Progress in Accident Analysis of the Hylife-II Inertial Fusion Energy Power Plant Design

Abstract

The present work continues our effort to perform an integrated safety analysis for the HYLIFE-II inertial fusion energy (IFE) power plant design. Recently we developed a base case for a severe accident scenario in order to calculate accident doses for HYLIFE-II. It consisted of a total loss of coolant accident (LOCA) in which all the liquid flibe (Li₂BeF₄) was lost at the beginning of the transient. Results showed that the off-site dose was below the limit given by the DOE Fusion Safety Standards for public protection in case of accident, and that this dose was dominated by the tritium released during the accident.

In order to further advance a complete safety analysis for HYLIFE-II, a range of other accident scenarios must be considered. In this work, we introduce a new version of the MELCOR thermal-hydraulics code recently developed by the Idaho National Engineering and Environmental Laboratory (INEEL) that uses flibe as the working fluid. We have focused on a loss of flow accident (LOFA), with simultaneous failure of the blanket structure and the beam tubes that connect the chamber with the outside of the confinement building. This constitutes the bypass needed to communicate the target chamber with the environment. Once the release fractions of the various radioactivity sources are known, we calculate off-site doses under different conditions as a consequence of the accident.