Nugen Reactor

From the Third Age and past the Sixth Age, the NuGen Reactor was the preferred method of power generation throughout the Foundation. The name is short for "Nuclear Generation", but is often described as "New Generation" as they differ heavily from traditional reactor designs.

NuGen cores come in two types, called fixed and variable. Both work on similar principles. The underlying principle of the NuGen is variable decay: one material breaks down into another, which changes the interactions. The exact mix of fuels is a trade secret, but the function is as follows: the reactor core will continously generate heat for a known time period, at which point it will "go cold" and become inert.

NuGens are not "reactors" the traditional sense, in that the reaction(in a fixed core) cannot be externally changed. A fixed-core design will work for a set time frame(usually five years) before becoming inert. Variable-output reactors, which are not as common, have a number of "plugs"(not to be confused with control rodes) which can be inserted to increase pressure in the core, increasing heat output. Generally, ships bring additional steam turbines online, rather than increasing heat output, as doing so reduces the lifespan of the core.

Nugen cores are only marginally radioactive, with the lions share of the radiation being used up by the complex reactions going on inside. What little is not used is mostly contained by the cladding. Since coolant water never comes in contact with the fissile materials, once it cools it is technically safe to drink(though not advised, as it is highly purified and dangerous in it's own right).

Safety

A Nugen Core itself presents only marginal radiation concerns, and minimal shielding is required to protect personnel. Since the coolant does not come in to direct contact with any fissile materials, no protective gear is needed

NuGen reactors were prefered over other generators for their high degrees of safety, simplicity, reliability, and lack of possible ways to explode catastrophically. Following the de-militarization of the fleet around the begining of the Long Night, it became no longer economical to produce NuGen reactor cores. Since the Foundation continued to operate, it began fitting it's ships with nuclear reactors, which could be re-fueled and, while more dangerous, were easier to keep in operation. Following re-armament, a switch to Zero-Point Generators was made.

Errata

Part of The Furthest Star states that the Nugen Reactor is chemical. Since this story has never been published, that is getting changed.