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DOE OSTI2020

Materials Data on BaH2Se(S2O3)2 by Materials Project

BaH2(SO3)2Se(S)2 crystallizes in the orthorhombic Pnma space group. The structure is two-dimensional and consists of eight hydrogen sulfide molecules; four selenium molecules; and two BaH2(SO3)2 sheets oriented in the (0, 0, 1) direction. In each BaH2(SO3)2 sheet, Ba2+ is bonded in a 9-coordinate geometry to three H1+ and six O2- atoms. There are a spread of Ba–H bond distances ranging from 2.85–3.07 Å. There are a spread of Ba–O bond distances ranging from 2.71–2.80 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a bent 120 degrees geometry to two equivalent Ba2+ atoms. In the second H1+ site, H1+ is bonded in a single-bond geometry to one Ba2+ atom. S1+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of S–O bond distances ranging from 1.46–1.48 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+ and one S1+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+ and one S1+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+ and one S1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag(AsSe2)3 by Materials Project

Ag(AsSe2)2As(Se)2 crystallizes in the orthorhombic Cmmm space group. The structure is two-dimensional and consists of two arsenic molecules; four selenium molecules; and one Ag(AsSe2)2 sheet oriented in the (0, 0, 1) direction. In the Ag(AsSe2)2 sheet, Ag1+ is bonded in a distorted rectangular see-saw-like geometry to four equivalent Se2- atoms. All Ag–Se bond lengths are 2.68 Å. As+3.67+ is bonded in a linear geometry to two equivalent Se2- atoms. Both As–Se bond lengths are 2.39 Å. Se2- is bonded in a distorted linear geometry to one Ag1+, one As+3.67+, and one Se2- atom. The Se–Se bond length is 2.60 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Bi2Se5Cl7 by Materials Project

Bi2Cl7(Se)5 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is two-dimensional and consists of forty selenium molecules and two Bi2Cl7 sheets oriented in the (0, 0, 1) direction. In each Bi2Cl7 sheet, there are four inequivalent Bi+2.50+ sites. In the first Bi+2.50+ site, Bi+2.50+ is bonded in a 7-coordinate geometry to seven Cl1- atoms. There are a spread of Bi–Cl bond distances ranging from 2.53–3.32 Å. In the second Bi+2.50+ site, Bi+2.50+ is bonded in a 7-coordinate geometry to seven Cl1- atoms. There are a spread of Bi–Cl bond distances ranging from 2.56–3.20 Å. In the third Bi+2.50+ site, Bi+2.50+ is bonded in a 6-coordinate geometry to six Cl1- atoms. There are a spread of Bi–Cl bond distances ranging from 2.56–3.13 Å. In the fourth Bi+2.50+ site, Bi+2.50+ is bonded in a 7-coordinate geometry to seven Cl1- atoms. There are a spread of Bi–Cl bond distances ranging from 2.52–3.40 Å. There are fourteen inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a distorted water-like geometry to two Bi+2.50+ atoms. In the second Cl1- site, Cl1- is bonded in a distorted trigonal non-coplanar geometry to three Bi+2.50+ atoms. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Bi+2.50+ atom. In the fourth Cl1- site, Cl1- is bonded in a single-bond geometry to one Bi+2.50+ atom. In the fifth Cl1- site, Cl1- is bonded in a distorted water-like geometry to two Bi+2.50+ atoms. In the sixth Cl1- site, Cl1- is bonded in a distorted water-like geometry to two Bi+2.50+ atoms. In the seventh Cl1- site, Cl1- is bonded in a distorted trigonal non-coplanar geometry to three Bi+2.50+ atoms. In the eighth Cl1- site, Cl1- is bonded in a distorted water-like geometry to two Bi+2.50+ atoms. In the ninth Cl1- site, Cl1- is bonded in a distorted water-like geometry to two Bi+2.50+ atoms. In the tenth Cl1- site, Cl1- is bonded in a 3-coordinate geometry to three Bi+2.50+ atoms. In the eleventh Cl1- site, Cl1- is bonded in a single-bond geometry to one Bi+2.50+ atom. In the twelfth Cl1- site, Cl1- is bonded in a single-bond geometry to one Bi+2.50+ atom. In the thirteenth Cl1- site, Cl1- is bonded in a 2-coordinate geometry to three Bi+2.50+ atoms. In the fourteenth Cl1- site, Cl1- is bonded in a single-bond geometry to one Bi+2.50+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Si60Te13P32Se3 by Materials Project

(Si15P8)4(Te)13(Se)3 crystallizes in the orthorhombic Pmmm space group. The structure is three-dimensional and consists of three selenium molecules, thirteen tellurium molecules, and one Si15P8 framework. In the Si15P8 framework, there are fourteen inequivalent Si sites. In the first Si site, Si is bonded to four Si atoms to form SiSi4 tetrahedra that share corners with four SiSi2P2 tetrahedra and corners with eight PSi3P tetrahedra. All Si–Si bond lengths are 2.34 Å. In the second Si site, Si is bonded to four Si atoms to form SiSi4 tetrahedra that share corners with four SiSi2P2 tetrahedra and corners with eight PSi3P tetrahedra. All Si–Si bond lengths are 2.34 Å. In the third Si site, Si is bonded to four Si atoms to form SiSi4 tetrahedra that share corners with four SiSi2P2 tetrahedra and corners with eight PSi3P tetrahedra. All Si–Si bond lengths are 2.34 Å. In the fourth Si site, Si is bonded to two Si and two equivalent P atoms to form distorted SiSi2P2 tetrahedra that share corners with four PSi3P tetrahedra and corners with eight SiSi4 tetrahedra. Both Si–Si bond lengths are 2.34 Å. Both Si–P bond lengths are 2.32 Å. In the fifth Si site, Si is bonded to two Si and two equivalent P atoms to form distorted SiSi2P2 tetrahedra that share corners with four PSi3P tetrahedra and corners with eight SiSi4 tetrahedra. The Si–Si bond length is 2.34 Å. Both Si–P bond lengths are 2.32 Å. In the sixth Si site, Si is bonded to two Si and two equivalent P atoms to form distorted SiSi2P2 tetrahedra that share corners with four PSi3P tetrahedra and corners with eight SiSi4 tetrahedra. The Si–Si bond length is 2.34 Å. Both Si–P bond lengths are 2.32 Å. In the seventh Si site, Si is bonded to two Si and two equivalent P atoms to form distorted SiSi2P2 tetrahedra that share corners with four PSi3P tetrahedra and corners with eight SiSi4 tetrahedra. The Si–Si bond length is 2.34 Å. Both Si–P bond lengths are 2.32 Å. In the eighth Si site, Si is bonded to two Si and two P atoms to form distorted SiSi2P2 tetrahedra that share corners with four PSi3P tetrahedra and corners with eight SiSi4 tetrahedra. The Si–Si bond length is 2.34 Å. Both Si–P bond lengths are 2.32 Å. In the ninth Si site, Si is bonded to two Si and two equivalent P atoms to form distorted SiSi2P2 tetrahedra that share corners with four PSi3P tetrahedra and corners with eight SiSi4 tetrahedra. The Si–Si bond length is 2.34 Å. Both Si–P bond lengths are 2.33 Å. In the tenth Si site, Si is bonded to two Si and two equivalent P atoms to form distorted SiSi2P2 tetrahedra that share corners with four PSi3P tetrahedra and corners with eight SiSi4 tetrahedra. The Si–Si bond length is 2.34 Å. Both Si–P bond lengths are 2.32 Å. In the eleventh Si site, Si is bonded to two Si and two equivalent P atoms to form distorted SiSi2P2 tetrahedra that share corners with four PSi3P tetrahedra and corners with eight SiSi4 tetrahedra. The Si–Si bond length is 2.34 Å. Both Si–P bond lengths are 2.33 Å. In the twelfth Si site, Si is bonded to two Si and two equivalent P atoms to form distorted SiSi2P2 tetrahedra that share corners with four PSi3P tetrahedra and corners with eight SiSi4 tetrahedra. The Si–Si bond length is 2.34 Å. Both Si–P bond lengths are 2.32 Å. In the thirteenth Si site, Si is bonded to two Si and two equivalent P atoms to form distorted SiSi2P2 tetrahedra that share corners with four PSi3P tetrahedra and corners with eight SiSi4 tetrahedra. There are one shorter (2.33 Å) and one longer (2.34 Å) Si–Si bond lengths. Both Si–P bond lengths are 2.33 Å. In the fourteenth Si site, Si is bonded to two Si and two equivalent P atoms to form distorted SiSi2P2 tetrahedra that share corners with four PSi3P tetrahedra and corners with eight SiSi4 tetrahedra. Both Si–Si bond lengths are 2.34 Å. Both Si–P bond lengths are 2.32 Å. There are four inequivalent P sites. In the first P site, P is bonded to three Si and one P atom to form distorted PSi3P tetrahedra that share corners with three equivalent PSi3P tetrahedra and corners with nine SiSi4 tetrahedra. The P–P bond length is 2.29 Å. In the second P site, P is bonded to three Si and one P atom to form PSi3P tetrahedra that share corners with three equivalent PSi3P tetrahedra and corners with nine SiSi4 tetrahedra. The P–P bond length is 2.29 Å. In the third P site, P is bonded to three Si and one P atom to form PSi3P tetrahedra that share corners with three PSi3P tetrahedra and corners with nine SiSi4 tetrahedra. In the fourth P site, P is bonded to three Si and one P atom to form PSi3P tetrahedra that share corners with three PSi3P tetrahedra and corners with nine SiSi4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H6C2SeO by Materials Project

(CH3)2SeO is Ammonia-derived structured and crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of four methane molecules and two selenium oxide(1:2) molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba4Se4S16O31 by Materials Project

Ba2S4O15(BaS2O8)2(Se)4(S)8 crystallizes in the monoclinic Pm space group. The structure is two-dimensional and consists of eight hydrogen sulfide molecules; four selenium molecules; one Ba2S4O15 sheet oriented in the (0, 0, 1) direction; and one BaS2O8 sheet oriented in the (0, 0, 1) direction. In the Ba2S4O15 sheet, there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ba–O bond distances ranging from 2.70–2.89 Å. In the second Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.72–2.96 Å. There are two inequivalent S2+ sites. In the first S2+ site, S2+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is two shorter (1.46 Å) and one longer (1.47 Å) S–O bond length. In the second S2+ site, S2+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is two shorter (1.46 Å) and one longer (1.47 Å) S–O bond length. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+ and one S2+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+ and one S2+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Ba2+ atoms. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+ and one S2+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+ and one S2+ atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to one Ba2+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ba2+ and one S2+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ba2+ and one S2+ atom. In the BaS2O8 sheet, there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.75–2.97 Å. In the second Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.73–2.96 Å. There are two inequivalent S2+ sites. In the first S2+ site, S2+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is two shorter (1.46 Å) and one longer (1.47 Å) S–O bond length. In the second S2+ site, S2+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is two shorter (1.46 Å) and one longer (1.47 Å) S–O bond length. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+ and one S2+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+ and one S2+ atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Ba2+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Ba2+ atoms. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+ and one S2+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+ and one S2+ atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to one Ba2+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to one Ba2+ atom. In the ninth O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+ and one S2+ atom. In the tenth O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+ and one S2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LuSeI by Materials Project

LuISe crystallizes in the orthorhombic Pmmm space group. The structure is zero-dimensional and consists of two selenium molecules and two LuI clusters. In each LuI cluster, Lu3+ is bonded in a single-bond geometry to one I1- atom. The Lu–I bond length is 2.75 Å. I1- is bonded in a single-bond geometry to one Lu3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag(BiSe2)3 by Materials Project

Ag(BiSe2)2Bi(Se)2 crystallizes in the orthorhombic Cmmm space group. The structure is two-dimensional and consists of two bismuth molecules; four selenium molecules; and one Ag(BiSe2)2 sheet oriented in the (0, 0, 1) direction. In the Ag(BiSe2)2 sheet, Ag1+ is bonded in a distorted rectangular see-saw-like geometry to four equivalent Se2- atoms. All Ag–Se bond lengths are 2.63 Å. Bi+3.67+ is bonded in a linear geometry to two equivalent Se2- atoms. Both Bi–Se bond lengths are 2.71 Å. Se2- is bonded in a distorted linear geometry to one Ag1+, one Bi+3.67+, and one Se2- atom. The Se–Se bond length is 2.51 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Phase Equilibria and Thermochemistry of Advanced Fuels: Modeling Burnup Behavior (Final Report)

Achieving the goal of developing advanced fuel concepts that meet the DOE objectives of being robust, demonstrating high performance, and are more tolerant of accident conditions than current fuel systems will require a thorough understanding of the thermophysical and thermochemical properties of the constituent materials. Non-oxide fuel systems are being explored under the Advanced Fuels Program that hold significant promise for improved performance and accident tolerance, including the uranium silicide-based system considered in the current work. Prospective cladding materials currently considered that contribute to improved accident tolerance include silicon carbide composites and ferritic alloys (Fe-Cr-Al base compositions). Thus, the effort developed thermochemical models and values, supported with targeted experiments, to evaluate the ferritic alloy and silicon carbide composite cladding systems in contrast to current zirconium alloy cladding. The developed detailed understanding will serve to aid in relatively early screening of candidate systems to avoid wasted effort, guide development of new fuel forms, and to provide a basis for predicting and modeling fuel performance. Major deliverables for the project included: Thermochemical assessment and models of phases in the U-Si and U-Si-N systems; thermochemical evaluation supported by experimental measurements of fuel-cladding interactions of silicide fuel with baseline zirconium, ceramic composite, and ferritic alloy cladding; thermochemical assessment and models of phases supported by experimental measurements for silicide fuel with key fission products provided in a dataset and reported in refereed publications. Within the project a significantly refined U-Si phase diagram was developed and reported that now includes homogeneity ranges for key phases, such at the U 3 Si 2 proposed fuel phase, and settles issues with regard to uncertainty in the stability of some phases. Computational efforts together with key experiments has determined phase formation in interactions between U 3 Si 2 and Zircaloy-4 cladding material, a ferritic FeCrAlY alloy of interest as an advanced cladding material, and silicon carbide, also of interest as a fiber-reinforced composite cladding. As expected, very significant reactions occur between U3Si2 and Zircaloy-4, with much less interaction at higher temperatures for the ferritic alloy, and finally interactions with SiC only in the region of contact. A potentially major issue is the stability of U 3 Si 2 fuel that has undergone significant burnup. The result is the loss of the uranium metal, liberating silicon, and the formation of concomitant fission product elements that either dissolve in the U 3 Si 2 phase or form independent, and possibly silicide phases. A combination of experimental determinations of phase formation of U 3 Si 2 reacted with representative fission products yttrium, gadolinium, cerium, zirconium, and molybdenum and first principles calculations has helped understand the fuel chemistry. The behavior of the U 3 Si 2 phase and the partitioning of silicon to possible fission product phases with burnup was thus determined, with significant dissolution in U 3 Si 2 of cerium, gadolinium, zirconium, and plutonium predicted along with independent phase formation of a U-Mo-Si ternary phase, yttrium silicide, and elemental selenium. It can be concluded that at significant burnup there will be a very minor amount of the U 3 Si 2 fuel phase that will decompose to a lower silicide or a uranium alloy as silicon preferentially forms a secondary phase.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Production of Radiohalogens: Bromine and Astatine for Imaging and Therapy

Over the course of this two year grant, we have developed and optimized new methods for the production of clinical quality 76 Br, 77 Br, and 80m Br at the University of Wisconsin. This includes the synthesis of a novel isotopically enriched cobalt-selenium intermetallic compound, its fabrication into robust cyclotron targets, and the chemical isolation of the resulting bromine radionuclide. Compared with the previous state-of-the-art, these methods demonstrate a six-times larger 76 Br and three-times larger 77 Br production capacity for a 3-hour cyclotron irradiation. Additionally, the cyclotron targets are exceptionally robust to this process, allowing for their reuse for dozens of radiobromine productions.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Biological Treatment of Flue Gas Desulfurization Wastewater

In order to limit and mitigate the environmental impacts associated with coal combustion, flue gas desulfurization (FGD) systems have been put into place to reduce the release of contaminates. The main constituent targeted by FGD systems is sulfur oxide gasses (SOx). While FGD systems have been able to achieve high removal rates of SOx gasses, the wastewater effluent requires treatment before release back into the environment. The release of wastewater is heavily regulated by the U.S. Environmental Protection Agency (EPA) and their effluent guideline limitations rule (ELG). The ELG rule set new limits on discharges containing constituents such as selenium, nitrogenous species, mercury, and arsenic in the effluent. This report seeks to give background on abiotic removal methods as well as highlight the most important issues when utilizing biological treatment to treat the FGD wastewater for the constituents of interest mentioned. This report also seeks to discuss the issues of foaming which can occur during biological treatment.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2020

Improved Performance of Cu(InGa)(SeS) 2 PV Modules Using the Reaction of Metal Precursors. Final Report

This project “Improved Performance of Cu(InGa)(SeS) 2 PV Modules using the Reaction of Metal Precursors” was a partnership led by the Institute of Energy Conversion (IEC) at the University of Delaware with Columbia University and the Molecular Foundry at the Lawrence Berkeley National Laboratory. The aim was to develop pathways to improve Cu(InGa)(SeS) 2 (CIGSS) thin film photovoltaic modules using processes compatible with low manufacturing cost. The CIGSS approach investigated was a two-step process including deposition of metal precursor films following by reaction in hydride gases utilizing IEC’s novel reactor. The process was similar to that under commercial development by the project’s industry partner Stion. When Stion went out of business mid-project the focus changed to a rapid thermal process considered more commercially viable. Approaches to improve the performance of solar cells using the reacted films focused on two material innovations. First, the overall Ga content was increased to increase the operating voltage, which is desirable for scale-up to commercial modules. Second, the processing and performance advantages arising from Ag alloying were investigated. Advanced characterization guided process and material development including control of relative composition gradients. Research on the formation of Cu-Ga-In metal precursors utilized sputtering deposition which is normally used in commercial applications. The work resulted in processes for deposition of precursor stacks with increased relative Ga content and effects of deposition parameters on morphology and phase composition were established. It was shown that the metal precursor films have comparable phase composition and morphology so subsequent reaction follows from the same starting point. The addition of Ag to the metal precursors gave more uniform morphology and improved adhesion of reacted films which enable higher reaction temperature for faster processing. A novel outcome was the discovery of a previously undocumented material phase in sputter-deposited and evaporated Ag-Cu-In-Ga thin films. Hydride gas reaction processes including time-temperature-concentration profiles were developed for different precursor compositions. This enables control of composition profiles to engineer through-film gradients for solar cell optimization with characterization and simulations used to correlate measured film composition profiles to measurements of devices. In particular, the gradient of sulfur at the front of the CIGSS film was found to be critical. The simulations guided process development leading to improved reproducibility of devices improved performance with higher Ga content and higher voltage. With Ag-alloyed precursors, the reaction pathways leading were determined. A significant finding was that Ag-alloying increases the reaction rate to completely convert precursor films to the final chalcopyrite which could enable reduced reaction time to benefit manufacturability. To maintain potential commercial viability, the process under investigation was refocused to a rapid thermal process that could potentially be incorporated into an in-line process for manufacturing. Precursors with different composition were capped with an extra selenium layer and reacted in hydrogen sulfide 5-15 minutes, compared to typically 2 hours in the previous multi-step batch process. Critical RTP parameters were identified to control the reaction. Further optimization would be needed for high efficiency solar cells but pathways to high quality devices with further optimization and improved heating uniformity were developed. The project also developed new optoelectronic characterization approaches with a focus on development and application of spatial- and time-resolved photoluminescence and a custom mapping photoluminescence microscope built. It was shown how critical electronic transport properties strongly depend on the chemical composition of the material and that a wide range of samples show inhomogeneity on a length scale larger than the grains in the films. Additionally, two-photon excitation capability was developed to distinguish bulk vs surface losses. The project advances the state-of-the -art for precursor reaction processes in several ways that could impact manufacturing. This includes validation of approaches to increase voltage and establishment of model-guided control to form optimal composition profiles. The application of process control approaches with knowledge of phase formation and reaction pathways can be critically valuable in designing a large-scale process.

14 SOLAR ENERGY↗
DOE OSTI2021

Exploring Covalency in the Actinides Using Soft Donor-Based Ligands and Metal-Ligand Multiple Bonding

Closing the fuel cycle is critical to the renaissance of nuclear energy in the United States. Essential in closing the fuel cycle is identification of separation strategies for actinides and fission products from spent fuels and identification of host matrices for storage or transmutation of fission products. These issues are intensified due to the complex nature of the problem (e.g., high radiation fields, high thermal fields, long half-lives of certain fission products). The use of extractor ligands with soft donor atoms has been demonstrated to selectively sequester actinides over their lanthanide counterparts. This has been presumed to be enhanced covalent bonding between the actinide 5f orbitals and the valence ligand-based orbitals; however, the coordination chemistry and reactivity with ligands containing selenium, tellurium, phosphorus, and arsenic are underdeveloped. Additionally, compounds containing actinide-ligand multiple bonding will be explored to examine pi-bonding with 5f orbitals. Efforts will be made to develop this chemistry with neptunium as well. This research explores the unique structure, bonding, and reactivity of the actinide elements while developing the underlying fundamental science involved in the separation of actinides.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Alpha Spectrometry Results for Groundwater Samples Collected in Northern Iraq and a Summary of the Environmental Setting of the Adaya Burial Site

The Radiation Protection Center (RPC) of the Iraqi Ministry of Environment continues to evaluate the potential health impacts associated with the Adaya Burial Site, which is located 33 kilometers (20.5 miles) southwest of Mosul. This report documents the radiological analyses of 16 groundwater samples collected from wells located in the vicinity of the Adaya Burial Site and at other sites in northern Iraq. The Adaya Burial Site is a high-risk dump site because a large volume of radioactive material and contaminated soil is located on an unsecure hillside above the village of Tall ar Ragrag. The uranium activities for the 16 water samples in northern Iraq are considered to be naturally occurring and do not indicate artificial (man-made) contamination. With one exception, the alpha spectrometry results for the 16 wells that were sampled in 2019 indicate that the water quality concerning the three uranium isotopes (Uranium-233/234, Uranium-235/236, and Uranium-238) was acceptable for potable purposes (drinking and cooking). However, Well 7 in Mosul had a Uranium-233/234 activity concentration that slightly exceeded the World Health Organization guidance level. Eight of the 16 wells are located in the villages of Tall ar Ragrag and Adaya and had naturally occurring uranium concentrations. Wells in the villages of Tall ar Ragrag and Adaya are located near the Adaya Burial Site and should be sampled on an annual schedule. The list of groundwater analytes should include metals, total uranium, isotopic uranium, gross alpha/beta, gamma spectroscopy, organic compounds, and standard water quality parameters. Our current understanding of the hydrogeologic setting in the vicinity of the Adaya Burial Site is solely based on villager's domestic wells, topographic maps, and satellite imagery. To better understand the hydrogeologic setting, a Groundwater Monitoring Program needs to be developed and should include the installation of twelve groundwater monitoring wells in the vicinity of Tall ar Ragrag and the Adaya Burial Site. Characterization of the limestone aquifer and overlying alluvium is needed. RPC should continue to support health assessments for the villagers in Tall ar Ragrag and Adaya. Collecting samples for surface water (storm water), airborne dust, vegetation, and washway sediment should be conducted on a routine basis. Human access to the Adaya Burial Site needs to be strictly limited. Livestock access on or near the burial site needs to be eliminated. The surface-water exposure pathway is likely a greater threat than the groundwater exposure pathway. Installation of a surface-water diversion or collection system is recommended in order to reduce the potential for humans and livestock to come in contact with contaminated water and sediment. To reduce exposure to villagers, groundwater treatment should be considered if elevated uranium or other contaminants are detected in drinking water. Installing water-treatment systems would likely be quicker to accomplish than remediation and excavation of the Adaya Burial Site. The known potential for human exposure to uranium and metals (such as arsenic, chromium, selenium, and strontium) at the Adaya Burial Site is serious. Additional characterization , mitigation, and remediation efforts should be given a high priority.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Coal Fired Power Plant Configuration and Operation Impact on Plant Effluent Contaminants and Conditions

The primary objective of this project is to characterize coal contaminants in coal-fired power plant wastewater as a function of coal type, unit configurations, and unit operation profile with uncertainty analysis. This project was in response to the U.S. Department of Energy (DOE) Solicitation DE-FOA-0001842. The project duration was between September 01, 2018, and December 31, 2021 (no-cost extension filed, due to the Covid-19 pandemic restrictions, and approved). Field and lab test program was conducted with the main goal to characterize coal contaminants in coal-fired power plant wastewater as a function of coal type, unit configurations, and unit operation profile with uncertainty analysis. In this project, the team of Lehigh University (prime recipient) and Western Kentucky University identified two suitable Thermoelectric Power Plants (TTPs) firing bituminous and sub-bituminous coals respectively, designed test plans, and performed sample collection. Sampling included coal from each TTPs power generation units, Wet Flue Gas Desulfurization (WFGD) slurry material and waste-water samples taken from the outlet of the water treatment tank prior to discharge and other pertinent locations. Coal samples are dried, crushed, and pulverized according to the American Society for Testing and Materials (ASTM) methods. The prepared coal samples are analyzed for normal proximate and ultimate analysis tests in addition to the toxic metals and anions according to ASTM methods. The FGD slurry materials are analyzed for toxic metals and anions according to Electric Power Research Institute (EPRI) or Environmental Protection Agency (EPA) methods, as appropriate. The wastewater samples from the water treatment tank outlet are analyzed for toxic metals and anions according to EPA methods. The effluent species analyzed include mercury, arsenic, selenium, nitrate/nitrite, bromide, and chlorine. This project provided results of effluent conditions as a function of coal type, unit configuration, and unit operation profile, and identified the levels of uncertainty in the effluent results.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2021

Techno-Economic Analysis of Chemical Precipitation Followed by Low Hydraulic Residence Time Biological Treatment, Including Ultrafiltration

This National Energy Technology Laboratory (NETL) analysis is a techno-economic evaluation of chemical precipitation followed by low hydraulic residence time biological treatment, which was identified as Best Available Technology for treatment and control of selenium emissions from wet flue gas desulfurization wastewater streams.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Nuclear Global Talent Development Program (Final Report)

Lawrence Livermore National Laboratory (LLNL) have developed sorption database named as L-SCIE (LLNL Surface Complexation/Ion Exchange). This framework (L-SCIE) includes not only a community database of sorption data but also a fitting workflow to produce optimized surface complexation reaction constants. Through this fellowship program we have updated the L-SCIE database for selenium (Se) sorption and potentiometric titration data of iron oxides. In addition, the relevant surface complexation models (SCMs) have been updated and details in model construction are given in the following section.

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DOE OSTI2023

Rogers Quarry Special Studies Report 2023

Rogers Quarry (RQ) has a history of elevated Se concentrations in water and fish caused by inputs from the Y-12 National Security Complex Filled Coal Ash Pond (FCAP). Selenium is acutely toxic at high concentrations, and chronic toxicity occurs at low aqueous concentrations because Se bioaccumulates in fish tissues. The US Environmental Protection Agency (EPA) recently developed water quality criteria for Se that include fish tissue as well as aqueous Se concentrations. The water column concentration criterion is 1.5 µg L -1 for lentic ecosystems and 3.1 µg L -1 for lotic ecosystems. The fish tissue criteria include both an egg/ovary concentration (15.1 μg/g dry weight) and a concentration for whole-body (8.5 μg/g dry weight) or fish muscle (11.3 μg/g dry weight). The egg/ovary criterion supersedes the fillet and aqueous concentrations if measured because Se toxicity manifests via reproductive effects in birds and fish. It is maternally transferred through eggs, leading to teratogenicity (i.e., deformities, developmental effects) in young fish.

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