The tritium breeding and energy absorption in an inertial fusion energy (IFE) reactor chamber have been investigated with variable coolant zone thickness using different materials. Examples are given for HYLIFE-II (an IFE reactor design) and for magnetohydrodynamic (MHD) energy conversion chambers using Flibe (Li2BeF4) as coolant. Investigations related to MHD are extended to the use of LiH, lithium, and Li17-Pb83 eutectic as working fluid. Natural lithium is used in all cases, except in the case of LiPb, for which both natural and enriched options were calculated. To achieve a useful energy density for energy conversion purposes with a sufficient tritium breeding ratio (TBR = 1.1 to 1.2), coolant zone thicknesses must be 25 cm for LiH, 50 to 60 cm for Flibe, and 80 cm for lithium. The use of Li17-Pb83 with natural lithium and with lithium enriched to 90% Li-6 requires coolant zone thicknesses of 120 and 60 cm, respectively, to obtain a tritium breeding of TBR = 1.1, which gives an extremely low energy deposition density. This low density and the large coolant mass make LiPb unattractive for MHD and HYLIFE-II applications.