Three-dimensional plume dynamics in the vadose zone: PORFLO-3 modeling of a defense waste leak at Hanford.

摘要

In 1973, approximately 450 m(sup 3) of liquid containing radioactive and chemical wastes leaked from the 241-T-106 single-shell tank into the vadose zone at the US Department of Energy's Hanford Site in south-central Washington State. The extent of the (sup 137)Cs, (sup 144)Ce, and (sup 106)Ru contaminant plumes in the vadose zone was estimated in 1973 and 1978 by gamma spectrometry in monitoring wells. Using site data and the PORFLO-3 computer model, a three-dimensional, transient plume migration model was developed for (sup 106)Ru and (sup 137)Cs. The model was calibrated to the 1973 measured plumes of (sup 106)Ru and (sup 137)Cs. The calibrated model was then used to study plume migration up to 1990. The simulated (sup 106)Ru distribution for 1978 extended deeper than reported values. The simulated distribution of (sup 137)Cs for 1978 approximated the measured distribution; the 1973 and 1978 (sup 137)Cs distributions are similar because of the long half-life and high sorption coefficient of (sup 137)Cs. 8 figs., 15 refs.