In the very unlikely event of a loss-of-flow accident in a liquid-metal fast breeder reactor being accompanied by complete failure to scram, the reactor could go prompt critical, generating a large amount of neutronic heat on a millisecond time scale. We find that fuel-to-steel heat transfer has a minimal influence upon the neutronic energy deposition during the prompt burst but that it can play an important role in material behavior in later stages of the hypothetical core disruptive accident. Furthermore, results obtained indicate that calculations of thermodynamic potential energy through adiabatic expansion to one atmosphere are conservative if performed at the end of the prompt burst and that fuel-to-steel heat transfer may significantly reduce the available work energy within the next 20 ms.