Assessment of the system code through thermal-hydraulic test with He supplying system using the first wall mockup for the Korean He cooled test blanket

Abstract

Through consideration of the requirements for a DEMO-relevant blanket concept,Korea (KO) has proposed a He Cooled Molten Lithium (HCML) Test Blanket Module (TBM) for testing in the International Thermonuclear Experimental Reactor (ITER). The performance analysis for thermal-hydraulics and safety analysis for an accident caused by loss of a coolant for the KO TBM have been carried out with a commercial CFD code, ANSYS-CFX and system code,GAMMA (GAs Multicomponent Mixture Analysis). In order to verify the codes,the preliminary study was performed by Lee with a single TBM First Wall (FW) mock-up made from the same material as the KO TBM, ferritic martensitic steel,using the 6 MPa nitrogen gas loop. The test was performed at pressures of 11, 19 and 29 bar and under various flow rates ranging from 0.63 to 2.44 kg/min with a constant wall temperature condition. In the present study, several points in experiment were modified for satisfying KO TBM condition; adopting constant wall heat flux condition using high heat load test facility and using helium as a coolant etc. A thermal-hydraulic test was performed with the newly constructed He loop, in which the design pressure and temperature were 9 MPa and 500 oC, respectively. In the experiment, the same mock-up was used but the number of installed thermocouples was increased from 8 to 17 to enhance the accuracy of validation for CFX-11.0. And the test was performed under the conditions of 8 MPa pressure, and 70m/s velocity, which are the same conditions of the KO TBM FW. One-side of the mock-up was heated with constant heat flux, 0.5 MW/m2 using graphite heating system KoHLT-2(Korea Heat Load Test Facility-2). The wall temperatures were measured by installed thermocouples and they show a strong parity with codes results simulated with the same test conditions. By the aid of CFX-11, heat transfer coefficient was calculated from experiment. And this result was compared with the heat transfer coefficient from GAMMA output. Through the comparison, it was found that 2 results have different tendency with one another. And because GAMMA code adapts Dittus-Boelter correlation for analyzing heat transfer phenomena, and using the film temperature not bulk temperature, 2 code calculations showed different results. After confirming these problems, modification of GAMMA code was performed. And modified GAMMA code showed good agreement with CFX-11.0 results.