In situ γ-irradiated dissolution of the International Simple Glass (ISG) 1 & 2 and a UK high-level waste glass (post-operational-clean-out (POCO)) was investigated following a modified Product Consistency Test-B protocol for 158 d at 40 °C in ultra-high-quality water. Tests were conducted under atmospheric conditions and received a total dose of 21.6 MGy delivered at a rate of 0.137 MGy d –1 . The normalised mass loss of B, Na, Ca and Mg were slightly higher in γ-irradiated tests when compared to non-irradiated tests whilst the normalised mass loss of Si was comparable or slightly lower. Boron-normalised mass losses of 0.87 ± 0.31, 0.60 ± 0.04 and 0.68 ± 0.07 g m –2 were calculated for γ-irradiated ISG-1, ISG-2 and POCO, respectively, whilst normalised mass losses in non-irradiated controls were 0.62 ± 0.01, 0.57 ± 0.01 and 0.41 ± 0.06 g m –2 . The difference was tentatively attributed to acidification during irradiation. Graphical abstract

The safe decommissioning of nuclear reactors is a complex process, requiring a range of technological options for it to be done effectively. It has become more important in recent years, with the substantial number of reactors entering the decommissioning phase. This paper details the use of functionalised silica for the recovery of uranium from aqueous hydrochloric acid solutions, a potential agent for the treatment of steel reactor components during nuclear reactor decommissioning. Silica functionalised with either phosphonic acid, bistriazine, or bistriazinylbipyridine ligands was shown to extract uranium, with the commercially available phosphonic acid functionality being the most effective. Extractions of 100 % were observed at [H+] + ] <= 0.24 M, further the phosphonic acid functionality also had the highest loading capacity. Increasing [H+] + ] has a suppressive effect on uranyl recovery, which was more pronounced for the in-house synthesized silica, and was attributed to protonation of the extracting moiety. Extended x-ray absorption fine structure spectroscopy was also used to determine the uranium coordination environments on the functionalised silica, and gain insights into the extraction mechanism. The uranyl cation was bound by two phosphonic acid groups, two bis-triazine groups, and one bistriazinylbipyridine group, respectively on each respective extractant. Uranyl was found to be pentacoordinate in the equatorial plane for all systems, with oxygen and/or chloride always present in the first coordination sphere. Evaluation of the mechanism indicated that uranyl must be loading onto the phosphonic acid functionality via multiple mechanisms, to both the phosphonic acid and silica related surface groups, although preferential binding of uranyl to the phosphonic acid groups was observed.

The chemistry of iodine in spent nuclear fuel (SNF) solutions is extremely complex and numerous species have been identified. These include iodine (I-2), iodide (I-), iodate (IO3-), triiodide (I-3(-)) and insoluble colloidal compounds with the fission products silver and palladium (AgI and PdI2). The experimental parameters that control the removal of iodine from SNF solutions are poorly understood. Experiments were performed at two temperatures representative of dissolver conditions. It was found that iodine, added as iodide, was rapidly removed from solution; within 30 s over 70% and 90% of the initially added amount was removed at 60 and 80 degrees C, respectively.

Alternative UO 2 nuclear fuels, incorporating Cr as a dopant, are currently in use in light–water reactors. Dissolution experiments using Cr-doped UO 2 , performed as a function of Cr content in a simplified groundwater solution and under oxic conditions, established that the addition of Cr to the UO 2 matrix systematically reduced the normalised dissolution rate of U at 25 and 40 °C. This effect was most notable under dilute solution conditions, and is the result of galvanic coupling between Cr and U, resulting from the presence of Cr 2+ in the UO 2 matrix, as corroborated by activation energy determination. Under conditions of solution saturation, where schoepite ((UO 2 ) 8 O 2 (OH) 12 ·(H 2 O) 12 ) and Na 2 U 2 O 7 ·6H 2 O were identified as secondary phases, the rate of U dissolution was invariant with Cr content. Moreover, at 60 °C, the trend was reversed and the rate of U dissolution increased with increasing Cr content. Under these conditions, other factors, including U solubility or bicarbonate-surface interactions, exert a stronger influence on the U dissolution kinetics than Cr. Increased grain size, a feature of Cr-doped UO 2 fuel, was also found to reduce the normalised dissolution rate of U. In establishing the mechanisms by which Cr dopants influence UO 2 fuel dissolution, it can be concluded that, overall, Cr-doped UO 2 nuclear fuel possesses similar dissolution kinetics to undoped UO 2 fuel, giving confidence for its eventual disposal in a geological facility.

Decommissioning is one of the most important phases in the life of a nuclear reactor, having a major influence on public perception of such technology. Therefore, development of technologies that make decommissioning more safe, effective and efficient is integral to the success of the nuclear industry. In this paper, phosphonic acid functionalised silica has been studied to determine its suitability for treating nuclear decommissioning effluents produced in the HYBRID process, developed in South Korea. Cu(2+ )recovery from HCl media in both static and dynamic modes was investigated, as well as the effect of Cu2+ on Co2+ and Ni2+ recovery in a column loading system. Isothermal loading studies predicted a maximum loading capacity for Cu2+ of 22.82 mg g(-1), however complex loading behaviour was observed. Cu2+ sorption followed pseudo-second order kinetics with rapid uptake. Thermodynamic parameters have been extracted from collected kinetic data. Cu2+ outcompetes both Co2+ and Ni2+ for binding to the silica in column studies, which has implications for the use of phosphonic acid functionalised silica in treating decommissioning effluents. This work presents initial lab scale experiments, but shows the potential of Si based extractants for use in metals recovery in the nuclear industry. (C) 2019 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Two weak base anion exchange resins, Lewatit A365 and Purolite MTS9850, have been tested for the removal of aqueous iodide from conditions simulating nuclear waste reprocessing streams. pH variation and relevant co-contaminant addition (nitrate, molybdate and iodine) allowed for assessment of iodide extraction behaviour of each resin. Isotherm experiments were performed and maximum uptake capacities obtained exceed current industrial adsorbents, such as silver-impregnated zeolites. Maximum loading capacities, determined by Dubinin-Radushkevich isotherm, were 761 +/- 14 mg g(-1) for MTS9850 and 589 +/- 15 mg g(-1) for A365. Uptake for both resins was significantly suppressed by nitrate and molybdate ions. The presence of dissolved iodine in the raffinate however, was found to increase iodide uptake. This was explained by characterisation of the spent resin surface by infrared and Raman spectroscopy, which determined the presence of triiodide, indicating charge-transfer complex formation on the surface. Dynamic studies assessed the effect of co-contaminants on iodide uptake in a column environment. Data was fitted to three dynamic models, with the Dose-Response model providing the best description of breakthrough. In all cases iodide breakthrough was accelerated, indicating suppression of uptake, but capacity was still significant. (C) 2019 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

A Prussian blue (PB)-embedded coordination polymer (COP) was prepared by simple incorporation of PB into a COP composed of 1,1,2,2-tetrakis(4-carboxyphenyeethane and the Zn ion during the synthesis of COP. The PB-COP was prepared as micro-sized particles with green emission (490 nm) from the strongly fluorescent tetra-phenylethene group in the solid state through aggregation-induced emission. The PB-COP showed particle shape with sizes ranging from 1 to 6 mu m. As the PB in PB-COP efficiently adsorbed Cs ions, the microstructure of PB-COP was degraded to smaller particles, along with a concomitant decrease in the green fluorescence of the PB-COP. Such a decrease in the green emission of PB-COP was used as a signal for the presence of Cs ions, in which the limit of detection for Cs ions was found to be 73.8 ppb. The hybridized material of the PB-COP can be used as both an efficient adsorbent and a sensor for Cs ions, achieving simultaneous removal and detection.

Extraction behaviours of Co(II), Cu(II), Fe(III), Ni(II), U(VI), Th(IV) and Zn(II) mixed metal solutions were examined in chloride media using chelating ion exchange resins Purolite S930+, Purolite S950, Purolite S957 and Dowex M4195 to understand mechanisms of extraction and to identify a potential steel decontamination process to reduce intermediate-level waste volume from nuclear reactor decommissioning. Effects of acidity and ionic strength were considered in batch extraction tests. Breakthrough behaviours were modelled with the Dose-Response model to give an indication to maximum loading capacities. A two-stage process for radioactive steel decontamination is proposed.

The pK(a)s of ethyl/butyl phosphonate silica (EBP-Si) have been determined, and the removal of cobalt and nickel from solution was investigated as a function of various parameters and compared with those of Purolite S950. pH uptake experiments suggested a combination of ion exchange and acid dissociation of the surface occurring. Isotherm data, fitted using the Langmuir and Dubinin-Radushkevich (D-R) models, indicated that stronger complexes formed with S950 than with EBP-Si. Kinetic data, fitted using a pseudo-second-order model, suggested that the rate-determining process is the reaction of metal ions with the chelating functionality of the resin. Uptake by EBP-Si is two to three times faster than that on S950.

Work has been carried out screening hydrometallurgical resins for application in the valorization of industrially produced jarosite. Of the seven resins tested, anion exchange resins performed poorly for valuable metal recovery. Purolite S950+ and S957, along with a strong acid resin, show good extraction properties, but are selective for Fe3+ over the other (divalent) metals. Purolite S930+ (iminodiacetic acid-functionalized resin) demonstrates selectivity for Cu2+ over Fe3+, but poor selectivity for Ni2+, Zn2+, and Co2+. Dowex M4195 (bispicolylamine-functionalized resin) demonstrates promise for extracting metals of value away from a mixed metal pregnant liquor solution (PLS). A three-stage column-based recovery process is proposed for jarosite leachate treatment.

The use of untreated seawater or bore water in uranium mineral processing circuits may represent a cheaper and more sustainable water resource for Australia's mining operations. Using present technologies, the increased salinity from these water sources results in decreased uranium extraction and increased extraction of impurities. There is incentive to overcome these challenges, either through new technologies, or repurposing existing technologies. The ion exchange behaviour of U from sulfate media on the weakly basic chelating resin Dowex M4195 (bis-picolylamine functionality) and the effect of competing chloride and impurity metal ions (Th, Fe, Al, Cu, Ni) has been studied. Experiments to determine acid, and sulfate media behaviour, and extraction thermodynamics including the effect of increasing chloride concentration upon extraction behaviour were carried out. Dowex M4195 was found to have pK1 and pK2 values at 4.13 ± 0.04 and 2.1 ± 0.1 determined at 1.0 M NaCl. Dowex M4195 shows affinity for U(VI) over Fe3+ and Al3+ in sulfuric acid media with a U(VI) pH50 a full pH unit below that of Fe3+ at 0.17 and 1.82 respectively. With increasing chloride concentrations U and Th extraction is suppressed but Fe extraction increases. At the highest chloride concentrations explored Fe is preferentially extracted over U, and Th is not extracted at all. As chloride concentration increases the extraction of U passes through a minimum (40%) before increasing to around 60% for 4.0 M chloride at pH 1.80. Al3+ is not extracted by M4195 under any conditions explored. Dowex M4195 does show high selectivity for Cu and Ni over everything else.

The solvent extraction of rhenium (VII) from chloride solutions by Cyphos 101-IL in toluene has been studied. Distribution values for the extraction of perrhenate are extremely high leading to almost quantitative extraction. From slope analysis, an anion exchange extraction mechanism is proposed, with formation of a ReO4- association with one Cyphos IL-101 cation. The extraction kinetics are fast, with complete equilibration occurring within 60 s. Under identical conditions, distribution coefficients for Cyphos 101-IL are greater than for Aliquat-336. Extraction of the perrhenate anion does not seem to be negatively impacted by common environmental contaminants including iron, sulphate and nitrate at the pH values tested. (C) 2013 Elsevier B.V. All rights reserved.

Experiential avoidance (EA) is a process in which a person attempts to avoid, dismiss, or change experiences such as emotions, behaviors, and thoughts. EA is associated with a number of psychological disorders and is generally harmful to psychological well-being. Various studies have explored the role of EA as a mediator, while others have studied EA as a moderator. The current study aimed to further understand and broaden the knowledge of the role of EA in regard to trauma, substance abuse, aggression, and impulsivity by examining relationships between these variables with EA as a mediator and as a moderator. Experientially avoidant behaviors (i.e., substance abuse, aggression, and impulsivity) were related to higher levels of EA. EA was found to partially mediate the relationship between the number of traumatic experiences and posttraumatic stress disorder (PTSD) symptoms, as well as the relationship between substance abuse and PTSD. EA was also found to moderate the relationship between PTSD symptoms and aggression. Findings from the present study as well as its limitations and future directions for research are discussed.

A solvent extraction method was employed to determine ferrous and ferric iron in aqueous samples. Fe3+ is selectively extracted into the organic phase (n-heptane) using HDEHP (bis(2-ethylhexyl) hydrogen phosphate) and is then stripped using a strong acid. After separation, both oxidation states and the total iron content were determined directly by ICP-MS analysis. This extraction method was refined to allow determination of both iron oxidation states in the presence of strong complexing ligands, such as citrate, NTA and EDTA. The accuracy of the method was verified by crosschecking using a refinement of the ferrozine assay. Presented results demonstrate the ability of the extraction method to work in a microbiological system in the presence of strong chelating agents following the bioreduction of Fe3+ by the Shewanella alga BrY. Based on the results we report, a robust approach was defined to separately analyze Fe3+ and Fe2+ under a wide range of potential scenarios in subsurface environments where radionuclide/metal contamination may coexist with strongly complexing organic contaminants.

A cloud point extraction method followed by inductively coupled plasma-mass spectrometry (ICP-MS) has been developed for the detection of trivalent lanthanides (Ln(III)) in aqueous samples. Ammonium pyrrolodinedithiocarbamate (APDC) was used as the chelating ligand with 2 wt% Triton X-114 as the surfactant. Various experimental parameters were investigated and the extraction efficiency, distribution ratios and concentration factors for the extraction of lanthanum (La), neodymium (Nd), europium (Eu) and thulium (Tm) were determined.

Bio-mediated reduction of multivalent actinide contaminants plays an important role in their fate and transport in the subsurface. To initiate the process of extending recent progress in uranium biogeochemistry to plutonium, a side-by-side comparison of the bioreduction of uranyl and plutonyl species was conducted with Shewanella alga BrY, a facultative metal-reducing bacterium that is known to enzymatically reduce uranyl. Uranyl was reduced in our system, consistent with literature reports, but we have noted a strong coupling between abiotic and biotic processes and observe that non-reductive pathways to precipitation typically exist. Additionally, a key role of biogenic Fe2+, which is known to reduce uranyl at low pH, is suggested. In contrast, residual organics, present in biologically active systems, reduce Pu(VI) species to Pu(V) species at near-neutral pH. The predominance of relatively weak complexes of PuO2+ is an important difference in how the uranyl and plutonyl species interacted with S. alga. Pu(V) also led to increased toxicity towards S. alga and is also more easily reduced by microbial activity. Biogenic Fe2+, produced by S. alga when Fe(III) is present as an electron acceptor, also played a key role in understanding redox controls and pathways in this system. Overall, the bioreduction of plutonyl is observed under anaerobic conditions, which favors its immobilization in the subsurface. Understanding the mechanism by which redox control is established in biologically active systems is a key aspect of remediation and immobilization strategies for actinides when they are present as subsurface contaminants.