Lead-cooled fast reactor
In simple terms, if a neutron hits a particle with a similar mass (such as hydrogen in a Pressurized Water Reactor PWR), it tends to lose kinetic energy.
Temperatures higher than 800 °C are theoretically high enough to support thermochemical production of hydrogen through the sulfur-iodine cycle, although this has not been demonstrated.
They were significantly lighter than typical water-cooled reactors and had an advantage of being capable to quickly switch between maximum power and minimum noise operation modes.
[1] A joint venture called AKME Engineering Archived 24 December 2018 at the Wayback Machine was announced in 2010 to develop a commercial lead-bismuth reactor.
In 2013, the project entered a further development phase when a contract for the front-end engineering design was awarded to a consortium led by Areva.
Moreover, such a highly enriched MOx fuel has never been industrially produced and poses severe technical and safety challenges in order to prevent any criticality accident during handling in the factory.
[25] Beside the technical challenges identified, they were also financial and economical risks related to the construction and exploitation costs expected to strongly increase when the project should enter a more detailed design stage.
Long construction delays related to design complications, underestimated technical difficulties and insufficient budget are not uncommon for such a project.
The limited participation of the Belgian State (40% of all the costs) and the uncertain benefits for the external project owners were also pointed out.
The mass inventory of the lead-bismuth eutectic (LBE) for the proposed pool-type design of MYRRHA considered in the preliminary FEED analyses of 2013-2015 represents 4500 tons metallic Pb-Bi.
After the first operating cycle, 350 g of 210Po would already be formed in the LBE exposed to a high neutron flux of the order of 1015 neutrons・cm–2・s–1, typical for a materials testing reactor (MTR).
The presence of such a large ponderable quantity of highly radiotoxic 210Po represents a considerable radiological safety challenge for the maintenance operations and the storage of the MYRRHA nuclear fuel.
All operations in 210Po contaminated areas will require appropriate radiological protection measures much more severe than for the 239Pu handling, or to be completely performed by remotely-operated robots.
An envisaged mitigation strategy[29] could consist into a continuous removal of polonium from LBE, but the considerable heat generated by 210Po represents a major obstacle.
[29] In 2023, based on interviews with key SCK CEN players and documents publicly available, Hein Brookhuis explored the interactions between the MYRRHA promoters and the Belgian media and political spheres to show how MYRRHA was developed in a narrative that made the project seems essential to the future of SCK CEN, the Belgian nuclear research center.
In February 2021, the project was transferred to a newly founded Canadian company, Dual Fluid Energy Inc., to industrialize the concept.
Due to the high thermal conductivity of the molten metal, the residual decay heat of a DFR reactor could be passively removed.
[35][36] The Government of Sweden committed 720 million Swedish krona and started building a test facility in early 2025 for a lead-cooled prototype reactor.
[40][41] The initial design of the Hyperion Power Module was to be of this type, using uranium nitride fuel encased in HT-9 tubes, using a quartz reflector, and lead-bismuth eutectic as coolant.
