[mrgoodbytes87]

I've spent the last couple of years working on getting the radionuclide analysis program up and running at my work and I need some assistance with this method. We have had a constant problem with passing our Performance Test studies, which are made up using Th-230 as an alpha emitter and Cs-137 as a beta emitter. Our gas-flow proportional counter is calibrated using mass attenuation standards prepared with Th-230 and Sr/Y-90.

Initially, the problem originated (I believe) from using a Meeker burner to flame the planchets, which resulted in volatilization of the Cs-137 and a low beta result. We tweaked the method by using a muffle furnace at 400C, which is hot enough to convert nitrates to oxides without over-volatilization of the Cs-137. This improved the beta recovery, but the recovery is still too low (off by ~30%). I'm wondering if anyone knows of a different method that allows calibration with Cs-137 or some work around that I've missed. Any and all advice is appreciated.