Activation, decay heat, and waste disposal analyses for the ARIES-AT power plant

Detailed activation, decay heat and waste disposal calculations of the ARIES-AT design are performed to evaluate the safety aspects of the device. The high initial activity of the SiC highly irradiated components translates directly into a higher initial decay heat for these structures than for the well-protected steel-based components. However, after a one-hour cool-down period, the SiC decay heat drops by two decades to levels comparable to the steel-based components. The decay heat of the LiPb coolant was found to exceed that of the SiC components for several days after shutdown. This implies that a loss of flow accident (LOFA) event is more critical than a loss of coolant accident (LOCA) event for LiPb/SiC systems. Regarding waste disposal, all structures can easily meet the Class C Low-Level Waste (LLW) requirements established for the ARIES power plants. Many components could qualify as Class A LLW after a 100-year storage period after selection of low activation materials and control of the Nb and Mo impurities in ferritic steel. A purification system will be required to remove the Po-210 and Hg-203 generated by Pb during operation.