Takemurium 9839 was a high yield reactant which was used for emergency ignition of microfusion devices. This reactant was manufactured in 2.7 kilogram slugs for powering Type VI reactors. According to Starfleet guidelines, this reactant was not recommended in high gravity environments due to its relatively low DT plasma cohesion characteristics. In 2367, this explosive was stored on aboard the Federation starship USS Enterprise-D.
In that year, Takemurium 9839 was on a list of explosives that Lieutenant Commander Data and Counselor Deanna Troi searched through in an attempt to find one that could produce enough energy to release the USS Enterprise-D and an alien ship from the Tyken's Rift. (TNG: "Night Terrors")