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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Effect of sucrose on technetium and rhenium retention during vitrification of low-activity wastes

Sucrose (C 12 H 22 O 11 ) has been used in low-activity waste (LAW) melter feeds containing large fractions of nitrates, nitrites, or both because it facilitates foam suppression and denitration. This study focused on the effect of sucrose in LAW feeds on technetium (Tc) and rhenium (Re) retention. The amount of sucrose added in feeds was varied to differentiate the carbon-to-nitrogen mole ratio (C/N ratio). The results show that larger sucrose addition (higher C/N ratio) enhances Tc and Re retention. Reducing conditions induced by sucrose decomposition and early chemical reactions between sucrose and NaNO 3 /NaNO 2 are expected to increase Tc and Re retention. However, high sucrose addition decreased sulfur (S) retention slightly because sodium sulfate decomposes in reducing conditions at lower temperature. This early sulfate decomposition can affect Tc and Re retention partly because these species can be soluble in sulfate phases. This correlation indicates that the decrease of sulfate phases in the glass by early decomposition can reduce the solubility of Tc and Re in the sulfate phases, which may increase Tc and Re retention in the glass. In addition, continuous gas evolution and vigorous foaming at the foaming temperature range of 700–900°C may influence Tc and Re retention process interrupting retention or facilitating volatilization.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Deep Learning Experiments for Tropical Cyclone Intensity Forecasts

Reducing tropical cyclone (TC) intensity forecast errors is a challenging task that has interested the operational forecasting and research community for decades. To address this, we developed a deep learning (DL)-based multilayer perceptron (MLP) TC intensity prediction model. The model was trained using the global Statistical Hurricane Intensity Prediction Scheme (SHIPS) predictors to forecast the change in TC maximum wind speed for the Atlantic basin. In the first experiment, a 24-h forecast period was considered. To overcome sample size limitations, we adopted a leave one year out (LOYO) testing scheme, where a model is trained using data from all years except one and then evaluated on the year that is left out. When tested on 2010–18 operational data using the LOYO scheme, the MLP outperformed other statistical–dynamical models by 9%–20%. Additional independent tests in 2019 and 2020 were conducted to simulate real-time operational forecasts, where the MLP model again outperformed the statistical–dynamical models by 5%–22% and achieved comparable results as HWFI. The MLP model also correctly predicted more rapid intensification events than all the four operational TC intensity models compared. In the second experiment, we developed a lightweight MLP for 6-h intensity predictions. When coupled with a synthetic TC track model, the lightweight MLP generated realistic TC intensity distribution in the Atlantic basin. Therefore, the MLP-based approach has the potential to improve operational TC intensity forecasts, and will also be a viable option for generating synthetic TCs for climate studies.

58 GEOSCIENCES↗
DOE OSTI2020

Materials Data on TlZn2Tc by Materials Project

TcZn2Tl crystallizes in the cubic F-43m space group. The structure is three-dimensional. Tc is bonded in a distorted body-centered cubic geometry to ten Zn and four equivalent Tl atoms. There are four shorter (2.81 Å) and six longer (3.24 Å) Tc–Zn bond lengths. All Tc–Tl bond lengths are 2.81 Å. There are two inequivalent Zn sites. In the first Zn site, Zn is bonded in a 8-coordinate geometry to six equivalent Tc, four equivalent Zn, and four equivalent Tl atoms. All Zn–Zn bond lengths are 2.81 Å. All Zn–Tl bond lengths are 2.81 Å. In the second Zn site, Zn is bonded in a 8-coordinate geometry to four equivalent Tc and four equivalent Zn atoms. Tl is bonded in a distorted body-centered cubic geometry to four equivalent Tc and four equivalent Zn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tc3Rh by Materials Project

Tc3Rh is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Tc1- sites. In the first Tc1- site, Tc1- is bonded to eight equivalent Tc1- and four equivalent Rh3+ atoms to form distorted TcTc8Rh4 cuboctahedra that share corners with four equivalent RhTc12 cuboctahedra, corners with fourteen equivalent TcTc8Rh4 cuboctahedra, edges with six equivalent RhTc12 cuboctahedra, edges with twelve equivalent TcTc8Rh4 cuboctahedra, faces with four equivalent RhTc12 cuboctahedra, and faces with sixteen TcTc8Rh4 cuboctahedra. There are six shorter (2.67 Å) and two longer (2.86 Å) Tc–Tc bond lengths. There are two shorter (2.74 Å) and two longer (2.76 Å) Tc–Rh bond lengths. In the second Tc1- site, Tc1- is bonded to eight equivalent Tc1- and four equivalent Rh3+ atoms to form distorted TcTc8Rh4 cuboctahedra that share corners with four equivalent RhTc12 cuboctahedra, corners with fourteen TcTc8Rh4 cuboctahedra, edges with six equivalent RhTc12 cuboctahedra, edges with twelve equivalent TcTc8Rh4 cuboctahedra, faces with four equivalent RhTc12 cuboctahedra, and faces with sixteen TcTc8Rh4 cuboctahedra. There are six shorter (2.67 Å) and two longer (2.86 Å) Tc–Tc bond lengths. There are two shorter (2.74 Å) and two longer (2.76 Å) Tc–Rh bond lengths. Rh3+ is bonded to twelve Tc1- atoms to form RhTc12 cuboctahedra that share corners with six equivalent RhTc12 cuboctahedra, corners with twelve TcTc8Rh4 cuboctahedra, edges with eighteen TcTc8Rh4 cuboctahedra, faces with eight equivalent RhTc12 cuboctahedra, and faces with twelve TcTc8Rh4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tc3Os by Materials Project

Tc3Os is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Tc+2.33- is bonded to eight equivalent Tc+2.33- and four equivalent Os7+ atoms to form distorted TcTc8Os4 cuboctahedra that share corners with four equivalent OsTc12 cuboctahedra, corners with fourteen equivalent TcTc8Os4 cuboctahedra, edges with six equivalent OsTc12 cuboctahedra, edges with twelve equivalent TcTc8Os4 cuboctahedra, faces with four equivalent OsTc12 cuboctahedra, and faces with sixteen equivalent TcTc8Os4 cuboctahedra. There are a spread of Tc–Tc bond distances ranging from 2.71–2.77 Å. There are two shorter (2.71 Å) and two longer (2.77 Å) Tc–Os bond lengths. Os7+ is bonded to twelve equivalent Tc+2.33- atoms to form OsTc12 cuboctahedra that share corners with six equivalent OsTc12 cuboctahedra, corners with twelve equivalent TcTc8Os4 cuboctahedra, edges with eighteen equivalent TcTc8Os4 cuboctahedra, faces with eight equivalent OsTc12 cuboctahedra, and faces with twelve equivalent TcTc8Os4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoTc3 by Materials Project

Tc3Co is Magnesium-derived structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Tc+0.67- is bonded to eight equivalent Tc+0.67- and four equivalent Co2+ atoms to form TcCo4Tc8 cuboctahedra that share corners with four equivalent CoTc12 cuboctahedra, corners with fourteen equivalent TcCo4Tc8 cuboctahedra, edges with six equivalent CoTc12 cuboctahedra, edges with twelve equivalent TcCo4Tc8 cuboctahedra, faces with four equivalent CoTc12 cuboctahedra, and faces with sixteen equivalent TcCo4Tc8 cuboctahedra. There are a spread of Tc–Tc bond distances ranging from 2.66–2.70 Å. There are two shorter (2.65 Å) and two longer (2.69 Å) Tc–Co bond lengths. Co2+ is bonded to twelve equivalent Tc+0.67- atoms to form CoTc12 cuboctahedra that share corners with six equivalent CoTc12 cuboctahedra, corners with twelve equivalent TcCo4Tc8 cuboctahedra, edges with eighteen equivalent TcCo4Tc8 cuboctahedra, faces with eight equivalent CoTc12 cuboctahedra, and faces with twelve equivalent TcCo4Tc8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SiTc3 by Materials Project

Tc3Si is Magnesium-derived structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Tc+1.33- is bonded to eight equivalent Tc+1.33- and four equivalent Si4+ atoms to form TcSi4Tc8 cuboctahedra that share corners with four equivalent SiTc12 cuboctahedra, corners with fourteen equivalent TcSi4Tc8 cuboctahedra, edges with six equivalent SiTc12 cuboctahedra, edges with twelve equivalent TcSi4Tc8 cuboctahedra, faces with four equivalent SiTc12 cuboctahedra, and faces with sixteen equivalent TcSi4Tc8 cuboctahedra. There are a spread of Tc–Tc bond distances ranging from 2.64–2.78 Å. There are two shorter (2.68 Å) and two longer (2.71 Å) Tc–Si bond lengths. Si4+ is bonded to twelve equivalent Tc+1.33- atoms to form SiTc12 cuboctahedra that share corners with six equivalent SiTc12 cuboctahedra, corners with twelve equivalent TcSi4Tc8 cuboctahedra, edges with eighteen equivalent TcSi4Tc8 cuboctahedra, faces with eight equivalent SiTc12 cuboctahedra, and faces with twelve equivalent TcSi4Tc8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ReTc3 by Materials Project

ReTc3 is Magnesium-derived structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Re7+ is bonded to twelve equivalent Tc+2.33- atoms to form ReTc12 cuboctahedra that share corners with six equivalent ReTc12 cuboctahedra, corners with twelve equivalent TcRe4Tc8 cuboctahedra, edges with eighteen equivalent TcRe4Tc8 cuboctahedra, faces with eight equivalent ReTc12 cuboctahedra, and faces with twelve equivalent TcRe4Tc8 cuboctahedra. There are six shorter (2.73 Å) and six longer (2.76 Å) Re–Tc bond lengths. Tc+2.33- is bonded to four equivalent Re7+ and eight equivalent Tc+2.33- atoms to form TcRe4Tc8 cuboctahedra that share corners with four equivalent ReTc12 cuboctahedra, corners with fourteen equivalent TcRe4Tc8 cuboctahedra, edges with six equivalent ReTc12 cuboctahedra, edges with twelve equivalent TcRe4Tc8 cuboctahedra, faces with four equivalent ReTc12 cuboctahedra, and faces with sixteen equivalent TcRe4Tc8 cuboctahedra. There are a spread of Tc–Tc bond distances ranging from 2.74–2.78 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AlTc2 by Materials Project

Tc2Al crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Tc is bonded in a 8-coordinate geometry to four equivalent Tc and four equivalent Al atoms. All Tc–Tc bond lengths are 2.62 Å. All Tc–Al bond lengths are 2.66 Å. Al is bonded in a body-centered cubic geometry to eight equivalent Tc atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3Tc2Cl8O3 by Materials Project

K3Tc2O3Cl8 crystallizes in the trigonal P3_121 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 8-coordinate geometry to two equivalent O2- and six Cl1- atoms. Both K–O bond lengths are 2.83 Å. There are a spread of K–Cl bond distances ranging from 3.23–3.43 Å. In the second K1+ site, K1+ is bonded in a 10-coordinate geometry to ten Cl1- atoms. There are a spread of K–Cl bond distances ranging from 3.25–3.82 Å. Tc+5.50+ is bonded in a 4-coordinate geometry to four Cl1- atoms. There are a spread of Tc–Cl bond distances ranging from 2.33–2.41 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one K1+ and one O2- atom. The O–O bond length is 1.31 Å. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent O2- atoms. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a distorted single-bond geometry to two equivalent K1+ and one Tc+5.50+ atom. In the second Cl1- site, Cl1- is bonded in a 1-coordinate geometry to four K1+ and one Tc+5.50+ atom. In the third Cl1- site, Cl1- is bonded in a 1-coordinate geometry to four K1+ and one Tc+5.50+ atom. In the fourth Cl1- site, Cl1- is bonded in a 1-coordinate geometry to three K1+ and one Tc+5.50+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tc3Pb by Materials Project

Tc3Pb is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Tc+0.67- is bonded to eight equivalent Tc+0.67- and four equivalent Pb2+ atoms to form distorted TcTc8Pb4 cuboctahedra that share corners with four equivalent PbTc12 cuboctahedra, corners with fourteen equivalent TcTc8Pb4 cuboctahedra, edges with six equivalent PbTc12 cuboctahedra, edges with twelve equivalent TcTc8Pb4 cuboctahedra, faces with four equivalent PbTc12 cuboctahedra, and faces with sixteen equivalent TcTc8Pb4 cuboctahedra. There are a spread of Tc–Tc bond distances ranging from 2.72–3.10 Å. There are two shorter (2.89 Å) and two longer (2.91 Å) Tc–Pb bond lengths. Pb2+ is bonded to twelve equivalent Tc+0.67- atoms to form PbTc12 cuboctahedra that share corners with six equivalent PbTc12 cuboctahedra, corners with twelve equivalent TcTc8Pb4 cuboctahedra, edges with eighteen equivalent TcTc8Pb4 cuboctahedra, faces with eight equivalent PbTc12 cuboctahedra, and faces with twelve equivalent TcTc8Pb4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tc3W by Materials Project

WTc3 is Uranium Silicide-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. W5+ is bonded to twelve equivalent Tc+1.67- atoms to form WTc12 cuboctahedra that share corners with six equivalent WTc12 cuboctahedra, corners with twelve equivalent TcTc8W4 cuboctahedra, edges with eighteen equivalent TcTc8W4 cuboctahedra, faces with eight equivalent WTc12 cuboctahedra, and faces with twelve equivalent TcTc8W4 cuboctahedra. There are six shorter (2.75 Å) and six longer (2.78 Å) W–Tc bond lengths. Tc+1.67- is bonded to four equivalent W5+ and eight equivalent Tc+1.67- atoms to form distorted TcTc8W4 cuboctahedra that share corners with four equivalent WTc12 cuboctahedra, corners with fourteen equivalent TcTc8W4 cuboctahedra, edges with six equivalent WTc12 cuboctahedra, edges with twelve equivalent TcTc8W4 cuboctahedra, faces with four equivalent WTc12 cuboctahedra, and faces with sixteen equivalent TcTc8W4 cuboctahedra. There are a spread of Tc–Tc bond distances ranging from 2.76–2.79 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tc3Ge by Materials Project

Tc3Ge is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Tc+1.33- is bonded to eight equivalent Tc+1.33- and four equivalent Ge4+ atoms to form TcTc8Ge4 cuboctahedra that share corners with four equivalent GeTc12 cuboctahedra, corners with fourteen equivalent TcTc8Ge4 cuboctahedra, edges with six equivalent GeTc12 cuboctahedra, edges with twelve equivalent TcTc8Ge4 cuboctahedra, faces with four equivalent GeTc12 cuboctahedra, and faces with sixteen equivalent TcTc8Ge4 cuboctahedra. There are a spread of Tc–Tc bond distances ranging from 2.69–2.79 Å. There are two shorter (2.72 Å) and two longer (2.74 Å) Tc–Ge bond lengths. Ge4+ is bonded to twelve equivalent Tc+1.33- atoms to form GeTc12 cuboctahedra that share corners with six equivalent GeTc12 cuboctahedra, corners with twelve equivalent TcTc8Ge4 cuboctahedra, edges with eighteen equivalent TcTc8Ge4 cuboctahedra, faces with eight equivalent GeTc12 cuboctahedra, and faces with twelve equivalent TcTc8Ge4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tc3Mo by Materials Project

MoTc3 is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Mo5+ is bonded to twelve equivalent Tc+1.67- atoms to form MoTc12 cuboctahedra that share corners with twelve equivalent MoTc12 cuboctahedra, edges with twenty-four equivalent TcTc8Mo4 cuboctahedra, faces with six equivalent MoTc12 cuboctahedra, and faces with twelve equivalent TcTc8Mo4 cuboctahedra. All Mo–Tc bond lengths are 2.77 Å. Tc+1.67- is bonded to four equivalent Mo5+ and eight equivalent Tc+1.67- atoms to form TcTc8Mo4 cuboctahedra that share corners with twelve equivalent TcTc8Mo4 cuboctahedra, edges with eight equivalent MoTc12 cuboctahedra, edges with sixteen equivalent TcTc8Mo4 cuboctahedra, faces with four equivalent MoTc12 cuboctahedra, and faces with fourteen equivalent TcTc8Mo4 cuboctahedra. All Tc–Tc bond lengths are 2.77 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TcP2H18(C3Br)2 by Materials Project

TcP2H18(C3Br)2 crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of four TcP2H18(C3Br)2 clusters. there are two inequivalent Tc3- sites. In the first Tc3- site, Tc3- is bonded in a 5-coordinate geometry to one Tc3-, two equivalent P5+, and two equivalent Br1- atoms. The Tc–Tc bond length is 2.19 Å. Both Tc–P bond lengths are 2.46 Å. Both Tc–Br bond lengths are 2.56 Å. In the second Tc3- site, Tc3- is bonded in a 5-coordinate geometry to one Tc3-, two equivalent P5+, and two equivalent Br1- atoms. Both Tc–P bond lengths are 2.46 Å. Both Tc–Br bond lengths are 2.56 Å. There are five inequivalent C+3.83- sites. In the first C+3.83- site, C+3.83- is bonded to one P5+ and three H1+ atoms to form distorted corner-sharing CPH3 tetrahedra. The C–P bond length is 1.83 Å. All C–H bond lengths are 1.10 Å. In the second C+3.83- site, C+3.83- is bonded to one P5+ and three H1+ atoms to form distorted corner-sharing CPH3 tetrahedra. The C–P bond length is 1.82 Å. All C–H bond lengths are 1.10 Å. In the third C+3.83- site, C+3.83- is bonded to one P5+ and three H1+ atoms to form distorted corner-sharing CPH3 tetrahedra. The C–P bond length is 1.83 Å. All C–H bond lengths are 1.10 Å. In the fourth C+3.83- site, C+3.83- is bonded to one P5+ and three H1+ atoms to form distorted corner-sharing CPH3 tetrahedra. The C–P bond length is 1.82 Å. There is one shorter (1.09 Å) and two longer (1.10 Å) C–H bond length. In the fifth C+3.83- site, C+3.83- is bonded to one P5+ and three H1+ atoms to form distorted corner-sharing CPH3 tetrahedra. The C–P bond length is 1.82 Å. All C–H bond lengths are 1.10 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to one Tc3- and three C+3.83- atoms to form distorted corner-sharing PTcC3 tetrahedra. In the second P5+ site, P5+ is bonded to one Tc3- and three C+3.83- atoms to form distorted corner-sharing PTcC3 tetrahedra. The P–C bond length is 1.83 Å. There are eighteen inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the sixteenth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. The H–C bond length is 1.10 Å. In the seventeenth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. The H–C bond length is 1.10 Å. In the eighteenth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. The H–C bond length is 1.10 Å. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a single-bond geometry to one Tc3- atom. In the second Br1- site, Br1- is bonded in a single-bond geometry to one Tc3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Assessing whole-sounder removal versus traditional control for reducing invasive wild pig ( Sus scrofa ) populations

Trapping is commonly used as the primary management tool in attempts to reduce invasive wild pigs (Sus scrofa), but traditional trapping techniques are often ineffective. However, recently developed traps permit the capture of entire social groups (sounders) of wild pigs, and the strategy of whole-sounder removal may achieve more effective control. Our objective was to experimentally compare traditional control (TC; primarily traditional trapping, but including hunting with dogs, and opportunistic shooting) and whole-sounder removal (WSR) strategies by assessing density reduction and removal rate after 1 and 2 years of treatment. After 1 year of trapping, average wild pig density on WSR units declined 53% and remained stable after the second year, whereas on TC units, pig density did not differ after trapping, although it declined 33% and remained stable after the second year of trapping. The median removal rate (percentage of uniquely marked pigs present at the beginning of each year that were removed) was 42.5% for WSR units and 0.0% for TC units during 2018 and were 29.6% from WSR units and 5.3% from TC units during 2019. WSR removal was more effective at reducing wild pig density than TC, but factors such as previous exposure of this population to traditional traps and the lack of barriers to recolonization from surrounding areas may have reduced WSR efficacy. WSR can effectively reduce wild pig density to a greater extent than TC, but managers should recognize the additional time and expense necessary for implementation.

Sus scrofa↗
DOE OSTI2024

The simultaneous removal of technetium and iodine from Hanford tank waste

The simultaneous removal of radionuclides technetium-99 and iodine-129 from an actual decontaminated Hanford tank waste sample (a mixture of decontaminated waste from tanks 241-AP-105 and 241-AP-107) was demonstrated for the first time in this work. A series of commercially available ion exchange resins were evaluated in batch contact tests in the tank waste, and all showed removal of both Tc and I. The highest Tc removal was observed for Purolite A530e while the highest iodine removal was observed for ResinTech SIR-110-MP. Batch tests in simulated tank waste with these two resins showed that the SIR-110-HP-MP had consistently higher K d for both pertechnetate and iodide and much higher K d than previous works on Tc removal from Hanford waste. As such, the SIR-110-MP was evaluated in a dual -column (lead/lag) test processing 5.2L of the tank waste mixture showing 60% breakthrough of Tc on the lead column and no significant breakthrough on the lag after 625 bed volumes (BV, 6 mL size) while significant iodine breakthrough (>50%) occurred after 28 BV. The limited iodine uptake was attributed to the column conditions generating mass transfer limitations. A fraction of the Tc and I was not captured by the resin (<10%) in either the batch tests or column tests. The iodine fraction was identified to be an iodide, likely organo-iodide. The fraction of the Tc was identified as a non-pertechnetate species, which is the first time non-pertechnetate has been identified in AP-105 and AP-107 tanks, although the exact species is still unknown.

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

Human DNA polymerase η promotes RNA-templated error-free repair of DNA double-strand breaks

A growing body of evidence indicates that RNA plays a critical role in orchestrating DNA double-strand break repair (DSBR). Recently, we showed that homologous nascent RNA can be used as a template for error-free repair of double-strand breaks (DSBs) in the transcribed genome and to restore the missing sequence at the break site via the transcription-coupled classical nonhomologous end-joining (TC-NHEJ) pathway. TC-NHEJ is a complex multistep process in which a reverse transcriptase (RT) is essential for synthesizing the DNA strand from template RNA. However, the identity of the RT involved in the TC-NHEJ pathway remained unknown. Here, we report that DNA polymerase eta (Pol η), known to possess RT activity, plays a critical role in TC-NHEJ. We found that Pol η forms a multiprotein complex with RNAP II and other TC-NHEJ factors, while also associating with nascent RNA. Moreover, purified Pol η, along with DSBR proteins PNKP, XRCC4, and Ligase IV can fully repair RNA templated 3'-phosphate-containing gapped DNA substrate. In addition, we demonstrate here that Pol η deficiency leads to accumulation of R-loops and persistent strand breaks in the transcribed genes. Finally, we determined that, in Pol η depleted but not in control cells, TC-NHEJ-mediated repair was severely abrogated when a reporter plasmid containing a DSB with several nucleotide deletion within the E. coli lacZ gene was introduced for repair in lacZ-expressing mammalian cells. Thus, our data strongly suggest that RT activity of Pol η is required in error-free DSBR.

59 BASIC BIOLOGICAL SCIENCES↗