It is shown that for two-temperature steady state accretion disks with viscosity generated be neutron collisions there is a lower (upper) bound on the viscosity (accretion rate). Assuming 4 He breakup as the source for the neutrons in accretion disks with the usual α viscosity prescription, taking into account cooling due to breakup ignition, thermalization of the reactant particles and radiation losses, we have found absence of steady-state solutions for accretion rates below M˙ c 17 =3.14×10 2 α 2 M 34 . It is also shown that, close to the breakup temperature, unsaturated inverse Comptonization cooling dominates over other processes and breakup is unlikely to occur. For bremsstrahlung, radiation losses are small compared to other cooling processes