Progress in accident analysis of the HYLIFE-II inertial fusion energy power plant design

The present work continues our effort to perform an integrated safety analy sis for the HYLIFE-II inertial fusion energy (IFE) power plant design. Rece ntly we developed a base case for a severe accident scenario in order to ca lculate accident doses for HYLIFE-II. It consisted of a total loss of coola nt 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 i n case of accident, and that this dose was dominated by the tritium release d during the accident. In order to further advance a complete safety analysis for HYLIFE-II, a ran ge of other accident scenarios must be considered. In this work, we introdu ce a new version of the MELCOR thermal-hydraulics code recently developed b y 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 Cu bes that connect the chamber with the outside of the confinement building. This constitutes the bypass needed to communicate the target chamber with t he environment. Once the release fractions of the various radioactivity sou rces are known, we calculate off-site doses under different conditions as a consequence of the accident.