AREVA and international chemical company Solvay have signed an agreement to develop new applications for thorium.

The agreement, announced 20 December, includes research & development to study the use of thorium as a potential fuel in nuclear power plants, as a complement to fuels using uranium and plutonium.

Both AREVA and Solvay have inventories of thorium in France, which have been gained through the extraction of rare earth elements or uranium.

AREVA said the partnership is in line with its sustainable development policy. "This will allow us to offer additional options within the nuclear cycle in the future," said Olivier Wantz, senior executive vice president of AREVA, Mining Business Group.

About thorium

Thorium-232 is a naturally occurring element that is more abundant than uranium in the earth's crust.

Known and estimated world thorium resources total 4.4 million tonnes, according to Uranium 2011: Resources, Production and Demand, a joint IAEA and OECD Nuclear Energy Agency publication, often referred to as the 'Red Book'

Thorium fuels, which can breed fissile uranium-233, could be used in the following reactor designs, according to the World Nuclear Association:

Heavy water reactors (PHWRs),High temperature gas cooled reactors (HTRs)Boiling water reactors (BWRs)Pressurized water reactors (PWRs)Fast neutron reactors (FNRs)Molten salt reactors (MSRs) - conceptualAccelerator Driven Systems (ADS) - conceptual

One advantage of thorium is its high melting point (around 3300ºC for ThO2) and high thermal conductivity, which allows for higher margins in the design and for operation of reactor cores.