Gas dynamics in the heavy-ion inertial-fusion-energy power plant, HYLIFE-II, have been modeled using the code TSUNAMI. Simulations were run and results compared using both ideal-gas and the partial-ionization equations of state. Developed by Zeldovich and Raizer, the partial-ionization model approximates the Saha equation for multiply ionized species in a gas mixture. Results from a cylindrically symmetric simulation indicate an initial, low density, burst of high energy particles enters the final-focus transport beam line within 28 microseconds after the blast, much faster than the proposed 1 millisecond shutter closing time. After approximately 300 microseconds the chamber debris flux levels off to one eighth its peak value and maintains this level until the shutter closes. Uncertainty in IFE target design motivated the adjustment of two target parameters: target mass and the ratio of x-ray to debris kinetic energy. Although initial jet x-ray ablation is considered, neither secondary radiation nor condensation were modeled. Therefore results are conservative.