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  2 H (n,γ) 3 H  6 Li (n,α) 3 H  others Amounts (TBq/GWe.a)  LWR: 700 or 2 g T 2  HWR: or 250 g T 2  CTR: or 110 kg T 2

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 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  SCKCEN has a vast experience in water detritiation:  SCKCEN invented a hydrophobic catalyst HT/HTO  SCKCEN tested different improved types of catalyst  SCKCEN built a 0.12 m³/day pilot WDS, based on CECE (LPCE)  SCKCEN has experience in handling different forms of tritiated waste in general.

Type of waste Type of contaminant Possible origin Liquids Tritiated water HTO Leakage collection Oil, lubricants HTO/OBT Maintenance of vacuum pumps Solids 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 Typical tritiated wastes expected to arise from fusion reactors

HTO/H 2 O 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 metals & concrete Most of the fusion tritiated waste already exists or can easily be transformed into tritiated water  Tritiated soft waste  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 H 2 O/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/H 2  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

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 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