Overview of the Nuclear Fuel Cycle and

Generated Waste over the Plant Life Cycle

Amparo Gonzalez Espartero, PhD

a.g.espartero@iaea.org

Technical Lead of Spent Fuel Management

NE/NEFW/NFCMS

TM on Fuel Cycle Strategies and Options for the Management of Spent Nuclear Fuel and Radioactive Waste for Countries Embarking on the Use of Nuclear Power

Troyes, France. 14-18 November 2016

Nuclear Fuel Cycle

• Uranium Mining and

Milling

• Uranium Conversion

• Uranium Enrichment

• Fuel Fabrication

• In-Reactor Fission

• Spent Fuel

Management

• Spent Fuel

Reprocessing and

Recycling

• Disposal of Spent Fuel

and HLW

Disposal

Disposal

Nuclear Fuel Cycle:

Terminology

Back End

Front End

Disposal

Options of Nuclear Fuel Cycle

Open Fuel Cycle

Disposal

Options of Nuclear Fuel Cycle

Closed Fuel Cycle

Disposal

Mining and Milling

Uranium Mining Methods

Depends on the orebody, Uranium is mined in one of

three ways:

• Open pit

• Underground

• In-situ leach – ISL

By-product recovery

Ranger Uranium Mine, Australia

– Orebody close to the surface

– Large stockpiles of waste rock

– Tailings dam covered by water

to reduce radon emissions

– May be a possibility for in-pit

disposal of tailings

– Relatively large footprint at the

surface

Ranger Uranium Mine, Australia

World #2 producing mine

Uranium Mining Methods:

Open Pit

Open pit / surface excavations:

Kayelekera Mine, Malawi

Uranium Mining Methods:

Open PitRossing Mine, Namibia, 2008

(World #3 producing mine)

Andújar Mine, Spain

Underground mining

– Orebody deeper

– Much smaller waste rock

production volumes

– Less environmental impact

– Smaller infrastructure footprint at

the surface

– Ventilation required to protect

workers against airborne radiation

exposure

McArthur River uranium mine, Canada

World #1 Producing mine

Uranium Mining Methods:

Underground

• Sometimes called solution mining or

ISR (in situ recovery)

• Minerals recovered by dissolving

them

• Can be acid or alkali leach solution

• Very small volume of waste

generation

• Limited surface disturbance

• Do not contaminate groundwater

away from the orebody

• Less environmental impact

Uranium Mining Methods:

In-situ Leach (ISL)

Beverley ISL mine, Australia

Uranium Mining Methods

By-product recovery

• Phosphates: • Rock phosphate deposit contains U

• Economic benefit will be both in the

value of U and in reduced NORM

waste

• 20 kt U has already been obtained

from rock phosphate deposits

By product recovery, USA

Distribution of Identified

Resources

• Uranium relatively common, widespread – challenge is finding economically mineable deposits

• Great deal of exploration since 2006 – new discoveries, even when concentrating on previously known areas

13 countries represent approx. 96% of

total world U resources

1. Australia (31%)

2. Kazakhstan (12%)

3. Russian Fed (9%)/Canada (9%)

Resources geographically widespread

Uranium Recovery Process

Uranium Milling

–Crushing

–Grinding

–Leaching with H2SO4 (original orebody may content 0.1% U)

–Liquid-solid separation (Filtration)

–Purification and concentration

–Precipitation as U3O8, drying

–Packing & dispatch

Uranium mill, Ranger mine, Australia

Yellow Cake

• Product is called “yellow

cake” but can be any uranium

concentrate: UO4, U3O8,

Ammonium diuranate, etc

• These products may be

coloured reddish, orange to

yellow naturally; or dark

green to grey or black when

calcined

• Contains 85% U

• Packed in 220L drums &

shipped to conversion plant

Yellowcake

Drums of U3O8

Calcined U3O8

Disposal

Uranium Conversion

Uranium Conversion

• Yellowcake is converted to: − UO2

− UF6

• UF6 is the only gaseous form of uranium

• All current industrial uranium enrichment processes work with gas

A “48Y” Cylinder containing natural UF6

Yellowcake (U3O8); Uranyl nitrate solution;

Solid ammonium diuranate; Uranium dioxide

Disposal

Uranium Enrichment

Uranium Enrichment

• Several enrichment processes demonstrated

• Only two, gaseous diffusion and gas centrifuge, are currently operating on a commercial scale

• Both exploit the mass difference between 235U atoms and 238U atoms

• During enrichment gaseous UF6 is separated into two streams:

− Low-enriched Uranium

− Depleted Uranium or “tails”

Uranium Enrichment: Gaseous

Diffusion

• UF6 forced through porous membranes

• Lighter, faster moving 235U molecules more likely to pass through the membrane

• UF6 diffused through the membrane is slightly enriched

• Process is repeated some 1.400 times to obtain 4% 235U

• 2.400 kWh/SWU

Uranium Enrichment: Centrifuge

Process

• Vacuum tubes, each containing a rotor

• Spin at very high speeds:– 50,000 to 70,000 rpm

– Outer wall moves at >400 m/s

– 106 G

• 238U concentration greater near outer cylinder wall,

• 235U concentration greater near the centre

• < 50 kWh/SWU

Uranium enrichment centrifuges

Reference: World Nuclear Association. http://www.world-nuclear.org/information-library/nuclear-fuel-cycle/conversion-

enrichment-and-fabrication/uranium-enrichment.aspx

World Enrichment Capacity – Operational and Planned

Waste Generated from

Enrichment

• Depleted uranium (DU)– that requires long-

term isolation due to buildup of radioactive

decay products

• It could be stored as UF6 or de-converted

back to U3O8 (less chemically toxic)

• 50.000 kt/y produced worldwide

• World stock of DU is about 1,5 Mt

• It can be used to dilute HEU (>90%) from

weapons programmes to feed civil NPP

Disposal

Fuel Fabrication

Fuel Fabrication

• Fuel must be placed in a robust physical form capable of enduring high operating

temperatures and an intense neutron radiation environment

• Fuel assembly needs to keep its integrity

Uranium Oxide Fuels

PHWR /

Candu

Natural

UO2

Enriched

UO2

UO2 Pellets

17 x 17

Zircaloy

<5% 235U

9 x 9

Zircaloy

<5% 235U

36 Rods

Zircaloy

Natural or SEU312 rods

Zr-Nb

<5% 235U

AGRVVERBWRPWR

36 pins

SS

<5% 235U

Fuel Fabrication and

Engineering

LMFR

SS

(U,Pu)O2

FA is engineered with extremely tight tolerances

U-238, 92.4%

U-235, 1.0%

Pu, 1.3%

FP, 5.2%MA, 0.1%

U-238, 95.0%

U-235, 5.0%

Nuclear Fuel Composition

Fresh Fuel

Spent Fuel

In the reactor, the fission reaction gradually accumulates FPs and TRU elements

Disposal

Spent Fuel Storage

Spent Fuel Storage Technologies

AR Pools

Centralized

Passive Pools

Dry Storage

Vault Stores

Metal Casks

Concrete Casks

Ventilated Concrete

Casks

Vertical Ventilated

Silos

Horizontal Ventilated

Silos

Canisters

Spent Fuel Storage

• Water provides cooling and

shielding as well as facilities

accountancy and visual inspection

• Chemistry of water pool must be

carefully controlled

• SF after discharge requires to storage it under water in pools located at

reactor site

• FA are located in racks with neutron absorbers to avoid criticality

• Casks:

− Modular and Sealed systems

− Circular in cross-section,

Cylindrical shape

− Heat removed by conduction,

radiation and forced or natural

convection

• Vaults:

− Modular

− Array of storage cavities

− Above or below ground level

− Heat removed by forced or

natural convection

Spent Fuel Storage Technologies

Dry Storage

Disposal

Spent Fuel Reprocessing

U-238, 92.4%

U-235, 1.0%

Pu, 1.3%

FP, 5.2%MA, 0.1%

U-238, 92.4%

U-235, 1.0%

FP; 5,2%

MA; 0,1%

Pu; 1,3%

Reprocessing and Recycling today is largely based on:• Recovering U (RepU) and Pu• MOX fuel

Spent Fuel Composition

Recovered products

PUREX Process

Mechanical Disassembly

Dissolution (HNO3)

Solvent Extraction (TBP in kerosene)

Uranium/Plutonium split

PuO2 RepU UO3

Acid recovery

Solvent treatment

Hulls

FP & MA

Off-gas Treatment

Spent Fuel Reprocessing: Aqueous

Chopped

High Level

Waste

Long-lived

ILW

Recycled

products

Waste from Reprocessing Activities

Nuclear Power Plant

Reprocessing Plant

Uranium 95%

Plutonium 1%

Residues

Operational

Waste

Waste

Waste from Reprocessing

Activities

• Residues: originated from the irradiation of the fuel at the reactor

• Operational Waste: results from reprocessing operations. Includes

operating and maintenance equipment

Cladding sheared Hulles and end-fittings

MAs and FPs

Technological Waste: produced during operating and

maintenance activities (LLW or VLLW)

Effluents: liquids (HLW, LLW, …) and solid (ion exchange

resins, …)

• Reprocessed uranium can be re-enriched and re-used as

reactor fuel

• Plutonium can be used as fissile material in MOX fuel for

thermal reactors or saved for use as fuel in fast reactors

• PuO2 + depleted UO2 are mixed, pelletized and loaded into

fuel rods

• MOX fuel assembly externally identical to UO2 equivalent

• Plutonium is radiologically hazardous:

− Inhalation hazard

− Must be handled in shielded glove boxes

Spent Fuel Recycling

UOX Fuel Used FuelUranium

Front-End

Thermal Reactor

Direct

Disposal

Uranium Fuel Cycle Options /

Policies

Encapsulation and Disposal of Used Fuel

Light Water Reactors

WasteFast Reactor

Recycling

Recycled Fuel (U, Pu and minor actinides)

Used Fuel Final WasteDisposal

Reprocessing

Fast NeutronReactors

Used Fuel

Recycled Fuel (U, Pu)

WasteThermal Reactor

Recycling

Final WasteDisposal

Reprocessing

Light Water Reactors

UOX FuelUranium

Front-End

U-Pu LWR

Gen III

Recycling

Used fuel

Direct disposal

Uranium Ore (mine)

Time (years)

Pu

MA

FPs

MA

FPs

FPs

Repository Potential Radiotoxicity

U-Pu recycling + MA

transmutation

Gen IV Recycling

Assuming 100% efficiency in the partitioning and transmutation of all Minor

Actinides with FRs recycling

GANEXU extraction followed by group extraction of all actinides (Pu, MA)

UREX +• Separation of U & Tc by UREX• Recovery Cs & Sr by CCD-PEG• Recovery of Pu & Np by NPEX• Recovery of MA and Ln by TRUEX• Separation of MA from Ln

Advanced Aqueous

Partitioning Methods

DIAMEX, TODGASeparation of MA and

Ln from HLLW

SANEX, ARTIST, TALSPEAK

Separation of Am, Cm from Ln

TRUEXTRU elements extraction from

HLLW

SESAMESeparation of Am

from Cm

Advanced Aqueous Partitioning Methods

Advanced

Pyro-Metallurgical

Partitioning Methods

Advanced non-Aqueous Partitioning Methods

U deposit

U, MA and Pu

in a liquid Cd cathode

DEN/VRH/DRCP/SCPS (CEA) Laboratoire des Procédés Pyrochimique, S. BOURG

Disposal

Spent Fuel and HLW Disposal

Spent Fuel and High Level Waste Disposal

Thank you for your kind attention!

Questions?