The four-year project involves 16 organizations in a range of EU countries, including several universities and Westinghouse. Scientists running the project say the process they plan to develop would produce safe fuels that could be 80% recycled compared to the current 1 %.
Those involved would be producing compounds other than oxides, the nuclear fuels (mixed oxides or MOX) made from recycled waste today allowing scientists to develop other types of chemical compounds with uranium or plutonium, such as nitrides and carbides.
“We know it’s feasible to recycle 80% of it, but actually it’s more likely 95% of it will be recycled, while it could be re-used over and over again. There would still be a need for long term waste storage,” states Professor Christian Ekberg, the Chalmers nuclear chemist heading the project.
However, the amount of high-level, long-lived nuclear waste would be reduced and the space needed for it would be lower: “if you decrease waste by a factor of ten you can get ten times more waste into the repository,” Ekberg points out. Of course, the recycling also saves much more energy.
There could be other benefits, too. For instance, scientists believe the plutonium carbides and nitrides are safer to use in reactors because they have a higher melting point and thermal conductivity, producing a higher safety margin in terms of a nuclear meltdown.
Researchers had already studied the use of non-oxide fuels in the 1970s and considered it could be done, for instance at the Dounreay fast breeder reactor in Scotland. However, the recycling and use of the fuels was not taken up.
“This possibility has been around for a very long time – since the 1970s and even before that. But now, waste is considered more of a problem and the uranium price is going up so you need to recycle more. There’s a realisation we’ll not get rid of nuclear power in the short term so we need to do it as sustainably as possible,” argues Professor Ekberg.
Commenting on the study, Dr Bill Lee, a materials scientist at Imperial College London who is also deputy director for the University’s Centre for Nuclear Engineering – which has not been involved in the study – agreed the non-oxides had higher thermal conductivity and described the study as beneficial.
Lee indicates that people are starting to demonstrate a concern about the nuclear end-of-life cycle and that research in this field is already starting to take pace: “There’s a need for non-oxides for a range of applications, not just nuclear – it’s the next big thing in ceramics for instance.”
Technical issues involved in the nuclear application include “what to do with the spent fuel when it comes out of the reactor,” he states. There is, for instance, a need to alter the composition of the recovered waste before reconverting it into a fuel. Lee stated that options such as the transmutation of plutonium isotopes would need to be considered (helping eliminate some of the hazards).
The study will be taking place in the framework of the European Commission’s FP7 research funding programme, through which the EC plans to see pilot units built within the coming decades. Ekberg said a pilot plant could be built in the next 10-15 years in Sweden and a small reactor within 20 years.
New fuels for Generation III?
But Westinghouse, designers of the generation III AP1000 reactors, indicated there could be earlier use for the research. Johan Hallen, Vice President and Managing Director at Westinghouse Electric Sweden, which is also engaged in the research, stated: “Westinghouse’s primary interest in this is really that some of this research that is being done on new fuels of this type for generation IV could be used for generation III,” he stated.
Alternative fuels for existing reactors might be found, he suggested: “The standard fuel materials for life water reactors generation II and III are based on uranium dioxide. But there are other materials with uranium that could be used – such as uranium nitride. So we’re interested to learn more and whether that combination of materials could be used in reactor fuels. It has some of the right characteristics but we want to know and learn more.”
However, he could not confirm whether the use of alternative fuels in generation III reactors would mean adapting the reactors’ design and configuration, but stated this was a matter for further research.
“The fact that it is aimed at generation IV is of interest because it’s helping drive the research effort. These are learnings that can be applied in a shorter time frame and are useful.”
Source: NuclearEnergy Insider