[en] A previous study was performed to assess the hazards associated with an accidental leakage of cooling water into the crucible of molten ²³⁸U for the MARS laser isotope separation experiment. Since that study found that the probability of such an explosion is extremely low during an accidental cooling system failure, a study was conducted to define a more realistic design basis accident (DBA) for the final MARS configuration. If the vapor-phase explosion is considered to be a significant threat, the design criteria for the vacuum vessel should be a working pressure of 67 psig or 101 psig momentary single pulse equivalent static pressure