In the HIBALL heavy ion beam fusion reactor design, the INPORT concept is used to protect the first surface of the reactor from damage by the high energy X-rays, ion debris and fast neutrons from the exploding target. Liquid Li17Pb83 flows through porous SiC tubes and wets outside of the tubes with a layer of Li17Pb83. This Li17Pb83 film is evaporated on each shot by the target X-rays and ion debris. The mechanisms that control the vapor pressure of the chamber are: gas radiation, Li17Pb83 evaporation from the INPORT tubes, and gas condensation back onto the INPORT tubes. From the beam stripping cross section for Bi2+ ions on Pb the gas pressure (evaluated at 0°C) inside the chamber must be at or below 10−4 torr in order for the ion beam to reach the target and ignite it. The repetition rate is therefore determined by the time required to reestablish this pressure after a shot. Calculations are presented that indicate that this time is short enough to allow a 5 Hz repetition rate for a wide range of parameters.