1. Using Nuclear Brayton Combined Cycles
Flibe (6Li2BeF4) Blankets to Integrate Heat Production with Electricity Markets
Using Nuclear Brayton Combined Cycles
C. W. Forsberg1 and P. F. Peterson2
1Massachuestts Institute of Technology
2University of California at Berkeley
1Department of Nuclear Science and Engineering; Massachusetts Institute of Technology
77 Massachusetts Ave; Bld a; Cambridge, MA 02139; Tel: (617) ;

2. Market Needs May Define Fusion Reactor Power Cycles and Coolant Strategies
Understand Long-Term Electricity Markets
Base-load Electricity, Variable Electricity, Heat to Industry
Energy Conversion Systems to
Meet Market Requirements
Nuclear Air Brayton Combined Cycle (NACC)
Firebrick-Resistance Heated Energy Storage (FIRES)
Salt-Cooled Fusion and Fission Reactors 2

3. No Change In Energy Policy for 250,000 Years, Throw a Little Carbon on the Fire
Natural-Gas
Combined Cycle
Cooking Fire 3

4. Nuclear Energy Did Not Change Fossil Fuel Energy Policy or the Market
New England Electricity Demand 4
Low-capital-cost High-operating-cost fossil plants for variable energy production
High-capital-cost Low-operating-cost nuclear plants for base-load
Demand (104 MW(e))
Time (hours since beginning of year) 4

5. Variable Electricity Market
If No Fossil Fuels Because of Concerns About Climate Change, What Is Replacement For Variable Electricity Production? 5
Variable Electricity Market
Demand (104 MW(e))
Base-load Electricity Market
Time (hours since beginning of year) 5

6. If Add Wind/Solar Base-Load Electricity Demand
May Disappear: The California Duck Curve
Solar Eliminates Mid-Day Demand For Other Electricity Sources But More Variable Power Need When Sun Sets

7. Before and After Midday (Other Times for Wind)
Electricity Market Changes: Large Revenue Boost If Produce Energy When Needed
Before and After Midday (Other Times for Wind)
Large-Scale Solar Collapses Electricity Prices in the Middle of the Day—No Base Load Market

8. California Power Generation Late Spring Weekend Day

9. New Energy Conversion System to Address New Market Requirements
Understand Long-Term Electricity Markets
Base-load Electricity, Variable Electricity, Heat to Industry
Energy Conversion Systems to
Meet Market Requirements
Nuclear Air Brayton Combined Cycle (NACC)
Firebrick-Resistance Heated Energy Storage (FIRES)
Salt-Cooled Fusion and Fission Reactors 9

10. Salt-Cooled High-Temperature Fusion/Fission Reactors With Nuclear Air-Brayton Combined Cycle (NACC) and FIRES 10

11. Most Efficient Heat to Electricity Technology and Improving Rapidly
Modern Combined-Cycle Gas Turbines Have Heat-To-Electricity Efficiencies of 60%
Most Efficient Heat to Electricity Technology and Improving Rapidly
Used to meet variable electricity demand so replace natural gas with nuclear heat
Must deliver nuclear heat to compressed air above front-end jet-engine compressor exit temperatures of 300 to 450°C 11

12. Salt Coolants Designed to Couple to Gas Turbines
In the 1950s the U.S. Launched the
Aircraft Nuclear Propulsion Program
Bomb Russia → Jet Engine → Salt Coolant → Reactor
Salt Coolants Designed to
Couple to Gas Turbines 12

13. Salt-Cooled Reactors Deliver Heat to Power Cycle Between 600 and 700°C
Molten Salt Reactor (MSR)
Terrapower Design
FHR (Solid Fuel and Clean Salt)
Salt-Cooled Fusion Reactor 13

14. Gas Turbine Variable Electricity And Steam Fusion Reactor
Salt-Cooled Reactor with Nuclear Air-Brayton Combined Cycle (NACC)
FIRES Stored Heat and/or Natural Gas
Gas
Turbine
Variable Electricity
And Steam
Fusion
Reactor 14

15. Modified Natural-Gas-Fired Power Cycle
NACC Power System
Modified Natural-Gas-Fired Power Cycle
Filtered
Air
Compressor
Turbines
Heat Recovery SG
Generator
Reactor Salt-to-Air Heaters
Steam Sales or
Turbo-Generator
FIRES
Heat Storage
Natural gas
or H2
Electric Heating 15

16. Firebrick Resistance-Heated Energy Storage (FIRES)
Buy electricity when electricity prices are less than fossil fuels used by industry (natural gas)
Electrically heat insulated mass of firebrick to very high temperatures
Use stored heat delivered as hot air for two applications
Industrial heat
Peak electricity production
30, 30 16

17. Stored Heat (FIRES) Replaces Natural Gas for Low-Carbon System or Large Electricity Price Swings17

18. Added Natural Gas or Stored Heat For a Thermodynamic Topping Cycle
Topping Cycle: 66% Efficient for added Heat-to-Electricity; Future NACC Topping >70%: Stand-Alone Combined-Cycle NG Plants 60% Efficient 18

19. Salt Fusion and Fission Reactors Use Flibe (Li2BeF4) Coolant
FHR
MSR
Clean
6Li2BeF4
Solid Fuel
and Clean
7Li2BeF4
Fuel Dissolved in 7Li2BeF4 19

20. Rapid Growth of Interest in Fission Salt-Cooled Reactors
United States
Multiple startup companies
Federal government
Universities
China (SINAP)
Irradiations Corrosion Thermal
MIT Loops (UW) Loops (UCB)
(Simulants) 20

21. Flibe Coolant Development Major Component of Work
Massive overlap between fission and fusion coolant requirements
Important differences fusion vs. fission
Tritium production three orders of magnitude larger
Tougher challenge to meet tritium emission limits
Must recover and recycle tritium efficiently
May use different materials of construction 21

22. Large Incentives for Fusion and Fission on Work On Flibe Coolant Challenges
FHR
Gas Turbine 22

23. Biography: Charles Forsberg
Dr. Charles Forsberg is the Director and principle investigator of the High-Temperature Salt-Cooled Reactor Project and University Lead for the Idaho National Laboratory Institute for Nuclear Energy and Science (INEST) Nuclear Hybrid Energy Systems program. He is one of several co-principle investigators for the Concentrated Solar Power on Demand (CSPonD) project. He earlier was the Executive Director of the MIT Nuclear Fuel Cycle Study. Before joining MIT, he was a Corporate Fellow at Oak Ridge National Laboratory. He is a Fellow of the American Nuclear Society, a Fellow of the American Association for the Advancement of Science, and recipient of the 2005 Robert E. Wilson Award from the American Institute of Chemical Engineers for outstanding chemical engineering contributions to nuclear energy, including his work in hydrogen production and nuclear-renewable energy futures. He received the American Nuclear Society special award for innovative nuclear reactor design on salt-cooled reactors and the 2014 Seaborg Award. Dr. Forsberg earned his bachelor's degree in chemical engineering from the University of Minnesota and his doctorate in Nuclear Engineering from MIT. He has been awarded 12 patents and has published over 200 papers. 23 23 23 23

24. Market Change Requires Rethinking Fission and Fusion Power
Market change bad for high-capital-cost low-operating-cost nuclear, wind, and solar
Not a problem for low-capital-cost high-operating-cost natural gas, shut down when low prices

25. Base-Load NACC Operations25
42% Base-load efficiency if optimized for base-load power (GE 7FB Gas turbine)
Process description
Compress filtered air
Heat air with salt coolant
Turbine for power
Reheat air with salt coolant
Hot air to heat recovery steam generator with steam for electricity or industry
Exhaust air up stack

26. Peak Power NACC Operations26
Incremental heat-to-electricity efficiency 67%
Thermodynamic topping cycle more efficient than stand-alone natural gas combined cycle plant (60%)
Process
Add natural gas or stored heat to “low-temperature” 670°C compressed air
Added power from second gas turbine
Higher temperature to heat recovery steam generator with higher-temperature steam: more power

27. FHR with NACC and FIRES Buys and Sells Electricity
If >50% difference in electricity prices, buy electricity when low prices to sell at higher prices
Direct competitor to batteries and pumped storage
Unlike batteries and pumped storage, assured capacity with NG or oil peak power 27

28. Heat Storage Sends Added Hot Air to HRSG When High Electricity Demand
Firebrick Recuperator for Heat Recovery Steam Generator
Diverts Gas-Turbine Hot Gas to Heat Storage When Low-Priced Electricity
Heat Storage Sends Added Hot Air to HRSG When High Electricity Demand

29. NACC with Firebrick Recuperator
Very Low Cost (Low-Pressure, Lower Temperature)
Heat Storage Relative to Other Storage Technologies 29

30. Lower-Temperature Low-Pressure Firebrick Recuperator Stores Heat and Varies Heat to HRSG
Hot exhaust from turbine can heat firebrick rather than generate steam and then go to stack
Cold air can be blown through firebrick to provide added hot air to HRSG to generate more steam—greater variable power
Second storage system with very cost (low-pressure) heat storage system 30

31. Implications of Ultra-Low
Heat-Storage Costs
Address weekday/weekend storage challenge
Electricity demand lower on weekend but the sun shines and wind blows
Large fraction of cheap electricity on weekend
System stores weekend energy for the weekday
If very cheap or negative electricity, option to add electric heaters to dump cheap electricity as heat into firebrick recuperator