Safer, more efficient nuclear plants

By Lucy Sherriff

Researchers at MIT have developed technology they say will boost the power output of nuclear power plants by 50 per cent, and make them safer to run.

The technology applies to pressurised water reactors. In these, water is used as a coolant, and is kept under pressure to prevent it from boiling. The uranium is also used to heat water, stored separately from the coolant system, generating steam which in turn is used to generate electricity.

By modifying the shape of the uranium pellets used to fuel the plants, the researchers say they can lower the operating temperature of the plant, and increase heat transfer, Reuters reports.

On the face of it the technique seems very simple, although as it took three years to develop, it's probably actually quite complicated.

Normal uranium dioxide fuel is made into solid cylindrical pellets. The MIT researchers' technique works instead with hollow tubes of the fuel. This increases the surface area of the uranium exposed to the water, improving heat transfer.

It also means the plant can run at 700°C, less than half the standard operating temperature of 1,800°C, and much lower than the melting point of uranium (2,840°C).

Pavel Hejzlar, a principle research scientist in MIT's Department of Nuclear Science and Engineering, and his colleague Mujid Kazimi worked on the project for three years, in conjunction with the US department of energy.

Hejzlar says there was no time to patent the concept before he published his first paper on the work, and notes that it could take up to 10 years to commercialise the project.