Researchers at Switzerland’s Paul Scherrer Institute (PSI) used a new X-ray imaging technique to examine corrosion inside nuclear fuel rod cladding in 3D, detecting pores as small as 80 nanometers.

The study investigated whether the protective layers surrounding fuel rods remain effective after years of exposure to cooling water and radiation.

Working with samples from cladding tubes that had operated in a nuclear power station, the team used PSI’s Swiss Light Source to map internal structure. The tubes remained leak-tight after service, and the measurements showed that protective oxide layers continued to perform their function.

The findings help assess fuel rod safety and establish whether conventional laboratory corrosion tests accurately represent material exposed to reactor conditions. The supplied announcement did not specify when the experiments took place.

Fuel rod cladding must remain sealed throughout reactor operation, despite conditions that can cause corrosion. Researchers therefore need to understand how quickly corrosion layers form and how porous they become.

The cladding tubes typically contain more than 98 percent zirconium, with small amounts of other metals added to improve their properties. It encloses stacked uranium dioxide fuel pellets, forming the fuel rods used in nuclear reactors.

The study brought together three PSI research centers covering nuclear engineering, photon science, and neutron and muon sciences.

At the institute’s Hot Laboratory, staff used precision saws inside shielded hot cells to cut wafer-thin sections from spent fuel rod cladding. And then used a focused ion beam to shape the material into cylinders.

The samples came from the zirconium oxide layer formed on the cladding surface during operation.

Source link