Nuclear Waste Treatment Research Articles

DFT study on the bonding properties of Pu(III) and Pu(IV) chloro complexes

ABSTRACT Understanding of chemical bonding is a fundamentally important topic. Given the importance of bonding studies, we performed quantum calculations on plutonium chloro complexes (PuClx(III) and PuClx(IV)) that are believed to form as molten chloride salts during nuclear waste treatment. The result of these calculations was verified by comparing them to experimental data on a similar actinide chloro complex. Charge and bond order analyses of the complexes provide insight into the electronic properties, bonding, and nuclear magnetic resonance characteristics of the plutonium chloro complexes. The chemical shift of the Pu(III) complexes are found to be negative while those of Pu(IV) are positive.

Cancer incidence in adults living in the vicinity of nuclear power plants in France, based on data from the French Network of Cancer Registries.

Nuclear power plants (NPPs) release toxic emissions into the environment that may affect neighboring populations. This ecologic study was designed to investigate the possibility of an excess incidence of cancer in the vicinity of French NPPs by examining the incidence by municipality of 12 types of cancer in the population aged 15 years and older during the 1995-2011 period. Population exposure to pollution was estimated on the basis of distance from towns of residence to the NPP. Using regression models, we assessed the risk of cancer in a 20-km zone around NPPs and observed an excess incidence of bladder cancer (Relative Risk (RR), 95% Credibility Interval (95% CI)) in men and women (RRmen = 1.08; 95% CI: 1.00, 1.17 and RRwomen = 1.19; 95% CI: 1.02, 1.39). Women living within the 20-km proximity areas had a significantly reduced risk of thyroid cancer (RRwomen = 0.86; 95% CI: 0.77, 0.96). No excess risk of hematologic malignancies in either sex was seen. The higher than expected incidence of bladder cancer may be due to an excess incidence localized around the Flamanville NPP and the nearby La Hague nuclear waste treatment center, which is a source of chemical contaminants, many (including arsenic) of them known risk factors for bladder cancer. Differences in medical practices could explain the reduced risk of thyroid cancer. In this first study of adults living near NPPs in France, cancer incidence is significantly higher than in the references populations for one of the cancer types studied: bladder cancer.

Decoupling the autogenous swelling from the self-desiccation deformation in early age concrete with mineral additions: Micro-macro observations and unified modelling

Cements used in global nuclear waste treatment, storage, and disposal require thorough testing of fresh and cured properties to demonstrate regulatory compliance. Using actual radioactive wastes is often cost-prohibitive during early scoping tests necessitating the use of non-radiological surrogates. Cerium (Ce) is often used as a surrogate for actinides uranium (U) and plutonium (Pu) in spent nuclear fuel, yet few studies have explored how Ce impacts the properties used to qualify a cement for use. This work compares the fresh and cured properties of three classes of cements – ordinary portland cements, ultra-high performance cement composites, and magnesium phosphate cements – each with and without ceria (CeO2). Due to CeO2 sorption of water (54 vol%) that effectively decreases the water available to hydrate and form binding cement phases, variations in key cement properties were detected that suggest surrogate CeO2–cementitious matrices may not be representative of matrix behaviors when using U and Pu sources.

N,N,N',N'-Tetrabutyl-1,10-phenanthroline-2,9-dicarboxamide as Very Effective Extraction Agent for Trivalent Europium and Americium.

Solvent extraction of microamounts of Eu3+ and Am3+ from water into nitrobenzene by means of a mixture of hydrogen dicarbollylcobaltate (H+B-) and N,N,N',N'-tetrabutyl-1,10-phenanthroline-2,9-dicarboxamide (L) was studied. The equilibrium data were explained assuming that the species HL+, H2L2+, HL+2, ML3+2, and ML3+3 (M3+ = Eu3+, Am3+; L = N,N,N',N'-tetrabutyl-1,10-phenanthroline-2,9-dicarboxamide) are extracted into the nitrobenzene phase. Extraction and stability constants of the cationic complex species in nitrobenzene saturated with water were determined and discussed. From the experimental results it is evident that this effective N,N,N',N'-tetrabutyl-1,10-phenanthroline-2,9-dicarboxamide receptor for the Eu3+ and Am3+ cations could be considered as a potential extraction agent for nuclear waste treatment.

Highly Efficient Solvent Extraction of Americium and Europium by Using Hydrogen Dicarbollylcobaltate and N,N′-Diethyl-N,N′-bis(4-ethylphenyl)-1,10-phenanthroline-2,9-dicarboxamide

Solvent extraction of microamounts of Eu3+ and Am3+ from water into nitrobenzene by means of a mixture of hydrogen dicarbollylcobaltate (H+B−) and N,N′-diethyl-N,N′-bis(4-ethylphenyl)-1,10-phenanthroline-2,9-dicarboxamide (L) was studied. The equilibrium data were explained assuming that the species HL+, $$ \text{HL}_{\text{2}}^{ + } $$ , $$ \text{ML}_{2}^{3 + } $$ , and $$ \text{ML}_{\text{3}}^{{\text{3} + }} $$ (M3+ = Eu3+, Am3+; L = N,N′-diethyl-N,N′-bis(4-ethylphenyl)-1,10-phenanthroline-2,9-dicarboxamide) are extracted into the organic phase. Extraction and stability constants of the cationic complex species in nitrobenzene saturated with water were determined and are discussed. The reached separation factors SFAm/Eu in this two-phase system are in the range of 19–99. From the experimental results it is apparent that this very effective N,N′-diethyl-N,N′-bis(4-ethylphenyl)-1,10-phenanthroline-2,9-dicarboxamide receptor for the Eu3+ and Am3+ cations could be considered as a potential extraction agent for nuclear waste treatment.

N,N′-diethyl-N,N′-diphenyl-1,10-phenanthroline-2,9-dicarboxamide as an extraordinarily effective extraction agent for trivalent europium and americium

Solvent extraction of microamounts of Eu3+ and Am3+ from water into nitrobenzene by means of a mixture of hydrogen dicarbollylcobaltate (H+B−) and N,N′-diethyl-N,N′-diphenyl-1,10-phenanthroline-2,9-dicarboxamide (L) was studied. The equilibrium data were explained assuming that the species HL+, H2L2+, HL2+, ML23+, and ML33+ (M3+=Eu3+, Am3+; L=N,N′-diethyl-N,N′-diphenyl-1,10-phenanthroline-2,9-dicarboxamide) are extracted into the organic phase. Extraction and stability constants of the cationic complex species in nitrobenzene saturated with water were determined and discussed. From the experimental results it is evident that this very efficient N,N′-diethyl-N,N′-diphenyl-1,10-phenanthroline-2,9-dicarboxamide receptor for the Eu3+ and Am3+ cations could be considered as a potential extraction agent for nuclear waste treatment.

Cobalt bis(dicarbollide) anion and its derivatives

Owing to high chemical and thermal stability, ionic character, low nucleophilicity and peculiar solubility, cobalt bis(dicarbollide) anion occupies a unique position among the metallacarboranes. Derivatives of cobalt bis(dicarbollide) find applications in different areas such as in the treatment of nuclear waste, conducting polymers and medicinal chemistry. In this paper, we have presented an overview of cobalt bis(dicarbollide) anion and its derivatives.

In situ characterization of mixing and sedimentation dynamics in an impinging jet ballast tank via acoustic backscatter

Impinging jets are utilized in numerous applications, including nuclear waste treatment, for both the erosion of sediment beds and maintaining particulates in suspension. Pulse‐echo ultrasonic methods offer great potential for the in situ monitoring of critical mixing and settling dynamics, in concentrated dispersions. A non‐active scaled version of a Highly Active Storage Tank at Sellafield, UK, was profiled with an acoustic backscatter system under various jet firing conditions. An advanced analysis technique enabled the direct quantification of dispersion concentration changes from the converted backscatter attenuation. Hence, the erosion and mixing capability of the jets, and settling kinetics were characterized. It was found that jet operation alone provided inadequate localized mixing of eroded sediment. An additional air‐lift process operation was required to hinder the rapid re‐settling of dispersed particulates. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2618–2629, 2017

Displacement Prediction Possibilities from Bátaapáti Radwaste Repository

The program for the final disposal of low and intermediate level radioactive waste was established by Paks Nuclear Power Plant, Hungary. Preparation of final disposal has been done as part of a national program since 1993. The Central Nuclear Financial Fund and the Public Limited Company for Radioactive Waste Management (Puram) have been established to coordinate organizations and activities for all tasks in connection with nuclear waste treatment. The project was started with a geological screening in order to find the most suitable geological formation for radioactive waste repository. The selected potential host rock is a granite complex in the Mórágy Granite Formation in the south-western part of Hungary, close to the village of Bátaapáti.In the underground facility different measuring systems have been used (extensometers, inclinometers, convergence measurements), requiring a transformation into radial and tangential displacements. Until now not much emphasis was laid on the 3D geodetical displacement monitoring measurements or on the use of advanced methods such as the evaluation of displacement vector orientations.The final survey results are ensured by the Mecsekérc Ltd. Department of Geodesy as a daily actualized database with Unified National Projection system (EOV) coordinates. Upon request the surveyors provide data in local coordinates (they provide relative and absolute coordinates simultaneously), allowing a meaningful analysis. The aim of this paper is to shortly introduce the surveying process and interpretation of the 3D optical displacement measurement methodology. Our research is related to geodetic measurements which were carried out in the repository chambers and some exploratory tunnels. The mentioned exploratory tunnels crossed through fault zones. We have studied the effect of the fault zones on the measured 3D displacements, using the common evaluation and displacement prediction methodologies, and we show the results obtained during the control of the “normality” of the displacements from the underground spaces which were excavated full face and at larger sections by top heading and bench method. The results of the presented case studies show that the 3D optical displacement monitoring enables the prediction of the geotechnical conditions ahead of the face and the influence of fault zones located outside of the excavated space.

Functionalized metal organic frameworks for effective capture of radioactive organic iodides.

Highly efficient capture of radioactive organic iodides (ROIs) from off-gas mixtures remains a substantial challenge for nuclear waste treatment. Current materials utilized for ROI sequestration suffer from low capacity, high cost (e.g. use of noble metals), and poor recyclability. Recently, we have developed a new strategy to tackle this challenge by functionalizing MOF materials with tertiary amines to create molecular traps for the effective capture and removal of ROIs (e.g. radioactive methyl iodide) from nuclear wastes. To further enhance the uptake capacity and performance of CH3I capture by ROI molecular traps, herein, we carry out a systematic study to investigate the effect of different amine molecules on ROI capture. The results demonstrate a record-high CH3I saturation uptake capacity of 80% for MIL-101-Cr-DMEDA at 150 °C, which is 5.3 times that of Ag0@MOR (15 wt%), a leading adsorbent material for capturing ROIs during nuclear fuel reprocessing. Furthermore, the CH3I decontamination factors (DFs) for MIL-101-Cr-DMEDA are as high as 5000 under simulated reprocessing conditions, largely exceeding that of facility regulatory requirements (DF = 3000). In addition, MIL-101-Cr-DMEDA can be recycled without loss of capacity, illustrating yet another advantage compared to known industrial adsorbents, which are typically of a "single-use" nature. Our analysis also shows that both physisorption and chemisorption of CH3I occur at the three amine-grafted MOFs. While chemisorption takes place at the amine functionalized sites, the amount of physisorption correlates with the MOF porosity. A possible binding site of amine-CH3I interaction has been identified via an in situ IR spectroscopic study. The results suggest that CH3I interacts strongly and directly with the tertiary nitrogen of the amine molecules. The CH3I uptake amount decreases as the amine chain length increases, in trend with the decreasing pore space of the corresponding framework. The strategy to build MOF-based molecular traps developed in this work not only leads to a new record-high performance for ROI capture, but also offers an effective way of systematically tuning the porosity by varying the length of functionalized amine molecules. This study also demonstrates that MOFs represent a promising new platform for selective capture and removal of radioactive nuclear waste.

Behaviour of the extractant Me-TODGA upon gamma irradiation: quantification of degradation compounds and individual influences on complexation and extraction

Understanding of ligand–metal interactions is crucial to develop new processes for nuclear waste treatment.

Loading Actinides in Multilayered Structures for Nuclear Waste Treatment: The First Case Study of Uranium Capture with Vanadium Carbide MXene.

Efficient nuclear waste treatment and environmental management are important hurdles that need to be overcome if nuclear energy is to become more widely used. Herein, we demonstrate the first case of using two-dimensional (2D) multilayered V2CTx nanosheets prepared by HF etching of V2AlC to remove actinides from aqueous solutions. The V2CTx material is found to be a highly efficient uranium (U(VI)) sorbent, evidenced by a high uptake capacity of 174 mg g(-1), fast sorption kinetics, and desirable selectivity. Fitting of the sorption isotherm indicated that the sorption followed a heterogeneous adsorption model, most probably due to the presence of heterogeneous adsorption sites. Density functional theory calculations, in combination with X-ray absorption fine structure characterizations, suggest that the uranyl ions prefer to coordinate with hydroxyl groups bonded to the V-sites of the nanosheets via forming bidentate inner-sphere complexes.

New oxidation states for neptunium complexes

Understanding actinide chemistry is critical for nuclear waste treatment as well as for illuminating the role of f orbitals in bonding and reactivity. Researchers have made a leap forward in neptunium chemistry, preparing the first NpII and NpIII organometallic complexes (Nat. Chem. 2016, DOI: 10.1038/nchem.2520). Working at the Institute for Transuranium Elements, a team led by Polly L. Arnold of the University of Edinburgh combined radioactive NpCl4 and a macrocyclic ligand, trans-calix[2]benzene[2]pyrrole, to form a mononuclear NpIII complex with the Np bound to the nitrogens of the pyrrole groups and sandwiched between the aryl rings; a fifth bond goes to Cl. The researchers reduced the complex to form a similar NpII structure in which the Cl is replaced by a neutral molecule of the solvent, dimethoxyethane, bound through its oxygens via a bidentate linkage. The NpII complex decays to a binuclear NpIII complex. Analysis of the mononuclear NpIII complex indicates

Magnesium ionophore II as an extraction agent for trivalent europium and americium

Abstract Solvent extraction of microamounts of trivalent europium and americium into nitrobenzene by using a mixture of hydrogen dicarbollylcobaltate (H+B−) and magnesium ionophore II (L) was studied. The equilibrium data were explained assuming that the species HL+, H L 2 + ${\rm{HL}}_2^ + $ , M L 2 3 + ${\rm{ML}}_2^{3 + }$ , and M L 3 3 + ${\rm{ML}}_3^{3 + }$ (M3+ = Eu3+, Am3+; L=magnesium, ionophore II) are extracted into the nitrobenzene phase. Extraction and stability constants of the cationic complex species in nitrobenzene saturated with water were determined and discussed. From the experimental results it is evident that this effective magnesium ionophore II receptor for the Eu3+ and Am3+ cations could be considered as a potential extraction agent for nuclear waste treatment.

Sodium Ionophore III as Very Effective Receptor for Trivalent Europium and Americium

Solvent extraction of micro amounts of europium and americium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H+B−) in the presence of Sodium ionophore III (L) was investigated. The equilibrium data were explained assuming that the species HL+, $$ \text{HL}_{2}^{ + } $$ , ML3+, $$ \text{ML}_{\text{2}}^{{\text{3} + }} $$ , and $$ \text{ML}_{\text{3}}^{{\text{3} + }} $$ (M3+ = Eu3+, Am3+; L = Sodium ionophore III) are extracted into the organic phase. The values of extraction and stability constants of the cationic complex species were determined in nitrobenzene saturated with water. It was found that the values of the stability constants of the corresponding complexes $$ {\text{EuL}}_{n}^{ 3+ } $$ and $$ {\text{AmL}}_{n}^{ 3+ } $$ , where n = 1, 2, 3 and L is Sodium ionophore III, in water-saturated nitrobenzene are comparable. Finally, it was proven experimentally that in the considered nitrobenzene medium, the investigated Sodium ionophore III ligand is a very effective receptor for the Eu3+ and Am3+ cations. It means that this receptor can be considered as a potential extraction agent for nuclear waste treatment.

Titanium and zirconium silicate ion-exchange materials for the treatment of nuclear waste

Titanium and zirconium silicate ion-exchange materials for the treatment of nuclear waste

One‐Dimensional Cold Cap Model for Melters with Bubblers

The rate of glass production during vitrification in an all‐electrical melter greatly impacts the cost and schedule of nuclear waste treatment and immobilization. The feed is charged to the melter on the top of the molten glass, where it forms a layer of reacting and melting material, called the cold cap. During the final stages of the batch‐to‐glass conversion process, gases evolved from reactions produce primary foam, the growth and collapse of which controls the glass production rate. The mathematical model of the cold cap was revised to include functional representation of primary foam behavior and to account for the dry cold cap surface. The melting rate is computed as a response to the dependence of the primary foam collapse temperature on the heating rate and melter operating conditions, including the effect of bubbling on the cold cap bottom and top surface temperatures. The simulation results are in good agreement with experimental data from laboratory‐scale and pilot‐scale melter studies. The cold cap model will become part of the full three‐dimensional mathematical model of the waste glass melter.

Thermodynamic representation of aqueous sodium nitrate and nitric acid solution with electrolyte NRTL model

Nitric acid solution has been widely used in nuclear waste treatment processes. To support heat and mass balance calculations and process simulation, a comprehensive thermodynamic model is developed for sodium nitrate–water binary, nitric acid–water binary, and nitric-acid–sodium nitrate–water ternary systems. Based on symmetric electrolyte NRTL (eNRTL) activity coefficient model, the present work takes into account complete dissociation of sodium nitrate and partial dissociation of nitric acid in aqueous solution. With up to three temperature coefficients for each eNRTL binary interaction parameter, the model provides an accurate and thermodynamically consistent representation for phase equilibrium properties such as vapor pressure, boiling point, dew point and salt solubility, calorimetric properties such as enthalpy and heat capacity, and speciation properties. The model is validated with data covering temperature up to 473.15K and sodium nitrate concentration up to saturation for the sodium nitrate–water binary system, temperature up to 379.15K and nitric acid concentration up to pure acid for the nitric acid–water binary system, and sodium nitrate concentration up to 0.21 mole fraction and nitric acid concentration up to 0.3 mole fraction for the nitric acid–sodium nitrate–water ternary system.

The Fission Programme at the CERN n_TOF Facility

Since 2001, the scientific programme of the CERN n_TOF facility has focused mainly on the study of radiative neutron capture reactions, which are of great interest to nuclear astrophysics and on neutron-induced fission reactions, which are of relevance for nuclear technology, as well as essential for the development of theoretical models of fission. In particular, taking advantage of the high instantaneous neutron flux and high energy resolution of the facility, as well as of high-performance detection and acquisition systems, accurate new measurements on several long-lived major and minor actinides, from 232Th to 245Cm, have been performed so far. Data on these isotopes are needed in order to improve the safety and efficiency of conventional reactors, as well as to develop new systems for nuclear energy production and treatment of nuclear waste, such as Generation IV reactors, Accelerator Driven Systems and reactors based on innovative fuel cycles. A review of the most important results on fission cross-sections and fragment properties obtained at n_TOF for a variety of (radioactive) isotopes is presented along with the perspectives arising from the coming on line in the second half of 2014 of a new 19 m flight-path, which will allow n_TOF to expand its measurement capabilities to even more rare or short-lived isotopes, such as 230Th, 232U, 238,240Pu and 244Cm.

Development of RFQ power source for ADS injector I

The Accelerator Driven Subcritical System (ADS), using proton beam hitting on the target to produce neutron for spending fuel stable increment or accelerating evolution, aims at finding key solutions for nuclear fuel stable provision and for the safe nuclear waste treatment. The injector I and the main linac will be designed and fabricated by IHEP. The RF power source system provides 325 MHz continuous wave power for RFQ cavity of ADS injector I and beam energy reaches several MeV through RFQ cavity. RF power source system includes 600 kW continuous wave klystron, 80 kV/18 A PSM power supply based on pulsed step modulation techniques, circulator and corresponding waveguide transmission system for ADS injector I. According to the overall design for ADS system and RFQ technical parameters, overall layout, technical specifications and design requirements of RF power source system are proposed, equipment installation and commissioning are carried out, and the system has passed the expert acceptance testing. ©, 2015, Editorial Office of High Power Laser and Particle Beams. All right reserved.