A high convertor pressure tube reactor is presented and analyzed from the standpoint of neutronics. High conversion and for some cases even breeding are obtained because of the hard neutron spectrum in a tight lattice reactor as well by reducing the parasitic absorptions through constant refueling. Eight different cases are analyzed with different fuels (232Th, 233U, 235U, 238U, and plutonium) and different coolants (H2O and D2O). The advantage of pressure tube reactors compared to pressure vessel reactors is demonstrated from the standpoint of the neutronics. This advantage is demonstrated by the improved fuel utilization associated with pressure tube reactors.