Fast Reactor technologies, with their closed fuel cycle, have the potential to multiply the energy output from a given amount of natural uranium by a factor 100; improve high level radioactive waste management through the transmutation of minor actinides; avoid the loss of coolant possible with water-cooled reactors because lead is kept at atmospheric pressure and contained in a double-wall vessel; validate lead technologies as a necessary step for the development of ADS.
Thorium is three times more abundant in Earth’s crust than uranium and doesn't need enrichment. LFR reactors with a thorium blanket can generate power from the plutonium left by uranium thermal reactors. The use of thorium as fertile element eliminates the production of minor actinides. A reliable and economic ADS paves the way to the adoption of a fuel cycle based on the use of thorium as proposed by Carlo Rubbia at CERN.
An ADS is an innovative concept formed by coupling a substantially subcritical nuclear reactor core with a high-energy proton accelerator. The high energy proton beam, provided by a particle accelerator, impacts a molten lead target inside the core, “spalling” neutrons from the lead nuclei. These neutrons enable the fission process to take place without needing to take the reactor to a critical state. The fission process stops when the proton beam stops and the power goes down because the reactor is subcritical. The accelerator current modulates power production with precision. ADSs can be used to eliminate the plutonium and MA stockpile produced by present-day reactors and efficiently use thorium as fertile element.