A tritium intermix is a component of Klingon starships.
Shortly before the Second Battle of Chin'toka, the chief engineer of the Klingon Bird-of-Prey 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 are not designed in this exact manner as their ships needed a different way to compensate for the weapon. (DS9: "When It Rains...")