Nuclear Technology / Volume 154 / Number 3 / June 2006 / Pages 374-388
Technical Paper / Radioactive Waste Management and Disposal
The release of radionuclides from the conceptual low- and intermediate-level radioactive waste (LILW) repository in Korea is analyzed by establishing a multicompartment model. The model takes into account the vault-array configuration consisting of multiple waste types, multimember radioactive decay chains, and radionuclide transport through the water-unsaturated regions and water-saturated aquifer. Observations of the repository performance have been made with the radiological exposure dose rates and with the radiotoxicities in the environment.
Numerical results show that, among all the radionuclides in the waste, 129I is the predominant contributor to the overall peak exposure dose rate. The peak exposure dose rate of 129I can be affected by a migration distance in the geosphere and the vault-array configuration. Reducing the initial inventory of 129I stored in the waste vaults or spreading its release over a longer time period by modification of the engineered barrier system would effectively reduce the exposure dose rate because the release rate of 129I from the repository is reduced.
The total radiotoxicity in the environment is dominated by 129I at early times and by 238U and its daughters after 106 yr. Because of the long half-lives of these nuclides, the radiotoxicity in the environment is insensitive to the vault-array configuration or to the transport distance in the geosphere.