Technique for Producing a Continuous Interference-Free Stream of Argon-41 in Air

A monitoring system was developed for the detection of ¹³¹I in the presence of orders of magnitude higher concentrations of radioactive noble gas. During the course of this work, a technique was developed for producing a continuous air stream of ⁴¹ Ar required for testing this concept. The ⁴¹ Ar stream is produced by the neutron activation of air using a research reactor. The ⁴¹ Ar content of the air stream can be varied by many orders of magnitude by varying the reactor power level and the rate at which the air is pumped through a vertically positioned tube in or in front of the reactor. It was found that the neutrons also activate other air constituents, producing undesirable interference radionuclides. Selective filtering techniques have therefore been developed to remove these interference radionuclides from the ⁴¹ Ar air stream.