Development of High-Performance Block Fuel for High Temperature Reactors. Final report

Automatic translation: As an alternative to the one constructed by GAC and incorporated into the FSVRactor The block fuel element used was manufactured by NUKEM/HOBEG designed the pressed block fuel element and in the BMFT funded development projects in the years 1972-1977 brought technical maturity. The work was based on design work at HRB and on development work, in particular on reactor testing at KFA. The development was up brought to a state that a block fuel assembly having excellent properties was reproduced and that the basis for economical production is given. Development and production of pressed block fuel elements With the tried and tested A3 graphite matrix for pressed spherical fuel elements pressed block fuel assemblies were initially produced on a smaller scale. As raw material for pressing the Graphite matrix of these blocks became isotropic graphite granules Developed with A3 matrix composition and pressing aid additives. In addition to the graphite granules, coated fuel particles were provided for pressing the blocks. To produce the small cylindrical blocks (24 cm diameter, 38 cm height). developed a pressing process: First, in a steel matrix with built-in parallel displacement rods, the filled isotropic graphite granules are pre-pressed at 70°C to form a structural block, in the fuel channels are in a special dosing and Pressing device from coated coated fuel particles filled at 70 ° C pre-pressed fuel inserts, and the The entire block is finish-pressed at 170°C and 105 bar. After Heat treatment up to 1800°C is a block element with good Strength and heat conduction properties. Small blocks made in this way were used to work out samples for reactor tests.