Natural Analogues: Their Application to the Prediction of the Long-Term Behavior of Nuclear Waste Forms

1986 ◽  
Vol 84 ◽  
Author(s):  
Rodney C. Ewing ◽  
Michael J. Jercinovic
Keyword(s):  
Nuclear Waste ◽  
Borosilicate Glass ◽  
Large Scale ◽  
Laboratory Data ◽  
Waste Form ◽  
Long Time ◽  
Natural Analogues ◽  
Long Term Behavior ◽  
Nuclear Waste Forms

AbstractOne of the unique and scientifically most difficult aspects of nuclear waste isolation is the extrapolation ofshot-term laboratory data (hours to years) to the long time periods (103-105 years) required by regulatory agencies for performance assessment. The direct verification of these extrapolations is not possible, but methods must be developed to demonstrate compliance with government regulations and to satisfy the lay public that there is a demonstrable and reasonable basis for accepting the long-term extrapolations. Natural analogues of both the repository environment (e.g. radionuclide migration at Oklo) and nuclear waste form behavior (e.g. alteration of basaltic glasses and radiation damage in minerals) have been used to demonstrate the long-term behavior of large scale geologic systems and, on a smaller scale, waste form durability. This paper reviews the use of natural analogues to predict the long-term behavior of nuclear waste form glasses. Particular emphasis is placed on the inherent limitations of any conclusions that are based on “proof” by analogy. An example -- corrosion of borosilicate glass -- is discussed in detail with specific attention to the proper and successful use of natural analogues (basaltic glass) in understanding the long-term corrosion behavior of borosilicate glass.

Ion Implantation Studies of Nuclear Waste Forms

1981 ◽  
Vol 6 ◽  
Author(s):  
Clyde J. M. Northrup ◽  
George W. Arnold ◽  
Thomas J. Headley
Keyword(s):  
Nuclear Waste ◽  
Borosilicate Glass ◽  
Alpha Decay ◽  
Lead Ions ◽  
Waste Form ◽  
Elastic Recoil ◽  
Elastic Recoil Detection ◽  
Waste Forms ◽  
Basic Studies ◽  
Nuclear Waste Forms

ABSTRACTThe first observations of physical and chemical changes induced by lead implantation damage and leaching are reported for two proposed U.S. nuclear waste forms (PNL 76–68 borosilicate glass and Sandia titanate ceramics) for commercial wastes. To simulate the effects of recoil nucleii due to alpha decay, the materials were implanted with lead ions at equivalent doses up to approximately 1 × 1019 a decays/cm3 . In the titanate waste form, the zirconolite, perovskite, hollandite, and rutile phases all exhibited a mottled appearance in the transmission electron microscope (TEM) typical of defect clusters in radiation damaged, crystalline solids. One titanate phase containing uranium was found by TEM to be amorphous after implantation at the highest dose. No enhanced leaching (deionized water, room temperature, 24 hours) of the irradiated titanate waste form, including the amorphous phase, was detected by TEM, but Rutherford backscattering (RBS) suggested a loss of cesium and calcium after 21 hours of leaching. The RBS spectra also indicated enhanced leaching from the PNL 76–68 borosilicate glass after implantation with lead ions, in general agreement with the observations of Dran, et al. [6,7] on other irradiated materials. Elastic recoil detection spectroscopy (ERD), used to profile hydrogen after leaching, showed penetration of the hydrogen to several thousand angstroms for both the implanted and unimplanted materials. These basic studies identified techniques to follow the changes that occur on implantation and leaching of complex amorphous and crystalline waste forms. These studies were not designed to produce comparisons between waste forms of gross leach rates.

Glass/Water Reaction with and without Bentonite Present - Experiment and Model

1985 ◽  
Vol 50 ◽  
Author(s):  
B. Grambow ◽  
H. P. Hermansson ◽  
I. K. Björner ◽  
L. Werme
Keyword(s):  
Nuclear Waste ◽  
Water Permeability ◽  
Borosilicate Glass ◽  
Waste Form ◽  
Nuclear Waste Repository ◽  
Aqueous Environment ◽  
Long Term Stability ◽  
Chemical Effects ◽  
Waste Repository

In nuclear waste repository design bentonite has been included as part of the backfill for its sorbtive capacity and low water permeability. Nevertheless, it cannot keep the waste form dry once intrusion of groundwater has occured [1]. Leach experiments [2], [3] with the radioactive nuclear waste form borosilicate glass JSS-A have been performed with and without bentonite present to provide a database which allows the long term stability of the glass in aqueous environment to be forecasted and the chemical effects of bentonite to be studied.

Comparison of in Situ and Laboratory Corrosion Experiments with Borosilicate Nuclear Waste Glass

1991 ◽  
Vol 257 ◽  
Author(s):  
Werner Lutze ◽  
Rodney C. Ewing
Keyword(s):  
Nuclear Waste ◽  
Laboratory Data ◽  
Waste Glass ◽  
Simulation Test ◽  
In Situ Tests ◽  
Nuclear Waste Glass ◽  
Systems Simulation ◽  
Long Term Behavior

ABSTRACTThe comparison of laboratory data from the corrosion of borosilicate nuclear waste glass (German SM513LW11 and French R7T7) with data from the Materials Interface Interactions Test (MIIT) and Repository Systems Simulation Test (RSST) illustrates the inherent limitations of in situ tests. Although in situ tests may confirm the short term behavior of waste forms and identify phenomena associated with the repository system, they do not provide the fundamental basis for the extrapolation of long-term behavior.

A Flow Model for the Kinetics of Dissolution of Nuclear Waste Forms; A Comparison of Borosilicate Glass, Synroc and High-Silica Glass

1981 ◽  
Vol 11 ◽  
Author(s):  
Pedro B. Macedo ◽  
Aaron Barkatt ◽  
Joseoph H. Simmons
Keyword(s):  
Nuclear Waste ◽  
Borosilicate Glass ◽  
Flow Model ◽  
Release Rates ◽  
Waste Forms ◽  
High Silica ◽  
Kinetics Of Dissolution ◽  
Kinetics Of ◽  
Nuclear Waste Forms

A model has been developed to predict the long-term leach or release rates of various waste-form materials under repository conditions.

The Long-Term Performance of Nuclear Waste Forms: Natural Materials - Three Case Studies

1992 ◽  
Vol 294 ◽  
Author(s):  
Rodney C. Ewing
Keyword(s):  
Case Studies ◽  
Nuclear Waste ◽  
Experimental Results ◽  
Waste Form ◽  
Short Term ◽  
Waste Forms ◽  
Long Term Performance ◽  
Term Performance ◽  
Nuclear Waste Forms

ABSTRACTNatural materials may be used to advantage in the evaluation of the long-term performance of nuclear waste forms. Three case studies are presented: (I) radiation effects in ceramic waste forms; (II) corrosion products of U02 under oxic conditions; (III) corrosion rate of nuclear waste glasses. For each case, a natural phase which is structurally and chemically analogous to the waste form is identified and used to evaluate the long-term behavior of a nuclear waste form. Short-term experimental results are compared to the observations made of analogous natural phases. The three case studies illustrate that results may range between providing fundamental data needed for the long-term evaluation of a waste form to only providing qualitative data of limited use. Although in the most rigorous view the long-term behaviour of a phase cannot be predicted, the correspondence between short-term experimental results and observations made of natural phases provides confidence in the “predicted” behavior of the waste form. The strength of this approach rests with the degree to which a mechanistic understanding of the phenomenon is attained.

scholarly journals Basalt Glass: An Analogue for the Evaluation of the Long-Term Stability of Nuclear Waste form Borosilicate Glasses

1984 ◽  
Vol 44 ◽  
Author(s):  
C. D. Byers ◽  
M. J. Jercinovic ◽  
R. C. Ewing ◽  
K. Keil
Keyword(s):  
Nuclear Waste ◽  
Laboratory Data ◽  
Waste Form ◽  
Borosilicate Glasses ◽  
Term Stability ◽  
Long Term Stability ◽  
Basalt Glass ◽  
Time Periods ◽  
Basalt Glasses

AbstractThe long-term stability of nuclear waste form borosilicate glasses can be evaluated by understanding the processes that effect the long-term alteration of glass and by comparing laboratory alteration of synthetic basalt and borosilicate glasses with the observed stability of naturally occurring basaltic glasses in diverse geologic environments. This paper presents detailed electron microprobe analyses of naturally altered basaltic glasses (with maximum ages of 10,000 to 20 million years) from low-temperature environments. These results are compared to laboratory data on the corrosion of a synthetic basaltic glass in MCC-1 tests (90°C, a SA/V of 0.1 cm−1 and time periods up to 182 days), MCC-2 tests (190°C, a SA/V of 0.1 cm−1 and time periods up to 210 days) and hydration tests in saturated water vapor (240°C, an estimated SA/V of ∼ 106 cm−1 and time periods up to 63 days). Additionally, laboratory induced hydration alteration of synthetic basalt and borosilicate glasses is compared. These preliminary experiments provide evidence that the alteration processes observed for natural basalt glasses are relevant to understanding the alteration of nuclear waste glass, as both appear to react via similar processes.

Ion Implantation Damage in Silicate Glasses

1982 ◽  
Vol 15 ◽  
Author(s):  
George W. Arnold
Keyword(s):  
Ion Implantation ◽  
Nuclear Waste ◽  
Silicate Glasses ◽  
Glass Waste ◽  
Leach Rate ◽  
Implantation Damage ◽  
Waste Forms ◽  
Long Term Behavior ◽  
Nuclear Waste Forms

ABSTRACTIon implantation is a rapid technique for simulating damage induced by α-recoil nuclei in nuclear waste forms. The simulation has been found to be quite good in TEM comparisons with natural α-decay damage in minerals, but leach rate differences have been observed in glass studies and were attributed to dose-rate differences. The similarities between ion implantation and recoil nuclei as a means of producing damage suggest that insights into the long-term behavior of glass waste forms can be obtained by examination of what is known about ion-implantation damage in silicate glasses. This paper briefly reviews these effects and shows that leaching results in certain nuclear waste glasses can be understood as resulting from plastic flow and track overlap. Phase separation is also seen to be a possible consequence of damage-induced compositional changes.

The Use of Hot-Isostatic Pressing to Process Nuclear Waste Forms

2009 ◽  
Author(s):  
Martin W. A. Stewart ◽  
Sam A. Moricca ◽  
Tina Eddowes ◽  
Yingjie Zhang ◽  
Eric R. Vance ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Nuclear Waste ◽  
Borosilicate Glass ◽  
Hot Isostatic Pressing ◽  
Processing Technology ◽  
Nuclear Wastes ◽  
Isostatic Pressing ◽  
Waste Forms ◽  
Nuclear Waste Forms ◽  
Glass Viscosity

ANSTO has developed a combination of tailored nuclear waste form chemistries coupled with the use of flexible hot-isostatic pressing processing technology to enable the successful incorporation of problematic nuclear wastes into dense, durable monoliths. This combined package also enables the design of waste forms with waste loadings well in excess of those achievable via baseline melting routes using borosilicate glass, as hot-isostatic pressing is not constrained by factors such as glass viscosity, crystallisation and electrical conductivity. In this paper we will discuss some of our experiences with problematic wastes, namely plutonium wastes, sludges and HLW such as the Idaho calcines.

A Study of Radiation Effects in Curium-Doped Gd2Ti2O7 (Pyrochlore) and CaZrTi2O7 (Zirconolite)

1981 ◽  
Vol 11 ◽  
Author(s):  
J.W. Wald ◽  
P. Offemann
Keyword(s):  
Radiation Damage ◽  
Nuclear Waste ◽  
Radiation Effects ◽  
Laboratory Data ◽  
Primary Host ◽  
Waste Forms ◽  
Rare Earth Titanate ◽  
Effects Of Radiation ◽  
Similar Phase ◽  
Nuclear Waste Forms

Radiation effects studies in both glass and glass ceramic nuclear waste forms have identified a rare-earth titanate phase of the general formula (RE) 2Ti207 which is capable of acting as a host phase for actinides.1,2 Ringwood and co-workers3 have also proposed a structurally similar phase, zirconolite (CaZrTi2 07), as one of the primary host phases in the SYNROC waste form. Data from these and other previous studies, as well as mineralogical information available on these titanate phases, have not provided an unambiguous interpretation of the effects of radiation damage relative to nuclear waste forms. This paper reports new laboratory data concerning radiation damage effects in both of these phases.

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