COMPARISON OF WASTE DUE TO IRRADIATED STEELS IN THE ESFR AND DEMO

For either nuclear fusion or generation IV fission reactors to be viable as a commercial energy source the decommissioning and waste disposal solutions must be considered during the design. A multi-step simulation process combining Monte Carlo Neutron Transport simulations with inventory simulations have been performed to estimate the activation of steels in key reactor components of the European Sodium-cooled fast Reactor (ESFR). Waste classifications based on UK waste disposal regulations have been applied to the key components to estimate the expected masses of low level and intermediate level waste. The use of reduced activation steels, EUROFER and F82H, in reactor components external to the core results in a factor of 10 reduction in the percentage of waste classified as Intermediate Level Waste (ILW). Waste estimates are compared to existing waste estimates for the European Demonstration fusion reactor (DEMO). The ESFR has a lower percentage of ILW per total reactor mass due to irradiated steels compared to DEMO. However, there is no Higher Activity Waste (HAW) associated with DEMO, compared with arisings from the ESFR spent fission fuel.

Thermodynamic Analysis for the Magnetic-Field-Induced Precipitation Behaviours in Steels

Alloy carbide M23C6 plays a significant role in the creep strength of reduced activation steels. Experiments have proven that a magnetic field accelerates the precipitation of M23C6 at intermediate temperature. A scheme that combines first-principle calculations, Weiss molecular field theory and equilibrium software MTDATA is proposed to investigate the thermodynamic features of magnetic-field-induced precipitation. The calculated results reveal that the origin of the magnetic moment is the NaCl-like crystal structure. The magnetic field enhances the exchange coupling and stabilizes the ferromagnetic phase region. The external field influences the Curie temperature, thereby changing the magnitude and position of the maximum magnetic heat capacity, magnetic entropy and enthalpy. The strong magnetic field improves the stability of M23C6, and the theoretical results agree well with the previous experiment. The study provides a theoretical basis for the magnetic-field-induced precipitation behaviours in steels.