Experimental setup development and preliminary results on radioactive noble gas transport in liquid lead using the gas-jet facility at PSI

Radioisotopes of Kr and Xe are proposed as indicators for the detection and localization of nuclear fuel cladding failures in lead-cooled fast reactors (LFRs). To address existing knowledge gaps regarding the transport behavior of Kr and Xe in liquid lead coolant, a dedicated experimental setup was developed to enable the controlled introduction, extraction, trapping, and real-time monitoring of radioactive noble gases. Cryogenic traps were designed and demonstrated to efficiently capture (> 85%) and quantitatively measure Xe radioisotopes. Offline transport experiments were performed using 135 Xe collected from the PSI gas-jet facility. Comparable recovery yields obtained for different Xe injection configurations indicated no measurable effect of liquid Pb on the overall transport of 135 Xe under the investigated conditions. Mass-balance calculations further suggested that the measured recovery yield was influenced primarily by gas circulation within the experimental system. The developed experimental setup provides a basis for future investigations of noble-gas transport and the validation of fuel failure detection methods in LFRs.