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

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.

Titanate Waste Forms for High Level Waste — An Evaluation of Materials and Processes

1981 ◽  
pp. 123-130 ◽  
Author(s):  
R. G. Dosch ◽  
A. W. Lynch ◽  
T. J. Headley ◽  
P. F. Hlava
Keyword(s):  
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.

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.

Affinity Rate Law Failure to Describe Sodium Borosilicate Glass Alteration Kinetics

2003 ◽  
Vol 807 ◽  
Author(s):  
P. Frugier ◽  
S. Gin ◽  
C. Jégou
Keyword(s):  
Borosilicate Glass ◽  
Chemical System ◽  
High Level Waste ◽  
Critical Examination ◽  
Sodium Borosilicate Glass ◽  
Kinetic Rate ◽  
Rate Law ◽  
Passionate Debate ◽  
Experimental Findings ◽  
High Level

ABSTRACTSimplified glass compositions were chosen to improve our knowledge of the alteration kinetics of complex glasses dedicated to the confinement of high-level waste. Since 1998, the sodium borosilicate glass system is at the center of a passionate debate between an affinity-based kinetic rate law and a protective surface layer theory. All the authors who have investigated ternary 68/14/18 SiO2–B2O3–Na2O glass agree on the fact that the affinity law cannot satisfactorily account for its alteration kinetics. Some authors explained that these discrepancies between classical kinetic rate law and experimental findings could be due to macromolecular amorphous separation in the 68/14/18 sodium borosilicate system and that this simplified glass could be divided into 90% reedmergnerite (NaBSi3O8) and 10% diborate (Na2O–2B2O3). This article provides evidence of the homogeneity of ternary 68/18/14 SiO2–B2O3–Na2O glass at nanometric scale and shows that even phase separation at less than nanometric scale could not explain the inability of hydrated glass-solution affinity laws to describe its alteration. The relative simplicity of the SiO2–B2O3–Na2O chemical system allows a critical examination of the macroscopic alteration laws developed over the last twenty years based only on the hydrated glass-solution chemical affinity without taking into account the formation and reactivity of the gel or its passivating properties.

scholarly journals Stability of High-Level Waste Forms

2004 ◽  
Author(s):  
Theodore M Besmann ◽  
John D Vienna
Keyword(s):  
High Level Waste ◽  
Waste Forms ◽  
High Level
Sign in / Sign up

Export Citation Format

Share Document