Tritium Breeding Requirement in Next Step Fusion Nuclear Facility

(FNF)Mohamed Sawan

University of Wisconsin-Madison

Mohamed AbdouUCLA

With input from Scott Willms-LANL

FNST Meeting at UCLAAugust 12-14, 20081

Objective Determine the required TBR in the FNF as a function of

fusion power and available external tritium supply

TBR determined for three options Required FNF TBR to ensure it does not run out of

tritium fuel during its lifetime Required FNF TBR to ensure that 5 kg of tritium is

available at end of ITER and FNF operation for startup of DEMO

Required FNF TBR to ensure that 10 kg of tritium is available at end of ITER and FNF operation for startup of DEMO

Assume that ITER has priority over FNF for using external tritium supply from CANDU reactors

2

Projected World-Wide CANDU Tritium (from Scott Willms, LANL)

3

External Tritium Supply Available for FNF(from Scott Willms, LANL)

4

Assumptions:•2016 ITER start•2 kg working inventory that builds up over 2 years preceding DT operation•At end of 20 ITER operation half of working inventory lost to waste

FNF Assumptions

5

2021 FNF start 1 year HH followed by 1 year DD operation 3 years DT operation at 10% availability followed by 10 years DT

operation at 30% availability Fusion power in the range 50-400 MW considered A tritium inventory is maintained at all time during DT operation to

cover hold-up in chamber components, tritium processing system, and needed reserve

This working inventory is assumed to be 0.4 kg at 100 MW fusion power (scaling from ITER)

Working inventory scales linearly with fusion power and builds up over the 2 years preceding DT operation

At end of 15 year FNF operation half of the working inventory is lost to waste with the rest added to supply available for DEMO

Tritium burn rate is 55.6 kg/GWy Tritium decays at rate of 5.5% per year

Total External Tritium Supply Required by FNF Has Strong Dependence on TBR and Pf

6

0

5

10

15

20

0 5 10 15

TBR=0TBR=0.5TBR=0.8TBR=1.0TBR=1.045

Years from start of FNF operation

100 MW Fusion Power

0

5

10

15

20

0 5 10 15

50 MW100 MW150 MW200 MW300 MW400 MW

Years from start of FNF operation

TBR=0.8

Tritium Inventory Available for DEMO at End of ITER and FNF Operation Depends Strongly on TBR in FNF

7

0

5

10

15

20

25

30

2000 2005 2010 2015 2020 2025 2030 2035 2040 2045

Supply w/o fusionWith ITERFNF- 0 TBRFNF- 0.5 TBRFNF- 0.8 TBRFNF- 1.2 TBRFNF- 1.4 TBR

Year

100 MW FNF2021 FNF start

Required TBR in FNF

8

0.0

0.5

1.0

1.5

2.0

50 100 150 200 250 300 350 400

FNF does not run out of T5 kg T available after ITER and FNF10 kg T available after ITER and FNF

Fusion Power of FNF (MW)

2021 FNF start

TBR required to ensure that FNF does not run out of tritium supply during its operation increases as the fusion power increases

Incremental TBR required to provide a given additional tritium for DEMO is larger for low fusion power FNF

How Does FNF Start Date Affect Tritium Supply?

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With 2021 FNF start, both ITER and FNF end operation at same time and FNF is competing with ITER for tritium supply for all of its lifetime

With 2026 FNF start, FNF is the sole fusion user of available external supply for 5 years following ITER which has a slight net increase (0.2 kg/y Canada + 0.4 kg/y Korea – 0.1 kg/y non-fusion use – decay)

With delayed FNF start, cumulative tritium use in FNF at end of ITER operation is reduced Without adequate TBR, delay of FNF start by 5 years results in FNF running out of tritium

supply faster (for 0.5 TBR, FNF runs out of T after 13 years for 2021 start and after 10 years for 2026 start)

0

5

10

15

20

25

30

2000 2005 2010 2015 2020 2025 2030 2035 2040 2045

Supply w/o fusionWith ITERFNF- 0 TBRFNF- 0.5 TBRFNF- 0.8 TBRFNF- 1.2 TBRFNF- 1.4 TBR

Year

100 MW FNF2026 FNF start

0

5

10

15

20

25

30

2000 2005 2010 2015 2020 2025 2030 2035 2040 2045

Supply w/o fusionWith ITERFNF- 0 TBRFNF- 0.5 TBRFNF- 0.8 TBRFNF- 1.2 TBRFNF- 1.4 TBR

Year

100 MW FNF2021 FNF start

Required TBR in FNF Slightly Affected by Start Date

10

Delay in FNF start results in slight reduction in required TBR

This is due to reduced cumulative amount of tritium used in FNF at end of ITER and availability of tritium resources in the 5 years after ITER for FNF without competition from ITER

0.0

0.5

1.0

1.5

2.0

50 100 150 200 250 300 350 400

FNF does not run out of T5 kg T available after ITER and FNF10 kg T available after ITER and FNF

Fusion Power of FNF (MW)

2021 FNF start

0.0

0.5

1.0

1.5

2.0

50 100 150 200 250 300 350 400

Fusion Power of FNF (MW)

2021 FNF start

2026 FNF start

Conclusions

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With the limited external supply and taking into account ITER operating schedule, any next step FNF should provide significant part of its tritium need

Delay of ITER makes the problem worse with higher required TBR in FNF

With available external tritium supply, a small fusion power and a modest TBR are required for FNF to have enough tritium for its operation

Another part of FNF mission is to provide the initial tritium inventory needed for startup of DEMO. This increases the required TBR in FNF. Incremental TBR required to provide a startup tritium inventory for DEMO is larger for low fusion power FNF and large initial startup inventory for DEMO (significantly greater than 5Kg)

• To achieve this mission, FNF can have a TBR that increases with time with possible extension of its operation at a higher TBR