Spent nuclear fuel (SNF) from nuclear power generation requires long-term safeguarding in dedicated storage facilities and geological repositories. Current safeguards approaches use a combination of containment and surveillance, and design information verification. Antineutrino emissions from the ongoing beta decay of fission fragments provide a potential complementary information on potential diversion of nuclear material or misuse of the facility, as antineutrinos pass through any shielding, structure, or geology effectively unhindered. This study investigates a novel antineutrino detection concept using a liquid-organic (LOr) time projection chamber (TPC), combining scalability and high-resolution particle reconstruction of TPCs with the large quantity of target hydrogen atoms provided by organic compounds. Geant4- based simulations and subsequent modelling of the electron drift behavior are used to understand inverse beta decay (IBD) event topologies and reconstruction in an ISO container-sized concept detector. The concept detector's expected signal rate, sensitivity to inventory changes and directional capabilities are then estimated for a representative example repository with varying deployment distances and scenarios. This estimation is compared to other state-of-the-art antineutrino detection technologies, including liquid and segmented plastic scintillation detectors, that have been proposed for nuclear monitoring. This comparison will be used to determine the feasibility and suitability of antineutrino detectors currently under development as complementary safeguards measure for final disposal of SNF in geological repositories.