ESBWR

The Economic Simplified Boiling Water Reactor is the Generation III+ design of GE Hitachi (now GE Vernova Hitachi) that takes BWR simplification to its limit: water circulates through the core by density difference alone, thanks to a tall chimney above the core, and the recirculation pumps disappear along with their piping, power supplies and heat exchangers. It produces 4,500 MWt, 1,594 MWe gross and 1,535 net, with a plant efficiency of about 35%.

Decay-heat removal is fully passive: isolation condensers that condense the vessel's steam in pools, a gravity-driven cooling system that floods the core from elevated tanks, and a passive containment cooling system. None of them uses pumps, and the plant stays in a safe state for 72 hours with no operator action and no electricity. The NRC estimated a core damage frequency of 1.65 × 10⁻⁸ per year. It certified the design on September 16, 2014 and in May 2017 issued the combined license for North Anna 3, but no ESBWR has been built. Its direct descendant is the BWRX-300.