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Sources of Radiation

Fuel Cycle - Overview

Day 4 – Lecture 5 (1)

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Objective

To have an overview of the elements of Fuel Cycle starting from Uranium mining to waste disposal*:

• Mining• Milling• Conversion• Enrichment• Fuel Fabrication• Power Generation• Spent Fuel• Reprocessing• Waste Disposal

*Note: These elements of fuel cycle will be discussed in detail in the following presentations

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Contents

• Energy Resources• Uranium Resources• Other Sources of Fuel• Properties of Uranium• Fuel Cycle Components

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Overview

• In this session we will discuss the Nuclear Fuel Cycle including:

• Mining• Milling• Conversion• Enrichment• Fuel Fabrication• Power Generation• Spent Fuel• Reprocessing• Waste Disposal

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Energy Resources

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ppmSource (part per million)*

Typical Uranium Concentrations

 Very high-grade ore (Canada) - 20% U

200,000 ppm U

High-grade ore - 2% U, 20,000 ppm U

Low-grade ore - 0.1% U, 1,000 ppm U

 Very low-grade ore* (Namibia) - 0.01% U

100 ppm U

Granite 3-5 ppm U

Sedimentary rock 2-3 ppm U

Earth's continental crust (av)2.8 ppm U

Seawater 0.003 ppm U

* Data from WNA (August 2012)http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Uranium-Resources/Supply-of-Uranium/

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Country tonnes percentage of world*

Australia 1,661,000 31%

Kazakhstan 629,000 12%

Russian Fed. 487,200 9%

Canada 468,700 9%

Niger 421,000 8%

South Africa 279,100 5%

Brazil 276,700 5%

Namibia 261,000 5%

USA 207,400 4%

China 166,100 3%

Ukraine 119,600 2%

Uzbekistan 96,200 2%

Others 253,500 5%

World Total 5,327,200

* Data from WNA (August 2012)

Known RecoverableUranium Resources

http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Uranium-Resources/Supply-of-Uranium/

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Uranium Decay Chain

Primary Isotopes 238U -

alpha emitter 235U and 234U –

alpha/gamma emitters

Decay Products 231Th and 234Th -

beta/gamma emitters 234mPa -

beta/gamma emitter

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Decommissioned Nuclear Weapons

over 90% 235U (must be downblended for commercial fuel)

Thorium

coverts to 233U after neutron capture 3 times more abundant than uranium

Other Sources of Fuel

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Natural uranium consists of three isotopes:

Isotope % Abundance Half Life (106 years)

238U 99.284 4,500235U 0.711 704234U 0.005 0.245

Properties of Natural Uranium

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Uranium Properties

238U is most abundant234U increases with

enrichment

Note activity ratios

0.00010.0010.01

0.1

110

100

Nat

ural

Uranium Isotope Percent

U-238

U-235

U-234

LEU

Dep

lete

d

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Uranium Specific Activity

Type (enrichment) Specific Activity(Bq/gram)

Depleted (0.2%) 1.5 x 104

Natural (0.71%) 2.6 x 104

Enriched (4%) 8.9 x 104

Enriched (93%) 4.1 x 106

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Uranium Compounds

• UF6 produced at conversion plants

• U3O8 is yellowcake from milling

• UO2 is dominant fuel type (ceramic)

used to produce pellets

• UF4 is intermediate form in conversion

• Uranyl nitrate is important in recovery

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Fuel Cycle

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Fuel Cycle Around the World

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Reference

http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Uranium-Resources/Supply-of-Uranium/

International Atomic Energy Agency, Postgraduate Educational Course in Radiation Protection and the Safety of Radiation Sources (PGEC), Training Course Series 18, IAEA, Vienna (2002)