In-reactor behaviour and economic assessment of enriched gadolinia burnable absorbers

Abstract

The increasing demand for energy and rising energy prices have increased the importance of the efficiency and economic viability of operating nuclear power plants. One approach to improving the reactivity control in such cases is the use of burnable absorbers such as gadolinium oxide (Gd2O3). While Gd2O3 has proven effective in regulating reactivity in light water reactors, it has certain drawbacks, including the displacement of fissile isotopes from the fuel composition and residual reactivity penalties caused by isotopes other than the main neutron absorbers. In this study, the potential impacts of 157Gd-enriched Gd2O3 on the operation, safety, and economy of nuclear power plants were assessed. Fuel cycle analyses were conducted using the advanced nuclear design code system Studsvik CASMO4/SIMULATE3. Several aspects were analysed, including peaking factors, reactivity feedback parameters, power distribution, and shutdown margin. The results of the analysis revealed that by removing the isotopes responsible for residual reactivity from Gd2O3, it was possible to achieve the same fuel cycle length with lower uranium enrichment levels, enabling a higher concentration of fissile isotopes and yielding economic benefits without compromising safety.