r and d work is reported that accompanied the process engineering work for the fabrication of mtr fuel elements with low u-235 enrichment, results to be used for the design of the series production process. the fabrication of the fuel elements for a first leu core of the geesthacht research reactor is the case studied in order to see whether the fabrication process meets the requirements of series production with higher materials throughput, and the quality requirements. the project goals were achieved. the 78 leu fuel elements for the research reactor were produced in series without any problem, the fuel elements are up to specifications and meet all requirements. the project work resulted in some process engineering and mechanical improvements, regarding the fabrication of the u3 si2 pellets and of the fuel powder, standardization of surface treatment for roll bonding, adjustment of the rolling bonding technique to the conditions of the 'harder' fuel plates, test methods for quality control. all improvements have been worked in into the series production process. (orig./hp). (copyright (c) 1989 by fiz citation no. 89:081126.)