An experimental study of transient thermal-hydraulics in LBE-cooled system using a single fuel rod simulator

As part of R and D support for safety design of Lead alloy cooled Fast Reactors (LFR) and Accelerator Driven Systems (ADS) dedicated for the transmutation of long-lived fission products, experiments were performed on a test facility named TALL to investigate thermal-hydraulics of an annular channel accommodating a single fuel rod simulator cooled by lead bismuth eutectic (LBE). This paper presents the measured thermal-hydraulic characteristics of transient and natural circulations which are of importance to safety assessment of lead alloy cooled systems. The transient scenarios examined include start-up, loss of heat sink, loss of pump, and loss of both primary and secondary flows. The experiments exhibit a benign response of the LBE-cooled system under the loss-of-pump transient, showing the maximum temperature of the rod below 550degC, thanks to the prompt establishment of natural circulation in the LBE loop. The comparison of the results with the data obtained from the previous tests conducted on the same facility but with other test sections provides additional insights on how the characteristics of a LBE-cooled system may affect its thermal-hydraulics and dynamic response. (author)