Advanced boiling water reactor
The advanced boiling water reactor (ABWR) is a Generation III boiling water reactor. The ABWR is currently offered by GE Hitachi Nuclear Energy (GEH) and Toshiba. The ABWR generates electrical power by using steam to power a turbine connected to a generator; the steam is boiled from water using heat generated by fission reactions within nuclear fuel.
Boiling water reactors (BWRs) are the second most common form of light water reactor with a direct cycle design that uses fewer large steam supply components than the pressurized water reactor (PWR), which employs an indirect cycle. The ABWR is the present state of the art in boiling water reactors, and is the first Generation III reactor design to be fully built, with several reactors complete and operating. The first reactors were built on time and under budget in Japan, with others under construction there and in Taiwan. ABWRs are on order in the United States, including two reactors at the South Texas Project site.
The standard ABWR plant design has a net electrical output of about 1.35 GW (3.926 MW of thermal power).
The ABWR represents an evolutionary route for the BWR family, with numerous changes and improvements to previous BWR designs.
Major areas of improvement include:
The RPV and Nuclear Steam Supply System (NSSS) have significant improvements, such as the substitution of RIPs, eliminating conventional external recirculation piping loops and pumps in the containment that in turn drive jet pumps producing forced flow in the RPV. RIPs provide significant improvements related to reliability, performance and maintenance, including a reduction in occupational radiation exposure related to containment activities during maintenance outages. These pumps are powered by wet-rotor motors with the housings connected to the bottom of the RPV and eliminating large diameter external recirculation pipes that are possible leakage paths. The 10 internal recirculation pumps are located at the bottom of the annulus downcomer region (i.e., between the core shroud and the inside surface of the RPV). Consequently, internal recirculation pumps eliminate all of the jet pumps in the RPV, all of the large external recirculation loop pumps and piping, the isolation valves and the large diameter nozzles that penetrated the RPV and needed to suction water from and return it to the RPV. This design therefore reduces the worst leak below the core region to effectively equivalent to a 2-inch-diameter (51 mm) leak. The conventional BWR3-BWR6 product line has an analogous potential leak of 24 or more inches in diameter. A major benefit of this design is that it greatly reduces the flow capacity required of the ECCS.
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