Radionuclides in shallow groundwater at Solid Waste Storage Area 5 North, Oak Ridge National Laboratory

Ashwood, T.L.; Marsh, J.D.

doi:10.2172/10141790

Cited by 2 publications

(1 citation statement)

References 4 publications

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“…Dai et al postulated that the difference in the isotope trends in the 1998 data may be the result of source-dependent control on 240 Pu speciation, namely the decay of 244 Cm to 240 Pu. 244 Cm was produced at SRS and the Oak Ridge National Laboratory for use in experimental programs as a heat source for isotopic electrical power generators , , and by 1968 approximately 5 kg had been produced at SRS. With an 18.1 year half-life and several decades since its release, it has the ability to serve as a primary 240 Pu source in SRS groundwater ( 243 Cm was also released, but at much lower levels that are insignificant for 239 Pu concentrations here).…”

Section: Resultsmentioning

confidence: 99%

Source-Dependent and Source-Independent Controls on Plutonium Oxidation State and Colloid Associations in Groundwater

Buesseler

Kaplan

Dai

et al. 2009

Environ. Sci. Technol.

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Plutonium (Pu) was characterized for its isotopic composition, oxidation states, and association with colloids in groundwater samples near disposal basins in F-Area of the Savannah River Site and compared to similar samples collected six years earlier. Two sources of Pu were identified, the disposal basins, which contained a 24Pu/l39Pu isotopic signature consistent with weapons grade Pu, and 244Cm, a cocontaminant that is a progenitor radionuclide of 24Pu. 24Pu that originated primarily from 244Cm tended to be appreciably more oxidized (Pu(V/VI)), less associated with colloids (approximately 1 kDa - 0.2 microm), and more mobile than 239Pu, as suggested by our prior studies at this site. This is not evidence of isotope fractionation but rather "source-dependent" controls on 240Pu speciation which are processes that are not at equilibrium, i.e., processes that appear kinetically hindered. There were also "source-independent" controls on 239Pu speciation, which are those processes that follow thermodynamic equilibrium with their surroundings. For example, a groundwater pH increase in one well from 4.1 in 1998 to 6.1 in 2004 resulted in an order of magnitude decrease in groundwater 239Pu concentrations. Similarly, the fraction of 239Pu in the reduced Pu(III/IV) and colloidal forms increased systematically with decreases in redox condition in 2004 vs 1998. This research demonstrates the importance of source-dependent and source-independent controls on Pu speciation which would impact Pu mobility during changes in hydrological, chemical, or biological conditions on both seasonal and decadal time scales, and over short spatial scales. This implies more dynamic shifts in Pu speciation, colloids association, and transport in groundwater than commonly believed.

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Section: Resultsmentioning

confidence: 99%

Source-Dependent and Source-Independent Controls on Plutonium Oxidation State and Colloid Associations in Groundwater

Buesseler

Kaplan

Dai

et al. 2009

Environ. Sci. Technol.

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Mobilization of transuranic radionuclides from disposal trenches by natural organic matter

McCarthy

Czerwinski

Sanford

et al. 1998

Journal of Contaminant Hydrology

136

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Allocation of Environmental Remediation Funds Using Economic Risk‐Cost‐Benefit Analysis: A Case Study

James

Huff

Trabalka

et al. 1996

Groundwater Monitoring Rem

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Efficient allocation of remediation resources is a critical need throughout the nation. Economic risk‐cost‐benefit analysis is an important tool for meeting this need. This paper provides site engineers, geologists, and managers with a conceptual understanding of economic risk‐cost‐benefit analysis and shows how it can be applied, even in situations where existing data are sparse or poor in quality. An example analysis is applied to the remediation of radioactive waste at Oak Ridge National Laboratory, in which the cost‐effectiveness is compared for two remediation alternatives: containment of the waste or monitoring only. A data‐worth analysis is also carried out to estimate the maximum justifiable exploration budget and the cost‐effectiveness of two proposed data collection programs. Results indicate that the methodology has potential in making robust remediation decisions regarding certain types of questions.

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Radionuclides in shallow groundwater at Solid Waste Storage Area 5 North, Oak Ridge National Laboratory

Cited by 2 publications

References 4 publications

Source-Dependent and Source-Independent Controls on Plutonium Oxidation State and Colloid Associations in Groundwater

Source-Dependent and Source-Independent Controls on Plutonium Oxidation State and Colloid Associations in Groundwater

Mobilization of transuranic radionuclides from disposal trenches by natural organic matter

Allocation of Environmental Remediation Funds Using Economic Risk‐Cost‐Benefit Analysis: A Case Study

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