A thermally activated crack-velocity formulation that includes a threshold at thermodynamic equilibrium is used in the prediction of long-term time-to-failure for brittle materials. A new closed-form time-to-failure solution is derived for straight cracks propagating under the influence of constant stress. Explicit connections are made between the macroscopic crack-velocity parameters and the underlying bond-rupture parameters. A feature of the solution is the divergence of time-to-failure for applied loading approaching the thermodynamic threshold. A new reliability framework is developed and long-term reliability and hazard predictions made using the time-to-failure solution. A bathtub hazard curve is shown to be generated by a single crack-velocity failure mechanism.