In 1992, GE began to design a natural circulation, boiling water reactor (BWR) featuring passive safety systems. This effort produced a 670 MWe reactor known as the Simplified BWR (SBWR). The development program was later re-directed to design a larger reactor that used economies of scale, proven technology, and components from the Advanced BWR (ABWR) to create a new reactor at reduced capital cost. The new advanced reactor is known as the Economic Simplified BWR (ESBWR).