Any thorium-cycle reactor can use any fissile material that is available for startup....U-235, U-233, or Pu-238. The excess neutrons from that "starter fuel" then "breed" Th-232 into U-233, which continues the cycle until all Th has been converted and "burned".
The TE IMSR is a single fluid burner that will need infusions of Uranium. Disposal of spent fuel I suppose is the selling point.