KAERI’s Development of LWR Accident-Tolerant Fuel

TLDR

The Fukushima accident highlighted the need for nuclear fuel with greater inherent tolerance to severe accidents, prompting international consensus to enhance fuel safety. This study aims to develop accident‑tolerant fuel that can withstand loss of active cooling for extended periods while preserving or improving normal operation performance and bolstering safety for beyond‑design‑basis events. The Korea Atomic Energy Research Institute is testing surface‑coated zirconium cladding, metal‑ceramic hybrid cladding to reduce hydrogen generation, and microcell UO₂ pellets to trap fission products, with selected materials undergoing irradiation tests in a research reactor after initial out‑of‑pile screening.

Abstract

The Fukushima accident has had a tremendous impact on Japan and the rest of the world in the areas of public health, economy, and nuclear energy policy. Thus, international consensus has been reached that inherent tolerance of nuclear fuel to severe accidents needs to be increased significantly to prevent accidents or to mitigate their consequences. In this respect, several countries have started to develop accident-tolerant fuel (ATF) that can tolerate loss of active cooling for a considerably longer time period than current fuels, while maintaining or improving performance during normal operations and operational transients and also enhancing fuel safety for beyond-design-basis events. The Korea Atomic Energy Research Institute is also developing ATF: surface-coated Zr cladding and metal-ceramic hybrid cladding for the purpose of suppressing hydrogen generation during severe accidents, and microcell UO2 pellets to enhance the retention of highly radioactive and corrosive fission products such as Cs and I, where all UO2 grains are enveloped by thin cell walls that act as chemical traps or physical barriers for the movement of fission products. When the screening of developing fuel materials has been performed through various out-of-pile tests, irradiation tests of the selected materials will be carried out in a research reactor to demonstrate their enhanced accident tolerance.