David JC MacKay on his website mentions two main fission possibilities : fast breeders and thorium and fusion. We will have a look at thesemost promising solutions as well as to other technologies.

The needs for safer, cheaper and cleaner nuclear solutions are important as the IAEA forecasts the demand for nuclear is to increase by 60 percent in the next twenty years.

Fast breeders

Fast breeders are interesting as they burn up Uranium 60 times more efficiently and can thus enable us to use our current nuclear waste to generate low carbon electricity.

Even if research has been carried out since the 1950s in many countries (the United States, the United Kingdom, Japan, Germany, Russia, India and France) no country is currently using it for commercial application.

This soon may change as India and China (and many other countries) are planning to build fast breeder reactors to answer their fast increasing energy needs. India’s is due to be ready next year.

It would also make using Uranium from our oceans a viable option that would answer all our energy needs for millenia.

As MacKay notes :

If fast reactors are 60 times more efficient, the same extraction of ocean uranium could deliver 420 kWh per day per person. At last, a sustainable figure that beats current consumption! – but only with the joint help of two technologies that are respectively scarcely-developed and unfashionable:  ocean extraction of uranium, and fast breeder reactors.

For more, please check out the following links :

- World Nuclear page on fast neutron reactors ;
- Scientific American : How do fast breeder reactors differ from regular nuclear power plants?
- Japanese Nuclear Agency page on fast breeders ;
- Wikipedia page on fast breeder reactors.

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Thorium

Here again are extracts of MacKay’s book :

Thorium is a radioactive element similar to uranium. Formerly used to make gas mantles, it is about three times as abundant in the earth’s crust as uranium. Soil commonly contains around 6 parts per million of thorium, and some minerals contain 12% thorium oxide.

(…) Thorium can be completely burned up in simple reactors (in contrast to standard uranium reactors which use only about 1% of natural uranium). Thorium is used in nuclear reactors in India.

(…) An alternative nuclear reactor for thorium, the “energy amplifier” or “accelerator-driven system” proposed by Nobel laureate Carlo Rubbia and his colleagues would, they estimated, convert 6 million tons of thorium to 15 000 TWy of energy, or 60 kWh/d per person over 1000 years. Assuming conversion to electricity at 40% efficiency, this would deliver 24 kWh/d per person for 1000 years.

And the waste from the energy amplifier would be much less radioactive too. They argue that, in due course, many times more thorium would be economically extractable than the current 6 million tons. If their suggestion – 300 times more – is correct, then thorium and the energy amplifier could offer 120 kWh/d per person for 60 000 years.

For more on thorium please check out the following resources :

- World Nuclear page on thorium ;
- Wikipedia page on thorium as a nuclear fuel ;
- www.thorium.tv ;
- Energy from thorium.

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Other solutions

Many other solutions are being explored within the Generation IV International Forum (GIF) a group of thirteen countries and group of countries cooperating to develop the future generation of nuclear reactors.

• Gas-Cooled Fast Reactor (GFR)
  features a fast-neutron-spectrum, helium-cooled reactor and closed fuel cycle;
• Very-High-Temperature Reactor (VHTR)
  a graphite-moderated, helium-cooled reactor with a once-through uranium fuel cycle;
• Supercritical-Water-Cooled Reactor (SCWR)
  a high-temperature, high-pressure water-cooled reactor that operates above the thermodynamic critical point of water;
• Sodium-Cooled Fast Reactor (SFR)
  features a fast-spectrum, sodium-cooled reactor and closed fuel cycle for efficient management of actinides and conversion of fertile uranium;
• Lead-Cooled Fast Reactor (LFR)
  features a fast-spectrum lead of lead/bismuth eutectic liquid-metal-cooled reactor and a closed fuel cycle for efficient conversion of fertile uranium and management of actinides;
• Molten Salt Reactor (MSR)
  produces fission power in a circulating molten salt fuel mixture with an epithermal-spectrum reactor and a full actinide recycle fuel cycle.

Fusion will conclude our series of articles next week, so stay tuned !

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1. 10 reasons to support nuclear power
2. The end of nuclear waste ? Part II
3. Nuclear : Past and present
4. Mini-nuclear plants available within five years
5. A look at the main future automotive technologies