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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Chlorination of low-band-gap polymers: Toward high-performance polymer solar cells

Here, halogenation is an effective way to tune the energy levels of organic semiconducting materials. To date, fluorination of organic semiconducting materials to fabricate polymer solar cells (PSCs) has been used far more than chlorination; however, fluorine exchange reactions suffer from low yields and the resulting fluorinated polymer always comes with higher price, which will greatly hinder their commercial applications. Herein, we designed and synthesized a series of chlorinated donor-acceptor (D-A) type polymers, in which benzo[1,2-b:4,5- b]dithiophene and chlorinated benzothiadiazole units are connected by thiophene π-bridges with an asymmetric alkyl chain. These chlorinated polymers showed deep highest occupied molecular orbital energy levels, which promoted the efficiency of their corresponding PSCs by increasing the device open circuit voltage. The asymmetric alkyl chain on the thiophene moieties gave the final polymer sufficient solubility for solution processing and strong π-π stacking in films allowed for high mobility. Although the introduction of a large chlorine atom increased the torsion angle of the polymer backbone, the chlorinated polymers maintained high crystallinity and a favorable backbone orientation in the blended films. These factors contributed to respectable device performances from thick-film devices, which showed PCEs as high as 9.11% for a 250 nm-thick active layer. These results demonstrate that chlorination is a promising method to fine tune the energy levels of conjugated polymers, and chlorinated benzothiadiazole may be a versatile building block in materials for efficient solar energy conversion.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Synthetic Chlorins, Possible Surrogates for Chlorophylls, Prepared by Derivatization of Porphyrins

Chlorophylls make Earth green, are the central constituents in the engine of photosynthesis, and not surprisingly have garnered extensive attention. A chlorin, the core chromophore of a chlorophyll, is a dihydroporphyrin macrocycle that contains one pyrroline ring and three pyrrole rings. The dominant method for the synthesis of chlorins has entailed the derivatization of porphyrins. The present review covers the ostensibly simple conversion of porphyrins, regardless of synthetic or biological origin, to chlorins. The period covered encompasses the entire history since the beginnings of chlorin synthetic chemistry in the early 20th century through 2015. Representative transformations include hydrogenation, cycloaddition, annulation, and diverse “breaking and mending” approaches. Altogether, the synthesis of >1000 chlorins or chlorin-like compounds (containing >50 distinct pyrroline motifs) is described. Such diversity animates the question “what structural features are essential for a chlorin to resemble chlorophyll?” To begin to address the structure–spectrum relationship, > 250 absorption spectra are provided for representative structures. The synthesis and spectral properties of the vast collection of compounds described herein are expected to illuminate the scope to which synthetic chlorins can serve as surrogates for chlorophylls and be exploited in diverse ways.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Synthesis of (oxo)chlorin dimers chelated with thallium(III)

Two target dimers have been prepared for fundamental studies of hole/electron transfer. Metalation with thallium(III) enables clocking of the rate of hole/electron transfer between the two macrocycles. Each dimer contains a diphenylethyne linker joining two identical hydroporphyrins (chlorin or oxochlorin). The linker is substituted at the 4,4′-positions whereas each (oxo)chlorin is joined at the 10-position. Each (oxo)chlorin is equipped with a gem-dimethyl group at the 18-position to stabilize the hydroporphyrin chromophore toward adventitious dehydrogenation and a 3,5-di-tert-butyl group at the 5-position to achieve increased solubilization in organic media. The dimers parallel a prior set of diphenylethyne-linked (oxo)chlorin constructs containing zinc-free base, zinc-zinc, and copper-copper metalation states that have been examined in studies of electronic communication. The building block (oxo)chlorins for preparing the thallium-containing dimers have been prepared in quantities of 32–404 mg, a scale up to 14-fold larger than previously. Thallation of the free base (oxo)chlorin dimers was achieved with excess TlCl 3 ⋅4H 2 O in CH 2 Cl 2 /CH 3 OH (3–4:1) upon overnight reaction at room temperature. The long-wavelength (Q[Formula: see text] absorption band of (oxo)chlorins lies between that of the zinc(II) and free base counterparts. Absorption spectral comparisons are provided of the thallium(III) and free base (oxo)chlorin monomers and dimers.

Chemistry↗
NASA NTRS1995

Estimates of total organic and inorganic chlorine in the lower stratosphere from in situ and flask measurements during AASE 2

Aircraft sampling has provided extensive in situ and flask measurements of organic chlorine species in the lower stratosphere. The recent Airborne Arctic Stratospheric Expedition 2 (AASE 2) included two independent measurements of organic chlorine species using whole air sample and real-time techniques. From the whole air sample measurements we derive directly the burden of total organic chlorine (CCl(y)) in the lower stratosphere. From the more limited real-time measurements we estimate the CCl(y) burden using mixing ratios and growth rates of the principal CCl(y) species in the troposphere in conjunction with results from a two-dimensional photochemical model. Since stratospheric chlorine is tropospheric in origin and tropospheric mixing ratios are increasing, it is necessary to establish the average age of a stratospheric air parcel to assess its total chlorine (Cl(sub Total)) abundance. Total inorganic chlorine (Cl(y)) in the parcel is then estimated by the simple difference, Cl(y) = Cl(sub Total) - CCl(y). The consistency of the results from these two quite different techniques suggests that we can determine the CCl(y) and Cl(y) in the lower stratosphere with confidence. Such estimates of organic and inorganic chlorine are crucial in evaluating the photochemistry controlling chlorine partitioning and hence ozone loss processes in the lower stratosphere.

Woodbridge, E. L.↗
DOE OSTI2016

Development and assessment of countermeasure formulations for treatment of lung injury induced by chlorine inhalation

Chlorine is a commonly used, reactive compound to which humans can be exposed via accidental or intentional release resulting in acute lung injury. Formulations of rolipram (a phosphodiesterase inhibitor), triptolide (a natural plant product with anti-inflammatory properties), and budesonide (a corticosteroid), either neat or in conjunction with poly(lactic:glycolic acid) (PLGA), were developed for treatment of chlorine-induced acute lung injury by intramuscular injection. Formulations were produced by spray-drying, which generated generally spherical microparticles that were suitable for intramuscular injection. Multiple parameters were varied to produce formulations with a wide range of in vitro release kinetics. Testing of selected formulations in chlorine-exposed mice demonstrated efficacy against key aspects of acute lung injury. The results show the feasibility of developing microencapsulated formulations that could be used to treat chlorine-induced acute lung injury by intramuscular injection, which represents a preferred route of administration in a mass casualty situation. - Highlights: • Chlorine causes lung injury when inhaled and is considered a chemical threat agent. • Countermeasures for treatment of chlorine-induced acute lung injury are needed. • Formulations containing rolipram, triptolide, or budesonide were produced. • Formulations with a wide range of release properties were developed. • Countermeasure formulations inhibited chlorine-induced lung injury in mice.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

The chlorination and separation of aluminum using low-temperature sulfur chloride reagents

There is currently no strategy for the permanent waste disposal or recycling for used nuclear fuelsfrom research reactors. For this reason, low-temperature reactions have been developed for thechlorination of the Al alloys and subsequent separation from used nuclear fuels to reducethe volume of high-level waste in storage. Three sulfur chloride reagents – S 2 Cl 2 , SOCl 2 , and SO 2 Cl 2 —were tested, and two were found to quantitatively chlorinate Al metal and Al alloys undermild conditions. Further, these low-temperature reactions proceed between 298 and 411 K, and up to 5 gof metal is chlorinated in 1–3 h. Preliminary results indicate that the reactivity and exothermicity ofthe reaction between the Al and sulfur chloride reagents is highly dependent on the surface area-to-volume ratio of the metal and the volume of solvent. Elemental S is produced as a by-productduring the chlorination with S 2 Cl 2 but can be quantitatively rechlorinated under mild conditions toregenerate the initial chlorination reagent. Therefore, in this case, chlorine is the only elementconsumed in the reaction, thus minimizing the waste generated during the chlorination process.The AlCl 3 may then be separated from other materials present in Al 6061 or Al 8001 because of itshigh solubility in the sulfur chloride reagents. This process may also be extended to chlorinate Alfrom research reactor fuels.

aluminum↗
DOE OSTI2015

Validation Study for Crediting Chlorine in Criticality Analyses for US Spent Nuclear Fuel Disposition

Spent nuclear fuel (SNF) management practices in the United States rely on dry storage systems that include both canister- and cask-based systems. The United States Department of Energy Used Fuel Disposition Campaign is examining the feasibility of direct disposal of dual-purpose (storage and transportation) canisters (DPCs) in a geological repository. One of the major technical challenges for direct disposal is the ability to demonstrate the subcriticality of the DPCs loaded with SNF for the repository performance period (e.g., 10,000 years or more) as the DPCs may undergo degradation over time. Specifically, groundwater ingress into the DPC (i.e., flooding) could allow the system to achieve criticality in scenarios where the neutron absorber plates in the DPC basket have degraded. However, as was shown by Banerjee et al., some aqueous species in the groundwater provide noticeable reactivity reduction for these systems. For certain amounts of particular aqueous species (e.g., chlorine, lithium) in the groundwater, subcriticality can be demonstrated even for DPCs with complete degradation of the neutron absorber plates or a degraded fuel basket configuration. It has been demonstrated that chlorine is the leading impurity, as indicated by significant neutron absorption in the water that is available in reasonable quantities for the deep geological repository media under consideration. This paper presents the results of an investigation of the available integral experiments worldwide that could be used to validate DPC disposal criticality evaluations, including credit for chlorine. Due to the small number of applicable critical configurations, validation through traditional trending analysis was not possible. The bias in the eigenvalue of the application systems due only to the chlorine was calculated using TSURFER analysis and found to be on the order of 100 percent mille (1 pcm = 10 -5 k eff ). This study investigated the design of a series of critical configurations with varying amounts of chlorine to address validation gaps. Such integral experiments would support the crediting of the chlorine neutron-absorption properties in groundwater and the demonstration of subcriticality for DPCs in deep geologic repositories with sufficient chlorine availability.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Validation Study for Crediting Chlorine in Criticality Analyses for Spent Nuclear Fuel Disposition

Spent nuclear fuel (SNF) management practices in the United States rely on dry storage systems that include both canister- and cask-based systems. The United States Department of Energy Used Fuel Disposition Campaign is examining the feasibility of direct disposal of dual-purpose (storage and transportation) canisters (DPCs) in a geological repository. One of the major technical challenges for direct disposal is the ability to demonstrate the subcriticality of the DPCs loaded with SNF for the repository performance period (e.g., 10,000 years or more) as the DPCs may undergo degradation over time. Specifically, groundwater ingress into the DPC (i.e., flooding) could allow the system to achieve criticality in scenarios where the neutron absorber plates in the DPC basket have degraded. However, as was shown by Banerjee et al., some aqueous species in the groundwater provide noticeable reactivity reduction for these systems. For certain amounts of particular aqueous species (e.g., chlorine, lithium) in the groundwater, subcriticality can be demonstrated even for DPCs with complete degradation of the neutron absorber plates or a degraded fuel basket configuration. It has been demonstrated that chlorine is the leading impurity, as indicated by significant neutron absorption in the water that is available in reasonable quantities for the deep geological repository media under consideration. This paper presents the results of an investigation of the available integral experiments worldwide that could be used to validate DPC disposal criticality evaluations, including credit for chlorine. Due to the small number of applicable critical configurations, validation through traditional trending analysis was not possible. The bias in the eigenvalue of the application systems due only to the chlorine was calculated using TSURFER analysis and found to be on the order of 100 percent mille (1 pcm = 10 -5 k eff ). This study investigated the design of a series of critical configurations with varying amounts of chlorine to address validation gaps. Such integral experiments would support the crediting of the chlorine neutron-absorption properties in groundwater and the demonstration of subcriticality for DPCs in deep geologic repositories with sufficient chlorine availability.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Validation study for crediting chlorine in critically analyses for spent nuclear fuel disposition - 14428

Spent nuclear fuel (SNF) management practices in the United States rely on dry storage systems that include both canister- and cask-based systems. The United States Department of Energy Used Fuel Disposition Campaign is examining the feasibility of direct disposal of dual-purpose (storage and transportation) canisters (DPCs) in a geological repository. One of the major technical challenges for direct disposal is the ability to demonstrate the subcriticality of the DPCs loaded with SNF for the repository performance period (e.g., 10,000 years or more) as the DPCs may undergo degradation over time. Specifically, groundwater ingress into the DPC (i.e., flooding) could allow the system to achieve criticality in scenarios where the neutron absorber plates in the DPC basket have degraded. However, as was shown by Banerjee et al., some aqueous species in the groundwater provide noticeable reactivity reduction for these systems. For certain amounts of particular aqueous species (e.g., chlorine, lithium) in the groundwater, subcriticality can be demonstrated even for DPCs with complete degradation of the neutron absorber plates or a degraded fuel basket configuration. It has been demonstrated that chlorine is the leading impurity, as indicated by significant neutron absorption in the water that is available in reasonable quantities for the deep geological repository media under consideration. This paper presents the results of an investigation of the available integral experiments worldwide that could be used to validate DPC disposal criticality evaluations, including credit for chlorine. Due to the small number of applicable critical configurations, validation through traditional trending analysis was not possible. The bias in the eigenvalue of the application systems due only to the chlorine was calculated using TSURFER analysis and found to be on the order of 100 percent mille (1 pcm = 10-5 k{sub eff}). This study investigated the design of a series of critical configurations with varying amounts of chlorine to address validation gaps. Such integral experiments would support the crediting of the chlorine neutron-absorption properties in groundwater and the demonstration of subcriticality for DPCs in deep geologic repositories with sufficient chlorine availability. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Synergistic Effect of Chlorination and Selenophene: Achieving Elevated Solar Conversion in Highly Aggregated Systems

Chlorination and selenophene were used to develop benzothiadiazole-based polymers for high-performance polymer solar cells (PSCs). The introduction of selenophene can increase crystallinity due to the metalloid nature of selenium and thus facilitate charge transport. Chlorination can tune the energy levels and induce strong aggregation due to its unique features. A non-chlorinated polymer with selenophene, PBT3TSe, shows a highly crystalline structure and a dominant face-on orientation, consequently attaining a high short-circuit current (J(SC)). Chlorinated PBT3TClSe displays synergy between the advantages of chlorination and selenophene to achieve elevated photovoltaic performance, with a power conversion efficiency (PCE) approaching 9.89% in PC 71 BM-based devices. Interestingly, chlorination has an important influence on morphology of the polymer and polymer blend films, resulting in a severe aggregation and mixed face-on and edge-on orientation in the blend film. But the sufficient intermingling of donor and acceptor and the closer distances between molecules from the introduction of the chlorine and selenophene offset their morphological inferiority to achieve higher solar conversion.

14 SOLAR ENERGY↗
DOE OSTI2023

Widespread detection of chlorine oxyacids in the Arctic atmosphere

Chlorine radicals are strong atmospheric oxidants known to play an important role in the depletion of surface ozone and the degradation of methane in the Arctic troposphere. Initial oxidation processes of chlorine produce chlorine oxides, and it has been speculated that the final oxidation steps lead to the formation of chloric (HClO 3 ) and perchloric (HClO 4 ) acids, although these two species have not been detected in the atmosphere. Here, we present atmospheric observations of gas-phase HClO 3 and HClO 4 . Significant levels of HClO 3 were observed during springtime at Greenland (Villum Research Station), Ny-Ålesund research station and over the central Arctic Ocean, on-board research vessel Polarstern during the Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC) campaign, with estimated concentrations up to 7 × 10 6 molecule cm -3 . The increase in HClO 3 , concomitantly with that in HClO 4 , was linked to the increase in bromine levels. These observations indicated that bromine chemistry enhances the formation of OClO, which is subsequently oxidized into HClO 3 and HClO 4 by hydroxyl radicals. HClO 3 and HClO 4 are not photoactive and therefore their loss through heterogeneous uptake on aerosol and snow surfaces can function as a previously missing atmospheric sink for reactive chlorine, thereby reducing the chlorine-driven oxidation capacity in the Arctic boundary layer. Our study reveals additional chlorine species in the atmosphere, providing further insights into atmospheric chlorine cycling in the polar environment.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Constraining the impact of chlorine as a neutron absorber in next-gen fast reactor designs

The role of chlorine as a neutron poison and as a seed for producing radioactive waste in nuclear systems has driven a renewed interest to improve its nuclear data uncertainties. Additionally, basic and applied science programs that use CLYC (Cs 2 LiYCl 6 :Ce) detectors for neutron spectroscopy and monitoring are also very sensitive to any change in chlorine nuclear data for simulations of the detector response. In this work, sensitivities relevant for these different applications are addressed through simulations of the efficiency of CLYC detectors in a fast fission spectrum when applying new chlorine nuclear data as input. These simulations are validated by an experimental measurement using CLYC detectors coupled to an ionization chamber loaded with a 252 Cf spontaneous fission source. The results are then used to obtain the first reliable direct measurement of the 35 Cl(n,p 0 ) and summed Cl(n,p+n,α) fission spectrum average cross sections, found to be 54.7(32) and 105.0(98) mb, respectively. The results are within uncertainty of calculated fission spectrum averaged cross sections based on recently re-evaluated chlorine nuclear data, which confirm recent impact studies performed for the Molten Chloride Reactor Experiment. Meanwhile, there currently exists only one published criticality benchmark experiment that is sufficiently sensitive to chlorine nuclear data. Discrepancies are found with this set of criticality safety benchmarks, which are more sensitive to thermal and epithermal neutron energies than the energies, above 100 keV, tested in this current work. Hence, there is still a need to re-evaluate the chlorine nuclear data at lower energies to assess these discrepancies. Interpretation of the data from future “faster” criticality benchmarks, which are needed for next-gen fast reactor designs, benefit from the improved constraints on the chlorine nuclear data validated in this work.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

A two-stage strategy for upcycling chlorine-contaminated plastic waste

Abstract Chemical upcycling of polyolefin plastic waste to lubricant, wax and fuel-range hydrocarbons over metal-based catalysts is a crucial technological solution to the enormous environmental threat posed by plastic waste. However, currently available methods are incompatible with chlorine-contaminated feedstocks. Here we report a two-stage strategy for upcycling chlorine-contaminated polypropylene. First, magnesia–alumina mixed oxide at 30 bar H 2 and 250 °C serves as a chlorine trap by rapidly forming solid chloride, resulting in nearly complete chlorine extraction from the polyolefin melt. This enables the upcycling of plastic waste with up to 10% polyvinyl chloride content to lubricants over ruthenium-based catalysts, in the second stage. The strategy is also applicable to chlorinated aromatics and alkanes. The proposed strategy renders hydrocracking and hydrogenolysis catalysts less sensitive to the chlorine impurities in feedstocks while eliminating HCl emissions and chlorine contamination in products. It could incentivize further progress in plastics upcycling.

Environmental Sciences & Ecology↗
DOE OSTI2017

The integrated adjustment of chlorine substitution and two-dimensional side chain of low band gap polymers in organic solar cells

A series of conjugated T2 polymers (PBBF1-T2 and PBBCl1-T2), and T3 polymers (PBBF1-T3, PBBCl1-T3 and PBBCl2-T3) were synthesized using chlorinated/fluorinated benzothiadiazole (BT) and the two-dimensional benzo[1,2-b:4,5-b']dithiophene (BDT) units as the building blocks. When compared to the fluorinated polymer, the performance of the polymer photovoltaic devices showed that these chlorinated polymers gave extended optical absorption spectrum, and lower highest occupied molecular orbital (HOMO) energy levels. The introduction of chlorine atoms increases the twist angle between the polymer backbones, and led to a lower HOMO energy level and resulted in the increase of open circuit voltage (V oc) up to 0.84 V in PBBCl2-T3 based devices with a two chlorine substitution. However, the device based on PBBCl1-T3 with only one chlorine atom exhibited the best power conversion efficiency (PCE) which was as high as 6.87% with a V oc of 0.73 V, and this was about 10% higher than that of its fluorinated analogs. Here, this result indicated that the introduction of chlorine atoms into polymers is not only a simple route to synthesize a large amount of material and which avoids the tedious synthesis steps in widely used fluorinated polymers, but it is also a feasible and effective strategy to fine tune the energy level of polymer solar cell with optimized PCE. Furthermore, it is worth noting that the introduction of longer π-conjugation side chains could minimize the influence of chlorine substitution by reducing the twist angle between the polymer backbones, which would reduce the gap of V oc between the chlorinated polymers and their fluorinated analogs.

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

Progress towards synthetic chlorins with graded polarity, conjugatable substituents, and wavelength tunability

Advances in chlorin synthetic chemistry now enable the de novo preparation of diverse chlorin-containing molecular architectures. Five distinct molecular designs have been explored here, including hydrophobic bioconjugatable (oxo)chlorins; a hydrophilic bioconjugatable chlorin; a trans -ethynyl/iodochlorin building block; a set of chlorins bearing electron-rich (methoxy, dimethylamino, methylthio) groups at the 3-position; and a set of ten 3,13-disubstituted chlorins chiefly bearing groups with extended π-moieties. Altogether 23 new chlorins (17 targets, 6 intermediates) have been prepared. Lastly, the challenge associated with molecular designs that encompass the combination of “hydrophilic, bioconjugatable and wavelength-tunable” chiefly resides in the nature of the hydrophilic unit.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

A Review of Advanced Test Reactor Fuel and Assessment of Its Compatibility with the ZIRCEX Chlorination Process

Advanced Test Reactor (ATR) fuel has been identified as a resource for high-assay low-enriched uranium (HALEU) production. A survey was performed on the published literature describing ATR fuel. The geometry of the fuel is complex; different parts of the fuel compact experience differing neutron flux and burnup. The literature is sparse, and access is controlled. Therefore, fundamental studies of fuel reprocessing must use a model fuel that represents the main chemical and structural features. Advanced chlorination, or chlorination with sulfur-chlorine bearing reagents is being investigated as way to separate the fuel from metal matrix alloys. A UAl x alloy will be fabricated with x = 3, 4, and 5. The potential chlorination of individual UAl x intermetallics will be assessed in the advanced chlorination process of Al-8001 and Al-6061 as well as a representative mixture. Initial studies will track the alloying elements of the Al, which are Si, Fe, Cu, Mn, Mg, Cr, Zn, and Ti, in addition to the U itself. Further studies will include fission product simulants. Because advanced chlorination solvents include sulfur, the chemistry of sulfur with major and minor constituents will also be investigated. The experimental work accompanied by neutronic calculations will allow the assessment of the feasibility of advanced chlorination to separate aluminum from uranium. If bench-scale testing appears promising, then small-scale tests in shielded facilities with irradiated cladding, lightly irradiated fuel, and spent nuclear fuel are recommended to track the complete inventory of fissile actinides, fission product impurities, and reagent solids and liquids.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1977

On the formation and destruction of chlorine negative ions in the D region

We have investigated the possible reactions of chlorine atoms, chlorine monoxide, and hydrogen chloride with D region negative ions. The mesospheric concentrations of the neutral chlorine gases have been predicted with a diurnally varying one-dimensional model of the upper atmosphere. Despite the low abundances of chlorine compounds in air their high reactivity leads to the formation of substantial quantities of clorine negative ions at high altitudes. The concentration of chlorine ions is limited in daylight by rapid reactions with oxygen and hydrogen atoms and at night by the competitive production of other stable ions. The presence of chlorine negative ions in the upper atmosphere is consistent with in situ mass spectrometer observations of charged species. The abundance of chlorinated ions in the D region may be correlated with mesospheric nitric oxide and water vapor concentrations.

Turco, R. P.↗
DOE OSTI2025

Radiation Effects on the Performance of Advanced Sulfur Monochloride Chlorination Processes

Advanced sulfur chloride-based chlorination technologies are being developed to enable efficient recycling of aluminum and zirconium-based materials used in the nuclear industry. However, the impacts of ionizing radiation on the performance of these sulfur chloride compounds are not well established, despite this being critical knowledge for assessing their feasibility and longevity under envisioned process conditions. Here, in the present article, we report on the effects of cobalt-60 gamma irradiation (≤ 5 MGy) on the aluminum alloy 6061 (AA6061-T6) chlorination yield in sulfur monochloride (S 2 Cl 2 ). Our findings indicate that, compared to nonirradiated solvent, radiation-induced changes in the chemical composition of S 2 Cl 2 —identified using Raman spectroscopy—afford an additional, dose-dependent exothermic process prior to the chlorination reaction’s typical thermodynamic behavior. We attribute this new process to reactions involving aluminum species (metal, oxide, or [oxy]hydroxides) and sulfur dichloride (SCl 2 ), an S 2 Cl 2 radiolysis product that accumulates with absorbed gamma dose, but is absent following an AA6061-T6 chlorination study. Despite the exothermicity of this new process, the overall yield of chlorination decreased with increasing preirradiation dose. Consequently, the chemical reactivity, specificity (aluminum metal vs aluminum passivation and corrosion layer constituents), and byproducts of SCl 2 must be more thoroughly evaluated to support the continued development of advanced S 2 Cl 2 chlorination technologies.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗