1. Sources of Radiation Fuel Cycle - Overview
Day 4 – Lecture 5 (1)

2. 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
The various activities associated with the production of electricity from nuclear reactions are referred to collectively as the nuclear fuel cycle. The nuclear fuel cycle starts with the mining of uranium and ends with the disposal of nuclear waste. With the reprocessing of spent fuel as an option for nuclear fuel, the stages form a true cycle.

3. Contents Energy Resources Uranium Resources Other Sources of Fuel
Properties of Uranium
Fuel Cycle Components
The various activities associated with the production of electricity from nuclear reactions are referred to collectively as the nuclear fuel cycle. The nuclear fuel cycle starts with the mining of uranium and ends with the disposal of nuclear waste. With the reprocessing of spent fuel as an option for nuclear fuel, the stages form a true cycle.

4. 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
The various activities associated with the production of electricity from nuclear reactions are referred to collectively as the nuclear fuel cycle. The nuclear fuel cycle starts with the mining of uranium and ends with the disposal of nuclear waste. With the reprocessing of spent fuel as an option for nuclear fuel, the stages form a true cycle.

5. Energy Resources

6. Typical Uranium Concentrations
ppm
Source (part per million)*
 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) % 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
Uranium is a slightly radioactive metal that occurs throughout the earth's crust. It is about 500 times more abundant than gold and about as common as tin. It is present in most rocks and soils as well as in many rivers and in sea water.
There are a number of areas around the world where the concentration of uranium in the ground is sufficiently high that extraction of it for use as nuclear fuel is economically feasible.
* Data from WNA (August 2012)

7. Known Recoverable Uranium Resources
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)
Current usage is about 68,000 tU/yr.  Thus the world's present measured resources of uranium (5.3 Mt) in the cost category around present spot prices and used only in conventional reactors, are enough to last for about 80 years.  This represents a higher level of assured resources than is normal for most minerals.  Further exploration and higher prices will certainly, on the basis of present geological knowledge, yield further resources as present ones are used up. 
An initial uranium exploration cycle was military-driven, over 1945 to The second cycle was about 1974 to 1983, driven by civil nuclear power and in the context of a perception that uranium might be scarce. There was relatively little uranium exploration between 1985 and 2003, so the significant increase in exploration effort since then could conceivably double the known economic resources despite adjustments due to increasing costs. In the two years the world’s known uranium resources tabulated above and graphed below increased by 15% (17% in the cost category to $80/kgU). World uranium exploration expenditure is increasing, as the the accompanying graph makes clear. In the third uranium exploration cycle from 2003 to the end of 2011 about US$ 10 billion was spent on uranium exploration and deposit delineation on over 600 projects. In this period over 400 new junior companies were formed or changed their orientation to raise over US$ 2 billion for uranium exploration. About 60% of this was spent on previously-known deposits. All this was in response to increased uranium price in the market and the prospect of firm future prices.

8. 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
Most of the radioactivity associated with uranium in nature is in fact due to other minerals derived from it by radioactive decay processes, and which are left behind in mining and milling. The table shows only the 238U decay chain.

9. Other Sources of Fuel 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
Nuclear Weapons as a source of fuel
An increasingly important source of nuclear fuel is the world's nuclear weapons stockpiles. Since 1987 the United States and countries of the former USSR have signed a series of disarmament treaties to reduce the nuclear arsenals of the signatory countries by approximately 80 percent by 2003.
The weapons contain a great deal of uranium enriched to over 90 percent U‑235. Some weapons have plutonium‑239, which can be used in diluted form in either conventional or fast breeder reactors. From 2000 the dilution of 30 tonnes of military high‑enriched uranium is displacing about 9000 tonnes of uranium oxide per year from mines, which represents about 14% of the world's reactor requirements.
Thorium as a nuclear fuel
Today uranium is the only fuel supplied for nuclear reactors. However, thorium can also be utilised as a fuel for CANDU reactors or in reactors specially designed for this purpose. Neutron efficient reactors, such as CANDU, are capable of operating on a thorium fuel cycle, once they are started using a fissile material such as U‑235 or Pu‑239. Then the thorium (Th‑232) captures a neutron in the reactor to become fissile uranium (U‑233), which continues the reaction. Some advanced reactor designs are likely to be able to make use of thorium on a substantial scale.
Thorium is about three times as abundant in the earth's crust as uranium.

10. Properties of Natural Uranium
Natural uranium consists of three isotopes:
Isotope % Abundance Half Life (106 years)
238U ,500
235U
234U

11. Uranium Properties Uranium Isotope Percent 238U is most abundant
100
238U is most abundant
234U increases with enrichment
Note activity ratios 10 1
U-238
0.1
U-235
0.01
U-234
0.001
0.0001
LEU
Natural
Depleted

12. 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

13. 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

14. Fuel Cycle
We will now discuss each step in the fuel cycle.

15. Fuel Cycle Around the World
This map provides an overview indicating which countries participate in each step of the fuel cycle. Nations such as the USA and Russia conduct all the activities from mining to fuel fabrication while other nations may only conduct one or two of the steps.

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