Studies of super-critical CO2 gas turbine power generation fast reactor (Contract research, translated document)

The following studies have been executed for a super-critical CO2 turbine system of an SFR. (1) Preliminary design of a SFR adopting a super-critical CO2 cycle turbine. Preliminary system design of an SFR that adopts a super-critical CO2 cycle turbine has been made. This SFR system eliminates secondary sodium circuits because of no sodium/water reaction. The power generation efficiency of the SFR has been estimated to be approximately 42%. Compared to a conventional SFR that adopts a steam Rankine cycle with secondary sodium circuits, the volume of the reactor building of the SC-CO2 SFR has been reduced by 20%. (2) Thermal-hydraulic experiment of a super-critical CO2 cycle loop. A test loop that simulates a super-critical CO2 whole cycle was fabricated. An electrical heater was used for a heat source of the test loop. The high efficiency of the compressor has been experimentally confirmed near the super-critical region. The temperature efficiencies of PCHE recuperators have been approximately 98-99% (hot leg), and the recuperators have exhibited high heat transfer performance. No significant flow instability has been observed in the test loop operation. (3) Liquid sodium/CO2 reaction test. Reaction tests have been executed by contacting a small amount of liquid sodium and CO2 gas. Continuous sodium/CO2 reactions with flame have occurred at the temperature higher than 570-580degC. Main reaction products have been Na2CO3 and CO gas. The reaction heat has been also measured to be 50-75kJ/Na-mol. (4) Computer code safety analysis for tube failure of sodium/CO2 heat exchanger. Safety calculation has been done for one double ended guillotine tube failure (1 DEG) of a helical coil type sodium/CO2 heat exchanger. The analysis has showed that the maximum pressure in the primary sodium circuit is 0.28MPa due to a gas leak. It has been, however, below the allowed level of the primary circuit structural integrity. The void reactivity of the reactor core has reached to 0.046$, and it has had no affect to the core safety. The layer thickness of the solid reaction product (Na2CO3) on fuel assemblies has been estimated to be at most 10mm, and no sodium flow blockage has occurred in the assemblies. (5) Material test in super-critical CO2. The corrosion and carbonization data of 12Cr steel and 316FR have been acquired in high temperature super-critical CO2 flow environment. No breakaway phenomenon has been observed in 5000hour test in both the materials. The corrosion of 12Cr steel has increased with parabolic curve, and the amount of the corrosion has been 170g/m2 after an exposure of 600degC-5000hours. The amount of corrosion of 316FR has been 5g/m2 in the same test condition (600degC-5000hours), and it has showed a good corrosion resistant property. (author)