Transcript Document
Uranium Fuel Cycle 1 Conventional Mining: Underground/Open Pit Ranger, Australia, Northern Territories Olympic Dam, South Australia 2 ISR: Drilling – Well Construction 3 ISR: Minimum Disturbance of Environment 4 ISR Plant – Schematic 5 ISR Plant – Beverley, South Australia 6 Ion Exchange Resins 7 Beverley Plant – Impressions IX columns Yellowcake Sampling Filtration units The product BACKUP 9 SiC-SiC Composite Cladding has Potential to Significantly Improve Safety of Light Water Reactors m3 H2 generated/m2 rod surface 2.0 Zircaloy 100% consumed 1.5 1400oC Fukushima Daiichi 1100oC 1.0 0.5 1400oC 1100oC SiCβ <1% consumed 0.0 0 1 2 Eliminate hydrogen explosions reaction time (days) Zr + 2H2O ZrO2 + 2H2 SiC + 4H2O SiO2 + CO2 + 4H2 For Zircaloy, destruction by steam reaction occurs at lower temp than fuel melt For SiC/SiC, structural failure occurs at lower temp than steam reaction At higher temps (~1400oC) Zircaloy reaction heat exceeds decay heat General Atomics Proprietary Data 10 Comparison of EM2 vs Fukushima Plant To Earthquake & Tsunami 9.0 magnitude earth quake/tsunami: reactor vessels and containments are intact but all electrical power is severed air draft heat exchanger Fukushima EM2 Grade level Reactor Redundant shutdown cooling Turbinegenerator Leak-tight, below-grade containment • Without power, cooling systems are inoperable • Fuel heats up causing high pressure and hydrogen producing reactions from zircalloy clad • External means of cooling is needed until power to cooling systems is restored • Reactor cooling by natural convection – no power needed • Silicon-carbide clad does not react with helium coolant at high temperature • Walk-away safe – no external intervention needed General Atomics Proprietary Data Fuel Resources for Electric Power Generation in the U.S.A. U.S. Energy Reserves (Trillion Bbls Oil Energy Equivalent) Depleted uranium (DU)/ Used nuclear fuel (UNF) inventories 8 TBbl Depleted Uranium 1 TBbl Used Nuclear Fuel 12 Energy supply for > 300 years electric power generation “Convert & Burn” reactor achieves a 30-year fuel life by converting 238U to 239Pu and burning in situ BeO reflector Graphite reflector Starter Control drum location B4C neutron Shield LEU: ~ 12% Lowenriched uranium DU: Depleted uranium TRU: Transuranics UNF: Used nuclear fuel MOX: Mixed U/Pu oxides NU: Natural uranium Recycled EM2 discharge 30% 232Th 70% 238U Core support floor 316L General Atomics Proprietary Data 13 Fertile EM2 Changes the Game Relative to Nuclear Waste EM2 vs LWR Waste LWR Waste Disposal based on 5000 GWe/days production EM2 Waste Disposal 100 Uranium Plutonium Fission Products • Deep geologic repository Waste mass, tonnes 80 • Million year life 60 40 •Above ground storage 20 Only 0.1% are long lived fission products (e.g. Tc-99 and I-129) • Large storage capacity • Long term heat • Long term radioactivity 3.4 0 LWR EM2 General Atomics Proprietary Data • 400 year life •Small storage capacity •Short term heat •Short term radioactivity BACKUP 2 General Atomics Proprietary Data 15 ISR Mining Process • • • • • • • Groundwater pumped to surface (at start-up) Small amount of acid and oxidant added Water pumped back into aquifer Uranium leached Water pumped to surface Uranium recovered by ion exchange (IX) Water recycled [up to 100 recycles (pore volume exchanges)] 16 Leaching Chemistry • Uranium ore – Uranium as U(IV) fixed in minerals, e.g. pitchblende UO2, coffinite USiO4 • Mobilization of uranium by oxidation and complexation – Uranium needs to be oxidized to U(VI) to form soluble uranyl ions UO22- • Leaching methods – Alkaline (carbonate) leaching: UO2(CO3)22- and higher-order complexes – Acidic (sulfuric acid) leaching: UO2(SO4)22- and higher-order complexes – Application of oxidants: O2, H2O2 17 Uranium Recovery • Mining solution contains anionic uranyl complexes like UO2(CO3)22- or UO2(SO4)22• Recovery from mining solution by ion-exchange (IX) – Resin (in form of beads at 0.5-1 mm diameter) – Resin beds in big columns (about 2-4 m diameter, 3-10 m height) – Mining fluid passes IX columns and recycles to wellfields – Uranium is adsorbed on the resin • Strip of uranium from IX resin by highly-ionic solution, e.g. salt solutions (NaCl) • Further processing includes precipitation of uranium as uranium oxide, thickening, de-watering, drying, packaging 18 ISR – Hydrogeology For ISR mining, ore body must have following properties: – Ore body must be in an aquifer (sedimentary formation) – Aquifer sediments must be permeable – Aquifer should be vertically confined (above and below) by impermeable layers 19 Beverley ISR Mine – Processing Plant 20