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[1] 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 GW of thermal power).

Overview of the design

Pressure vessel from the ABWR. 1: Reactor core 2: Control rods 3: Internal Water Pump 4: Steam pipeline to the Turbine generator 5: Cooling water flow to the core

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.

The first reactors to use internal recirculation pumps were designed by ASEA-Atom (now Westinghouse Electric Company by way of mergers and buyouts, which is owned by Toshiba) and built in Sweden. These plants have operated very successfully for many years.

The internal pumps reduce the required pumping power for the same flow to about half that required with the jet pump system with external recirculation loops. Thus, in addition to the safety and cost improvements due to eliminating the piping, the overall plant thermal efficiency is increased. Eliminating the external recirculation piping also reduces occupational radiation exposure to personnel during maintenance.

An operational feature in the ABWR design is electric fine motion control rod drives, first used in the BWRs of AEG (later Kraftwerk Union AG, now AREVA). Older BWRs use a hydraulic locking piston system to move the control rods in six-inch increments. The electric fine motion control rod design greatly enhances positive actual control rod position and similarly reduces the risk of a control rod drive accident to the point that no velocity limiter is required at the base of the cruciform control rod blades.

Certifications and approvals

In 1997 it was certified as a final design in final form by the U.S. Nuclear Regulatory Commission, meaning that its performance, efficiency, output, and safety have already been verified, making it bureaucratically easier to build it rather than a non-certified design.[2]

In 2013, following its purchase of Horizon Nuclear Power, Hitachi applied to the UK Office for Nuclear Regulation for assessment, which is likely to take from two to four years.[3]

In July 2016 Toshiba withdrew the U.S. design certification renewal for the ABWR because "it has become increasingly clear that energy price declines in the US prevent Toshiba from expecting additional opportunities for ABWR construction projects".[4]


The ABWR is licensed to operate in Japan, the United States and Taiwan.

Japan and Taiwan

As of December 2006, four ABWRs were in operation in Japan: Kashiwazaki-Kariwa units 6 and 7, which opened in 1996 and 1997, Hamaoka unit 5, opened 2004 having started construction in 2000, and Shika 2 commenced commercial operations on March 15, 2006. Another two partially re reactors at Lungmen in Taiwan, and one more (Shimane Nuclear Power Plant 3) in Japan. Work on Lungmen halted in 2014. Work on Shimane halted after the 2011 earthquake[5]

United States

On June 19, 2006 NRG Energy filed a Letter Of Intent with the Nuclear Regulatory Commission to build two 1358 MWe ABWRs at the South Texas Project site. On September 25, 2007, NRG Energy and CPS Energy submitted a Construction and Operations License (COL) request for these plants with the NRC. NRG Energy is a merchant generator and CPS Energy is the nation's largest municipally owned utility. The COL was approved by the NRC on February 9, 2016.[6] Due to market conditions, these two planned units may never be built and do not have a planned construction date.[7]

United Kingdom

Horizon Nuclear Power has plans to build ABWRs at Wylfa in Wales[8] and Oldbury in England.[9]


In comparison with comparable designs, the four ABWRs in operation are often shut down due to technical problems . The International Atomic Energy Agency documents this with the 'operating factor' (the time with electricity feed-in relative to the total time since commercial operation start). The first two plants in Kashiwazaki-Kariwa (block 6 & 7) reach total life operating factors of 70%, meaning that about 30% of the time, since commissioning, they were not producing electricity.[10][11] For example, in 2010 Kashiwazaki-Kariwa 6 had an operating capacity of 80.9%, and an operating capacity of 93% in 2011.[12] However, in 2008 it did not produce any power as the installation was offline for maintenance, and therefore had an operating capacity of 0% for that year.[12] In contrast other modern nuclear power plants like the Korean OPR-1000 or the German Konvoi show operating factors of about 90%.[13]

The output power of the two new ABWRs at the Hamaoka and Shika power plant had to be lowered because of technical problems in the power plants steam turbine section.[14] After throttling both power plants down, they still have a heightened downtime and show a lifetime operating factor under 50%.[15][16]

Reactor block[17] Net output power
(planned net output power)
Commercial operation
Operating Factor[18] since commissioning start
until 2011
HAMAOKA-5 1212 MW (1325 MW) 18.01.2005 46,7%
KASHIWAZAKI KARIWA-6 1315 MW 07.11.1996 72%[12]
KASHIWAZAKI KARIWA-7 1315 MW 02.07.1996 68,5%
SHIKA-2 1108 MW (1304 MW) 15.03.2006 47,1%


Plant Name Number of Reactors Rated Capacity Location Operator Construction Started Year Completed (First criticality) Cost (USD) Notes
Kashiwazaki-Kariwa Nuclear Power Plant 2 1356 MW Kashiwazaki, Japan TEPCO 1992,1993 1996,1996 First Installation
Shika Nuclear Power Plant 1 1358 MW Shika, Japan Hokuriku Electric Power Company 2001 2005
Hamaoka Nuclear Power Plant 1 1267 MW Omaezaki, Japan Chuden 2000 2005 On May 14, 2011 Hamaoka 5 was shut down by the request of the Japanese government.
Shimane Nuclear Power Plant Reactor 3 1 1373 MW Matsue, Japan Chugoku Electric Power Company 2007 Construction suspended in 2011
Longmen Nuclear Power Plant 2 1350 MW Gongliao Township, Republic of China Taiwan Power Company 1997 After 2017 $9.2 Billion Construction halted in 2014
Higashidōri Nuclear Power Plant 3 1385 MW Higashidōri, Japan Tohoku Electric Power and TEPCO No firm plans
Ōma Nuclear Power Plant 1 1383 MW Ōma, Japan J-Power 2010 After 2014 Under Construction, First nuclear plant for J-Power
South Texas Project 2 1358 MW Bay City, Texas, United States NRG Energy, TEPCO and CPS Energy $14 billion License granted 2016, construction is currently not scheduled[19]

ABWR-II design

A number of design variants have been considered, with power outputs varying from 600 to 1800 MWe.[20] The most developed design variant is the ABWR-II, started in 1991, an enlarged 1718 MWe ABWR, intended to make nuclear power generation more competitive in the late 2010s.[21] None of these designs have been deployed.

The new designs hoped to achieve 20% reductions in operating costs, 30% reduction in capital costs, and tight planned construction schedule of 30 months. The design would allow for more flexibility in choices of nuclear fuels.[22]

See also

References and notes

  2. "Design Certification Information Page - ABWR". Design Certification Applications. Federal Government of the United States, U.S. Nuclear Regulatory Commission, Rockville, MD, USA. June 3, 2009. Retrieved 2009-08-28.
  3. "ABWR set for UK design assessment". Nuclear Engineering International. January 16, 2013. Retrieved January 26, 2013.
  4. "Toshiba withdraws ABWR certification application". World Nuclear News. 1 July 2016. Retrieved 5 July 2016.
  5. url=
  10. Archived June 4, 2011, at the Wayback Machine.
  11. 1 2 3
  12. IAEA - Nuclear Power Reactors in the World - 2010 Edition - Vienna 2010
  13. IAEA Archived June 4, 2011, at the Wayback Machine.
  14. Power Reactor Information System of the IAEA: Japan: Nuclear Power Reactors - Alphabetic“ (englisch)
  15. NEPIS Manual
  16. NRG ends project to build new nuclear reactors
  17. "Nuclear Power in Japan". World Nuclear Association. October 22, 2012. Retrieved October 31, 2012.
  18. Katsumi Yamada1; Satoko Tajima; Masaaki Tsubaki; Hideo Soneda (September 15–19, 2003). "ABWR Design and Its Evolution - Primary System Design of ABWR and ABWR-II" (PDF). International Conference on Global Environment and Advanced Nuclear Power Plants. GENES4/ANP2003, Sep. 15-19, 2003, Kyoto, JAPAN - Paper 1161. Retrieved October 31, 2012.

External links

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