The first boiling water reactor experiments (BORAX-1) were carried out at the National Reactor Testing Station (NRTS) in Idaho by the Argonne National Laboratory (ANL) in 1953. This proved that in-core boiling would be stable and also verified that the void coefficient was negative and so could be used to control the reactor. The first experimental boiling water reactor (EBWR) was then built by ANL in 1956 near Chicago. Development of commercial BWRs was undertaken by General Electric (GE) and the prototype Vallecitos Boiling Water Reactor was built in 1957 near San Jose, California. This then led on to the development of commercial BWRs.

The development of the GE BWRs is illustrated in Fig. 10.10 . The first US commercial nuclear power plant Dresden 1 was a BWR1. The early BWRs had relatively low power densities and used both internal or external (steam drum) separation and were dual cycle providing direct cycle steam as well as producing steam from steam generators. The designs were simplified and pure direct cycle operation was adopted. The early BWR plants were successfully exported and adopted. Other manufacturers emerged often initially as partners of GE. BWRs were manufactured by Toshiba, Hitachi (Japan), ASEA Atom (Sweden) and KWU (Germany).