A preconceptual engineering design has been developed for the Spallation Induced Lithium Conversion (SILC) Target/Blanket System for the Accelerator Production of Tritium (APT) project. The concept uses an array of pressure tubes containing aluminum clad lead rods for the neutron spallation target, and lithium‐aluminium alloy plates clad in pure aluminium for the tritium production blanket. The engineering design is based on a physics model optimized for efficient tritium production and is an evolution of the tritium production techniques used successfully at the Savannah River Site for over thirty years.Major engineering considerations were: provisions for cooling the low melting temperature lead and aluminum; retention of tritium; containment of radionuclides; material compatibility; minimization of D2O inventory; and reduction of structural materials that produce no tritium and contribute to the postprocess wastestream. The design is based on a concept of modular inseparable assemblies that reduces the number of sealed connections to target cooling systems and simplifies the handling of target components. The design evolved from a preliminary cost‐to‐produce study that yielded significant reductions in mass, envelope, and total cost‐to‐produce when compared to other concepts. ©American Institute of Physics 1995