Continuous measurement of uranium concentrations with the laser spark

Continuous measurement of uranium concentrations in liquid streams is necessary for criticality safety, process control, and nuclear materials accounting. The solutions may contain high concentrations of fission products or neutron emitters that interfere with nondestructive gamma-ray, neutron, or X-ray techniques. A technique that is rapid, noninvasive, unaffected by radioactivity, and that requires neither sample handling nor preparation is desirable. The laser spark, more formally known as laser-induced breakdown spectroscopy (LIBS), appears to have all of these properties. The use of LIBS to analyze static uranium solutions at concentrations of interest for process stream analysis has been successfully demonstrated. A test loop and flow cell have been constructed and experiments are being conducted on flowing streams. The results of these experiments will be reported. The authors plan to investigate its applicability to the determination of uranium, plutonium, americium, thorium, zirconium, and others in the future. It is probably impossible to measure isotopic compositions because the high electrical field in the laser spark produces Stark broadening of the uranium emission lines