The Pool Type Critical Facility (PTCF) is a low powered, highly eariched (90 to 95% U/sup 235/) ordinary light water cooled and moderated, beryllium oxide reflected assembly. It is generally similar to the present BSR at ORNL, the principal modification being that the grid plate is arranged to accommodate both ORR and BSR fuel elements. The PTCF is located in the northwest corner of the existing BSR pool. The 9 x 7 lattice provides 63 fuel, control rod, or reflector positions. (W.D.M.)