Sodium-cooled reactors

Other newer designs include the advanced, gas-cooled reactor (AGR), Canadian deuterium reactor (CANDUR), sodium-cooled reactor (SCR), sodium-heated reactor (SHR), and fast breeder reactor (FBR). These reactors employ either natural or enriched uranium fuels that may be modified in some way (e.g., graphite-moderated fuels). 

It should be mentioned that boiling within a liquid metal-cooled reactor (such as a sodium-cooled reactor) is an accident condition and may give rise to rapid fuel failure. In designing a reactor core, on the other hand, sodium boiling should... 

Peppier, W., E. G. Schlechtendhl, and G. F. Schultheiss, 1970, Investigation of the Dynamics of Boiling Events in Sodium-Cooled Reactors, Nuclear Eng. Design 14 23-42. (4)... 

The application of this method is shown in Figure 5, where hydrogen is produced by the nuclear-heated steam methane reforming (using a sodium-cooled reactor and natural gas), and then this hydrogen is converted into electricity in the alkaline-type fuel cell. 

Figure 5 Application of synergistic electric generation using natural gas and sodium cooled reactor...

Sodium-cooled reactor (SCR), with an indirect steam power cycle and... 

Chikazawa et al.86,87 evaluated the feasibility of small sodium-cooled reactor as a diversified power source in terms of economical and safety potential and reviewed... 

Chikazawa, Y., Okano, Y., Hori, T., Ohkubo, Y., Shimakawa, Y., and Tanaka, T. A feasibility study on a small sodium cooled reactor as a diversified power source. Journal of Nuclear Science and Technology, 2006, 43 (8), 829. 

The thermal and nuclear properties of sodium (it scatters neutrons without absorbing them) made it the heat exchange fluid of choice for fast-flux reactors in spite of its nasty chemical properties when exposed to air or water. The French Superphenix, a commercial-scale sodium cooled reactor, was beset with technical problems, but demonstrated that fast-flux reactors can produce electric power at the 1000 MW level. 

Y. Chikazawa et al., Conceptual Design of Hydrogen Production Plant with Thermochemical and Electrolytic Hybrid Method Using a Sodium Cooled Reactor , ICAPP 05-5084, 2005 International Congress on Advances in Nuclear Power Plants, Seoul (May 2005). 

In the 1980s, a new generation of nuclear fission reactors called Integral Fast Reactors was under development by the U.S. Department of Energy. This was a liquid sodium cooled reactor which was expected to be safer with minimal corrosion. It was also to be more efficient and able to use 15 to 20% of the uranium fuel instead of 1 to 2%. 

Because thorium metal is unattacked by sodium at temperatures up to 500°C, it is compatible with the coolant in sodium-cooled reactors. 

The ability of sodium-cooled reactors to produce steam at current commercial conditions of superheat and pressure has resulted in considerable design effort to prevent this direct leakage. At present, two methods are available to reduce the probability of direct leakage to a safe level. The first of these employs an intermediate alkali-metal heat-transfer system between the sodium reactor coolant and the steam generating system. This method is generally applicable only when space limitations are not present. 

Figure 2 (A)- D) Pictures of a disposed submarine at a depth of c. 30 m in the Stepovogo Fiord, east coast of Novaya Zemyla. The submarine contains a sodium-cooled reactor with spent fuel. Some of the hatches of the submarine are open which allows for free circulation of water inside the vessel.

The basic nuclear reactor fuel materials used today are the elements uranium and thorium. Uranium has played the major role for reasons of both availability and usability. It can be used in the form of pure metal, as a constituent of an alloy, or as an oxide, carbide, or other suitable compound. Although metallic uranium was used as a fuel in early reactors, its poor mechanical properties and great susceptibility to radiation damage excludes its use for commercial power reactors today. The source material for uranium is uranium ore, which after mining is concentrated in a "mill" and shipped as an impure form of the oxide UjO (yellow cake). The material is then shipped to a materials plant where it is converted to uranium dioxide (UO2), a ceramic, which is the most common fuel material used in commercial power reactors. The UO2 is formed into pellets and clad with zircaloy (water-cooled reactors) or stainless steel (fast sodium-cooled reactors) to form fuel elements. The cladding protects the fuel from attack by the coolant, prevents the escape of fission products, and provides geometrical integrity. 

Safety and Economic Characteristics of a 100-MWe Fast Sodium-Cooled Reactor Design... 

Maintaining required purity of the coolant and cover gas is a necessary condition for successful operation of any reactor facility. In case of sodium cooled reactor these requirements are determined by Specifications on sodium coolant for nuclear reactors (TV - 6 - 01 - 788 - 73) and Rules of the BN-600 reactor operation. They are most rigid for the primary circuit, since nuclear safety of the reactor is immediately concerned. 

BRcore l even in sodium cooled reactor (on condition that higher density nitride fuel is used), in spite of elimination of both radial and axial fertile blankets. 

Also, it should be noted that sodium cooled reactor is nuclear technology system, having maximum flexibility extent, i.e. it is capable of assuring the following operation modes in accordance with the user requests ... 

Thus, sodium cooled reactors as well would fully come up to the concept of development of nuclear technology systems having no enriched uranium, declared at the UN Millenium Summit. Moreover, no Pu stocks will exist outside LMFR with attached plant for fuel reprocessing and fabrication (e g. similar to that developed at the ANL for the IFR). 

Thus, in terms of thermohydraulics, sodium cooled reactor parameters such as pressure drop (5-6 times lower) and required pumping power (3-4 times lower) are preferable. 

Local pressure drop in the subassemblies (for instance that due to spacing elements) can make significant contribution to the total pressure drop [6.7, 6.8]. It is unlikely, that spacing elements used in the fuel subassemblies of sodium cooled reactors (wire, etc.) could be applied for lead cooled reactors. Therefore, if the new spacers are designed, the available data cannot be applied. This would require special-purpose experiments not only for determining hydrodynamics, but to test structure for vibration and attrition. 

The compact sodium cooled reactor facility KNK (20 MW(e)) was shut down in 1991 and currently is in the state of advanced dismantling. The nuclear fuels and sodium were disposed off. All systems were removed. Disassembly of the activated reactor tank and its internals has been started. Complete dismantling of the reactor building is planned to be completed by... 

The American Nuclear Society standard, "Design Bases for Facilities for LMFBR Spent Fuel Storage in Liquid Metal Outside the Primary Coolant Boundary," ANSI/ANS-54.2-1985, provides guidance for the storage of fuel from sodium cooled reactors. 

Pothergill J R and Macleod I D. "Ultrasonic inspection systems for sodium cooled reactors." TRG report 1981(R) 1973. 

The key issues for sodium cooled reactors are addressed in the near and medium term design and development programme. This programme takes advantage of international collaboration and has as an important objective the expansion of the collaboration. 

Prototype Fast Breeder Reactor (PFBR) is a 500 MWe pool type sodium cooled reactor. The 4-loop concept which was taken as the reference for the preliminary design and analysis during 1985-1992 has been reviewed thoroughly mainly from economic considerations. The outcome of these studies helped to arrive at a compact 2-loop concept which is expected to be the fore-runner of commercial FBR in the country. For the 2-loop concept, all the major conceptual issues have been finalised. The main options selected are given below (fig 3)... 

The LS-VHTR combines technologies from three other reactor technologies (molten-salt reactors, high-temperature reactors, and sodium-cooled reactors) consequently, refiieling technology and refueling options are also based on these technologies. 

Refueling differences exist between sodium-cooled reactors and the AHTR. For the AHTR, refueling temperatures are somewhat higher, the fuel geometry is different, the power density of the prismatic-block fuel-type SNF is 1 to 2 orders of magnitude lower, the vapor pressures of the liquid salts are much lower than those of sodium, and the liquid salt is transparent whereas the sodium is opaque. This section provides discussions of design considerations for the LS-VHTR fuel-handling system relative to sodium-cooled fast reactors. 

Inspection, refueling, and maintenance test facility (engineering). Reactor inspection, maintenance, and refueling operations will occur at high temperatures relative to sodium-cooled reactors. At the same time, molten salts are transparent and allow for the use of optical systems. There has been limited experience with lead-cooled reactors in the chemical industry at these temperatures. A facility is required to develop the technology and test designs for these operations. 

Typical Ccxjlant Characteristics for Water-, Gas-, and Sodium-Cooled Reactors... 

SAFETY AND ECONOMIC CHARACTERISTICS OF A 1000-MWe FAST SODIUM-COOLED REACTOR DESIGN... 

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