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 TW417 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 producedTrapping as HTO(l)

● Large isotopic dilutionWater 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/HTOSCK•CEN tested different improved types of catalystSCK•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.

Type of wasteType of wasteType of Type of contaminantcontaminant

Possible originPossible origin

LiquidsLiquidsTritiated waterTritiated water HTOHTO Leakage collectionLeakage collection

Oil, lubricantsOil, lubricants HTO/OBTHTO/OBT Maintenance of vacuum pumpsMaintenance of vacuum pumps

SolidsSolids

Decontamination solutionsDecontamination solutions HTO/OBTHTO/OBT Decontamination of equipmentDecontamination of equipment

Tritium permeated hard Tritium permeated hard wastewaste

HT/activation HT/activation prod.prod.

First wall/blanketFirst wall/blanket

Exhausted molecular Exhausted molecular sievessieves

HTOHTO Maintenance of cryopumps, Maintenance of cryopumps, adsorption bedsadsorption beds

Exhausted catalystExhausted catalyst HT/HTOHT/HTO Systems for purification of Systems for purification of gaseous/liquid wastegaseous/liquid waste

Exhausted IX-resins, Exhausted IX-resins, activated carbonactivated carbon

HTO/activation HTO/activation prod.prod.

Decontamination of various aqueous Decontamination of various aqueous waste streamswaste streams

Exhausted gettersExhausted getters HTHT Plasma exhaust purification systemPlasma exhaust purification system

Typical tritiated wastes expected Typical tritiated wastes expected to arise from fusion reactorsto arise from fusion reactors

• 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 waterAgain large fraction for dischargeSmall fraction with (nearly) all tritium

• Solutions for conversion of other types of tritiated waste are suggested: Tritiated organic liquids Tritiated metals & concrete

Most of the fusion tritiated waste already exists or can easily be transformed into

tritiated water

Tritiated soft wasteTritiated soft waste

Tritiated molecular sieves & gettersTritiated 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

LP

CE

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Oxygen purification

Permeator

Water purification

Water purification

H2OHDO HTO

H2O

Electrolyser

H2 , HD H2 , HD

H2

HTHDDTD2

D2 DT

O2

Stack

Stack

GC-AGHS

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 SCKCEN pilot installation WDS at JET BR2-reactor water detritiation

• ELEX SCKCEN: 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