Implications for Waste Handling of the Energy Multiplier Module by John Rawls June 29, 2010 132-10/rs 1 Changing the Game for Nuclear Energy Key National Issues EM2 Goals 1. Economics – To reduce capital investment and power cost by 30% compared to ALWRs 2. Used Nuclear Fuel – To consume & reduce used nuclear fuel inventory, i.e. minimize need for long-term repositories 3. Non-Proliferation – To reduce need for uranium enrichment; eliminate conventional fuel reprocessing 4. Energy Security – To advance electrification through site- flexibility & process heat applications; to reduce foreign energy imports 5. Human Dimension – To attract eager young minds to a challenging new enterprise 132-10/rs 2 EM2 is a Fast Gas-Cooled Reactor in which Fuel is Made and Burned in situ Schematic EM2 core Basics of the breed and burn in situ approach • A starter region containing fissile material provides initial criticality fertile • The burn spreads to the fertile region, where it is sustained by newly bred fuel starter • The geometrical arrangement has low excess reactivity for decades, improving fuel utilization and simplifying control control drum 1.15 2 1.10 EM core reactivity reflector 1.05 1.00 k-effective 0.95 Argonne National Laboratory predicted longer core life and 0.90 lower excess reactivity 0.85 0 10 20 30 40 Time (Yr) 132-10/rs 3 Reactor Concept Point design features Grade • 500 MWt, He cooled at 850oC outlet suitable for process heat applications Power • 240 MWe at ~48% net efficiency (~45% Conversion with dry cooling), at power cost Module comparable to natural gas at $7/Mbtu • Burns used LWR fuel w/o reprocessing (also DU, natural U, WPu, Th admixture) • 30+-yr core w/o refueling or reshuffling; 18 m EOL core can be recycled with 30-60% fission product removal 5 m • Passively safe, underground sited Reactor • Modules factory manufactured & shipped by commercial trucks 132-10/rs 4 Core Composition and Arrangement Fuel Element 5.19kg 5.0 m (15.6 ft) 17,136 units Fuel Elements (typ. of 21 per SiC-SiC Fission gas layer) clad movement porous UC plate Reactor Fission gas Return Flow movement Annulus SiC-SiC Assembly Frame B4C Layer (100 mm thickness) Positions plates Graphite for cooling & FP Core Barrel Reflector Layer control (500 mm Fuel Assembly 257kg thickness) 357 units Reactor Vessel Wall BeO Layer (250 mm minimum thickness) • Handling unit Material irradiation data is encouraging about the life of SiC structure • Stackable • Transfers fission gas 132-10/rs 5 Used Nuclear Fuel/DU and Partial Closing of the Fuel Cycle 132-10/rs 6 Energy Security: Fuel Utilization1 Improves with Number of Cycles 50% 45% 40% 35% SNF waste EM2 First Cycle: U.S. SNF inventory: 61,000 t 30% 2X LWR Utilization 25% Fuel Utilization Fuel 20% 15% 2U.S. DOE NE Goal: 10% 10% DU waste 5% U.S. DU inventory: 700,000 t LWR 0.5% 0% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Energy in U.S. SNF & DU Number of EM2 Cycles inventory is 5 x world’s 1Percent of mined heavy metal that is fissioned 2U.S. Department of Energy, Nuclear Energy proven oil reserves 132-10/rs 7 Quantity of Waste Produced 12000 Impact on repository sizing (stated on a per unit energy 10000 supplied basis) 8000 ) • Higher burnup and higher LWR 6000 efficiency mean lower end of life fuel mass & volume tonnes 4000 • These amounts are reduced 2000 2 further (linearly) by the Waste ( Waste EM 0 number of times fuel is reused 0 100 200 300 400 -2000 • These figures of merit are Waste vs years of operation for a further improved if spent LWR continuously operating1.2 GWe plant fuel is used as fuel Total waste in 400 years: LWR 12,000t, EM2 < 400t 132-10/rs 8 Implications for Nuclear Waste EM2 Decay After 30-year Burnup EM2 Core Decay Heat After 30-year Burnup 1.E+07 1.E+05 Actinides Fission Products 1.E+04 1.E+06 1.E+03 Actinides Fission Products 1.E+05 1.E+02 1.E+01 Decay Energy (Watts) Energy Decay Decay Activity (Curies) Activity Decay 1.E+04 1.E+00 1.E+03 1.E-01 1 10 100 1000 10000 1 10 100 1000 10000 Decay Time (years) Decay Time (years) __________________________________________________________________________________________ FP radiological data Actinide radiological data • FP makeup quite similar to that of LWRs except • If restricted to one burn cycle, actinide content that Cs is removed from the core during the burn per unit energy produced is similar to that of LWRs • After 300 yrs, primary FPs are 99Tc & 151Sm, two and is reduced linearly with the number of cycles weak beta emitters; FP heat load is few W/core • Long core residence postpones repository need 132-10/rs 9 Non-Proliferation Dry cask storage 1. Reduces fuel handling and eliminates long-term storage of spent fuel containing significant Pu. 2. Eliminates need for conventional reprocessing Uranium enrichment (heavy metal chemical separation). 3. Both discharged and refabricated EM2 fuel meets self-protection requirements for 20 yrs. 4. Below-grade reactor core is inaccessible without Geological repositories special remote handling equipment. 5. Low excess reactivity- core cannot be easily reconfigured for material insertion/extraction 132-10/rs 10 10 185-09/RWS/rs Comparative Power Generation Costs 30% cost reduction is a result of the following attributes • Less materials • Factory labor • Shorter construction time • Smaller facility footprint • Higher efficiency • Decades of life — no refueling/no shuffling • Simple control • Bankablility of fuel ALWR, coal and natural gas data source: MIT 2009 Cost Update; EM2 model estimate. All power generation costs evaluated for a 30-yr levelization period 132-10/rs 11 DOE-NE Comprehensive EM2 Peer Review - Core physics and depletion - Core thermal hydraulics - Fuels - Fission product transport - Used fuel management - Structural materials - Balance of plant - Safety - Non-proliferation - Cost/economics Key findings: • Most significant risks are associated with 30-yr core in fast neutron fluence, including fuel thermal-chemical performance and dimensional stability, SiC clad integrity, and fission product transport • Report affirms the reactor physics design and that EM2 supports all five DOE-NE goals 132-10/rs 12 185-09/RWS/rs GA’s Internally-Funded Program Addresses Fuel and Power Conversion UC Lab CY2010 GA-Funded Work - Bench-scale UC fab facility - Bench-scale SiC fab facility - Fuel fab process optimization - Physics methods upgrade - Reactivity control design - EM2 fuel metrology lab - High-speed generator SiC Composite Lab - High-voltage inverter - Reactor concept optimization - Power conversion design - Selected accident analyses - FP transport component fab High-speed SiC coater Gas Turbine 132-10/rs 13 13 185-09/RWS/rs Summary • Significant capital & power cost reduction • Reduces (and potentially consumes) the used nuclear fuel inventory, thereby easing repository requirements and possibly delaying their need • Reduces long-term need for enrichment; eliminates need for conventional reprocessing • Formidable technical challenges are attracting eager young minds to a new nuclear enterprise with a long-term future 132-10/rs 14 Backup Slides 132-10/rs 15 EST Also Offers Promise for Used Nuclear Fuel Fission Products Heavy Metals • Uses mass gap between actinides and lanthanides • Separation of trivalent actinides and lanthanides considered to be the most difficult current reprocessing steps – Necessary for both repository management and recycled fuel • Filter throughput 30X less than wastes much smaller size plant 132-10/rs 16 EST Technology Proof of Principle has Occurred • Physically separates based on mass/charge using electromagnetic fields • Advantages for nuclear wastes – Relatively indifferent to waste complexity – Excellent separation efficiency – Single step process – Reduced waste streams – Significant net cost savings and risk reduction • Advantages for used nuclear fuel processing – Separates fission products – Not capable of TRU separation by element or isotopes – Supportive of new reprocessing-free closed fuel cycle options 132-10/rs 17 Technology Needs & Research Challenges • Efficient and effective separation of fission products from reactor discharge • Understanding properties of materials under high neutron fluences and high temperatures • Behavior of fuel and fission products over decades • Defining and establishing manufacturing base to realize the cost-effective fabrication of modular reactors like EM2 132-10/rs 18 EM2 is More Proliferation-Resistant than Alternative Reactor Concepts Portion of Attribute of Light Water Traditional EM2 Fuel Cycle Fuel Cycle Reactor Fast Reactor Gen 1: yes Gen 1: yes Front end Need for enrichment? Yes Gen 2: no Gen 2: no Operations Fuel residence time < 5 yr < 5 yr > 30 yr Sealed vessel? No No Yes Yes, with Pu Yes, without Back end Planned reuse of fuel None separation Pu separation Proliferation vulnerability legend LOW MODERATE HIGH 132-10/rs 19 185-09/RWS/rs.