Radiation stability of natural britholites

2006 ◽  
Vol 932 ◽  
Author(s):  
Tatiana S. Yudintseva
Keyword(s):  
Heavy Ions ◽  
Glass Ceramics ◽  
Radiation Stability ◽  
High Level Waste ◽  
Analogue Study ◽  
Natural Minerals ◽  
Waste Forms ◽  
Wide Range ◽  
Radiation Resistant ◽  
High Level

ABSTRACTBritholite, Ca-REE silicate with apatite structure, is an actinide host phase occurred in vitreous borosilicate waste forms. Such glass-ceramics are considered as potential host phases for immobilization of actinide-containing high-level waste. Crystalline phases have to be radiation resistant for this application. Radiation stability of the britholites was mainly studied by either heavy ions irradiation or incorporation of Cm-244 or Pu-238 and 240. A wide range of critical doses (0.15 - 0.6 dpa at 25°C) and temperatures have been obtained depending on the compositions of the samples. Natural analogue study of the waste forms allows to predict the behavior of actinide host phases for long periods after disposal. Britholites with age from 320 to 2600 millions years, ThO2+UO2 content from 1.0 to 12 wt.%, and cumulative doses from 0.6×1019 to 7.7×1019 α-decays/g have been studied. The britholite becomes amorphous at a dose of 1 dpa (0.9×1019 α-decays/g) and higher. Critical doses for natural minerals are higher than those for synthetic samples, most likely due to re-crystallization during annealing.

Development of Actinide-Containing Waste Immobilization Process

2003 ◽  
Author(s):  
S. V. Stefanovsky ◽  
A. G. Ptashkin ◽  
Y. M. Kuliako ◽  
S. A. Perevalov ◽  
S. V. Yudintsev ◽  
...  
Keyword(s):  
Rare Earth ◽  
Glass Ceramics ◽  
Radiation Stability ◽  
Ore Deposits ◽  
High Level Waste ◽  
Nuclear Accidents ◽  
Two Phase ◽  
Preparation Methods ◽  
Waste Forms ◽  
High Level

Actinide wastes involve actinide or rare earth–actinide fractions of high level waste (HLW), Pu-contaminated materials, including incinerator ashes, excess weapons plutonium, and some wastes formed during plutonium conversion in MOX fuel and nuclear accidents. SIA Radon in cooperation with Vernadsky Institute of Geochemistry, Institute of Geology of Ore Deposits, and D. Mendeleev University of Chemical Technology deals with development and testing of actinide waste forms and preparation methods. Zirconolite, pyrochlore, and murataite are considered as host phases for plutonium and other actinides. Two-phase ceramics based on zirconolite-perovskite, pyrochlore-perovskite, perovskite–cubic zirconia-based solid solution, murataite-perovskite, and zirconolite-murataite assemblages were designed for incorporation of actinide and rare earth–actinide fractions of HLW. Glass-ceramics containing apatite-britholite phases have been proposed for incinerator ash fixation. All these matrices have high chemical durability and radiation stability. The most promising method for production of these waste forms is an inductive melting in a cold crucible. Cold pressing and sintering technology is considered as alternative route. Mechanical activation intensifies ceramization process and reduces sintering temperature. Some new methods such as selfsustaining synthesis and plasma melting are being also examined.

Immobilization of high-level waste in ceramic waste forms

1986 ◽  
Vol 319 (1545) ◽  
pp. 63-82 ◽  
Keyword(s):  
Borosilicate Glass ◽  
Nuclear Industry ◽  
Waste Stream ◽  
High Level Waste ◽  
Phase Assemblage ◽  
Crystal Lattices ◽  
Ceramic Waste ◽  
Waste Forms ◽  
Wide Range ◽  
High Level

High-level wastes (HLW) can be incorporated in the crystal lattices of coexisting phases in ceramic waste forms. The properties and performances of ceramic waste forms are largely determined by their phase chemistry, phase assemblage and microstructure. Currently, the best categorized advanced ceramic waste form is SYNROC, a titanate ceramic composed of ‘ hollandite ’ Bat 1(Al,Ti)2^Ti|]*"70 16, zirconolite CaZrTi 2 O 7 , perovskite CaTiO 3 , rutile TiO 2 and minor amounts of metal alloys microencapsulated by the titanate matrix. Two factors contribute to the capacity of synroc to accommodate high (e.g. 20% ) loadings of HLW, together with variations in waste-stream composition. Firstly, the constituent phases can accept, as solid solutions in their crystal lattices, a broad spectrum of cationic species of diverse charge and radius, either singly or by complex substitution mechanisms. Secondly, the phase assemblage itself spontaneously adjusts its modal mineralogy in response to waste stream fluctuations. The presence of both rutile and a source of trivalent titanium (from reaction of rutile with added Ti metal) in the synroc phase assemblage is largely responsible for this flexible and accommodating nature. The titanate minerals in synroc also occur in Nature, where they have survived for many millions of years in a wide range of geological environments. Experimental studies show that synroc is vastly more resistant to leaching by groundwater than borosilicate glass; moreover, its high leach resistance is maintained at elevated temperatures. Experimental and analogue studies indicate that the HLW immobilization properties of synroc are not significantly impaired by radiation damage. These properties show that synroc would provide an effective immobilization barrier for HLW when buried in suitable repositories. They also permit the use of a wider range of geological disposal options than are appropriate for borosilicate glass. In particular, synroc is well suited for disposal in deep drill-holes, both in continental and marine environments. The fact that synroc is composed of minerals that have demonstrated long-term geological stability is important in establishing public confidence in the ability of the nuclear industry to immobilize high-level wastes for the very long periods required.

Radiation stability of regenerated stripping solutions for high-level waste processing

2005 ◽  
Vol 266 (2) ◽  
pp. 349-353 ◽  
Author(s):  
G. F. Egorov ◽  
G. P. Tkhorgnitsky ◽  
V. N. Romanovskiy ◽  
V. A. Babain ◽  
I. V. Smirnov ◽  
...  
Keyword(s):  
Radiation Stability ◽  
High Level Waste ◽  
Waste Processing ◽  
High Level

Experimental Glass-Ceramic Products to Immobilize ICPP HLW

1987 ◽  
Vol 112 ◽  
Author(s):  
Roseanne S. Baker ◽  
Bruce A. Staples ◽  
Dieter A. Knecht ◽  
Julius R. Berreth
Keyword(s):  
Glass Ceramic ◽  
Hot Isostatic Pressing ◽  
Glass Ceramics ◽  
High Level Waste ◽  
Processing Plant ◽  
Chemical Processing ◽  
Stabilized Zirconia ◽  
Experimental Glass ◽  
Ceramic Glass ◽  
High Level

AbstractCandidate products are being evaluated to immobilize the routinely calcined waste at the Idaho Chemical Processing Plant (ICPP). A potential product with minimal volume for immobilizing ICPP high-level waste (HLW) for final disposal is a high-waste-loading and high-density glass-ceramic. Glass-ceramics are formed by Hot Isostatic Pressing (HIPing) the HLW with selected additives, such as SiO2, B2O3, Li2O, Na2O, and Y2O3. Glass-ceramic products have been formed with calcine loa ings up to 80 wt% and densities up to 3.4 g/cm3. Crystalline phases observed in the glass-ceramic products include calcium fluoride, monoclinic and cubic zirconia, calcium- and yttrium-stabilized zirconia, and zircon. An interstitial amorphous phase also exists consisting of the oxides of silicon, aluminum, boron, and alkalis. The glass-ceramic waste forms give leach rates comparable to simulated HLW glass products.

Study of Glass-Ceramic Waste Forms

1997 ◽  
Vol 506 ◽  
Author(s):  
S.V. Stefanovsky ◽  
S.V. Ioudintsev ◽  
B.S. Nikonov ◽  
B.I. Omelianenko ◽  
T.N. Lashtchenova
Keyword(s):  
Glass Ceramic ◽  
Glass Composition ◽  
Glass Ceramics ◽  
High Level Waste ◽  
Matrix Glass ◽  
Crystalline Phases ◽  
Cell Parameters ◽  
The Matrix ◽  
High Level ◽  
Similar Unit

ABSTRACTSince the early of the 1990s the method of inductive melting in a cold crucible (IMCC) has been applied at SIA “Radon” for production of various wasteforms, including glasses and Synroc-type ceramics. Sphene-based glass-ceramics composed of glass and crystalline phases were considered as appropriate wasteform for High Level Waste immobilisation. Investigation of two glass-ceramic specimens prepared with the IMCC has been performed using optical microscopy, XRD, SEM/EDS, and TEM methods. The samples produced consist of vitreous and crystalline phases. The vitreous phase consists of two varieties of glass formed by the immiscibility of the initial melt onto two separate liquids. One of the glasses is observed as spherical microinclusions in the matrix glass. The glass of the microspheres are differed from the matrix glass composition by higher contents of Ca, Ti, Ce, Sr, Zr (or Cr), while the matrix glass contains higher amounts of Si, Al, and alkalies. The crystalline phases with sphene- and perrierite-like structures have been also occurred. Their total quantity reaches up to 50 vol.%. The synthetic perrierite has similar unit-cell parameters with its natural mineral analogs with the only exception in two-fold value of c dimension. Zr, Ce, and Sr are incorporated into synthetic sphene and perrierite, while Cs is hosted by the glass phases.

Performance of Borosilicate Glass High-Level Waste Forms in Disposal Systems

1986 ◽  
Vol 73 (2) ◽  
pp. 139-139
Author(s):  
Edward J. Hennelly ◽  
E. I. Du Pont de Nemours
Keyword(s):  
Borosilicate Glass ◽  
High Level Waste ◽  
Waste Forms ◽  
High Level

Dose-Dependence of Pb-Ion Implantation Damage in Zirconolite, Hollandite, and Zircon

1981 ◽  
Vol 11 ◽  
Author(s):  
T. J. Headley ◽  
G. W. Arnold ◽  
C. J. M. Northrup
Keyword(s):  
Radiation Damage ◽  
Structural Damage ◽  
Accelerated Aging ◽  
Dose Dependence ◽  
High Level Waste ◽  
Long Term Stability ◽  
Waste Forms ◽  
Recent Approach ◽  
High Level

The long-term stability of nuclear waste forms is an important consideration in their selection for safe disposal of radioactive waste. Stability against long-term radiation damage is particularly difficult to assess by short-term laboratory experiments. Much of the displacement damage in high-level waste forms will be generated by heavy recoil nuclei emitted during the α-decay process of long-lived actinide elements. Hence, an accelerated aging test which reliably simulates the α-recoil damage accumulated during thousands of years of storage is desirable. One recent approach to this simulation is to implant the waste form with heavy Pb-ions.I- 6 If the validity of this approach is to be fully assessed, two important questions which have not yet been investigated must be answered.(1) Is the structural damage, including cumulative effects, similar for irradiation by Pb-ions and a-recoil nuclei in a given material? (2) Is the dose-dependence of the accumulated damage similar? The purpose of this investigation was to assess the extent of these similarities in selected materials. We utilized transmission electron microscopy (TEM) to characterize the radiation damage and measure its dose-dependence.

An Approach to Analysis of High Level waste Container Performance in an Unsaturated Repository Environment

1993 ◽  
Vol 333 ◽  
Author(s):  
John C. Walton ◽  
Narasi Sridhar ◽  
Gustavo Cragnolino ◽  
Tony Torng ◽  
Prasad Nair
Keyword(s):  
Dominant Role ◽  
Near Field ◽  
Temperature Fields ◽  
Localized Corrosion ◽  
High Level Waste ◽  
Quantitative Methodology ◽  
Waste Container ◽  
Wide Range ◽  
Engineered Barrier ◽  
High Level

ABSTRACTOne of the requirements for the performance of waste packages prescribed in 10CFR 60.113 is that the high level waste must be “substantially completely” contained for a minimum period of 300 to 1000 years. During this period, the radiation and thermal conditions in the engineered barrier system and the near-field environment are dominated by fission product decay. In the present U.S design of the engineered barrier system, the outer container plays a dominant role in maintaining radionuclide containment. A quantitative methodology for analyzing the performance of the container is described in this paper. This methodology enables prediction of the evolution of the waste package environment in terms of temperature fields, stability of liquid water on the container surface, and concentration of aggressive ions such as chloride. The initiation and propagation of localized corrosion is determined by the corrosion potential of the container material and critical potentials for localized corrosion. The coiTOsion potential is estimated from the kinetics of the anodic and cathodic reactions including oxygen diffusion through scale layers formed on the container surface. The methodology described is applicable to a wide range of metals, alloys and environmental conditions.

Determination of the Corrosion Mechanisms of High-Level Waste Containing Glass

1981 ◽  
Vol 11 ◽  
Author(s):  
Horst Scholze ◽  
Reinhard Conradt ◽  
Heinrich Engelke ◽  
Hans Roggendorf
Keyword(s):  
Rock Salt ◽  
High Level Waste ◽  
Extreme Conditions ◽  
Safety Standard ◽  
Waste Forms ◽  
Corrosion Mechanisms ◽  
High Level

The German concept of high level waste final storage provides the use of certain glasses containing radioelement oxides as glass components. These waste forms are to be stored in rock salt formations in order to isolate the waste from the biosphere. The efficiency of this isolation is a most important question. The aim is to achieve a high safety standard that remains valid under extreme conditions such as the uncontrolled water entrance to the deposit.

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