A PROBABILISTIC ESTIMATION OF ATMOSPHERIC TRITIUM DOSE

A radiation dose distribution has been calculated for an individual ex posed to tritium oxide (tritiated water vapor) in the atmosphere. A sp ecific activity model was used that is similar to that detailed in the Nuclear Regulatory Commission's Regulatory Guide 1.109. The values of 19 parameters are sampled consistent with assigned probability distri butions using a Latin Hypercube approach(dagger). Dose was estimated a ssuming a concentration of tritium in atmospheric moisture of 0.13 +/- 0.16 Bq mL-1. Conventional dosimetric methods for tritium that were c onsistent with the Regulatory Guide result in an estimate of 0.63 muSv for annual exposures to airborne tritiated water. For the same atmosp heric tritium concentration, the estimated dose distribution is lognor mal and ranges from 0.08-3.2 muSv (at 95% confidence) with a median va lue of 0.59 muSv and a 95th percentile of 2.6 muSv.