Kaboomite

Kaboomite is a powerful explosive of unknown composition. The methods and processes of its manufacture and safe handling are closely-guarded secrets of high-ranking employees of the Stellvia Corporation, specifically Kohran Li and Sora Hasegawa. The general nature of kaboomite is also known to Noah Scott and S. Malaclypse Fnord, and was revealed to Commander Tom Dodge of the USS Stingray immediately before the final offensive in the Boskone War in January 2014.

"Use of a kaboomite warhead" is one of the very few known ways to reliably breach a large 'waved ship's hull quickly. However, this method tends to destroy anything smaller than a Space Vessel, rather than simply breaching its hull.

One of the persistent myths of Fenspace is that Kaboomite is nothing more than handwaved Pop Rocks and cola. Noah Scott has denied that rumor.

Because of the Kaboomite Incident at Islandcon (where a misfire of a test kaboomite warhead caused over $10,000,000 in property damage), one of the minor clauses in the Kandor Treaty prohibits the use of Kaboomite within 1000 km of any inhabited body or station.

Metafictional Data

While the characters have no idea what kaboomite is, the authors are aware that it is subcritical nuclear weaponry. The Stellvians took it upon themselves to gather all the easily-accessible fissionables (NPUs in hardtech space probes, 'wave-assisted extraction from depleted-uranium ammunition, and so on) before most Fen made it Up so that there wouldn't be a nuclear arms race in Fenspace. The last Kaboomite warheads were fired by the Stingray during the Fall of Boskone Prime (which is why Noah revealed the secret to the US Navy - there weren't any left after the three he gave them). In any imaginable Fenspace Infinities setting, Noah will have scrounged enough uranium to make two more warheads - one for the armory in Stellvia, the other for the one in the Epsilon Blade - but with the Space Patrol better able to monitor the use of radioactives than are the Stellvians, he won't have a driving urge to create more.

As to where Noah got the specs for subcritical nuclear warheads, and why he didn't end up in a very dark jail cell once Cmdr. Dodge found out about them... that's still a secret, but it's the same secret.