# Presentation: 018429

## Nuclear Fuel Cycle: Mining, Enrichment, and Fuel Fabrication

**Randall Fielding, INL**
**Email: **_**[randall.fielding@inl.gov](mailto:randall.fielding@inl.gov)**_
**Phone: (208) 533-7015**

## Presentation Summary

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

## 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**

## Mining: Minerals of interest

**Several uranium bearing minerals of interest for mining**
**Grades usually vary from 0.5% - 0.03%**

| Mineral name | Chemical Composition |
| --- | --- |
| Uraninite | UO2 |
| Davidite | (Fe, Ce, La, Y, U, Ca, Zr, Th) (Ti, Fe, Cr, V)3 (O,OH) |
| Brannerite | (U,Ca,Fe,Th,Y)3 Ti5O16 |
| Carnotite | K2 (UO2)2 (VO4) 2·3H2O |
| Tyuyaminite | Ca (UO2)2 (VO4) · 5-8 H2O |
| Autunite | Ca (UO2)2 (PO4)2 · 10-12 H2O |
| Torbernite | Cu (UO2)2 (PO4)2 · 8-12 H2O |
| Uranophane | Ca (UO2)2 SiO3(OH)2 · 5H2O |

## 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**

## 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”**

## Enrichment: Conversion from U3O8 to UF6

- Dry Hydrofluor Process

- Wet Solvent Extraction Process

## Enrichment: 235U 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.**

## Fuel Fabrication: UO2 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**

## 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**

## 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**

## Fuel Fabrication: Pellet Production

## 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**

- http://www.euronuclear.org/info/encyclopedia/f/fuel-rod.htm

## Fuel Fabrication: Assembly Fabrication

**Fuel rods are then bundled into fuel assemblies**

## Fuel Fabrication: Metal Fuel

- Assembly hardware

- Fabricate fuel assemblies

- Pull test

- Flow test

- Final inspection

- Bonding Furnace

- Bonding

- Final inspection

- Weld inspection

- Fuels feedstock

- Alloy production

- Injection casting

- Break molds

- Trim slugs

- Inspection

- Trimmings to chemistry

- Trimmings to casting furnace

## Fuel Fabrication: Metal Fuel

**Sodium bonded fuel**
**Provides good heat conduction**
**Metal fuel is compatible with Na**
**LMFBR use sodium as the coolant **

## 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**

## References:

**The Nuclear Fuel Cycle: Analysis and Management by R.G. Cochran and N. Tsoulfanidis**
**Figures were found on **_**[www.wikipedia.org](http://www.wikipedia.org/)**_** (unless otherwise noted)**