This effect is essential in fission reactors and nuclear weapons.

The papers described the outline of a design for a nuclear fission reactor.

We have an old fission reactor, from back when they first established Sovereignty.

I think the experimental nuclear airplane used a fission reactor.

Later, other natural nuclear fission reactors were discovered in the region.

Such a stream would emerge from a nuclear fission reactor in operation.

Or further back, even, for all I know; probably from the time of those disgusting old fission reactors.

Critical fission reactors are the most common type of nuclear reactor.

In 1972, remains of a natural nuclear fission reactor were found at the Oklo deposits.

A nuclear fission reactor might fulfill most of a Moon base's power requirements.