Immobilization of Simulant ILW Actinide Wastes Containing Halides: Effect of Process Parameters on Wasteform Properties

ABSTRACTThe applicability of a process, originally developed to immobilize a chloride-rich intermediate level waste (ILW) arising from the pyrochemical reprocessing of plutonium, to alternative ILW waste-streams containing a large variety of cations, present as oxides together with KCl and CaF2, has been investigated. Non-radioactive studies, using simulated wastes containing hafnium and samarium as surrogates for the actinides, have been performed to establish the optimum processing parameters for the manufacture of wasteforms suitable for long-term storage/disposal. It has been demonstrated that the wastes can be immobilized by calcining with either Ca3(PO4)2 or CaHPO4 as the host. In excess of 97.5 % of the chloride present in calcined wastes, containing up to 3.2 wt% halides as a mixture of F- and Cl-, is immobilized when using this process. Whereas in the original calcined waste, the Cl- (about 12 wt%) was immobilized as chlorapatite, Ca5(PO4)3Cl, and spodiosite, Ca2(PO4)Cl, in these current wastes fluorapatite is the predominant halide containing phase. Conversion of the immobilized waste powder into a monolithic wasteform was achieved by sintering the powder with the addition of a sodium aluminium phosphate based glass. Both the calcined powder and the sintered monolithic wasteforms showed excellent durability in aqueous solution.

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A Glass-Encapsulated Ceramic Wasteform for the Immobilization of Chloride-Containing ILW: formation of Halite Crystals by Reaction Between the Glass Encapsulant and Ceramic Host

MRS Proceedings ◽

10.1557/proc-713-jj2.1 ◽

2002 ◽

Vol 713 ◽

Cited By ~ 10

Author(s):

I. W. Donald ◽

B. L. Metcalfe ◽

R. S. Greedharee

Keyword(s):

Sintering Temperature ◽

Processing Parameters ◽

Chemical Durability ◽

Calcium Phosphate Ceramic ◽

Long Term Storage ◽

Mineral Phases ◽

Sintering Characteristics ◽

Pyrochemical Reprocessing ◽

Term Storage

ABSTRACTWe have developed a calcium phosphate ceramic based on the mineral phases chlorapatite, Ca5(PO4)3Cl, and spodiosite, Ca2(PO4)Cl, which, on the basis of evidence from non-active simulant studies, is expected to provide an extremely effective host for immobilizing the chloride constituents resulting from the pyrochemical reprocessing of Pu. The immobilized product is in the form of a free-flowing, non-hygroscopic powder in which the chlorides are chemically combined within the mineral phases. In order to provide a monolithic wasteform suitable for long term storage, the feasibility of encapsulating this product in a compatible glass is being assessed. The final wasteform will be manufactured by a pressureless sintering route with sodium aluminophosphate based glasses currently being developed for this purpose. These glasses are of particular interest due to a combination of useful properties which include good sintering characteristics, together with excellent chemical durability. We have noted, however, that during sintering the Na present in the glass reacts with the chlorapatite and spodiosite phases to form a dispersion of halite crystals within the final wasteform. The formation of free halite within the wasteform is clearly undesirable, but can be minimized by careful control over the processing parameters, in particular the sintering temperature, or by reducing the chloride loading in the wasteform. The implications of these findings are highlighted and discussed.

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Dissolution Characteristics and Morphology of Large-sized Scorodite Particles Synthesized from Fe(II) and As(V) in Aqueous Solution

High Temperature Materials and Processes ◽

10.1515/htmp-2012-0080 ◽

2012 ◽

Vol 31 (4-5) ◽

pp. 451-458 ◽

Cited By ~ 3

Author(s):

S. Fujieda ◽

K. Shinoda ◽

T. Inanaga ◽

M. Abumiya ◽

S. Suzuki

Keyword(s):

Electron Microscopy ◽

Aqueous Solution ◽

Surface Defects ◽

Atmospheric Temperature ◽

Orthorhombic Structure ◽

X Ray ◽

Long Term Storage ◽

Transmission Electron ◽

Term Storage

AbstractA novel process for preparing scorodite particles with a diameter of approximately 20 µm from Fe(II) and As(V) in aqueous solution has been developed by DOWA Metals and Mining. In the present study, the dissolution characteristics of iron and arsenic from the scorodite particles synthesized by this process have been investigated under different conditions. The results show that the concentration of arsenic dissolved from the particles in aqueous solution is very low, but it has a complicated dependence on the temperature and pH of the solution. Transmission electron microscopy (TEM) with an energy dispersive X-ray spectrometer (EDS) was used to analyze the morphology, structure, and composition of the scorodite particles. The results indicate that the scorodite particles exhibit a nearly octahedral shape with planes composed of almost (111) planes in the orthorhombic structure. The concentration of iron at the surface of the particles is higher than that of iron inside of the particles. This characteristic morphology, along with the minimal surface defects of the scorodite particles, is considered to be responsible for the low dissolution of arsenic from the particles in aqueous solution. Atmospheric temperature and solution conditions were also found to be important for the safe, long-term storage of arsenic using scorodite particles.

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CO2 Utilization and Long-Term Storage in Useful Mineral Products by Carbonation of Alkaline Feedstocks

Frontiers in Energy Research ◽

10.3389/fenrg.2021.592600 ◽

2021 ◽

Vol 9 ◽

Author(s):

Renato Baciocchi ◽

Giulia Costa

Keyword(s):

Raw Materials ◽

Mineral Carbonation ◽

Carbon Utilization ◽

Waste Streams ◽

Long Term Storage ◽

Current State ◽

Critical Issues ◽

Term Storage ◽

Change Mitigation

Accelerated carbonation is a carbon utilization option which allows the manufacturing of useful products, employing CO2-concentrated or -diluted emission sources and waste streams such as industrial or other processing solid residues, in a circular economy perspective. If properly implemented, it may reduce the exploitation of virgin raw materials and their associated environmental footprint and permanently store CO2 in the form of Ca and/or Mg carbonates, thus effectively contributing to climate change mitigation. In this perspective article, we first report an overview of the main mineral carbonation pathways that have been developed up to now, focusing on those which were specifically designed to obtain useful products, starting from different alkaline feedstocks. Based on the current state of the art, we then discuss the main critical issues that still need to be addressed in order to improve the overall feasibility of mineral carbonation as a CCUS option, as well as research needs and opportunities.

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THE USING OF NEW PRESERVING SOLUTION FOR THE STORAGE AND THE DEMONSTRATION OF ANATOMICAL PREPARATIONS

MORPHOLOGICAL NEWSLETTER ◽

10.20340/mv-mn.19(27).04.61-64 ◽

2019 ◽

Vol 27 (4) ◽

pp. 61-64

Author(s):

V. N. Nikolenko ◽

A. L. Urakov ◽

L. I. Rastegaeva ◽

E. A. Kozyreva ◽

L. A. Gridin ◽

...

Keyword(s):

Aqueous Solution ◽

Russian Patent ◽

Upper Respiratory Tract ◽

Museum Exhibits ◽

Long Term Storage ◽

Shape Structure ◽

Mucous Membranes ◽

Upper Respiratory ◽

Term Storage

For storage and open demonstration of moist anatomical educational preparations and museum exhibits proposed to use a new preservative, which is an aqueous solution of 0.014-0.019% 3-iodine-2-propinilbutilcarbonate. The solution has high antiseptic activity and does not have a local irritant effect on the skin, mucous membranes of the upper respiratory tract and oral cavity, as well as on the conjunctiva of the eyes. The proposed preservative is non-toxic and environmentally safety. Long-term storage and use of anatomical preparations in the proposed preservative does not cause any damaging changes, violations of their shape, structure and color. The method is patented by the Russian Patent Agency.

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Modelling of Moisture Movement in Wood during Outdoor Storage

Nonlinear Analysis Modelling and Control ◽

10.15388/na.2001.6.1.15210 ◽

2001 ◽

Vol 6 (2) ◽

pp. 3-14 ◽

Cited By ~ 23

Author(s):

R. Baronas ◽

F. Ivanauskas ◽

I. Juodeikienė ◽

A. Kajalavičius

Keyword(s):

Experimental Data ◽

Finite Difference ◽

Climatic Conditions ◽

Two Dimensional ◽

Moisture Movement ◽

Finite Difference Technique ◽

Long Term Storage ◽

Space Formulation ◽

Term Storage

A model of moisture movement in wood is presented in this paper in a two-dimensional-in-space formulation. The finite-difference technique has been used in order to obtain the solution of the problem. The model was applied to predict the moisture content in sawn boards from pine during long term storage under outdoor climatic conditions. The satisfactory agreement between the numerical solution and experimental data was obtained.

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