From the TBM and ITER Tritium Technologies to DEMO

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From the TBM and ITER Tritium Technologies to DEMO

• I. Ricapito
• Fusion for Energy, Josep Pla 2, 08019 Barcelona,
  Spain

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OUTLINE

• DT Fuel Cycle in ITER and DEMO
• Architecture of the Fuel Cycle in ITER
• Architecture of the Fuel Cycle in DEMO
• Peculiarities and similarities between ITER and
  DEMO
• Systems of the DT Inner Fuel Cycle in ITER
• Tokamak Exhaust Processing System
• Isotope Separation System
• Storage and Delivery System
• Tritium Systems for TBMs
• Tritium Systems for Breeding Blanket in DEMO
• Summary

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DT FUEL CYCLE IN ITER AND DEMO
08/29
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DT Fuel Cycle in ITER and DEMO
Reactors Parameters impacting the fuel cycle
continuous daily sequence of standard pulses
(repetition time of 1800 s)
Despite the 7 times larger fusion power than
in ITER, only 2.5 times higher fueling rate was
expected in PPCS-B due to higher burn-up
efficiency
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Architecture of the Fuel Cycle in ITER
DT Fuel Cycle in ITER and DEMO

• MAIN FUNCTIONS
• Storage/delivery of tritium from/to tokamak
  device (SDS)
• Recovery of Q (H,D,T) from different gas streams
  (TEP)
• Separation of pure Q streams into Q streams of
  specified composition for refueling
• Final detritiation before gas release into
  environment

08/29
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DT Fuel Cycle in ITER and DEMO
Architecture of the Fuel Cycle in DEMO
From R. Laesser
External T needed for start
D from external sources
Fuelling Systems Pellet Injection, Gas Puffing
Protium Release
BB WDS
Storage and Delivery System (SDS)
Neutral Beam Injection Cryo Pumps
BB tritium recovery syst.
DEMO Torus
Tritiated Water
Isotope Separation System (ISS)
Analytical System (ANS)
Breeding Blanket Tritium Processing Systems
Inner Fuel Cycle
Q2
To stack
Tokamak Exhaust Processing (TEP)
Torus Cryo-Pumps Roughing Pumps (RP)
Vent Detritiation System (VDS)
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DT Fuel Cycle in ITER and DEMO
Comparison between fuel cycle in ITER and DEMO

• Tokamak Exhaust Processing System (TEP)
• The DEMO TEP will be moderately bigger in size
  than ITER TEP. The contribution from Breeding
  Blanket in terms of T load becomes important
• Isotope Separation System (ISS)
• DEMO ISS will be similar/smaller than in ITER ISS
  as most of the recycled Q2 will bypass ISS.
• If lower throughput and inventories are confirmed
  it should be possible to produce pure H2, D2 and
  T2 gases, making easier the operation of ISS in
  DEMO than in ITER. Furthermore, isotopic
  composition changes of gas mixtures during
  delivery from metal tritide storage beds will be
  avoided
• Storage and Delivery System
• The tritium and deuterium storage beds could be
  very similar to the ones of ITER
• (designed for in-situ calorimetry and high supply
  rates)

• The continuous regime in DEMO will make the
  inner fuel cycle design and operation simplified
  compared to ITER
• Tritium inventory in the DEMO Fuel Cycle will
  become more critical

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SYSTEMS OF THE INNER DT FUEL CYCLE IN ITER
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Systems of the DT Fuel Cycle in ITER
Tokamak Exhaust Processing (TEP), 1/2

• Functions
• To purify Q from impurities
• To extract tritium from tritiated impurities
  (mainly Q2O and CxQy)
• To discharge into environment the detritiated
  impurity stream via Vent Detritiation

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Systems of the DT Fuel Cycle in ITER
Tokamak Exhaust Processing (TEP), 2/2

• Adopted Technology
• selective Pd-Ag permeators
• catalysts to crack hydrogen containing molecules

baseline 2001 currently under modification
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Systems of the DT Fuel Cycle in ITER
Isotope Separation System (ISS), 1/2

• Function
• To produce hydrogen isotope streams with a fixed
  isotopic composition

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Systems of the DT Fuel Cycle in ITER
Isotope Separation System (ISS), 2/2
Adopted Technology Cryogenic Distillation

• ISS utilizes four cryogenic distillation columns
  to process two feed streams
• from WDS and NBI feeding the column 1 (around 8
  Nm3/h)
• from TEP (around 7 Nm3/h)
• ISS produces five product streams
• T (90 of purity) for refueling
• DT (50) mixture T for refueling
• D contaminated with T for refueling
• D at high purity for NBI
• Pure H to Water Detritiation System

baseline 2001 currently under modification
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Systems of the DT Fuel Cycle in ITER
Storage and Delivery Systems (SDS), 1/2

• Functions
• Storage of Isotope Separation System product
  streams from ISS
• Release of Isotope Separation Systems for
  Fuelling
• Tritium accountancy by pVT-c measurements
  calorimetry

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Systems of the DT Fuel Cycle in ITER
Storage and Delivery Systems (SDS), 2/2

• Technology adopted Metal Hydride Bed

• Zirconium-cobalt, although very promising, was
  found to suffer the problem of dis-proportionation
  with consequent tritium trapping
• Although pyrophoric, Uranium still appears as the
  most suitable material for mainly two reasons
• defined stoichiometry (UT3) no problems of
  tritium trapping
• equilibrium pressure lt 1 Pa at RT safe storage
• equilibrium atmospheric pressure at only about
  430 ºC liberation of hydrogen isotopes under
  moderate conditions

2 ZrCoTx ? ZrCo2 ZrT2 (x - 1) T2
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TRITIUM SYSTEMS IN TBMs
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Tritium Systems in TBMs
Objectives of ITER campaign
Although of very small amount, in the order of
magnitude of some tens mg/day, tritium bred in
TBMs needs to be extracted and accounted for,
with the main aim of

• validating theoretical predictions on tritium
  breeding
• validating modelling tools on tritium recovery
  performance and inventory in structural and
  functional materials
• getting experience in technologies and components
  for tritium processing

In general, technologies envisaged for the
Tritium Systems in TBMs are not requested to be
DEMO relevant
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Tritium Systems in TBMs
Integration of HCLL-TBM in the ITER Fuel Cycle

TEP Tokamak Exhaust Processing HCS Helium
Cooling System TES Tritium Extraction
System CPS Coolant Purification System VDS Vent
Detritiation System
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Tritium Systems in TBMs
Tritium Extraction from HCLL-TBM

• In the design reference solution tritium
  extraction from lead-lithium proceeds in two
  steps
• in the first step tritium is extracted from the
  lead-lithium by a gas-liquid contactor (GLC)
  consisting of a packed column with He doped with
  H2 as stripping gas.
• in the second step, He containing Q2 (HTH2)
  stripped in the gas-liquid contactor, is
  processed by TRS (Tritium Removal from Purge Gas
  System), based on adsorption beds. Purified He is
  then routed back to GLC.

HeQ2
GLC
TBM
TRS
TES
HeH2
Q2
PbLi
TEP
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Tritium Systems in TBMs
Conceptual Design of TES for HCPB-TBM
Main components - adsorption column for Q2O
removal operated at RT in adsorption phase - two
bed TSA system for Q2 removal - U metal getter as
scavenger bed in a by-pass line, to be used
mainly in the low duty DT phase

• No demanding requirement on TES efficiency
  (3040)
• Feed flow-rate about in the range of 1040 Nm3/h

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Tritium Systems in TBMs
Conceptual Design of CPS for HCPB-TBM
Three Step Process 1) oxidation of Q2 to Q2O and
CO to CO2 by an oxidising reactor (Cu2O-CuO)
operated at 280C 2) removal of Q2O by two bed
PTSA operated at RT and 8 MPa and at 300C and
0.1 MPa in regeneration 3) removal of the
impurities in HCS by a two-bed cryogenic PTSA

• No demanding requirement on tritium/impurities
  extraction efficiency
• Feed flow-rate around 80 Nm3/h

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TRITIUM SYSTEMS FOR BREEDING BLANKET in DEMO
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Simplified Block Diagram for HCPB-DEMO
Tritium Systems for BB in DEMO
He (Q2 Q2O) 0.4 kg/s, 0.11 MPa, 400ºC Q2
110 Pa HT 1.6 Pa Q2O 1.6 Pa
He H2 H2O 2.4 kg/s, 8 MPa, 300 ºC Q2 1000
Pa H2O 50 Pa HT 0.08 Pa
He(Q2Q2O) 2400 kg/s, 8 MPa, 300ºC
He compr.
He blower
HCS
Purge
H2 6 Nm3/h H2O 5.8 kg/d
TES h0.9
Q2O 2 kg/d, 49500 Ci/kg
DEMO Breeding Blanket Pt3.0 GW GT0.385
kg/d T-perm15 g/d
SG
CPS h0.9
No Q2 (all oxidised)
Q2 0.65 kg/h 7.2 Nm3/h
Q2 11 Pa HT 0.16 Pa Q2O 0.16 Pa
Q2O 122 kg/d, 0.12 g T/kg
Impurities to TEP
H2 8 Nm3/h
HCS Helium Cooling System TES Tritium
Extraction System ISS Isotope Separation
System CPS Coolant Purification System WDS
Water Detritiation System TEP Tokamak Exhaust
Processing SG Steam Generator
He Q2 Q2O 2.4 kg/s, 8 MPa, 500 ºC Q2 1000
Pa HT 0.8 Pa Q2O 50 Pa
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Tritium Systems for BB in DEMO
Coolant Purification System (CPS) /1

• Critical is the size of the CPS which depends on
• tritium permeation rate into the primary cooling
  circuit
• maximum allowed tritium partial pressure in the
  cooling primary circuit

• On the other hands, the tritium permeation rate
  is a function of
• TES efficiency
• CPS efficiency
• PbLi-T Sieverts constant (for PbLi based BB)
• Efficiency of Tritium Permeation Barriers, if
  any

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Tritium Systems for BB in DEMO
Coolant Purification System (CPS) /2
T perm. 150 g/d
CPS feed flow-rate in HCLL BB for 650 g/d of
tritium generation rate
CPS feed flow-rate higher than 1x106 Nm3/h, 1
of the total coolant flow-rate, are at the border
of technicaleconomical feasibility because of
size of the system and decrease in the reactor
net efficiency
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SummaryConclusions /1
Inner Fuel Cycle

• Inner fuel cycle for DEMO needs more detailed
  studies. However, the general structure envisaged
  for ITER, developed under EFDA, could be applied
  to DEMO
• Different systems of ITER inner fuel cycle (TEP,
  ISS, SDS), developed under EFDA, are based on
  DEMO relevant technologies. As a consequence,
  important inputs can be envisaged from their
  operation in ITER
• TO BE DONE for DEMO
• Development of technologies for detritiation of
  highly tritiated water (presently, no solutions
  are available also for ITER)
• Review/new selection of technologies for the
  fuel cycle driven by minimization of tritium
  inventory
• Development of on-line tritium diagnostics
  (concentration, flows, inventories)

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SummaryConclusions /2
BB Fuel Cycle

• Different activities related to BB fuel cycle
  have been carried out during EFDA
• experimental campaigns on tritium permeation
  barriers
• measurements of solubility/diffusivity of H
  isotopes in PbLi
• development of conceptual design of TES and CPS
  for TBMs
• Although lasted for quite long time and well
  done, these activities didnt give definitive
  results.
• Compared to the systems for TBMs, higher
  performance will be required for DEMO systems
  (i.e. in the tritium extraction/purification
  systems)
• TO BE DONE for DEMO
• Review, selection, testing and validation of
  technologies for tritium extraction from PbLi to
  clarify their potential for high performance
• Development of predictive tools for optimization
  of the fuel cycle
• Continuation with the development of Tritium
  Permeation Barriers, compatible with the blanket
  environment