US-ABWR design features and flex concept for extended loss of AC power events

Abstract

The US-Advanced Boiling Water Reactor (ABWR), certified by the USNRC, is a third generation, evolutionary boiling water reactor design which is the reference for the South Texas Project Units 3 and 4 (STP3&4) Combined License Application (COLA) and incorporates numerous design and technology enhancements for improved safety performance. Nuclear Innovation North America (NINA) is the License Applicant for this new build project, and Toshiba is the selected primary technology contractor. The STP3&4 project is finishing the USNRC technical review of the COLA and the final safety evaluation report (FSER) is scheduled to be issued by the USNRC in 2015. Following the accident at the Fukushima Dai-ichi plant, the US-ABWR has been further reviewed for Beyond Design Basis Event (BDBE) safety using industry and regulatory guidance for USNRC Order EA-12-049 "Order Modifying Licenses with Regard to Requirements for Mitigation of Beyond Design Basis External Events (BDBEE)". By virtue of the design approach, the US-ABWR is capable of providing an indefinite coping period for a station blackout. The use of installed systems with extended coping times is a significant advantage of the US-ABWR compared to most of the plants currently operating in the U.S. In addition, STP3&4 design incorporates enhancements consistent with the current US industry Diverse and Flexible Coping Strategies (FLEX) initiative. This paper summarizes the progress of the US-ABWR licensing and describes the technology and features of the US-ABWR design that contribute to safety post-Fukushima.