Fire accident analyses for the DEMO fusion power plant

Fusion power plants are inherently safer than fission power plants, posing very low risk to populations in the vicinity and generating no long-lasting waste. However, there are still several safety topics to be studied and confirmed, one of those being fire safety. This paper describes the work on fire accident analyses for the DEMO fusion power plant. Fire accident analyses of the lithium-lead component room inside the DEMO Tokamak building were performed, and preliminary fire zoning principles of the DEMO power plant were studied. The analyses were performed utilizing computational fluid dynamics simulations with Fire Dynamics Simulator software, as well as fire zone models and analytical calculation methods. Based on the results, the fire safety of the lithium-lead component room is considered to be on an acceptable level. A fire originating in the room is likely to propagate to
or damage only equipment which are located relatively close to the fire origin, the exact distance depending on the size of the fire. For defining fire zoning principles, failure risks of fire sector partitions depending on room dimensions and fire load densities were mapped, and tables and graphs for design were produced.