A coil assembly for separation of Xenon-133 from an off gas stream includes a coil flange having first and second sides and defining a flange inlet and outlet. The coil assembly further includes a coil positioned on the first side of the coil flange. The coil includes inlet and outlet portions and a helical portion having a double-helix configuration. The helical portion has a top positioned a first distance from the first side of the coil flange. The inlet portion extends through the flange inlet, the outlet portion extends through the flange outlet, and the helical portion is fluidly connected to the inlet and outlet portions. The coil assembly further includes a fluid control assembly attached to the second side of the coil flange, including inlet and outlet assemblies. The inlet portion is fluidly connected to the inlet assembly and the outlet portion is fluidly connected to the outlet assembly.