- Direct conversion of fission energy to electricity can be achieved by collecting fission fragments before energy is turned into heat. Safety, simplicity, and high conversion efficiency are the unique advantages of direct energy conversion (DEC). The recently completed US DOE NERI DEC Project identified the fission fragment magnetic collimator reactor (FFMCR) as one of the promising DEC concepts. According to the computational studies, the FFMCR systems offer performance characteristics which cannot be achieved by conventional nuclear power methods. The calculated energy conversion efficiencies for the presented final technologically feasible designs are up to 60%. The analysis indicates that efficiencies up to 90% are potentially achievable. The US DOE NERI DEC Proof of Principle project began in October of 2002 with the goal to experimentally demonstrate performance principles of the promising DEC systems including FFMCRs. The hybrid Monte Carlo-deterministic methodology has been developed and applied for the coupled neutronics- electromagnetics-thermohydraulics design analysis of the FFMCR system. The created computer code system allows automated coupled 3D modeling with optimization of the major performance characteristics. The nuclear reactor calculations, electromagnetic component calculations and thermohydraulics calculations are joined together to provide the FFMCR system design characteristics. The DECA (Direct Energy Conversion Analyzer) driver code enables coupled modeling capability.