Field evaluation of passive HTO-in-air samplers at Chalk River Laboratories

A field trial was carried out in which passive HTO-in-air samplers were used in parallel with traditional gas-washing bottle-(bubbler)-based samplers in an HTO-in-air sampling program. The passive samplers were considerably easier to service than bubblers; however, as prepared during the field trial, the passive samplers were more sensitive to HTO contamination than the bubbler-based samplers. Since HTO contamination would result in an overestimation of the average HTO-in-air concentration in the sampling area, any resulting error would be on the side of safety. In general, the passive-sampler measurements agreed well with the bubbler measurements. Although the samplers used in our field trial proved to work satisfactorily, passive samplers with a sampling rate of 1 L/d were deemed more appropriate for the required sampling periods. The 1 L/d samplers would be appropriate for sampling periods of up to one week with a 1 mL charge of water, or up to 1 month with a 10 mL charge of water. Several 1 L/d samplers have been designed and built and they are being evaluated. We anticipate implementing a routine sampling program based on the 1 L/d sampler in the near future