Sid Meier's Alpha Centauri/Reactor

Fission Plant

 * Prerequisite Tech: N/A
 * Strength: 1

The default reactor for units. Later in the game, it is ideal for worm-killing units since psi combat ignores reactor strengths, and without a strong weapon, more advanced reactors will usually make the unit more expensive.

Fusion Reactor

 * Prerequisite: Fusion
 * Strength: 2

The first more powerful reactor you can get. The decrease in build costs is noticeable, and your units will be nearly unstoppable until your opponents discover Fusion as well.

Quantum Chamber

 * Prerequisite: Quantum Power
 * Strength: 3

Reactors beyond Fusion are of little use, since the game will probably be over by this point.

Singularity Engine

 * Prerequisite: Singularity Mechanics
 * Strength: 4