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Nuclear Fuel Cycle: Mining, Enrichment, and Fuel Fabrication Randall Fielding, INL Phone: (208)

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Presentation on theme: "Nuclear Fuel Cycle: Mining, Enrichment, and Fuel Fabrication Randall Fielding, INL Phone: (208)"— Presentation transcript:

1 Nuclear Fuel Cycle: Mining, Enrichment, and Fuel Fabrication Randall Fielding, INL Email: Phone: (208) 533-7015

2 Presentation Summary Nuclear Electricity 7 th Ed., Ian Hore-Lacy, Uranium Information Centre and World Nuclear Association

3 Mining: Surveying Surveying –Geological and satellite surveys Very high level –Aircraft surveys After areas of interest are seen with satellite a more detailed survey is done using planes and helicopters –Surface surveys Prospector and his donkey

4 Mining: Minerals of interest Several uranium bearing minerals of interest for mining Grades usually vary from 0.5% - 0.03% Mineral nameChemical Composition UraniniteUO 2 Davidite(Fe, Ce, La, Y, U, Ca, Zr, Th) (Ti, Fe, Cr, V) 3 (O,OH) Brannerite(U,Ca,Fe,Th,Y) 3 Ti 5 O 16 CarnotiteK 2 (UO 2 ) 2 (VO 4 ) 2·3H 2 O TyuyaminiteCa (UO 2 ) 2 (VO 4 ) · 5-8 H 2 O AutuniteCa (UO 2 ) 2 (PO 4 ) 2 · 10-12 H 2 O TorberniteCu (UO 2 ) 2 (PO 4 ) 2 · 8-12 H 2 O UranophaneCa (UO 2 ) 2 SiO 3 (OH) 2 · 5H 2 O

5 Mining: Types of mining Open pit mine –Most common Underground –Must have adequate ventilation because of radon, sometimes necessitating remote equipment In-situ leaching (solution mining) –Leaching solution pump down one hole and dissolved U 3 O 8 pump up adjacent holes –Somewhat experimental, ground water contamination concerns

6 Mining: Milling During milling the U 3 O 8 from the mine is concentrated –Incoming ore is crushed –Roasted to dive off organics –U 3 O 8 is leached or recovered through Sx/ion exchange –U 3 O 8 is precipitated out, washed, dried, and packaged –Finished product is termed “yellow cake”

7 Enrichment: Conversion from U 3 O 8 to UF 6 UO 2 UF 4 UF 6 U3O8U3O8 HF F2F2 Pure UF 6 Reduction Hydofluorination Fluorination Distillation H 2 +N 2 Dry Hydrofluor Process Wet Solvent Extraction Process UO 3 U3O8U3O8 Solvent Heat Pure UF 6 Digestion Sx Calcination Reduction HNO 3 H 2 +N 2 Hydro- fluorination Fluorination UO 2 HF UF 4 F2F2

8 Enrichment: 235 U Enrichment Gaseous Diffusion – 235 U molecules are faster, hence diffuse through a hole in a barrier more quickly Centrifugal method –Centrifugal forces compress the gas at the centrifuge wall, but thermal agitation separates lighter elements to the center of the chamber Atomic Vapor Laser Isotope Separation –A laser selectively excites 235 U atoms. UV light kicks some excited electrons free and ionizes the atoms. Ions are collected on a negatively charge Faraday cup.

9 Fuel Fabrication: UO 2 Production Fuel manufacturers receive the UF 6 which is solid at room temperature and convert it to UO 2 –Bubble UF 6 gas through water to form UO 2 F 2 –UO 2 F 2 is added to ammonia water to precipitate (NH 4 ) 2 U 2 O 2 –(NH 4 ) 2 U 2 O 2 is calcined to form U 3 O 8 –U 3 O 8 is reduced with H 2 to form UO 2

10 Fuel Fabrication: Pellet Production UO 2 is crushed and ground to a fine powder and mixed with an organic binder (e.g.. polyvinyl alcohol) Powder is pressed into pellets and sintered Sintering –Hydrogen –1650° C for 24 hours –Final density: 94% theoretical density

11 Fuel Fabrication: Pellet Production Pellet final diameter: ~10 mm diameter Pellets are ground to final diameters Ends are be cupped and corners chamfered –Grinding will reduce mechanical interaction during irradiation Each pellet is inspected

12 Fuel Fabrication: Pellet Production

13 Fuel Fabrication: Fuel Rod Production Pellets are segregated into stacks and weighed Loaded into zirconium alloy tubes Pressurized to 1000-2000 p.s.i. with helium and seal welded

14 Fuel Fabrication: Assembly Fabrication Fuel rods are then bundled into fuel assemblies

15 Fuel Fabrication: Metal Fuel Assembly hardware Fabricate fuel assemblies Pull testFlow test Final inspection Bonding Furnace Bonding Final inspection Weld inspection Load jackets with fuel Settle slugs Weld top endplug Fuels feedstock Alloy production Injection casting Break molds Trim slugs Inspection Trimmings to chemistryTrimmings to casting furnace Jacket hardware Bottom endplug welding Spacer wire wrap Inspections Sodium Loading

16 Fuel Fabrication: Metal Fuel Sodium bonded fuel –Provides good heat conduction –Metal fuel is compatible with Na –LMFBR use sodium as the coolant

17 Fuel Fabrication: Metal Fuel Metal fuel is injection cast –Alloys are melted under vacuum –Evacuated molds are lowered into melt and furnace is pressurized –Metal is forced up into the molds where it cools and solidifies –Fuel slugs are then removed from the molds Remaining fabrication steps similar to UO 2 fuel

18 References: The Nuclear Fuel Cycle: Analysis and Management by R.G. Cochran and N. Tsoulfanidis Figures were found on (unless otherwise noted)

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