SOMBRERO (solid moving breeder reactor) is a conceptual design of a 1000 MWe laser-driven inertial fusion energy (IFE) power plant. An important goal of the original study was the achievement of a safe and environmentally attractive reactor of relatively simple design. However, recent work has pointed out some key issues involving safety that were not completely addressed at that time, and which need to be reviewed in order to maximize the SOMBRERO design attractiveness.

The present work uses a set of computer codes traditionally used for magnetic fusion safety studies (CHEMCON, MELCOR), which have been adopted and adapted for use in IFE safety analysis. Here we consider a loss of flow accident (LOFA) combined with a simultaneous loss of vacuum accident (LOVA) produced by a breach in the confinement building. Although confinement failure would be a very unlikely event, it must be postulated in order to produce significant off-site doses. The CHEMCON code is used to simulate the long-term thermal transient in the reactor structures resulting from oxidation and radioactive decay heat. MELCOR is used to simulate a wide range of physical phenomena including thermal-hydraulics, heat transfer, aerosol physics and fusion product release and transport. As specified in the DOE Fusion Safety Standards, an off-site dose below 1 rem (10 mSv) is the requirement to avoid public sheltering and evacuation. The SOMBRERO accident analysis results will be evaluated according to this limit and suggestions will be made for improvements and future work.