OTTO-Kugelhaufenreaktor für eine 1000 MW$_{e}$-Heliumturbinenanlage

A 2700 MW$_{th}$ OTTO-pebble bed reactor for a direct cycle helium turbine plant is presented resulting from a technical and economical optimization. The calculational research presents the nuclear properties, thermal hydraulics and tost evaluation. Same more detailed analysis an reactor control fission product releaseand reflector are performed as far as required for assessing this concept. A discussion of alternatives in the design of fuel elements and reflector illustrate the flexibility inherent to this type of reactor. The characteristic data are : Fuel cycle with high enriched uranium and thorium, average power density of 9 MW/m$^{3}$, specific power of 2817 kW$_{th}$ /kg$_{fiss}$, average burn up of 106000 MWd/t, fuel cycle costs of 0.51 Dpf/kWh$_{e}$, maximal nominal fuel temperature of 1156 °C. Technological limits are reached far the fast neutron dosis in the radial reflectar and for the release of fission products. In order to reduce these figures the fuel elements being inserted adjacent to the reflectar are loaded with a reduced fissible and an increased fertile isotopic content. For the fabrication of the coated particles follows the requirement of a lower fissile isotopic contamination in the coatings. The aim of the study is to provide a basis for the pebble bed alternative reference design within the framework of the HHT-project