A tritium intermix was a component of Klingon starships.
Shortly before the Second Battle of Chin'toka, the chief engineer of the Klingon Bird-of-Prey IKS Ki'tang adjusted the tritium intermix to compensate for a containment problem in the ship's warp core.
The adjustment to the tritium intermix protected the Ki'tang from being disabled by the Breen's energy dissipators. Soon after, General Martok ordered every starship in the Klingon fleet to make the adjustment. Federation and Romulan starships were not designed in this exact manner (Federation ships used deuterium/antideuterium and Romulan ships used quantum singularities), thus their ships needed a different way to compensate for the weapon. (DS9: "When It Rains...")