Systems and methods for long term disposal of high level nuclear waste in deep geologic formations are described. Such systems and method may include largely intact spent nuclear fuel rods in a disassembled form that may be placed into waste-capsules (e.g., carrier tubes); which may then be placed into various well boreholes. Example embodiments may provide waste-capsules capable of containing and disposing of waste generated from spent nuclear fuel, including means for harvesting the nuclear waste from cooling pools and operationally processing the waste fuel assemblies for inclusion in the waste-capsules with various engineered barriers; along with storage in horizontal well boreholes drilled into closed deep geologic formations.