Editing Nuclear meltdown (section)

=== Experimental or conceptual designs ===
Some design concepts for nuclear reactors emphasize resistance to meltdown and operating safety.

The PIUS ([[light-water reactor|process inherent ultimate safety]]) designs, originally engineered by the Swedes in the late 1970s and early 1980s, are LWRs that by virtue of their design are resistant to core damage. No units have ever been built.

Power reactors, including the [[Nuclear reactor technology|Deployable Electrical Energy Reactor]], a larger-scale mobile version of the TRIGA for power generation in disaster areas and on military missions, and the [[TRIGA]] Power System, a small power plant and heat source for small and remote community use, have been put forward by interested engineers, and share the safety characteristics of the TRIGA due to the [[uranium zirconium hydride]] fuel used.

The [[Hydrogen Moderated Self-regulating Nuclear Power Module]], a reactor that uses [[uranium hydride]] as a moderator and fuel, similar in chemistry and safety to the TRIGA, also possesses these extreme safety and stability characteristics, and has attracted a good deal of interest in recent times.

The [[liquid fluoride thorium reactor]] is designed to naturally have its core in a molten state, as a eutectic mix of thorium and fluorine salts. As such, a molten core is reflective of the normal and safe state of operation of this reactor type. In the event the core overheats, a metal plug will melt, and the molten salt core will drain into tanks where it will cool in a non-critical configuration. Since the core is liquid, and already melted, it cannot be damaged.

Advanced liquid metal reactors, such as the U.S. [[Integral Fast Reactor]] and the [[Russian Federation|Russian]] [[BN-350]], [[BN-600]], and [[BN-800]], all have a coolant with very high heat capacity, sodium metal. As such, they can withstand a loss of cooling without SCRAM and a loss of heat sink without SCRAM, qualifying them as inherently safe.