The Molten Salt Fast Reactor is the only reactor that can efficiently consume thorium and process existing plutonium stocks as well. The fuel is dissolved in a molten fluoride salt that simultaneously serves as a coolant. By using thorium, the production of plutonium is reduced by a factor of one thousand which moreover remains circulating in the salt solution until it has been completely fissioned. This can reduce the required storage time of nuclear waste from 200,000 to less than 500 years.
Cooperation of leading institutes in Europe and beyond
SAMOFAR – Safety Assessment of the Molten Salt Fast Reactor – is a 5M€ project of the European Union research program Horizon 2020. The project consortium consists of 11 partners (CNRS, JRC, CIRTEN, IRSN, CINVESTAV, AREVA, CEA, EDF, PSI, KIT and TU Delft) exploiting each other’s unique expertise and infrastructure in the 4-year research programme. The grand objective of SAMOFAR is to prove the innovative safety concepts of the MSFR by advanced experimental and numerical techniques, to deliver a breakthrough in nuclear safety and optimal waste management, and to create a consortium of stakeholders to demonstrate the MSFR beyond SAMOFAR.
Besides the EU efforts in SAMOFAR, the consortium tightly connects with other large projects in China, Russia and the USA to exchange information, and to coordinate and share resources.
The project represents “the first step towards large scale validation and demonstration of the technology,” says Jan Leen Kloosterman, a professor of nuclear reactor physics at TU Delft and the coordinator of SAMOFAR. “We expect the project will lead to a large commitment from the nuclear community and industry towards the development of this new technology .”
At the end of August 2015 the kick –off meeting of the SAMOFAR project took place at Delft University of Technology with over 35 enthusiastic participants.
Contact TU Delft: Prof. dr. ir. Jan Leen Kloosterman
Phone: +31 15 278 1191
The management of the high-level radioactive waste (HLW) generated by the current fleet of light water reactors (LWR) is one of the most important issues that needs to be addressed. Due to the long-lasting radiotoxicity of the HLW this material needs to be isolated for thousands of years if directly disposed into a deep geological repository. Although minor actinides (MA)(neptunium, americium and curium) constitute a small fraction of the HLW, they are largely responsible for the long-lasting radiological toxicity and heat produced by the waste (Figure 1). For example, the heat generated by 241Am strongly influences the size of the repository to dispose HLW. Therefore, the destruction of these transuranic elements into stable or shorter-lived isotopes (transmutation) by further irradiation is of great benefit as it can reduce the long-term radiotoxicity of the waste and extend the repository capacity.
Time evolution of the radiotoxicity of high-level waste (HLW).
Under neutron irradiation MA can undergo neutron capture or fission reaction depending on the energy of the neutrons. Neutron capture is generally avoided as only produces heavier actinides, whereas fission reactions produce fission products with shorter half-lifes and lower radiotoxicity. In LWR, with neutron energies lower than 0.1 eV, MA mainly undergo neutron capture. In contrast, in Fast Reactors fission reactions are promoted by a factor of 2-6 depending of the isotope. Despite this improvement, MA fission rates can be between 15-30%, meaning that the fuel needs to be recycled a few times to ensure high performance levels. However, due to the impact of MA in the reactor core safety their concentration needs to be limited to 5% in an homogeneous cycle.
One dedicated system for the transmutation of MA is the accelerator driven system (ADS). Contrary to the fuel of the Fast Reactor, the fuel of the ADS can contain 30 wt% MA, 20 wt% Pu and 50 wt% ZrN as dilution material. It has been suggested that an 800 MWth ADS is capable of transmuting 500 kg of MA in 600 effective full power days, equivalent to the MA produced in 10 units of LWR with 1GWe.