Development Status of Control Rod Neutron Absorber Materials for Light Water Reactors with Extended Control Rod Lifetime and Enhanced Safety

The control rod neutron absorbers for light water reactors with extended control rod lifetime and enhanced safety are being developed. It is an innovative material concept that can extend the lifetime by reducing irradiation-induced swelling compared to the existing control rod neutron absorber materials by utilizing the oxide-based materials. Furthermore, it can enhance the safety by improving various characteristics such as oxidation, eutectic reaction, volatilization behaviors of neutron absorber material. First, the oxide-based composition composed of a combination of neutron absorbers and structure stabilizers has been designed as material candidates for neutron absorber materials for control rods. The preliminary manufacturability test of the designed neutron absorber material candidates, and it has been confirmed a possibility that the designed material candidates can be fabricated using the conventional ceramic manufacturing process. In addition, the neutronic calculation/analysis and various out-of-pile tests (neutron absorber phase stability, oxidation and corrosion resistance, interaction and eutectic reaction between neutron absorber material and control rod tube material, melting behavior, etc.) are in progress. It has been also preparing the in-reactor swelling test of the selected material candidates at the HANARO research reactor in KAERI.