INVESTIGATIONS ON THE ECONOMY OF THERMIONIC FUEL ELEMENTS IN HIGH- TEMPERATURE REACTORS

Nuclear reactors for space research purposes should be equipped with incore fuel elements. In that connection the question was studied if incore fuel elements might also be applied for economic electricity generation, because they lead to increase the efficiency rate of the total power plant. The computation of a high-temperature reactor of 600 MW(e) showed that for the wanted thermal neutron spectrum at which radiation damage of fuel elements can be kept possibly low, the parasitic absorption in the structure materials tungsten and niobium will be too high. In order to achieve reactor criticality, a high fission inventory is required. Also, the fabrication cost of thermionic fuel elements will considerably increase the fuel cycle cost. Even under the assumption of a fuel element price of 10 DM per element which actually never can be realized, the fuel cycle cost would then amount to still 2.7 DPfg/kWh with a load factor of 0.8. (translated)