Investigation of the use of ceramic materials in innovative light water reactor - fuel rod concepts

The RWTH Aachen and the TU Dresden have undertaken a joint research effort, the goal of which is the development of innovative fuel rods which would constitute a high-melting reactor core. An additional sintered silicon carbide (SSiC)-encasement of the UO2 pellets within the zircaloy cladding was planned. Various designs for the construction of the absorber rods were developed in order to achieve a failure temperature in excess of 1200°C. At the RWTH Aachen, a series of depleted UO2 pellets were enclosed in gaslight SSiC capsules through reaction sintering. The capsules were checked for leaks, and their thermomechanical behavior was analyzed after thermal strain; the capsules were heated to 1800°C (maximally 2070°C) in oxidizing water vapor as well as in air. Further series of experiments were conducted in order to examine the chemical behavior of the SSiC pellets in the presence of various reactor component materials at high temperatures. SSiC was heated to 1800°C while in contact with the following substances: zircaloy, steel, corium material, U(X Ag-ln-Cd-alloy. HfO2. Dy2O3 Gd2O3 Sm2O3 BN. and B4C. With the exception of steel and corium material containing steel, the substances proved relatively inert in reactions with SSiC, such that their use in combination with SSiC can be judged to be favorable.