The IRC tank, or auxiliary tank, was a component of impulse engines in Federation starships.

In the 23rd century, Montgomery Scott wrote the impulse engine specifications for this tank, including regulation 42/15, "Pressure Variances in IRC Tank Storage".

In 2369, as Geordi La Forge and Montgomery Scott were restoring power to the impulse engines of the USS Jenolan, Scott requested that La Forge shunt the deuterium from the main cryo pump into the auxiliary tank. La Forge objected, stating the tank could not handle the pressure, to which Scott asked him where he got that idea. La Forge mentioned the impulse engine specifications, for which Scott identified the regulation and its author as himself. Scott admitted that, as a good engineer, he wrote the regulation conservatively and that La Forge should ignore it. Subsequently, Scott requested La Forge to bypass the secondary valve and boost the flow. With the task completed, the Jenolan had impulse power. Upon checking the status of the tank, La Forge affirmed Scott's faith in the tank. (TNG: "Relics")