• Properties of tritium
• Introduction to the fusion fuel cycle
• Selected systems of the fusion fuel cycle using ITER as an example– Hydrogen isotope storage and delivery– Exhaust gas processing– Isotope separation and water detritiation– Fueling System configuration and Pellet Injection– Torus Cryo-pumping– Safe handling of tritium and confinement strategies at ITER
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 3
Historical Aspects and Background
• Deuterium was discovered about 80 years ago by H. Urey 1931
• Tritium synthesized by M. Oliphant, P. Harteck, E. Rutherford 1934
• Tritium is continuously produced in the upper earth atmosphere
– Amount produced negligible compared to anthropogenic tritium• Emissions from nuclear reactors and reprocessing plants• “Natural” global atmosphere inventory estimations between 4 to 7 kg
– Significant residual inventory from atmospheric nuclear weapons tests• Today’s total tritium atmosphere inventory estimated to about 40 kg
• Tritium has never been seen in space (but deuterium has)
HHHH 11
31
21
21
CHnN 126
31
10
147
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 4
Technical Tritium Production
• Tritium is produced by neutron irradiation of lithium-6
– Lithium aluminate or lithium silicates are irradiated in nuclear reactors• Natural lithium contains only 7.42% of lithium-6, the remaining is lithium-7
• Neutron capture of helium-3 produces tritium– Neutrons from proton accelerators (spallation)
• 100 to 150 g tritium per operational year isgenerated by a 600 MW CANDU reactor
– CANDU reactors are heavy water moderated and employ natural uranium as fuel
• 56 kg tritium is required per GW(thermal) year of DT fusion power
HeHnLi 43
31
10
63
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 5
Some Tritium Properties
• Tritium is the heaviest hydrogen isotope, radioactive (pure β emitter)– Half life t1/2 = 12.323 + 0.004 years
• about 100 g tritium per year is lost at an inventory of 1800 g
– Energetically almost weakest natural beta emitter Emax = 18.6 keV• 187Re has Emax = 2.5 keV, however at t1/2 = 5 * 1010 years is practically stable
– Maximum range of tritium decay electrons• Air : 6 mm• Metals: < 1 µm
– 1 g tritium• 324 mW decay heat• Activity 355.7 TBq or 9615 Ci• Volume 3.72 Liter (standard temperature / pressure)
– Largest known gyro magnetic ratio• Most sensitive nucleus for NMR spectroscopic investigations
tritium
helium-3
electron anti-neutrino
-
+ +
+
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 6
Areas of Tritium Handling and Usage
• Gaseous Tritium Light Sources (GTLS)– Usually hermetically sealed glass vials
• Contain between 1 Ci / 1 mg (exit lights) and1000 Ci / 0.1 g (aviation landing aids)
– Tritium watches (still on the market) contain about 0.1 Ci
• Neutron generators– Tritium in titanium (Cu substrate) as target for deuterons (50 to 400 keV)
• Tritium is used as tracer in many areas of science and medicine
• Tritium is a practical ionization source– Nuclear batteries (“betavoltaics”) employing porous silicon diodes– Ionization detectors in gas chromatography
• Meta-stable excited helium ionizes gases to be detected in the carrier gas
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 7
Radiochemistry of Tritium (1/2)
• Self-radiolysis of T2
• Self-radiolysis of T2O (liquid T2O is self heating)– β - radiation causes the formation of T2O+ ions, T3O+ ions, T• radicals, OT•
radicals, and T2O2 via consecutive chemical reactions• Due to the primary self-radiolysis products of T2O it is highly corrosive
– Gas phase above T2O becomes pressurized• Radiochemical equilibrium above T2O at 159 kPa
– Rate of gas production balanced by rate of (radiochemical) recombination
TeT 33
othersTT 22
TTTT 322
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 8
Radiochemistry of Tritium (2/2)
• Reaction of T2 with oxygen, nitrogen and air
– Reaction products are subject to (self-) radiolysis– Radiochemical equilibrium composition depends on tritium concentration
(ratio of T/ΣH) and presence of metal catalysts (especially precious metals such as Pt, Pd)
• Reaction of T2 with methane
– If deuterium is present 15 different labeled methanes appear in gas phase4322342 CTCHTTCHTCHCHT
OTOT 222 22
322 23 NHNT
22222 NONOOTOTairT
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 9
Hydrogen Isotope (Physical) Chemistry
• Hydrogen is ubiquitous and the most abundant element in space– Element with the largest number of chemical compounds– No other chemical element can react in such a diversity by either giving
or taking an electron to make a chemical bond– Hydrogen can interact with most metals
• Hydrogen atoms are occupying interstitial places of the metal lattice forming an interstitial alloy
– Only low activation energies are required to move a hydrogen atom to the next nearest neighbor place in the host lattice, leading to fast diffusion of hydrogen
• Exchange of protium with tritium “contaminates” material
• Largest relative mass difference between the hydrogen isotopes protium, deuterium and tritium
– Large isotope effects for chemical reactions• Significant differences in chemical equilibriums and in reaction kinetics
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 10
Periodic Table of Binary Hydrides
• Electropositivemetals aremost reactive
• Inter-metalliccompoundsform metalhydrides
• Metal hydridesstoichiometryMeHn oftennot simple(n ≠ 1,2,3)
• “Hydride gap”
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 11
H - Isotopes Gas Metal Interactions (1/3)
• No energybarrier for tritiumto become physisorbed
– Physisorptionis molecular
– Surfaces easilyget contaminatedwith tritium
• Chemisorption isassociated withactivation energies AEChem
– Chemisorptionis dissociative
AE = Activation Energy
Surface
Solid Phase Gas Phase
Chemisorption Physisorption
T-T
T
Ediss
AEdes
AEChem
Potential Energy
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 12
H - Isotopes Gas Metal Interactions (2/3)
• No energybarrier for tritiumto become physisorbed
– Physisorptionis molecular
– Surfaces easilyget contaminatedwith tritium
• Chemisorption isassociated withactivation energies AEChem
– Chemisorptionis dissociative
– AEChem can be < EPhys
AE = Activation Energy
Surface
Solid Phase Gas Phase
Chemisorption Physisorption
T-T
T
Ediss
AEdes
AEChem
Potential Energy
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 13
H - Isotopes Gas Metal Interactions (3/3)
AE = Activation Energy
Surface
Solid Phase Gas Phase
Chemisorption Physisorption
T-T
T
Ediss
AEdes
AEChem
AEChem AESolEsol
Solution
Potential Energy• OncechemisorbedH isotope atoms canbecome dissolved
– AEChem for H isotopes tobecome dissolved
– Electronjoins theconductionband
– Screenedprotons(tritons) oninterstitial latticeplaces
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 14
Diffusion of Hydrogen Isotopes inFace Centered Cubic Metals
• Hydrogen isotopes occupy octahedral interstitial sites– MeH1 is limiting
stoichiometry– Diffusion from
one octahedralsite to anadjacent site isthrough thetetrahedral site
– Diffusivity ofH isotopes canbe very high
• Up to about10-5 cm2s-1 at ambient temperature
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 15
Hydrogen, Deuterium & Tritium in Metals
22
21TT KpC
• Hydrogen isotopes are dissolved in metals (α-phase) before metal hydride (β-phase) formation (reversible absorption / desorption)
– β-phase change often leading to metal disintegration into hydride powder– Metal hydrides (MeHs) show very interesting physical properties
• Superconductivity at relativelyhigh temperatures(still cryogenic levels)
• hydrogen density in certainMeHs higher than inliquid hydrogen
• Order-disorder transitionsand phase transitions
• Etc.
• “Sieverts” law
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 16
Tritium and ITER
• ITER is the first fusion machine fully designed for operation with DT– Tokamak vessel will be fuelled through gas puffing and Pellet Injection– Neutral Beam heating system will introduce deuterium into the machine
• Employing DT as fusion fuel has quite a number of consequences– Alpha heating of the plasma, fusion reaction eventually provides energy– Closed DT loop is required (small burn-up fraction in the vacuum vessel)
• Primary tritium systems for processing of tritiated fluids • Auxiliary systems necessary for the safe handling of tritium
– Multiple barriers vital for DT confinement in its process components• Atmosphere & Vent Detritiation Systems are crucial elements in the concept
After all a rather complex chemical plant, i.e. the Tritium Plant of ITER is needed for deuterium-tritium fuel processing
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 17
Plasma
Li
Be
Li
PlasmaExhaust
DT FuelSupply
DeuteriumSupply
Clean-up and DTFuel Recovery
TritiumRe-
covery
Vacuum Pumps
Helium to Stack
BreedingBlanket
He Purge Gas+ Tritium fromBlanket
TritiumSupply
Blower
Inner/Outer Fuel Cycle of Fusion Reactors
• Technically most suitable fusion reactionis the one between deuterium and tritium
D + T→ 4He (3.5 MeV) + n (14.1 MeV)
• Deuterium can be extracted fromnatural water (SMOW 0.016%)
• Tritium must be imported (very limited)or bred internally from lithium
– Import from heavy water moderatedfission reactors (CANDU type)
• T from neutron capture by D • Waste product to be removed from D2O
– Breeding reactions in a fusion reactorn + 6Li → T + 4He or n + 7Li → T + 4He + n
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 18
Simplified ITER Fuel Cycle
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 19
ITER fuel cycle block diagram
14 highly interconnected, multi-functional systems
Will occupy 7-story building
~5 kg tritium inventory
19
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 20
The ITER Closed Tritium Deuterium Loop
Plasma
Tritium (T2)Deuterium (D2)
Fuelling
IsotopeSeparation
TokamakExhaust
Processing
HTO, CT4, ...He, N2, CO, CO2, ...T2, D2, H2, DT, HT, HD
T2, D2
He, N2, CO, CO2, ...H2O, CH4, ...
Tritium (T2)Deuterium (D2)
Storage
DT, HT, HD,T2, D2, H2
T2, D2
TritiumRecycling
with 1
Plasma
Tritium (T2)Deuterium (D2)
Fuelling
IsotopeSeparation
TokamakExhaust
Processing
HTO, CT4, ...He, N2, CO, CO2, ...T2, D2, H2, DT, HT, HD
T2, D2
He, N2, CO, CO2, ...H2O, CH4, ...
Tritium (T2)Deuterium (D2)
Storage
DT, HT, HD,T2, D2, H2
Detritiation Systems
T2, D2
TritiumRecycling
with 1
H2O, HDO, HTO
Water-Detritiiation
IsotopeSeparation
H2, D2,HD, O2
H2, HT(HD)H2
H2, HT
Plasma
Tritium (T2)Deuterium (D2)
Fuelling
IsotopeSeparation
TokamakExhaust
Processing
HTO, CT4, ...He, N2, CO, CO2, ...T2, D2, H2, DT, HT, HD
T2, D2
He, N2, CO, CO2, ...H2O, CH4, ...
Tritium (T2)Deuterium (D2)
Storage
DT, HT, HD,T2, D2, H2
Detritiation Systems
T2, D2
TritiumRecycling
with 1
TritiumRecycling
with 2
> 100 kg tritium per year20,000 $ per g> 1 billion €
< 2 kg tritium per yearburned in ITER
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 21
Deuterium Tritium Fuel Cycle Block Diagram of ITER
Torus
Cryostat Cryo Pumps
Fuelling Gas Distribution
Pellet Injection
Neutral Beam Injection
Neutral Beam Cryo Pumps
Roughing Pumps
Isotope Separation
Storage and Delivery
Tokamak Exhaust Processing
Analytical System
Atmosphere and Vent Detritiation
Water Detritiation
Tritium Depot
Torus Cryo Pumps
Disruption Mitigation System Gas Puffing
Leak Detection
Service Vacuum Systems
Glow DischargeCleaning
Hydrogen (Protium) Release
Off Gas Release
Fusion Power Shutdown System
Automated Control System, Interlock System, Security
Cryostat
External Supplies
MBA 2
Tritium PlantBuilding
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 22
Main Functions of ITER Tritium Systems
• Handling of incoming and outgoing tritium shipments
• Storage / delivery of tritium & deuterium to / from fuel cycle– Determination of nuclear inventories
• Torus vacuum pumping and off gas transfer to processing systems
• Processing of tritium containing fluid streams– Tokamak exhaust / other tritiated off-gases for DT recycling
• Decontamination of gases prior to controlled release into the environment
– Extraction / recovery of tritium from Test breeding Blanket Modules– Separation of hydrogen into specific isotopic species for refueling– Detritiation of water and recovery of the tritium
• Atmosphere and ventilation detritiation
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 23
Deuterium Tritium Fuel Cycle Block Diagram of ITER
Torus
Cryostat Cryo Pumps
Fuelling Gas Distribution
Pellet Injection
Neutral Beam Injection
Neutral Beam Cryo Pumps
Roughing Pumps
Isotope Separation
Storage and Delivery
Tokamak Exhaust Processing
Analytical System
Atmosphere and Vent Detritiation
Water Detritiation
Tritium Depot
Torus Cryo Pumps
Disruption Mitigation System Gas Puffing
Leak Detection
Service Vacuum Systems
Glow DischargeCleaning
Hydrogen (Protium) Release
Off Gas Release
Fusion Power Shutdown System
Automated Control System, Interlock System, Security
Cryostat
External Supplies
MBA 2
Tritium PlantBuilding
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 24
ITER Tritium / Deuterium Storage & Supply
• Criteria for technical applications of metal tritides– Low equilibrium pressure of hydrogen isotopes at room temperature
• Metal hydride acts as a highly effective pump / Save storage of tritium
– Low temperature for hydrogen equilibrium pressures around atmospheric• Liberation of H isotopes from the metal hydride under moderate conditions
– Flat plateau for the α-phase (dissolution) to β-phase (MeH) transition• H isotope pressure remains constant during release at constant temperature
• Metal hydride bed design– Effective heating and power dissipation
to allow fast hydrogen release• Hydrogen release reaction is
strongly endothermic• Thermal insulation to allow calorimetry• Decay heat is a measure for the tritium content of the bed
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 25
ZrCoHx (log scale) and UHx (lin) Isotherms
0
1
2
3
4
5
6
0 0.5 1.0 1.5 2.0 2.5 3.0
log
p/P
a
x in ZrCoHx
130 °C
Sorption
Desorption
365 °C
300 °C
250 °C
200 °C
160 °C
400 °C
0
4
8
12
16
20
24
28
0 0.30 0.60 0.90 1.20 1.50 1.80 2.10 2.40 2.70 3.00
PRE
SSU
RE
- A
TM
HYDROGEN COMPOSITION - ATOM RATIO H/U
450 °C
500 °C
550 °C
600 °C
650 °C
DesorptionSorption
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 26
ITER 1:1 MeH Storage Bed (Karlsruhe)
• Essential ITER requirements– Safe storage of tritium (ZrCo or U as hydride?)– Inventory measurement by calorimetry– Inherent inventory limitation– Fast, flat top tritium delivery
• Dissipation of a few kW into powder packing
GB-y-3x00y-3x02
y-3x91 y-3x90
TIR
FIR
FIRCA±
FIRy-3x01
y-3x00
y-3x92
PIRA+S++
TIR
to SafetyBuffer Vessel
Tritium Supply toTokamak
He CalorimetryLoop
Tritium fromIsotope Separation He
Supply
High Vacuum
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 27
The “Ash” of Fusion Reactors
Deuterium Tritium Helium
• Gas from plasma / first wall (carbon, beryllium, tungsten) interactions – Carbon oxides (CO, CO2)– Water (Q2O with Q=H,D,T; 6 isotopically different species)– Hydrocarbons (CQ4 (15 isotopically different species), CxQy with x < 8)
• Helium and other gases need to be continuously removed– Plasma confinement strongly dependent upon “impurity” content
A closed deuterium tritium fuel cycle is necessary
++ + + + + + 17.6 MeV
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 28
Deuterium Tritium Fuel Cycle Block Diagram of ITER
Torus
Cryostat Cryo Pumps
Fuelling Gas Distribution
Pellet Injection
Neutral Beam Injection
Neutral Beam Cryo Pumps
Roughing Pumps
Isotope Separation
Storage and Delivery
Tokamak Exhaust Processing
Analytical System
Atmosphere and Vent Detritiation
Water Detritiation
Tritium Depot
Torus Cryo Pumps
Disruption Mitigation System Gas Puffing
Leak Detection
Service Vacuum Systems
Glow DischargeCleaning
Hydrogen (Protium) Release
Off Gas Release
Fusion Power Shutdown System
Automated Control System, Interlock System, Security
Cryostat
External Supplies
MBA 2
Tritium PlantBuilding
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 29
The CAPER Facility at TLK
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 30
Deuterium Tritium Fuel Cycle of Block Diagram ITER
Torus
Cryostat Cryo Pumps
Fuelling Gas Distribution
Pellet Injection
Neutral Beam Injection
Neutral Beam Cryo Pumps
Roughing Pumps
Isotope Separation
Storage and Delivery
Tokamak Exhaust Processing
Analytical System
Atmosphere and Vent Detritiation
Water Detritiation
Tritium Depot
Torus Cryo Pumps
Disruption Mitigation System Gas Puffing
Leak Detection
Service Vacuum Systems
Glow DischargeCleaning
Hydrogen (Protium) Release
Off Gas Release
Fusion Power Shutdown System
Automated Control System, Interlock System, Security
Cryostat
External Supplies
MBA 2
Tritium PlantBuilding
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 31
Separation by Multi Stage Distillation• Mixtures of liquids with different
volatility can be separated by distillation
– Distillate is enriched in the more volatile component
– Residue is depleted in the more volatile component
– Composition of the distillate and residue obviously changes with time
Residue
Boiler
Condenser
Distillate
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 32
Separation by Multi Stage Distillation• Mixtures of liquids with different
volatility can be separated by distillation
– Distillate is enriched in the more volatile component
– Residue is depleted in the more volatile component
– Composition of the distillate and residue obviously changes with time
• Process can be made continuous in a multi stage arrangement
– Feed at a certain stage– Withdrawal of distillate and residue– Counter current vapor-liquid contacting
column instead of multiple boilers
Boiler
Residue
Feed
Boiler
Boiler
Boiler
Condenser
Condenser
Condenser
Condenser
Distillate
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 33
Cryogenic Separation of H Isotopomeres
• Six molecular hydrogen isotopomeres with different boiling points
• H isotopomere separation requires cryogenic temperature distillation
• Separation between HT and D2 is particularly difficult
• Side streams must be withdrawn, heated, equilibrated on a catalyst to split the heterogeneous isotopomeres and returned into the column
2 HD ↔ H2+D2
2 HT ↔ H2+T2
2 DT ↔ D2+T2
Isotopomere H2 HD HT D2 DT T2
Boiling Point [K] 20.7 22.1 23.5 23.8 25.0 25.5
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 34
Isotope Separation Part at ITER (1/2)• ITER cryogenic Isotope Separation
System comprises 4 interlinked columns– Two feed streams
• Tritiated hydrogen and deuterium from the Water Detritiation System mixed with tritiated deuterium from Neutral Beam injection and fed into column (1)
• Deuterium - Tritium design feed flow rate into column (4) from Tokamak Exhaust Processing (TEP) system is about 7 m3h-1
– Four product streams• Tritium (90% purity)• Deuterium contaminated with tritium
(refueling)• Deuterium at high purity
(Neutral Beam injection)• Hydrogen (protium) for return to
Water Detritiation System
ISSColumn-1
Protium Return
Eq-2
Eq-3
Eq-5
ISSColumn-2
ISSColumn-3
ISSColumn-4
Eq-6
Eq-1
D2 (NBInjection)
From Plasma Exhaust
Eq-4
H2 (D, T) Feed
D2 (T) Product to SDS
T2 (90 %) Product to SDS
Eq-7
DT (50 %) Product to SDS
DT Feed
H2 (T) from Neutral Beam
H2O Protium Reject
H2O (D, T)
WDSLPCE
Column
Electrolyzer
H2(D, T)
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 35
Isotope Separation Part at ITER (2/2)• ITER cryogenic Isotope Separation
System comprises 4 interlinked columns– ISS operation is characterized by
transients and non-steady states• ITER is a pulsed machine• Protium from Isotope Separation System is
returned to the Water Detritiation System for decontamination
– Complex operation of two interlinked systems
• Cryogenic Isotope Separation Systems have large tritium inventories
– Liquid tritium handling • Loss of refrigerant (cooled helium)
evaporates large amounts of liquid hydrogen (and tritium)
ISSColumn-1
Protium Return
Eq-2
Eq-3
Eq-5
ISSColumn-2
ISSColumn-3
ISSColumn-4
Eq-6
Eq-1
D2 (NBInjection)
From Plasma Exhaust
Eq-4
H2 (D, T) Feed
D2 (T) Product to SDS
T2 (90 %) Product to SDS
Eq-7
DT (50 %) Product to SDS
DT Feed
H2 (T) from Neutral Beam
H2O Protium Reject
H2O (D, T)
WDSLPCE
Column
Electrolyzer
H2(D, T)
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 36
Deuterium Tritium Fuel Cycle of Block Diagram ITER
Torus
Cryostat Cryo Pumps
Fuelling Gas Distribution
Pellet Injection
Neutral Beam Injection
Neutral Beam Cryo Pumps
Roughing Pumps
Isotope Separation
Storage and Delivery
Tokamak Exhaust Processing
Analytical System
Atmosphere and Vent Detritiation
Water Detritiation
Tritium Depot
Torus Cryo Pumps
Disruption Mitigation System Gas Puffing
Leak Detection
Service Vacuum Systems
Glow DischargeCleaning
Hydrogen (Protium) Release
Off Gas Release
Fusion Power Shutdown System
Automated Control System, Interlock System, Security
Cryostat
External Supplies
MBA 2
Tritium PlantBuilding
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 37
Water Detritiation by the Liquid Phase Catalytic Exchange Process (1/2)
• Counter current isotopic exchange– Tritiated water is fed into an electrolyzer, H2
(HT) sent through a boiler into the column– Fresh water introduced at column top (flow
rate roughly same as for tritiated water)– Water is condensed at the top of the
column, flows back (and is electrolyzed)– ITER Liquid Phase Catalytic Exchange
• requires decontamination factor of ≈ 108
– tritium feed concentration about 1011 Bqkg-1
– hydrogen with a tritium concentration of only 700 Bqm-3 will be stacked
• will employ a solid polymer electrolyzer– low tritiated water inventory
Condenser
Scrubbing Section:
Catalytic Section:
Boiler
HT, H2
H2
(H2O)l
(HTO)v + (H2O)l (H2O)v + (HTO)l
HT + (H2O)v (HTO)v + H2
Solid Polymer Electrolyzer
(H2O)l + (HTO)lHT, H2 to
Isotope Separation
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 38
Water Detritiation by the Liquid Phase Catalytic Exchange Process (2/2)
• Isotope exchange takes place in two sections– Catalytic section: HT + (H2O)v → (HTO)v + H2
– Scrubbing section (HTO)v + (H2O)l → (H2O)v + (HTO)l
Condenser
Scrubbing Section:
Catalytic Section:
Boiler
HT, H2
H2
(H2O)l
(HTO)v + (H2O)l (H2O)v + (HTO)l
HT + (H2O)v (HTO)v + H2
Solid Polymer Electrolyzer
(H2O)l + (HTO)lHT, H2 to
Isotope Separation
0.004 0.006 0.008 0.010 0.012 0.014 0.016 0.018 0.020 0.022 0.024 0.026 0.0280.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 39
Deuterium Tritium Fuel Cycle Block Diagram of ITER
Torus
Cryostat Cryo Pumps
Fuelling Gas Distribution
Pellet Injection
Neutral Beam Injection
Neutral Beam Cryo Pumps
Roughing Pumps
Isotope Separation
Storage and Delivery
Tokamak Exhaust Processing
Analytical System
Atmosphere and Vent Detritiation
Water Detritiation
Tritium Depot
Torus Cryo Pumps
Disruption Mitigation System Gas Puffing
Leak Detection
Service Vacuum Systems
Glow DischargeCleaning
Hydrogen (Protium) Release
Off Gas Release
Fusion Power Shutdown System
Automated Control System, Interlock System, Security
Cryostat
External Supplies
MBA 2
Tritium PlantBuilding
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 40
Calorimetry as aSelective Analytical Method for Tritium
• Thermal power produced by tritium ß-decay is used to measure the amount of tritium
• Calorimetry is a non-destructive method and can be used to determine tritium in gases, liquids and solids such as
– Tritium in gases or water– Tritium in structure materials– Tritium in waste for disposal
• Limitations of Calorimetry– No other heat-producing
components should be present– Sample size is restricted to the
measurement calorimeter volume
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 41
Principles of Calorimetry
• Two types of calorimeters– Isothermal system
• T(outside) = const.• T(inside) = const.• Heat flux detected to
provide a measurefor the tritium amountTritium amount= f (heat fluxthrough surface )
– Adiabatic system • T(outside) = const.• T(inside) detected to provide a
measure for the tritium amountTritium amount = f (T(inside) – T(outside))
T(inside)
T(outside)
Insulation
Calorimeter Cup
outercylinder
middlecylinder
innercylinder
Calorimeter Cup
Peltier Cooler
insulation
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 42
Deuterium Tritium Fuel Cycle of Block Diagram ITER
Torus
Cryostat Cryo Pumps
Fuelling Gas Distribution
Pellet Injection
Neutral Beam Injection
Neutral Beam Cryo Pumps
Roughing Pumps
Isotope Separation
Storage and Delivery
Tokamak Exhaust Processing
Analytical System
Atmosphere and Vent Detritiation
Water Detritiation
Tritium Depot
Torus Cryo Pumps
Disruption Mitigation System Gas Puffing
Leak Detection
Service Vacuum Systems
Glow DischargeCleaning
Hydrogen (Protium) Release
Off Gas Release
Fusion Power Shutdown System
Automated Control System, Interlock System, Security
Cryostat
External Supplies
MBA 2
Tritium PlantBuilding
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 43
Fueling System Configuration
• Gas Injection System (GIS)– Upper port level GIS : 4 ports– Divertor port level GIS : 3 ports
• Pellet Injection System (PIS)– 3 divertor ports (2 injectors each)
• 2 injectors at start-up• 6 injectors after up-grade
• Disruption Mitigation System (DMS)– Two locations at upper port level
• Fusion Power Shutdown System– Two locations at upper port level
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 44
Conceptual Design of ITER Pellet Injector(Pneumatic Accelerator)
Roots + Screw BlowerPropellant Compressor
Pellet Injector
V1
V2Cryocooler
Compressor
MicrowaveCavity
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 45
Fusion Plasma Fuelling Through Pellet Injection
• ITER plasma is fuelled by gas puffing andby Pellet Injection (PI)
– Twin screw extruder to producepellets of D and T ice(frozen deuterium and tritium)
– Typical pellet is a 6 mm by 6 mm cylinder– Pellets are injected through a gas gun
• Compressed deuterium employed as propellant
– Pellet speed is 1300 km per hour• Faster than the speed of sound in air
– Up to 20 pellets per second from a singlepellet injector
Pellet in ASDEX plasma
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 46
Flight Tube Layout
Cryopump housing
Divertor port
LFS flight tube
HFS flight tubeCryostat
DIIID Pellet Injection movie
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 47
Deuterium Tritium Fuel Cycle of Block Diagram ITER
Torus
Cryostat Cryo Pumps
Fuelling Gas Distribution
Pellet Injection
Neutral Beam Injection
Neutral Beam Cryo Pumps
Roughing Pumps
Isotope Separation
Storage and Delivery
Tokamak Exhaust Processing
Analytical System
Atmosphere and Vent Detritiation
Water Detritiation
Tritium Depot
Torus Cryo Pumps
Disruption Mitigation System Gas Puffing
Leak Detection
Service Vacuum Systems
Glow DischargeCleaning
Hydrogen (Protium) Release
Off Gas Release
Fusion Power Shutdown System
Automated Control System, Interlock System, Security
Cryostat
External Supplies
MBA 2
Tritium PlantBuilding
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 48
ITER torus exhaust vacuum system
Torus exhausthigh vacuum pumping system
Duct double bellows
Pumping duct
Entrance from the plasma
Installation points for torus cryopumps
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 49
Vacuum Systems Requirements and Design Basis
• Helium (the fusion reaction “ash”) need to be continuously removed– Continuous removal of helium together with unburned DT & other gases
• Plasma density control through fuelling and vacuum• Broad spectrum of gases will have to be pumped
• ITER vacuum pumping systems employscryo-panels forced cooled bysupercritical helium at 4.5 K and 0.4 MPa
– Helium & hydrogen isotopes pumpingassured via cryo-sorption
• Cryo-condensation for heavier gases
– Cryo-panels with micro porousactivated coconut charcoal
• Glued to the cryo panels by means of atritium compatible inorganic cement
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 50
1:2 Torus model cryopump (Karlsruhe)with outside valve (DN 700, 400 mm stroke)
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 51
Tritium Confinement Philosophy
• Confinement of tritium within its respective fuel cycle processing systems / components is in effect the most important safety objective
– Basic targets of confinement• Prevent spreading of radioactive material in normal operation
– Maintain contamination level as low as reasonably achievable (ALARA principle)• Keep radiological consequences for operators, public and environment in off-
normal conditions within acceptable levels
– Confinement function is achieved by a coherent set of physical barriersand / or auxiliary techniques intended to confine radioactive substances
• IAEA practice is to use the term “containment” for physical barriers– Term “confinement” is more general, refers to function of confining radioactive
material within a certain volume and includes filtering and atmosphere processing• Primary confinement system is designed to prevent releases of radioactive
materials into the accessible working areas• Secondary confinement system prevents releases to working areas accessible
by non-authorized radiological workers, general public and the environment
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 52
ITER Ventilation & Confinement Concept
• Secondary confinementcomprises sub-atmosphericpressure control andatmosphere detritiation
– Heating, Ventilation,Atmosphere Conditioning(HVAC) not categorized to beSafety Important Class (SIC)
– Vent detritiation is SIC
• Primary confinement caninclude more than one barrier
– Glove box (GB) formaintenance purposes
– GB atmosphere detritiation
PrimarySystem
HVACSupply
Fresh Air
(Glove Box)
ReleasePoint
ISS Cold Box
HVAC Exhaust
Glove BoxDetritiation
System (GDS)
VentDetritiation
AtmosphereDetritiation
ISS
Building Sector
Surrounding Barrier(Glove Box)
PrimarySystem
Surrounding Barrier
SecondaryConfinement
Building Sector/ Tritium Spill
PrimaryConfinement
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 53
Tritium Plant Building Systems Layout• 7 Stores
– 2 belowgrade
• L = 80 m
• W = 25 m
• H = 35 m
• Releasepoint elevation:60 m
– Tokamak building height: 57 m
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Fusion Reactor Fuel Cycle Manfred Glugla, Lecture INSTN Page 54
Summary
• Deuterium / tritium fusion reactors require a closed fuel cycle– Low burn-up fraction leads to high DT throughputs within Tritium Plant
• Unprecedented tritium flow rates and tritium processing requirements
– ITER relies on pellet injection for plasma density control– Distributed Vacuum System with cryo-pumps and roughing pumps
• Deuterium / tritium processes cover wide range in physical chemistry– Variety of overlapping effects when dealing with all 3 hydrogen isotopes
• Hydrogen isotopes in metals– Permeation of hydrogen isotopes, dissolution and hydride formation
• Heterogeneous catalysis, chemical reaction kinetics and chemical equilibria• Separation techniques in fluid systems• Analytical tools such as calorimetry
• Safe handling of tritium achieved by multiple confinement strategies