Abstract. The paper covers the results of VVER core reflooding studies in fuel assembly (FA) mockup of 126 fuel rod simulators with axial power peaking. The experiments were performed for two types of flooding. The first type is top flooding of the empty (steamed) FA mockup. The second type is bottom flooding of the FA mockup with level of boiling water. The test parameters are as follows: the range of the supplied power to the bundle is from 40 to 320 kW, the cooling water flow rate is from 0.04 to 1.1 kg/s, the maximum temperature of the fuel rod simulator is 800°C and the linear heat flux is from 0.1 to 1.0 kW/m. The test results were used for computer code validation.
Two computational fluid dynamic (CFD) benchmarks have been performed to assess the\ud
prediction accuracy and sensitivity of CFD codes for heat transfer in different geome-\ud
tries. The first benchmark focused on heat transfer to water in a tube (first benchmark),\ud
while the second benchmark covered heat transfer to water in two different channel geo-\ud
metries (second benchmark) at supercritical pressures. In the first round with the experi-\ud
mental data unknown to the participants (i.e., blind calculations), CFD calculations were\ud
conducted with initial boundary conditions and simpler CFD models. After assessment\ud
against measurements, the calculations were repeated with the refined boundary condi-\ud
tions and material properties in the follow-up calculation phase. Overall, the CFD codes\ud
seem to be able to capture the general trend of heat transfer in the tube and the annular\ud
channel but further improvements are required in order to enhance the prediction accu-\ud
racy. Finally, sensitivity analyses on the numerical mesh and the boundary conditions\ud
were performed. It was found that the prediction accuracy has not been improved with\ud
the introduction of finer meshes and the effect of mass flux on the result is the strongest\ud
among various investigated boundary conditions
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.