Effect of Soil Type on the Extractability of ²³⁷Np, ²³⁹Pu, ²⁴¹Am and ²⁴⁴Cm as a Function of pH

Technical Report · Sat Sep 01 00:00:00 EDT 1979

DOI:https://doi.org/10.2172/5806329· OSTI ID:5806329

Nishita, H. ^[1]; Wallace, A. ^[1]; Romney, E. M. ^[1]; Schulz, R. K. ^[1]

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1. Univ. of California, Los Angeles, CA (United States)

The extractability of ²³⁷Np, ²³⁹Pu, ²⁴¹Am and ²⁴⁴Cm from widely different kinds of soils as a function of pH was determined using an equilibrium batch technique. Hydrochloric acid or NaOH was used to adjust the pH. The sorption and extractability of the transuranics studied varied considerably with pH and the kind of soil. A general pattern of extractability that is common to all of the transuranics studied was exhibited to a varying degree by each mineral soil (except the calcareous soil). Typically the extractability was relatively high under strongly acidic condition, particularly below pH 2. Then, as the pH increased, there was a zone of rapid decrease, which was followed by a zone of relatively low extractability. Above the latter zone, there was an increase to a peak with increasing pH and then a decline. The organic soil used differed from this general pattern in that it showed a progressive increase of extractability in the alkaline pH range instead of peaking and declining. Among the mineral soils, the extractability of ²³⁷Np was markedly greater than those of ²³⁹Pu, ²⁴¹Am, or ²⁴⁴Cm in the pH range below pH 6. Above this pH, the relative extractability of the radionuclides depended on the soil. The extractability of ²⁴⁴Cm was practically the same as that of /sup 241/Am over the entire pH range. The relative magnitudes of the distribution coefficient, K_d, values around the pH levels of the soils were ²³⁷Np ²³⁹Pu ²⁴¹Am, ²⁴⁴Cm. Soil organic matter and hydrous oxides of Al, Fe, and Mn appeared to influence the sorption and extractability of the transuranics studied.

• Research Organization: Univ. of California, Los Angeles, CA (United States)
• Sponsoring Organization: USDOE; USNRC
• DOE Contract Number: EY-76-C-03-0012
• OSTI ID: 5806329
• Report Number(s): UCLA--12-1192; NUREG/CR-0997
• Country of Publication: United States
• Language: English

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ACTINIDE NUCLEI
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NEPTUNIUM 237
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PLUTONIUM 239
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YEARS LIVING RADIOISOTOPES
pH