Accelerated Degradation of Zirconium Fuel Cladding in Nuclear Reactors

Strategic Insights -

Research at the Chalmers University of Technology has revealed new insights into the mechanisms governing the in-reactor corrosion process of zirconium-based fuel cladding in water-cooled and-moderated nuclear power reactors. The study, published in Acta Materialia, used nano-scale characterization techniques, including atom probe tomography, to analyze high-burnup fuel cladding tubes from the boiling water reactor Oskarshamn 3. The researchers found that irradiation-induced defects and the interaction between alloying elements, irradiation-induced defects, and zirconium oxidation play a crucial role in the degradation process.

Key Takeaways:

  • The life-time-limiting factors of zirconium-based fuel cladding in water-cooled and-moderated nuclear power reactors are corrosion and associated hydrogen pickup.
  • The accelerated degradation becomes particularly severe with the accumulation of radiation damage caused by fast neutrons.
  • Irradiation-induced FeCrNi clusters seem to slightly accelerate the diffusion of oxygen within the basal plane of the hexagonal metal matrix.
  • C-component dislocation loops, characteristic of high damage levels, might offer enhanced oxide nucleation sites that potentially explain the rapid degradation observed after some years of reactor operation.
  • Pores can be construed as a potential pathway for accelerated hydrogen pickup, similar to processes postulated in the literature.
  • The results in this study give some novel insights into the mechanisms of in-reactor degradation of zirconium-based alloys and highlight the necessity to characterize materials from actual reactor operation.
  • The study has been peer-reviewed and published in Acta Materialia.
  • The research was funded by the Swedish Centre for Nuclear Technology, WSE, VF, OKG, and EPRI.

Statistics:

  • The corrosion performance in reactor is significantly worse in comparison to autoclave exposure (as cited in the study).
  • Researchers analyzed high-burnup fuel cladding tubes from the boiling water reactor Oskarshamn 3.
  • The study used atom probe tomography to characterize the materials.
  • The research was conducted by David Mayweg, Johan Eriksson, Mohammad Sattari, Hans-Olof Andren, and Mattias Thuvander at the Chalmers University of Technology.

Sources:

  • Acta Materialia, "Corrosion of Zirconium Fuel Cladding Inside a Boiling Water Reactor: a Post-irradiation Study By Atom Probe Tomography", June 2025.
  • News of Science, "Studies from Chalmers University of Technology Describe New Findings in Chemicals and Chemistry (Corrosion of Zirconium Fuel Cladding Inside a Boiling Water Reactor: a Post-irradiation Study By Atom Probe Tomography)", June 22, 2025.