Current Uranium Fuel Cycles

Why Isn't Uranium The Answer?

Natural uranium or low-enriched uranium is the fuel material used in the current generation of nuclear energy systems. At the current rate of use, the world's supply of uranium is expected to be sufficient for 85 years, or possibly longer at much higher cost.

As the emerging energy users increase global demand for energy and large-scale deployment of nuclear energy systems is needed, the demand for uranium will exceed its supply. The resulting volatility in the price of uranium may be similar to that of oil prices today, and will likely appear by the middle of this century.
Beyond this economic volatility, significant concerns have been raised about uranium fuel in the following areas:

• sustainability;
• accessibility; and
• proliferation-resistance.

Sustainability

The fissile U-235 isotope makes up only about 0.7% of the uranium in most ores. From a sustainable development point of view, burning uranium to make use of only this very small amount of fissile material is therefore not an efficient or responsible way of using a natural resource.

Accessibility

The fertile U-238 isotope makes up more than 99% of natural uranium. In fast reactors, enough fissile Pu-239 can be produced and used from U-238 to more than make up for the U-235 used (a process called "breeding").

Closing this uranium-plutonium fuel cycle by using fast reactors and reprocessing spent fuel is a scheme widely advocated and attempted today. The technology required for this, however, is sophisticated and requires significant infrastructure support, as well as intensive technical know-how. This makes Pu-239 inaccessible to the emerging majority of energy users.

On the other hand, creating fissile U-233 from fertile Th-232 and using it in fission reactions can be done at a relatively large scale today, in near-breeding conditions, in reactors with a thermal neutron spectrum. Producing fissile material using the thorium fuel cycle is therefore more within reach of the emerging energy users, since it can be achieved without sophisticated technologies such as fast reactors and chemical-based spent-fuel reprocessing facilities.

Proliferation-Resistance

Proliferation is a major concern if energy systems based on the uranium-plutonium fuel cycle are the only choice. As growing numbers of users of uranium-based energy systems accumulate plutonium and global demand for energy increases, spent-fuel plutonium-a potential weapon material-will likely need to be transported widely to countries around the world.