Transcript Technical and economical feasibility

TW3-TSW-001/D2:
Identification of decommissioning options for
reduction of tritiated waste quantities:
Technical and economical feasibility of water
detritiation
Johan Braet, Aimé Bruggeman
Final Meeting of contracts TW3 and TW4
17 January 2005
EFDA CSU, Garching
No nuclear energy without tritium
• Origin
 Ternary fission
 2H (n,γ) 3H
 6Li (n,α) 3H
 others
• Amounts (TBq/GWe.a)
 LWR: 700 or 2 g T2
 HWR: 90 000 or 250 g T2
 CTR: 40 000 000 or 110 kg T2
Management of tritium losses
• Discharge & dilute
 Cfr low radiotoxicity
 Common practice
• Or contain, separate &
 Condition & dispose (cfr T1/2 = 12.3 y)
 Or recover & recycle (?)
Fusion needs water detritiation
● Large amounts of T  Low T release limits
40 000 PBq per GW(e)a  0.4 PBq/a?
Trapping of T losses
● HTO prevailing or easily produced
Trapping as HTO(l)
● Large isotopic dilution
Water detritiation
Technical & economical feasibility of
water detritiation
• Incentives to initiate the task at SCK•CEN:
 Water detritiation is imperative for the future of fusion
energy
 SCK•CEN has a vast experience in water detritiation:
SCK•CEN invented a hydrophobic catalyst HT/HTO
SCK•CEN tested different improved types of catalyst
SCK•CEN built a 0.12 m³/day pilot WDS, based on CECE (LPCE)
 SCK•CEN has experience in handling different forms of
tritiated waste in general.
Typical tritiated wastes expected
to arise from fusion reactors
Liquids
Solids
Possible origin
Type of waste
Type of
contaminant
Tritiated water
HTO
Leakage collection
Oil, lubricants
HTO/OBT
Maintenance of vacuum pumps
Decontamination solutions HTO/OBT
Decontamination of equipment
Tritium permeated hard
waste
HT/activation
prod.
First wall/blanket
Exhausted molecular
sieves
HTO
Maintenance of cryopumps,
adsorption beds
Exhausted catalyst
HT/HTO
Systems for purification of
gaseous/liquid waste
Exhausted IX-resins,
activated carbon
HTO/activation
prod.
Decontamination of various aqueous
waste streams
Exhausted getters
HT
Plasma exhaust purification system
Most of the fusion tritiated waste already
exists or can easily be transformed into
tritiated water
• HTO/H2O is not only the prevailing form it is also the
thermodynamically favoured form
• Segregation limits volume of accumulated tritiated water
 Segregation allows direct free release of some water
 Further volume reduction is obtained by water detritiation for
(relatively) high tritiated water
Again large fraction for discharge
Small fraction with (nearly) all tritium
• Solutions for conversion of other types of tritiated waste are
suggested:
 Tritiated organic liquids
Tritiated soft waste
 Tritiated metals & concrete
Tritiated molecular sieves & getters
Requirements for water
detritiation
• Up till know little information
 No CTR’s running
 Little info on ITER estimated waste production
 Most relevant operational device: JET
• JET:
 ±48 tonnes accumulated from 1997 until 2002
 1.1 PBq collected
 Average annual production of 8 tonnes with 23.4 TBq/tonnes
 Higher than normal deuterium concentrations
 Pre-purification of water might be required
Requirements for water
detritiation (2)
• Design criteria for the facility at JET:
 10 tonnes/year tritiated water
 Discharge to the environment < 2 GBq/d
 Total tritium inventory < 37 TBq (1000 Ci or 0.1 g T)
 Concentration recovered tritium for re-entry in torus at
least 98 at% => extra enrichment after WDS
 As low as reasonable capital and operational cost
=>compliant with AGHS design
Review of technology for water
detritiation
• Potential methods tested at pilot/industrial scale:
 Water distillation
 Cryogenic distillation of hydrogen (CD)
 Vapour Phase Catalytic Exchange (VPCE)
 Liquid Phase Catalytic Exchange (LPCE)
 Combined Electrolysis and Catalytic Exchange (CECE)
 Combinations of the above
Review of technology for water
detritiation (2)
• Water distillation:
 Based on small difference in BP H2O/HTO => large energy
consumption
 Series of columns could be followed by electrolyser for final
concentration
 Considered for ITER & JET: combination of distillation, VPCE
and CD => abandoned
• Cryogenic distillation of hydrogen:
 Larger difference in boiling points HT/H2
 Huge cooling capacity needed to extract tritium from waste water
=> investment and energy cost
 Ideal technique in combination with others to extract tritium from
already concentrated tritiated water
VPCE versus LPCE
• VPCE:
 Catalytic isotopic exchange between water vapour and
gaseous hydrogen
 Catalyst poisoned by liquid water => Temp high
 Co-current mode=>limited transfer of T
 Multi stage needed for significant separation=> extra
auxiliary equipment needed (pumps, vessels, etc..)
• LPCE:
 Liquid water => Hydrophobic catalyst
 Counter current
 Easy multiplication of separation effect in one column
 In combination with electrolyser => CECE
Combined Electrolysis Catalytic
Exchange
Stack
H2 , HD
H2 , HD
LPCE column
Cryogenic distillation column
H 2O
H2
HT
HD
DT
D2
Permeator
Stack
Oxygen
purification
Water
purification
O2
Water
purification
GC-AGHS
Ele ctrolyse r
H 2O
HDO
HTO
D2
DT
R&D on hydrophobic catalyst
• LPCE filling:
 Hydrophobic catalyst (Pt, styrene-divenyl benzene; PTFE)
 Hydrophilic packing
• Decades of R&D and experience in many countries
(Japan, Russia, Romania, Germany, Canada,
Belgium, etc) in different laboratories
• Different filling methods
Economical feasibility of water
detritiation
• Cost illustrations are given for different WDS:
 ELEX SCKCEN pilot installation
 WDS at JET
 BR2-reactor water detritiation
• ELEX SCKCEN:
 Throughput 0.12 m³/day (column diameter 10 cm)
 Max. inventory (1000 Ci), concentration 100 Ci/m³
 Same order of magnitude as WDS JET
 Total investment cost: 1.8 M€ (currency 1985)
 Annual operation cost 0.145 M€
• WDS at JET:
 Investment 2.5 M€ is foreseen
Due to tightening regulation an option is
being studied to detritiate BR2 waste water
• Pre-dimensioning is done:
 Throughput 25 L/h or 200 m³/year
 Tritium concentration max. 30 MBq/L
 Two 2 meter columns (enrichment and stripping), 27
cm diameter
 Estimated total investment cost 1.55 M€ (including
building)
 Operation cost (excluding labour): 0.28 M€
 Overall unit cost: 1.8 €/L (depreciation over 20 years)
Conclusion
• It is clear that water detritiation plays a central
role in fusion reactor waste management
• Different (industrial) techniques for water
detritiation
• CECE followed by CD and/or gas
chromatography seems most promising one
• Industrial CECE application would need only
limited extra R&D
• Cost for CECE is limited