GE Hitachi Nuclear Energy’s Economic Simplified Boiling Water Reactor (ESBWR) is a 1520 MWe power plant design based on the earlier 670 MWe Simplified Boiling Water Reactor (SBWR) design. The ESBWR design incorporates innovative, yet proven, features to further simplify an inher­ently simple direct cycle nuclear plant. The ESBWR completely relies on passive safety systems for both normal and off-normal operating conditions, such as natural circulation, isolation condensers or gravity-driven cooling systems. The core of the ESBWR is shorter and the overall vessel height is larger than a conventional BWR, in an effort to maximize natural circula­tion and avoid the use of recirculation pumps or their associated piping. The US NRC provided the ESBWR with an advanced Safety Evaluation Report (SER) with no open items in August 2010, and the final design certification is expected by September 2011.