| Nuclear technology
The power of the Dual Fluid principle
High efficiency is a key differentiator of the new nuclear power technology being developed by Dual Fluid. Instead of fuel rods, a Dual Fluid reactor (right) contains two circulating fluids: one carries the fuel and the other extracts the heat. This concept “completely redefines nuclear power”, the start-up says. The Dual Fluid principle enables nuclear fuel to be utilised “up to a hundred times better than in today’s light water reactors”, while the “operating temperature of 1000°C enables new heat applications”
Dual Fluid was originally a German nuclear technology start-up, but it decided to become Canadian, and was incorporated as a public company in Vancouver in 2021 to better position it to benefit from Canada’s favourable disposition towards SMR development. “The Canadian government promotes SMRs as a technology of the future,” says Dual Fluid, “while the population predominantly sees nuclear power as an opportunity.” Also, “the country is experienced in nuclear technology and, unlike Germany, can look back on uninterrupted expertise” and “last but not least, there is an internationally recognised nuclear licensing authority.”
LWRs: an inadequate technology The light water reactors commonly used worldwide are inefficient, they can only convert about 1% of the natural uranium produced into electricity, argues Dual Fluid. In addition, the nuclear fuel is burned at low temperature, which makes “interesting chemical applications” impossible. How did this inadequate technology prevail over more promising designs that existed in the middle of the last century? The answer is found in its military advantages, argues Dual Fluid: reactors with fuel rods are well suited to powering submarines, plus they can provide plutonium for nuclear weapons in an uncomplicated way. Other concepts that were known to be more suitable for civilian use
Above: Figure 1. 300 MWe Dual Fluid power plant (DF300)
were dropped. The fact that we are still using the same LWR technology several decades on is attributable to the immense energy density of the fuel: it provides so much energy that even inefficient nuclear power plants are profitable.
Of the early designs that were not developed commercially, two stand out: one with liquid fuel; one with liquid lead cooling. In the 1960s, the USA successfully operated an experimental reactor with liquid fuel (molten salt reactor) that was able to make better
use of the fuel. However, since the fuel salt also transferred the heat, the power density was limited because the two functions are difficult to reconcile. Russia built a reactor with high-performance liquid lead cooling in the 1970s for its submarine fleet. But these reactors used fuel rods, making fuel supply and recycling difficult.
The Dual Fluid concept is a fast reactor that aims to combine the advantages of the molten salt reactor with those of a lead cooled reactor in a completely new design. The key innovation of Dual Fluid, as the name suggests, lies in using two liquids in the reactor core. There, liquid fuel can develop its full power, at around 1000°C (compared with 320°C for a typical LWR), while liquid lead handles the heat transfer.
High power density
The principle is completely new in nuclear technology, says Dual Fluid. The decisive advantage is the high power density, which is due to the compactness of the system and the high operating temperature.
Above: Figure 2. Life cycle energy consumption associated with a typical light water reactor, with today’s inefficient fuel cycle (source Vattenfall EPD Forsmark)
The fuel can circulate as slowly as required for an optimum burn-up rate, while the coolant can circulate as fast as required for optimum heat removal. As a result, undiluted liquid fuel – a metallic actinide mixture – can
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