Small reactors have been developed since 1950s: Army, Navy, AEC, and private industry

There is a history of development of small power reactors in the U.S. and overseas. In the 1950's the U.S. Army focused on reactor systems which were intended for transportation to remote areas or to areas requiring emergency power supplies. And the U.S. Navy program centered on reactor systems for operating ships. Also in the 1950's, the U.S. Atomic Energy Commission (AEC) initiated the Power Reactor Development Program (PRDP) which supported private industry's nuclear reactor R&D. This program helped research pressurized water reactors (PWRs), boiling water reactors (BWRs), fast neutron reactors and many other types and it helped to fund construction and generation of a few small commercial plants. However, it is noted that most of these early plants were significantly less than 100 MWe in size, although they were "one-off" plants and not intended for replication, nor were they compact.

[Source: Argonne National Laboratory, "Small Modular Reactors", August 30, 2001]