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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Conceptual Model of Subsurface Processes for Iodine at the Hanford Site

Currently, there are large dilute 129 I groundwater plumes at Hanford, including a groundwater plume in the 200-UP-1 operable unit (OU) located within the Central Plateau of the Hanford Site. The interim record of decision for the 200-UP-1 OU requires that the U.S. Department of Energy evaluate potential treatment options for 129 I through further technology evaluation. The approach to the evaluation was defined in the 129 I technology evaluation plan and includes an update to the conceptual model (CM) for the plume, as required by the 200 UP 1 remedial design/remedial action work plan. This report describes an updated CM of subsurface processes that affect 129 I behavior in the subsurface. This CM was developed to address identified data gaps and to provide input for fate and transport modeling needed to support the remedy evaluation. A significant advancement from previous the CM for the 200-UP-1 OU is recognition of the multiple iodine species in the subsurface and the biogeochemical processes that control their fate and transport. The CM was developed to incorporate the current information from samples of 200 West Area groundwater (including samples within the 200-UP-1 OU) that show iodine is present as a mix of iodide, iodate, and organo-I species, with iodate being the predominant species. Confirmation of iodine species distribution in the plume is recommended to help validate this CM basis. Plume behavior is affected by differential transport of iodine species due to their different sorption characteristics. This CM describes behavior for radioiodine ( 129 I) and non-radioactive iodine ( 127 I) because both isotopes have the same geochemical behavior. Non-radioactive iodine ( 127 I) concentrations are estimated to be 1000 times higher than radioiodine ( 129 I) in Hanford Site Central Plateau groundwater. This ratio has important implications for remedial strategies because remedies cannot specifically treat 129 I without also targeting 127 I. A network of biogeochemical processes controls the fate and transport behavior of iodine in the subsurface. A primary element of the effort to update the iodine CM was to quantify these processes and identify which are of importance at the Hanford Site, in particular for the 200-UP-1 OU.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Unbalanced Nested Random Effects Estimation of Variance Components

To investigate the contributing factors of variance in the measurement of an iodine 127 (127I) sample, we implement a nested random effects analysis of variance (ANOVA). Historically, the reported uncertainty on a measurement of 127I has been obtained by methods of forward uncertainty propagation because there is typically only one replicate of a given sample for which to estimate the uncertainty. When samples are processed there are several types of quality control (QC) standards analyzed along-side the unknown samples with two to five replicates for each. Assuming the variance observed in these replicate QC standards is representative of that of the unknown samples, we use these data in a nested random effects ANOVA to estimate the total uncertainty of a measurement. We demonstrate this approach with two sets of measurements from Idaho National Laboratory and compare the results with the forward uncertainty propagation approach. Variance component estimates for the coarsest level of the nesting structure were most imprecise because replicates were most limited at these levels. We find that the results largely agree between forward propagation and ANOVA, and the greatest contributors of variance are due to instrument variation and chemical processing, with human processing being among the smallest contributors. This analysis provides reassurance that the reported uncertainties using forward propagation are reasonable and the process is well controlled. We propose a future designed experiment to increase replicates at the coarsest level of the hierarchy to improve estimates of these variance components.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Sorption Behavior of Iodide Ions on Calcium Silicate Hydrate Formed under the Condition Saturated with Saline Water - 17069

The sorption behavior of iodide ions on calcium-silicate-hydrate (CSH gel) under the condition saturated with saline water was examined by using a Raman spectroscopy and ICP-AES, without drying process. In the sorption experiments, I-127 is a stable isotope was used as an alternative of I-129. CSH gel was synthesized with mixing CaO, SiO{sub 2}, and NaCl solution. The Ca/Si molar ratios of CSH gel were set to 0.4, 0.8, 1.2 and 1.6, and the concentration of NaCl solution was set to 0.6 M for simulating the condition of saline groundwater. The liquid/solid weight ratios of CSH gel were set to 10, 13, 15, 17, and 20, and the total weight of solid phase was 1.5 g. Furthermore, at the preparation of CSH gel, the substance of iodide ions in each sample was adjusted to 15 μmol. The synthesis procedure for all samples was conducted in a glove bag filled with nitrogen gas. The curing period was 7, 14, 30, and 60 days at a room temperature (298 K) with shaking at 120 strokes/min. The results of the sorption experiments, iodide ions adsorbed on CSH gel regardless of the high concentration of NaCl. The concentration of iodide ions in liquid phase was equal to the initial one under all experimental conditions. Moreover, the distribution coefficients, K{sub d}, were kept constant (K{sub d} = 1 mL/g) after 14 days. In the results of Raman analysis, the structure of CSH gel was scarcely influenced by incorporating iodide ions from the viewpoint of the silicate chain. These results suggest that iodide ions will be incorporated into CSH gel with the hydration water without changing its structure. Such effect of CSH gel formed with leaching cementitious constituents around the repository may retard the migration of radionuclide (I-129) in the natural barrier of the radioactive waste disposal system. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Sorption Behavior of Iodate Ions on Calcium Silicate Hydrate under a High Saline Condition - 18176

The sorption behavior of iodate ions on calcium-silicate hydrate (CSH) gel under high saline condition was examined by monitoring the concentrations of iodate ions and chloride ions using ion chromatography and Raman spectroscopy, without drying process. In the sorption experiments, a stable isotope I-127 was used as an alternative of I-129 which is radioactive one. Each sample was synthesized with mixing CaO powder, SiO{sub 2} as fumed silica and NaCl solution. Ca/Si molar ratios of CSH gel were set to 0.4, 0.8, 1.2 and 1.6 (add 0.2, 0.6, 1.0 and 1.4 only L/S = 20), and the concentration of NaCl solution was set to 0 M or 0.6 M for simulating the condition of fresh or saline groundwater. The liquid/solid (L/S) ratios of CSH gel were set to 10, 15 and 20, and the total weight of solid phase was 1.5 g. At the same time, NaIO{sub 3} solution was added to the sample in order to adjust its concentration to 1.0 mM, 0.67 mM and 0.5 mM for each L/S ratios. The synthesis procedure for all samples was conducted in a glove bag filled with nitrogen gas. The curing period was 7, 14, 30, and 60 days at a room temperature (298 K) with shaking at 120 strokes/min. As a results, the concentration of iodate ions in the liquid phase decreased for all samples under experimental conditions. Besides, the sorption behavior of iodate ions were hardly changed by the concentration of NaCl. That is, iodate ions migrated to solid phase in spite of the high concentration of NaCl. The distribution coefficients, Kd, increased as Ca/Si ratio increased, and hardly depended on NaCl concentration. The results of Raman analysis shows that the structure of CSH gel was almost not changed with or without NaCl from the viewpoint of the silicate chain under this condition. These results suggest that a sorption process except for the electrostatic process such as an ion exchange and a complexation exists between CSH gel and iodate ions. Besides, CSH gel might be able to contribute the retardation for the migration of iodate ions without changing its structure, even if the disposal environment are saturated by a high saline groundwater. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Analysis of Tc and U Spent Ion Exchange Resins from Hanford 200 West P and T Facility - 19202

The 200 West Area Pump-and-Treat (P and T) facility at the Hanford Site is being used to remove radionuclides such as uranium (U) and technetium-99 (Tc-99) from the contaminated groundwater. To support evaluation of U and Tc ion exchange (IX) treatment operational conditions and performance with various influent conditions, knowledge of resin capacity and contaminant retention is needed. To meet these objectives, samples of the spent Dowex{sup R} 21K and Purolite{sup R} A530E IX resins from the 200 West P and T facility used for the treatment of U and Tc, respectively, have been obtained and analyzed for the target analytes and other retained contaminants. The objectives of this work included 1) determination of the effective U and Tc loading on the resins, 2) evaluation of redox and chemical speciation of U and Tc retained by the resins and impact of the feed composition on the retention of U by the resin, and 3) quantification of other contaminants and groundwater constituents retained on the resins. Speciation of U and Tc-99 on the resin was determined by a combination of X-ray absorption fine structure, nuclear magnetic resonance, X-ray photoelectron spectroscopy (XAS), and optical spectroscopic techniques. Nondestructive analytical techniques including gamma energy analysis and low-energy photon spectroscopy were incorporated to quantify radionuclides retained on the resin. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to observe the IX beads and quantify chemical constituents on the surface and penetration through the beads. Destructive analysis of the resin was explored through wet oxidation to identify and quantify co-contaminants sorbed to the resins. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS) were used to analyze for metals, iodine, and specific isotopes retained on the resin, including Tc-99 and U-238. A single pertechnetate Tc-99 species was identified to be retained on the resin. For U, the obtained structural information was correlated with the laboratory findings using pristine resin as reference material to identify the nature of the U complexes and predict U retention by the resin as a function of variable influent conditions. Both resins demonstrated high loading with sulfate, silica, calcium, iron, zinc, and other groundwater constituents, suggesting that the competing anions, fouling, or a combination thereof significantly reduced their effective capacity for U and Tc-99. A significant amount of nonradioactive iodine-127 (I-127) and long-lived radioactive iodine-129 (I-129) isotope was also retained on the resins. Obtained quantitative information provided insights on the impact of water chemistry and the presence of common mineral constituents on the retention of contaminants of concern, including U, Tc-99, and I-129. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Preliminary Study on Sorption Behavior of Iodine on Ca-Al-Si Hydrate - 19310

Sorption behavior of Ca-Al-Si hydrate with iodine sign ion and iodide ion was investigated using ion chromatography and Raman spectroscopy. In the experiment I-127 which is a stable isotope was used instead of I-129 which is a radionuclide. Ca-Al-Si hydrate was synthesized by mixing fumed silica (SiO{sub 2}) calcium oxide (CaO) and aluminum nitrate nonahydrate (Al(NO{sub 3}){sub 3}.9H{sub 2}O) with the solution containing iodine in a polypropylene tube. Two chemical forms of iodine, i.e., iodide ion and iodate ion, were considered in this study. In the samples of Ca-Al-Si hydrate, the Ca/Si molar ratios were adjusted in the range from 0.8 to 1.6, and the Al / Si ratios were in the range from 0.0 to 0.5. The samples liquid / solid (L/S) ratio was 20. In order to adjust the concentration to 0.5 mM for each samples, NaIO{sub 3} solution or NaI solution were added to the sample. NaClO solution was added as an oxidizing agent to maintain the form of iodate ion. The synthesis procedure for all the samples was carried out in a glove bag filled with nitrogen gas. The curing time was 1, 7, 30 days at room temperature (298 K) with shaking at 120 strokes / minute. In the results, although the iodide ion concentration in the liquid phase hardly changed, the liquid phase amount had been reduced to less than the liquid phase amount initially added. This means that iodide ions are incorporated in the solid phase together with the water of hydration. Besides, the concentration of iodate ion remarkably decreased for all samples under experimental conditions. In the Raman analysis, some differences in structure due to incorporation of Al were observed, but the structure of the Ca-Al-Si hydrate hardly changed due to other factors. Based on the sorption distribution coefficients obtained in this study, the Ca-Al-Si hydrate can be expected to have a barrier performance against iodine. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Technology Assessment for Radioiodine at the Hanford Site - 20240

An evaluation was conducted to assess the practicability of technologies of sufficient promise and maturity to warrant treatability tests for remediating radioiodine (I-129) in groundwater at the 200-UP-1 operable unit at the U.S. Department of Energy Hanford Site. Technologies were evaluated based on recent updated knowledge of subsurface iodine transport behavior at Hanford, and the effectiveness, implementability, and cost of potential treatment technologies for I-129. Because more than two-thirds of the iodine at Hanford is estimated to be present in its oxidized form as iodate, treatment technologies were evaluated with respect to addressing iodate. In situ treatments were identified as having limited implementability because the plume core is located directly beneath the Environmental Restoration Disposal Facility disposal cells, a landfill used for the disposal of low-level radioactive, hazardous, and mixed wastes generated from Hanford cleanup activities. Further limitations in treatment technologies for radioiodine were due to the isotopic distribution of subsurface iodine. Data indicate that stable iodine (I- 127) concentrations are up to three orders of magnitude greater than I-129, limiting the effectiveness of potential technologies because they are not isotope-specific. Ex situ approaches also lacked the effectiveness and maturity required to treat I-129. Hence, the technology evaluation did not identify any technologies that needed treatability testing, driven by site and contaminant properties that hinder effectiveness and/or implementability of the technologies. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2011

Nuclear Data Sheets for A = 127

The 1996 evaluation for the A=127 mass chain (1996Ki01) has been revised. The experimental results from various decays and reactions for the A=127 mass chain have been compiled and evaluated. The nuclides covered in this evaluation are from {sup 127}Ag to {sup 127}Nd. The data are summarized and presented, together with adopted level schemes.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Laboratory report on iodine ( 129 I and 127 I) speciation, transformation and mobility in Handford groundwater, suspended particles and sediments

The Hanford Site in eastern Washington produced plutonium for several decades and in the process generated billions of gallons of radioactive waste. Included in this complex mixture of waste was 50 Ci of iodine-129 ( 129 I). Iodine-129’s high abundance, due to its high fission yield, and extreme toxicity result in iodine-129 becoming a key risk driver at many Department of Energy (DOE) sites. The mobility of radioiodine in arid environments, such as the Hanford Site, depends largely on its chemical speciation and is also greatly affected by many other environmental factors, especially natural sediment organic matter (SOM). Groundwater radioiodine speciation has not been measured in arid regions with major plumes or large disposed 129 I inventories, including the Hanford Site, Idaho National Laboratory, and Nevada Test Site. In this study, stable iodine-127 and radioiodine-129 speciation, pH, and dissolved organic carbon (DOC) of groundwater samples collected from seven wells located in the 200-West Area of the Hanford site were investigated. The most striking finding was that iodate (IO 3 - ) was the most abundant species. Unexpectedly, iodide (I - ), which was likely the form of iodine in the source materials and the expected dominant groundwater species based on thermodynamic considerations, only accounted for 1-2% of the total iodine concentration. It is likely that the relatively high pH and the low abundance of sedimentary organic matter (SOM) that is present at the site slowed down or even inhibited the reduction of iodate, as SOM abiotically reduce iodate into iodide. Moreover, a study on the kinetics of iodide and iodate uptake and aqueous speciation transformation by three representative subsurface Hanford sediments was performed over a period of about one month. This study was carried out by using iodide-125 or iodate-125 at the ambient iodine-127concentration found at the site. Iodate K d values were on average 89% greater than iodide K d values, and the K d values for both species tended to increase with the amount of organic carbon (OC) present in the sediment. It is especially noteworthy that this trend existed at the very low OC concentrations that naturally exist in the Hanford sediments. Iodine and OC can form essentially irreversible covalent bonds, thereby providing a yet unstudied 129 I retardation reaction at the Hanford Site. In addition to the transformation of iodine species, the sediment collected from the vadose zone also released stable iodide into the aqueous phase. It was found that the three sediments all took up the ambient iodate from the groundwater and slowly transformed it into iodide under the laboratory conditions, likely dependent on the abundance of reducing agents such as organic matter and Fe 2+ . Therefore two competitive iodine processes were identified, the tendency for the sediment to reduce iodate to iodide, and the groundwater chemistry to maintain the iodine as iodate, presumably it is largely the result of natural pH and dissolved O 2 /Eh levels. Suspended carbonate (and silica) particles collected from Hanford groundwater contained elevated amounts of iodine (142 ± 8 μg/g iodine), consisting mainly of iodate (>99%). Iodate was likely incorporated into the carbonate structure during calcite precipitation upon degasing of CO 2 as the groundwater samples were removed from the subsurface. This concentration of groundwater iodate in precipitated carbonate has implication to long-term fate and transport of 129 I and on active in-situ 129 I groundwater remediation. This study provides some of the first groundwater radioiodine speciation studies conducted in arid environments and provides much needed mechanistic descriptions to permit making informed decisions about low-cost/high intellectual input remediation options, such as monitored natural attenuation, or long-term stewardship of nuclear waste disposal sites.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Spectral-average cross section validation in LR-0 reactor spectrum of {sup 55}Mn(n,2n), {sup 90}Zr(n,2n) and {sup 127}I(n,2n) reactions - 25362

This article deals with the validation of spectral average cross-sections (SACS) of {sup 55}Mn(n,2n){sup 54}Mn, {sup 90}Zr(n,2n){sup 89}Zr and {sup 127}I(n,2n){sup 126}I reactions in well-defined LR-0 reactor spectrum. The measurement of SACS for selected reactions is of high interest because they are used for the practical reactor dosimetry and also for refinement of prompt fission neutron spectra of {sup 235}U in the region of higher energies. Various experiments for description of neutron field in reactor and detector characterization, which are necessary for validation, are described. The spectral average cross-sections are derived from Net Peak Areas of irradiated samples measured using a semiconductor high purity germanium detector. The spectral average cross section in {sup 235}U prompt fission neutron spectrum was experimentally determined to be 0.239 ± 0.015 mb for {sup 55}Mn, 1.209 ± 0.052 mb for {sup 127}I and 0.107 ± 0.005 mb for {sup 90}Zr. The obtained results were compared with MCNP6 calculations using ENDF/B-VII.0, ENDF/B-VII.1, JEFF-3.1, JEFF-3.2, JENDL-3.3, JENDL-4, ROSFOND-2010, CENDL-3.1 and IRDFF-1.05 nuclear data libraries. Notable discrepancies were found in {sup 90}Zr(n,2n){sup 89}Zr and {sup 127}I(n,2n){sup 126}I reactions. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2018

Resonance Structure of the Charge-Exchange Strength Function and Neutrino-Capture Cross Sections for the Isotopes {sup 71}Ga, {sup 98}Mo, and {sup 127}I

A resonance structure of the charge-exchange strength function S(E) and its effect on the neutrino-capture cross sections for the isotopes {sup 71}Ga, {sup 98}Mo, and {sup 127}I are studied within the self-consistent theory of finite Fermi systems. The calculation of the strength function S(E) takes into account Gamow–Teller, analog, and so-called lower lying pygmy resonances. The neutrino-capture cross sections σ(E) for the above three isotopes are calculated with allowance for the resonance structure of the strength function S(E), and the effect of each resonance on the energy dependence σ(E) is analyzed. It is found that all charge-exchange resonances in the strength function S(E) should be taken into account in calculating the neutrino-capture cross section σ(E) for the isotopes {sup 71}Ga, {sup 98}Mo, and {sup 127}I. The disregard of even highlying resonances leads to a substantial underestimation of the cross section σ(E), and this may affect the interpretation of respective experimental data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

NMR shielding and spin–rotation constants of {sup 175}LuX (X = {sup 19}F, {sup 35}Cl, {sup 79}Br, {sup 127}I) molecules

This presentation demonstrates the relativistic effects on the spin-rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants and shielding spans of {sup 175}LuX (X = {sup 19}F, {sup 35}Cl, {sup 79}Br, {sup 127}I) molecules. The results are obtained from calculations performed using density functional theory (non-relativistic and four-component relativistic) and coupled-cluster calculations. The spin-rotation constants are compared with available experimental values. In most of the molecules studied, relativistic effects make an order of magnitude difference on the NMR absolute shielding constants.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Electronic Structures and Magnetic Properties of Transition Metal Doped CsPbI{sub 3} Perovskite Compounds by First-Principles Calculation

Transition metal doped cesium lead halide (CsPbI{sub 3}) perovskite compounds were studied for application in photovoltaic solar cells. Electronic structures, chemical shifts of {sup 207}Pb and {sup 127}I-NMR, vibration modes in infrared and Raman spectra of transition metals (Mn{sup 2+}, Fe{sup 2+} or Cu{sup 2+})-doped CsPbI{sub 3} perovskite compounds were studied by the first-principles calculation using density functional theory. The CsPb(Fe)I{sub 3} perovskite crystals had a slight perturbation of crystal field in the coordination structure. The electron density distribution was delocalized on the 5p orbital of I atom, the 3d orbital of Fe atom and the 6p orbital of Pb atom. The first excited process was based on ligand metal charge transfer from the 5p orbital on I atom to the 3d orbital of Fe atom. The chemical shifts of {sup 127}I-NMR were associated with the electron correlation of electron-nuclear spin interaction and nuclear quadrupole interactions based on electron field graduate. The asymmetric vibrations of Pb–I bonds stretching mode related to electron conductivity with scattering of the carrier diffusion as phonon effectiveness. The slight perturbation of the coordination structure in the CsPb(Fe)I{sub 3} perovskite crystal will improve the photovoltaic and optical properties.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2012

Nuclear model calculations on the production of {sup 125,123}Xe and {sup 133,131,129,128}Ba radioisotopes

In this study, production rates of {sup 125,123}Xe and {sup 133,131,129,128}Ba medical isotopes produced by {sup 127}I(p, 3n){sup 125}Xe, {sup 127}I(p, 5n){sup 123}Xe, {sup 133}Cs(p, n){sup 133mg}Ba, {sup 133}Cs(p, 3n){sup 131mg}Ba, {sup 133}Cs(p, 5n){sup 129}Ba, and {sup 133}Cs(p, 6n){sup 128}Ba reactions have been investigated up to 100 MeV incident proton energy. The preequilibrium calculations involve the hybrid model, the geometry-dependent hybrid model and the cascade exciton model. The calculated results are compared with the experimental data taken from the literature.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

Absolute NMR shielding scales and nuclear spin–rotation constants in {sup 175}LuX and {sup 197}AuX (X = {sup 19}F, {sup 35}Cl, {sup 79}Br and {sup 127}I)

We present nuclear spin–rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants, and shielding spans of all the nuclei in {sup 175}LuX and {sup 197}AuX (X = {sup 19}F, {sup 35}Cl, {sup 79}Br, {sup 127}I), calculated using coupled-cluster singles-and-doubles with a perturbative triples (CCSD(T)) correction theory, four-component relativistic density functional theory (relativistic DFT), and non-relativistic DFT. The total nuclear spin–rotation constants determined by adding the relativistic corrections obtained from DFT calculations to the CCSD(T) values are in general in agreement with available experimental data, indicating that the computational approach followed in this study allows us to predict reliable results for the unknown spin–rotation constants in these molecules. The total NMR absolute shielding constants are determined for all the nuclei following the same approach as that applied for the nuclear spin–rotation constants. In most of the molecules, relativistic effects significantly change the computed shielding constants, demonstrating that straightforward application of the non-relativistic formula relating the electronic contribution to the nuclear spin–rotation constants and the paramagnetic contribution to the shielding constants does not yield correct results. We also analyze the origin of the unusually large absolute shielding constant and its relativistic correction of gold in AuF compared to the other gold monohalides.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Transition of Iodine Analysis to Accelerator Mass Spectrometry

The goal of the project, New Paradigms for Isotope Ratio Mass Spectrometry: Raising the Scientific Profile and Improved Performance for Accelerator Mass Spectrometry (AMS) and Thermal Ionization Mass Spectrometry (TIMS), is to ensure that the ongoing isotope ratio determination capability within the U.S. Department of Energy complex is the world’s best for application to nonproliferation. This report spells out the progress of Task 4, Transition of TIMS to AMS for Iodine Analysis, of the larger project. The subtasks under Task 4 and the accomplishments throughout the three year project life cycle are presented in this report. Progress was made in optimization of chemical extraction, determination of a detection limit for 127Iodine, production of standard materials for AMS analysis quality assurance, facilitation of knowledge exchange with respect to analyzing iodine on an AMS, cross comparison with a world-leading AMS laboratory, supercritical fluid extraction of iodine for AMS analysis and electrodeposition of seawater as a direct method of preparation for iodine analysis by AMS--all with the goal of minimizing the time required to stand up an AMS capability for iodine analysis of exposed air filters at INL. An effective extraction method has been developed and demonstrated for iodine analysis of exposed air filters. Innovative techniques to accomplish the cathode preparation for AMS analysis were developed and demonstrated and published. The known gap of a lack of available materials for reference standards in the analysis of iodine by AMS was filled by the preparation of homogenous materials that were calibrated against NIST materials. A minimum limit on the amount of abundant isotope in a sample was determined for AMS analysis. The knowledge exchange occurred with fantastic success. Scientists engaged the international AMS community at conferences, as well as in their laboratories for collaborative work. The supercritical fluid extraction work has positive data, but is not a replacement for leaching yet. The added seawater work has led to a good method and a possible publication. The focus of this project was to minimize the time to stand up the AMS capability, by having all the preparation and supporting functions worked out ahead of the instrument arrival. Due to all the preparatory work and its success, the instrument was delivered and turned over to the INL in February 2015. Since then, INL scientists have been successfully vetting the capabilities and accomplishing their own measurements that agree well with the leading laboratories of the world for iodine analysis by AMS. Initially, all AMS data was gathered on other laboratories instruments, but during the last six months data for this project has come from INL’s AMS.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Field-Scale Lysimeter Studies of Glass and Cementitious Waste Forms at the Hanford Site - 20392

The Hanford site Integrated Disposal Facility (IDF) will receive waste forms from vitrification activities at the Hanford Waste Treatment and Immobilization Plant (WTP). The waste form inventory to be disposed of at the IDF will consist of vitrified low-activity waste (LAW) in glass forms and solidified (or encapsulated) secondary wastes in cementitious forms. The IDF is a near-surface burial facility located near Hanford's Waste Treatment and Immobilization Plant in the 200 East Area of the site's Central Plateau. An extensive set of laboratory experimental data has been collected to support IDF performance assessment calculations of the eventual degradation of waste forms and mobility of contaminants. This paper describes the start of a field experiment to generate waste-form performance data on a larger scale (tens of centimeters), over a longer duration (five years or more), and under field conditions representative of the IDF. Results from this study are expected to improve model descriptions of contaminant mobility, reduce uncertainties about the representativeness of laboratory results in the IDF performance assessment, improve stakeholder confidence in the safe disposal of treated waste at the IDF, and facilitate the adoption of informed facility designs with the potential to reduce operational costs. A lysimeter test facility near Hanford's 200 West Area has been repurposed to carry out long-term assessments of waste forms buried in sediments excavated from the IDF. The waste forms are buried in large drainage lysimeters, open caissons that are two meters in diameter and three meters deep. Waste forms are buried in up to six locations in each lysimeter. Samplers collect pore water and drainage water beneath the waste forms and air from the pore space adjacent to waste forms. Sensors measure temperature, soil water content, soil water tension, and drainage flux. One lysimeter containing cementitious waste forms and one containing glass waste forms have been completed, along with a control lysimeter (without waste forms). The cementitious waste forms are Cast Stone grout formulations using a liquid secondary waste simulant and a generic Hanford high-salt simulant, as well as a hydrated lime-based grout formulation using a liquid secondary waste simulant. Technetium-99 and iodine-127 were added as tracers to monitor contaminant mobility. Glass waste forms were fabricated in two formulations (LAWA44 and ORLEC28), with rhenium and molybdenum tracers to monitor waste form degradation. The predicted performance of the waste forms in the lysimeters was modeled prior to installation to determine waste form size, tracer concentration/activity, and locations of sensors and samplers. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Identifying the Technical Basis for Technical Impracticability Waivers for Recalcitrant Radionuclides at Department of Energy Sites - 19055

Injection wells are currently used to hydraulically contain the leading edge of a radioactive iodine-129 ({sup 129}I) groundwater plume that underlies the Hanford Site's 200-UP-1 Operable Unit within the Central Plateau. Hydraulic containment has been implemented because to date, no viable treatment technologies have been identified that can achieve the federal drinking water standard of 1 pCi/L. The large spatial extent of the {sup 129}I plume limits the practical implementation of readily available remedy options, and the presence of large amounts of natural stable {sup 127}I as well as multiple iodine species (iodate, iodide, and organic-iodine complexes) in the groundwater present challenges for remedy performance. As evaluations of potential remediation technologies proceed, risk-informed remediation endpoints and alternatives- such as applicable or relevant and appropriate requirements technical impracticability (TI) waivers-are being evaluated as specified in the interim Record of Decision. A TI waiver may be necessary for {sup 129}I at 200-UP-1 to achieve a plume condition that is still protective of human health and the environment. Nearly 100 TI waivers have been granted at sites across the U.S.; however, a TI waiver has not yet been granted for a radionuclide nor has one been granted for a U.S. Department of Energy (DOE)-managed site. This situation underscores the importance of developing a methodology for risk-based decision-making for iodine and other contaminants of concern at DOE sites. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗