freidberg fission fusion hybrid rev1

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The Fission-Fusion Hybrid At last! A solution that has found a problem Jeff Freidberg MIT

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Freidberg Fission Fusion Hybrid Rev1

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Page 1: Freidberg Fission Fusion Hybrid Rev1

The Fission-Fusion Hybrid

At last! A solution that has found a

problem

Jeff Freidberg MIT

Page 2: Freidberg Fission Fusion Hybrid Rev1

What problem are we trying to solve?

• Future large demand for CO2-free base load electricity

• May need 10 TW CO2-free electricity by mid-century

• 20 times more CO2-free electricity than now

• Only coal and nuclear fission are realistic options

• Coal must solve the sequestration problem - tough job

• Nuclear must solve waste and proliferation problems – plausible solutions exist

• Nuclear must also solve the fuel supply problem – only 30 years of proven reserves at 10 TW level

Page 3: Freidberg Fission Fusion Hybrid Rev1

What problem are we trying to solve? (con’t)

• Mid-century uncertainties

1. Coal Sequestration

2. Discovery of new uranium

• Prudent to have other options

• Problem to be solved:

Produce large amounts of fissile fuel so that fission becomes a sustainable source of electricity

Page 4: Freidberg Fission Fusion Hybrid Rev1

How are we going to solve the problem?

• Revisit an old idea

Use a fission-fusion hybrid to produce fissile fuel

• What has changed to make this old idea interesting?

1. We may need a lot more uranium than we

thought

2. The fission community, at least at MIT, is

interested and receptive to the idea

Page 5: Freidberg Fission Fusion Hybrid Rev1

The fission-fusion energy park

• One 200 MWe-equivalent (i.e. 500 MWt) tokamak fusion core

• Surround with a thorium-lithium blanket – produces about 5500 kg of U-233 plus 20 kg of tritium per year

• Separate the U-233 and combine it with U-238 to form fissile fuel for a LWR

• This fuel is sufficient to power two 800 MWe LWRs

• Power gain = 8!

• Burn the resulting Pu and actinides in an onsite 300 MWe fast reactor.

• Store short lived radioactive byproducts on site

• Transmute long lived radioactive byproducts in the hybrid blanket

Page 6: Freidberg Fission Fusion Hybrid Rev1

Why is this good for fusion

• How can fusion make a contribution by mid-century?

– Fusion electricity is tough from a plasma physics and fusion

engineering point of view

• Fissile fuel from fusion is much easier

– Need Q = 2 -5 for success rather than Q = 50 for electricity

– Do not need steady state or ultra-high availability

– Even if fusion electricity is successful, it will likely cost more than

a comparable fission reactor

• What about tainting fusion with fission? If we can help fission

produce electricity we must do so and not be dilettantes posturing in

the wind

Page 7: Freidberg Fission Fusion Hybrid Rev1

Why is this good for fission?

• The fission-fusion hybrid converts fission energy from an

intermediate stop-gap energy source into one that is

sustainable for over 10,000 years

• Making fissile fuel from a fission-fusion hybrid may be

better than alternate options

Page 8: Freidberg Fission Fusion Hybrid Rev1

Comparison of options

• What are the options for producing fissile fuel?

Fuel Source Cost (cents/kW-hr)

Direct mining of U 0.5

Sea water extraction 1.6

Accelerator production 7.4

Breeder reactor 1.8

Fission-fusion hybrid 1.7

Page 9: Freidberg Fission Fusion Hybrid Rev1

From ITER to a fission-fusion DEMO

• Plasma physics1. MHD, transport, heating OK

2. Divertor and first wall scale-up problems remain

3. Current drive may not be necessary

4. Larger B field very desirable for plasma physics

• Fusion engineering1. Materials for the first wall and divertor

2. Tritium and fissile fuel breeding

3. Increased neutron fluence

4. Increased availability

Page 10: Freidberg Fission Fusion Hybrid Rev1

Recommendations for OFES

• Initiate a 2 year pre-ARIES scoping study

on the fission-fusion hybrid system

• Increase emphasis on the first wall and

divertor problems

• Initiate a superconducting magnet R&D

program to make higher field magnets