Johan Braet , Aimé Bruggeman Final Meeting of contracts TW3 and TW4 17 January 2005

1. 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

2. 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

3. 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 (?)

4. 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

5. 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.

6. Typical tritiated wastes expected to arise from fusion reactors

7. 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 metals & concrete • Tritiated soft waste • Tritiated molecular sieves & getters

8. 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

9. 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

10. 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

11. 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

12. 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

13. Combined Electrolysis Catalytic Exchange

14. 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

15. 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

16. 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)

17. 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