americium. During the same study, elution characteristics of plutonium were determined in several of the soils for which Kg had been measured. Figure 11 shows the distribution of plutonium in three of those soils. As the Ky increased so did the retention of plutonium in the upper- most portions of the soil column. Considerable amounts of ?3"pu are presently being used as heat sources for power generators particularly in space applications, Patterson et al. 300 | se FF FETT T ¥ cr FO FU eT a T (1976) conducted an experiment to determine the fate of metallic ?38py under environmental conditions. Within environmental test chambers, a77"%Pu heat source specimen or fragments thereof, were placed on soils under simulated climatic conditions. The first “rain water" rr that percolated through the test soil contained a small amount of 238 py. This very rapid 7?"pu breakthrough indicated that some of the material that spalled from the Y, C —F- ~a — E ae? E —« + T Ly Lo 7 4,5 , 29 1 4 Ww | a 7 t Np (Na .05 um diam., except for the occasional presence of a particle as large as 4 ym. Patterson presented a number of soil profiles taken in the test chamber at the conclusion of the long-term ] ; fo L by water were less than leaching experiments. ° Kd— 23’Np (ml/g) look- fuel was very small particulate or colloidal. Aito-radiography of the percolated rain water revealed plutonium oxide particles of 6.05 to 0.9 um diam. with a count median diameter of .095 \im. Nearly all of the plutonium oxide particles carried through the soil Using auto-radiography, it was observed that each plutonium oxide particle was associated with one microscopically visible soil particle. This indicated that trapping of plutonium oxide particles by soil was not a matter of filtration of the fine oxide particles, but that there was agglomeration of individual oxide and soil particles. . A recent, highly specialized, study on the distribution of actinides under waste disposal trenches at the Hanford Reservation in Washington was reported by Price and Ames (1976). This program was established to assess the future radiological impact of actinides in the ground underlying retired trenches and to develop methods for the long term control of contaminants. Samples were taken at 5 cm, 50 cm, 2 m, 4.5 m, and 9 m below the trench floor using a core sampler driven 0.5 m or 1 m for each profile increment. Both 7?%pu (799.?"%pu) and 2“lam were determined on the sediments from the core samples. the profiles is reproduced in Fig. 12. One of Examination of the core samples revealed both particulate and nonparticulate plutonium that may have been responsible for the observed distribution. Np (Ca 4 culate fraction consisted of discreet plutonium particles, The parti2 to 25 um diam., and was restricted to the top portions of the sediment columns. Price and Ames (1976) discussed in some detail hydrolysis and the possible soil-mineral-plutonium reactions which may have been responsible for sorption of plutonium in the lower profile fractions. 1.0 l 0.01 0.001 . a Fig. 10. | | 241 Am I Ou 0.01 and 237 Np Carolina Soil Ltd a Lett btoeee Distribution Coefficients 1.0 0.1 (Kg) for Sout (Adapted from Routson et al., 62 i Nat (M Ca** (M) Similar coring studfes by Holcomb ect al. Savannah River Plant. h 1975). 63 (1976) are in progress at