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Title: Mechanical environmental transport of actinides and ¹³⁷Cs from an arid radioactive waste disposal site

Particulate transport represents an important mechanism for actinides and fission products at the Earth's surface; soil samples taken in the early 1970's near the Subsurface Disposal Area (SDA) at Idaho National Laboratory (INL) provide a case study for examining the mechanisms and characteristics of actinide transport under arid conditions. Transuranic waste was disposed via shallow land burial at the SDA until shortly after a flooding event that occurred in 1969. In this study we analyze soils collected in the early 1970's for ¹³⁷Cs, ²⁴¹Am, and Pu using a combination of radiometric and mass spectrometric techniques. Two distinct ²⁴⁰Pu/²³⁹Pu isotopic ratios are observed for contamination from the SDA, with values ranging from at least 0.059 to 0.069. ²⁴¹Am concentrations are observed to increase only slightly in 0-4 cm soils over the ~40 year period since soil sampling, contrary to Markham's previous hypothesis that ²⁴¹Pu is principally associated with the 0-4 cm soil fractions (Markham 1978). The lack of statistical difference in ²⁴¹Am/²³⁹⁺²⁴⁰Pu ratios with depth suggests mechanical transport and mixing discrete contaminated particles under arid conditions. Occasional samples beyond the northeastern corner are observed to contain anomalously high Pu concentrations with corresponding low ²⁴⁰Pu/²³⁹Pu atoms ratios, suggesting the occurrence of "hotmore » particles;" application of a background Pu subtraction results in calculated Pu atom ratios for the "hot particles" which are statistically similar to those observed in the northeastern corner. Taken together, our data suggests that flooding resulted in mechanical transport of contaminated particles into the area between the SDA and the flood containment dike in the northeastern corner, following which subsequent contamination spreading resulted from wind transport of discrete particles.« less
 [1] ;  [2] ;  [2] ;  [3] ;  [3] ;  [3]
  1. Washington State Univ., Pullman, WA (United States); Idaho National Lab. (INL), Idaho Falls, ID (United States)
  2. Washington State Univ., Pullman, WA (United States)
  3. Idaho National Lab. (INL), Idaho Falls, ID (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0265-931X; PII: S0265931X15300229
Grant/Contract Number:
2012-DN-130-NF0001-02; SC000410
Accepted Manuscript
Journal Name:
Journal of Environmental Radioactivity
Additional Journal Information:
Journal Volume: 148; Journal Issue: C; Journal ID: ISSN 0265-931X
Research Org:
Idaho National Laboratory, Idaho Falls, ID (United States)
Sponsoring Org:
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES Pu; Am-241; Cs-137; wind; flood; particulate