CTU scientist develops more efficient and durable fuel for nuclear power plants

The results of several ongoing projects by Martin Ševeček's team at FNSPE have been excellent - and one of them will be used in US nuclear reactors. These are zirconium alloy tubes with chromium and niobium coatings, which an American company that produces fuel for commercial boiling water reactors wants to take over.

"The important thing for me is that in publicly funded projects our materials are open, so that the results, unlike industrial solutions, will go freely into the world," says the experienced nuclear engineer. "We could sell the solution, but getting patent protection takes several years with an uncertain outcome.This is how we have established cooperation withcommercial fuel producers, who can give money to foreign scientists to further research - unlike the US Department of Energy, which cannot give a cent outside the United States," explains Ševeček.

What exactly is meant by nuclear fuel coverage? "The fuel rod is composed of pellets of enriched uranium encased in a metallic covering that is typically made of zirconium.In particular, we are improving the coating, which is the main barrier between radioactive substances and the environment.It is therefore a coating made of a classic zirconium alloy with a combination of protective coatings or a complete replacement of zirconium with a new material," says Ševeček.

Economy comes first

The main objective of this effort is clear - to increase efficiency and safety. "This will be achieved by improving corrosion properties, particularly at the high temperatures expected in severe accidents, and the associated reduction in hydrogen production, which was problematic at Fukushima," says the scientist. But he adds that even the best fuel will not prevent an accident like the one in Japan in 2011 unless the reactor itself is specially modified.

"If you use our coatings in combinationwithan optimised reactor design, you get to a level of safety that would limit the consequences of the Fukushima events," adds Ševeček.

Companies are usually pushing the economics side of things, and this is where so-called ATFs (Advanced Technology Fuels) have a big advantage, because they allow more efficient use of fuel. "In practice, this means that the operator can get more power, i.e. electricity, out of the same amount of material at the end, byup to 20 percent," explains the young scientist.

Long distance running

Everything around the core is a very conservative field, like aviation. Before something new can be used, it has to go through hundreds of tests. And that's neither cheap nor fast.

"Some phenomena manifest themselves within seconds, others need to be tested for years while the reactor is operating.The experiments are corrosion, mechanical, we study thermophysical properties, radiation damage... Plus we do calculations, design and modification of experiments, evaluation of the results from these experiments and reporting in articles or presentations," Ševeček lists the testing procedure. The material we write about, for example, spent a year in a reactor at the Massachusetts Institute of Technology (MIT) in the US.

But this is where the power of international cooperation, currently represented by the Americans, comes into play. "The greatest value for me is the experience and contact with the best people in the field.Our solution can contribute to the development of new methodologies for evaluating fuel behaviour and provide unique data published in the scientific literature that will move the field forward," says Ševeček.

By the way, this expert is no newcomer to ATF development - he already won an award in the reactor system safety category from the European Commission in the Nuclear Innovation Prize last year for leading the development of a similar material innovation called MultiProtectFuel.

Moreover, Czech participation in such research opens the door for domestic scientists and students to other promising nuclear-related projects - from the development of small modular reactors (SMRs) to nuclear applications in space. Collaboration on nuclear space propulsion, reactors for bases on the Moon and Mars, and the development of radioisotope generators is currently taking concrete shape.

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