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. 24-207a; Cambridge, MA 02139; Tel: (617) 324-4010; Email: cforsber@mit.edu; http://web.mit.edu/nse/people/research/forsberg.html

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

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

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

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

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

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

California Power Generation Late Spring Weekend Day

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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. http://web.mit.edu/nse/people/research/forsberg.html 23 23 23 23

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

Base-Load NACC Operations 25 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

Peak Power NACC Operations 26 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

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

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

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

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

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