A prototype of an in-line vacuum-distillation sodium sampler has been successfully tested in the nonradioactive secondary sodium system at EBR-II. A 125-g sample of sodium is distilled in ∼3 h at an absolute pressure of 5µ and a temperature range of 675 to 700°F. Sample size is reproduced to better than 1%. The sampler is used to determine nonvolatile trace-metal and sodium-compound concentrations in the ppb-ppm range. Results of tests with the prototype are being used to design a model for installation in the radioactive EBR -II primary sodium system.