Sodium-Cooled Fast Reactor (SFR)

The SFR uses liquid sodium as the reactor coolant, allowing high power density with low coolant volume fraction and operation at low pressure. While the oxygen-free environment prevents corrosion, sodium reacts chemically with air and water and requires a sealed coolant system.

Plant size options under consideration range from small, 50 to 300 MW_e, modular reactors to larger plants up to 1 500 MW_e. The outlet temperature is 500-550°C for the options, which allows the use of the materials developed and proven in prior fast reactor programs.

The SFR closed fuel cycle enables regeneration of fissile fuel and facilitates management of minor actinides. However, this requires that recycle fuels be developed and qualified for use. Important safety features of the Generation IV system include a long thermal response time, a reasonable margin to coolant boiling, a primary system that operates near atmospheric pressure, and an intermediate sodium system between the radioactive sodium in the primary system and the power conversion system. Water/steam, supercritical carbon-dioxide or nitrogen can be considered as working fluids for the power conversion system to achieve high performance in terms of thermal efficiency, safety and reliability. With innovations to reduce capital cost, the SFR is aimed to be economically competitive in future electricity markets. In addition, the fast neutron spectrum greatly extends the uranium resources compared to thermal reactors. The SFR is considered to be the nearest-term deployable system for actinide management.

Much of the basic technology for the SFR has been established in former fast reactor programmes, and is being confirmed by the Phenix end-of-life tests in France, the restart of Monju in Japan and the lifetime extension of BN-600 in Russia. New programs involving SFR technology include the Chinese experimental fast reactor (CEFR) which was connected to the grid in July 2011, and India'’s prototype fast breeder reactor (PFBR) which is currently planned to go critical in 2013.

The SFR is an attractive energy source for nations that desire to make the best use of limited nuclear fuel resources and manage nuclear waste by closing the fuel cycle.

Fast reactors hold a unique role in the actinide management mission because they operate with high energy neutrons that are more effective at fissioning actinides. The main characteristics of the SFR for actinide management mission are:

• Consumption of transuranics in a closed fuel cycle, thus reducing the radiotoxicity and heat load which facilitates waste disposal and geologic isolation.

• Enhanced utilisation of uranium resources through efficient management of fissile materials and multi-recycle.

High level of safety achieved through inherent and passive means also allows accommodation of transients and bounding events with significant safety margins.

The reactor unit can be arranged in a pool layout or a compact loop layout. Three options are considered:

• A large size (600 to 1 500 MW_e) loop-type reactor with mixed uranium-plutonium oxide fuel and potentially minor actinides, supported by a fuel cycle based upon advanced aqueous processing at a central location serving a number of reactors.

• An intermediate-to-large size (300 to 1 500 MW_e) pool-type reactor with oxide or metal fuel.

• A small size (50 to 150 MW_e) modular-type reactor with uranium-plutonium-minor-actinide-zirconium metal alloy fuel, supported by a fuel cycle based on pyrometallurgical processing in facilities integrated with the reactor.

References

• Baque F., K. Paumel, G. Cornloup, M.A. Ploix and J.M. “Augem, Non-destructive Examination of Immersed Structures within Liquid Sodium,” ANIMMA 2011, Ghent, June 6-9 (2011).

• Joo Y.S., C.G. Park, J.B. Kim and S.H. Lim, “Development of Ultrasonic Waveguide Sensor for Under-sodium Inspection in a Sodium-cooled Fast Reactor,” NDT&E International 44, pp.239-246 (2011).

• Floyd J., N. Alpy, D. Haubensack, G. Avakian and G. Rodriguez, “On-design Efficiency Reference Charts for the Supercritical CO₂ Brayton Cycle coupled to a SFR,” Proc. ICAPP2011, Nice, France, 2-5 May 2011, Paper 11054.

• Moisseytsev A. and J.J. Sienicki, “Dynamic Simulation and Control of the S-CO₂ Cycle: From Full Power to Decay Heat Removal,” Proc. ATH ‘12, Embedded Topical Meeting of ANS 2012 Winter Meeting, San Diego, CA, USA, 11-15 November 2012, Paper 6461.

• Sienicki J. J. et. al., “Synthesis of Results Obtained on Sodium Components and Technology Through the Generation IV International Forum SFR Component Design and Balance-of-Plant Project,” Proc. FR13, Paris, France, 4-7, March 2013.

• Delage F. et. al., “Status of advanced fuel candidates for Sodium Fast Reactor within the Generation IV International Forum”, J. of Nuclear Materials, NUMA46668 (to be published), 2013.