AbstractThis paper details the initial modifications made to the melcor code that allow it to predict the consequences of lithium spill accidents for evolving fusion reactor designs. These modifications include thermodynamic and transport properties of lithium, and physical models for predicting the rate of reaction of, and energy production from the lithium-air reaction. A benchmarking study was performed with this new melcor capability. Two lithium-air reaction tests conducted at the Hanford Engineering Development Laboratory (HEDL) were selected for this benchmark study. Excellent agreement was achieved between melcor predictions and the measured data, when several empirically derived coefficients were used. Recommendations for modeling lithium fires with melcor and for future work in this area concluded this paper.