Jonathan S. Fruchter

Pattern of Bombardment-Produced Radionuclides in Rock 10017 and in Lunar Soil

A large number of radionuclides have been measured as a function of depth in lunar rock 10017 and in bulk fines. Data are reported on 10Be, 22Na, 26Al, 36Cl, 49V, 53mn, 54Mn 55Fe, 56Co, 57Co, and 59Ni and on upper limits for 46Sc, 48V, 51Cr, and 60Co. The results for several nuclides show striking evidence of excess surface production attributable to solar flare particles. Data for short-lived species, 56Co, 57CO, 54Mn, 55Fe, and 22Na, appear consistent with fluxes from known recent events. Long-lived species demonstrate the existence of solar flare protons and alphas at least for the last 105 to 106 years, at fluxes comparable to those now observerved.

Feasibility of In Situ Redox Manipulation of Subsurface Sediments for RDX Remediation at Pantex

This laboratory study was conducted to assess RDX (hexahydro-1,3,5-trinitro-1,3,5 triazine) abiotic degradation by chemically reduced sediments and other geochemical aspects of the application of this technology to remediation of RDX contamination in groundwater at the U.S. DOE Pantex facility...

300 Area Uranium Stabilization Through Polyphosphate Injection: Final Report

The objective of the treatability test was to evaluate the efficacy of using polyphosphate injections to treat uranium-contaminated groundwater in situ. A test site consisting of an injection well and 15 monitoring wells was installed in the 300 Area near the process trenches that had previously received uranium-bearing effluents. This report summarizes the work on the polyphosphate injection project, including bench-scale laboratory studies, a field injection test, and the subsequent analysis and interpretation of the results. Previous laboratory tests have demonstrated that when a soluble form of polyphosphate is injected into uranium-bearing saturated porous media, immobilization of uranium occurs due to formation of an insoluble uranyl phosphate, autunite [Ca(UO2)2(PO4)2•nH2O]. These tests were conducted at conditions expected for the aquifer and used Hanford soils and groundwater containing very low concentrations of uranium (10-6 M). Because autunite sequesters uranium in the oxidized form U(VI) rather than forcing reduction to U(IV), the possibility of re-oxidation and subsequent re-mobilization is negated. Extensive testing demonstrated the very low solubility and slow dissolution kinetics of autunite. In addition to autunite, excess phosphorous may result in apatite mineral formation, which provides a long-term source of treatment capacity. Phosphate arrival response data indicate that, under site conditions, the polyphosphate amendment could be effectively distributed over a relatively large lateral extent, with wells located at a radial distance of 23 m (75 ft) reaching from between 40% and 60% of the injection concentration. Given these phosphate transport characteristics, direct treatment of uranium through the formation of uranyl-phosphate mineral phases (i.e., autunite) could likely be effectively implemented at full field scale. However, formation of calcium-phosphate mineral phases using the selected three-phase approach was problematic. Although amendment arrival response data indicate some degree of overlap between the reactive species and thus potential for the formation of calcium-phosphate mineral phases (i.e., apatite formation), the efficiency of this treatment approach was relatively poor. In general, uranium performance monitoring results support the hypothesis that limited long-term treatment capacity (i.e., apatite formation) was established during the injection test. Two separate overarching issues affect the efficacy of apatite remediation for uranium sequestration within the 300 Area: 1) the efficacy of apatite for sequestering uranium under the present geochemical and hydrodynamic conditions, and 2) the formation and emplacement of apatite via polyphosphate technology. In addition, the long-term stability of uranium sequestered via apatite is dependent on the chemical speciation of uranium, surface speciation of apatite, and the mechanism of retention, which is highly susceptible to dynamic geochemical conditions. It was expected that uranium sequestration in the presence of hydroxyapatite would occur by sorption and/or surface complexation until all surface sites have been depleted, but that the high carbonate concentrations in the 300 Area would act to inhibit the transformation of sorbed uranium to chernikovite and/or autunite. Adsorption of uranium by apatite was never considered a viable approach for in situ uranium sequestration in and of itself, because by definition, this is a reversible reaction. The efficacy of uranium sequestration by apatite assumes that the adsorbed uranium would subsequently convert to autunite, or other stable uranium phases. Because this appears to not be the case in the 300 Area aquifer, even in locations near the river, apatite may have limited efficacy for the retention and long-term immobilization of uranium at the 300 Area site..

In Situ Redox Manipulation of Subsurface Sediments from Fort Lewis, Washington: Iron Reduction and TCE Dechlorination Mechanisms

The feasibility of chemically treating sediments from the Ft. Lewis, Washington, Logistics Center to develop a permeable barrier for dechlorination of TCE was investigated in a series of laboratory experiments.

300 Area Treatability Test: Laboratory Development of Polyphosphate Remediation Technology for In Situ Treatment of Uranium Contamination in the Vadose Zone and Capillary Fringe

A laboratory testing program has been conducted to optimize polyphosphate remediation technology for implementation through a field-scale technology infiltration demonstration to stabilize soluble, uranium-bearing source phases in the vadose zone and capillary fringe. Source treatment in the deep vadose zone will accelerate the natural attenuation of uranium to more thermodynamically stable uranium-phosphate minerals, enhancing the performance of the proposed polyphosphate remediation within the 300 Area aquifer. The objective of this investigation was to develop polyphosphate remediation technology to treat uranium contamination contained within the deep vadose zone and capillary fringe. This chapter presents the results of an investigation that evaluated the rate and extent of reaction between polyphosphate and the uranium mineral phases present within the 300 Area, and autunite formation as a function of polyphosphate formulation and concentration. This information is critical for identifying the optimum implementation approach and controlling the flux of uranium to the underlying aquifer during remediation. Results from this investigation may be used to design a full-scale remediation of uranium at the 300 Area of the Hanford Site.

Hanford 100-N Area In Situ Apatite and Phosphate Emplacement by Groundwater and Jet Injection: Geochemical and Physical Core Analysis

The purpose of this study is to evaluate emplacement of phosphate into subsurface sediments in the Hanford Site 100-N Area by two different technologies: groundwater injection of a Ca-citrate-PO4 solution and water-jet injection of sodium phosphate and/or fish-bone apatite. In situ emplacement of phosphate and apatite adsorbs, then incorporates Sr-90 into the apatite structure by substitution for calcium. Overall, both technologies (groundwater injection of Ca-citrate-PO4) and water-jet injection of sodium phosphate/fish-bone apatite) delivered sufficient phosphate to subsur¬face sediments in the 100-N Area. Over years to decades, additional Sr-90 will incorporate into the apatite precipitate. Therefore, high pressure water jetting is a viable technology to emplace phosphate or apatite in shallow subsurface sediments difficult to emplace by Ca-citrate-PO4 groundwater injections, but further analysis is needed to quantify the relevant areal extent of phosphate deposition (in the 5- to 15-ft distance from injection points) and cause of the high deposition in finer grained sediments.

100-NR-2 Apatite Treatability Test: High-Concentration Calcium-Citrate-Phosphate Solution Injection for In Situ Strontium-90 Immobilization

Following an evaluation of potential strontium-90 (90Sr) treatment technologies and their applicability under 100-NR-2 hydrogeologic conditions, the U.S. Department of Energy (DOE), Fluor Hanford, Inc. (now CH2M Hill Plateau Remediation Company [CHPRC]), Pacific Northwest National Laboratory, and the Washington State Department of Ecology agreed that the long-term strategy for groundwater remediation at the 100-N Area should include apatite as the primary treatment technology. This agreement was based on results from an evaluation of remedial alternatives that identified the apatite permeable reactive barrier (PRB) technology as the approach showing the greatest promise for reducing 90Sr flux to the Columbia River at a reasonable cost. This letter report documents work completed to date on development of a high-concentration amendment formulation and initial field-scale testing of this amendment solution.

Site Characterization Plan: Uranium Stabilization through Polyphosphate Injection

An initial feasibility study of options to treat the uranium plume at the 300-FF-5 Operable Unit considered hydraulic containment, slurry wall containment, and groundwater extraction as potential remedial action technologies. None were selected for interim action, and reduction of contamination levels by natural processes was considered a viable alternative while source removal actions continued. Subsequent planning for a Phase III feasibility study focused on methods that would reduce the concentration of uranium in the aquifer, including multiple methods to immobilize uranium using chemical-based technologies. Based on an initial technology screening, the polyphosphate technology was identified as the best candidate to treat the for further evaluation and selected for treatability testing. The overall objective of the polyphosphate treatability test is to evaluate the efficacy of using polyphosphate injections to treat uranium contaminated groundwater in situ. The objective of the work elements included in this site characterization plan is to collect site-specific characterization data that will be needed to design and implement a field-scale demonstration of the technology.

Use of Polyphosphate to Decrease Uranium Leaching in Hanford 300 Area Smear Zone Sediments

The primary objective of this study is to summarize the laboratory investigations performed to evaluate short- and long-term effects of phosphate treatment on uranium leaching from 300 area smear zone sediments. Column studies were used to compare uranium leaching in phosphate-treated to untreated sediments over a year with multiple stop flow events to evaluate longevity of the uranium leaching rate and mass. A secondary objective was to compare polyphosphate injection, polyphosphate/xanthan injection, and polyphosphate infiltration technologies that deliver phosphate to sediment.

Treatability Test Plan for an In Situ Biostimulation Reducing Barrier

This treatability test plan supports a new, integrated strategy to accelerate cleanup of chromium in the Hanford 100 Areas. This plan includes performing a field-scale treatability test for bioreduction of chromate, nitrate, and dissolved oxygen. In addition to remediating a portion of the plume and demonstrating reduction of electron acceptors in the plume, the data from this test will be valuable for designing a full-scale bioremediation system to apply at this and other chromium plumes at Hanford.