The Wikipedia article covers the development pretty well: https://en.wikipedia.org/wiki/Breeder_reactor https://en.wikipedia.org/wiki/Breeder_reactor In short:

The Wikipedia article covers the development pretty well: https://en.wikipedia.org/wiki/Breeder_reactor https://en.wikipedia.org/wiki/Breeder_reactor In short: > Breeders were at first found attractive because they made more complete use of uranium fuel than light-water reactors, but interest declined after the 1960s as more uranium reserves were found[2] and new methods of uranium enrichment reduced fuel costs.