Nuclear Fuel Alternatives After Fukushima Have Challenges Ahead

Researchers suggest that the preferred candidate fuel to replace uranium oxide in nuclear reactors may need further development before use. (Image:  	AvdaTørrissen via   wikimedia  /  CC BY-SA 3.0)
Researchers suggest that the preferred candidate fuel to replace uranium oxide in nuclear reactors may need further development before use. (Image: AvdaTørrissen via wikimedia / CC BY-SA 3.0)

Research at The University of Manchester suggests that the preferred candidate fuel to replace uranium oxide in nuclear reactors may need further development before use.

Dr. Robert Harrison led the research, published in the journal Corrosion Science, with colleagues from the University and the Dalton Nuclear Institute. Dr. Harrison explained:

One of these ATFs is a uranium silicon compound, U­­­­3Si2. This material conducts heat much better than the traditional uranium oxide fuels, allowing the reactor core to be operated at lower temperatures. In an emergency situation, this buys more time for engineers to bring the reactor under control.

(Image: Screenshot / YouTube)

The uranium silicon compound conducts heat much better than the traditional uranium oxide fuels, allowing the reactor core to be operated at lower temperatures. (Image: Screenshot / YouTube)

However, there are many unknowns about how U­­­­3Si2 will behave in the reactor core. Dr. Harrison said:

To investigate just how accident tolerant ATFs are, Dr. Harrison and his colleagues investigated how Ce3Si2 — a non-radioactive material analogous to U­­­­3Si2 — behaved under exposure to high-temperature air.

Using advanced electron microscopy techniques available at The University of Manchester Electron Microscopy Centre (EMC), the researchers were able to study the reaction products after Ce3Si2 was exposed to air at temperatures of up to 750o°C.

They discovered the material was prone to forming nanometer-sized grains of silicon and silicon oxide, as well as cerium oxide. These nano-grains may allow for enhanced corrosion of the fuel material or the escape of radioactive gasses formed during reactor activity.

(Image: Screenshot / YouTube)

The nano-grains may allow for enhanced corrosion of the fuel material or the escape of radioactive gasses formed during reactor activity. (Image: Screenshot / YouTube)

This is because the formation of nano-grains creates more grain boundary areas — interfaces between grains, which provide pathways for corrosive substances or fission gases to migrate along. Dr. Harrison added:

While Dr. Harrison stops short of saying that these ATFs are more unsafe under accident conditions than the current fuels they are looking to replace, he would argue they are currently not any better and “aren’t as tolerant to accident conditions as once hoped.”

Dr. Harrison concluded:

Provided by: University of Manchester [Note: Materials may be edited for content and length.]

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