Effects of Iron and pH on Glass Dissolution Rate

2002 ◽  
Vol 757 ◽  
Author(s):  
Seung-Young Jeong ◽  
William L. Ebert
Keyword(s):  
Dissolution Rate ◽  
Ph Dependence ◽  
High Level Waste ◽  
Total System ◽  
Degradation Model ◽  
Static Tests ◽  
Dissolved Iron ◽  
Glass Dissolution ◽  
License Application ◽  
High Level

ABSTRACTShort-term static tests were conducted with a surrogate high-level waste glass to measure the effects of pH and dissolved iron on the glass dissolution rate. The tests were conducted to determine if a term to account for the effects of dissolved iron is needed in the glass degradation model developed for Total System Performance Assessment (TSPA) calculations for the Yucca Mountain disposal system license application. The glass degradation model includes terms for dependencies on temperature, pH, and chemical affinity. A series of tests was conducted at 90 °C in various pH solutions without iron and with added FeCl3, Fe2O3, Fe3O4, and FeOOH. Tests were conducted at glass surface area/solution volume (S/V) ratios about 2 and 10 m-1for between 2 and 21 days. Solution concentrations of boron were used to measure the extent of reaction and calculate the glass dissolution rates. Similar rates were measured in tests conducted with and without iron at each pH. Both the results of the tests with and without iron showed V-shaped pH dependence curves with minima at near-neutral pH values. The pH dependencies (η) are about 0.44 in basic solutions and –0.49 in acidic solutions, based on the combined results of tests with and without iron. These are within the range of values for the pH dependence in the TSPA model for site recommendation.

Accounting For Corrosion Of Hlw Glasses By Humid Air In TSPA

2002 ◽  
Vol 757 ◽  
Author(s):  
W. L. Ebert ◽  
J. C. Cunnane ◽  
N. L. Dietz
Keyword(s):  
Rate Equation ◽  
Ph Dependence ◽  
Yucca Mountain ◽  
Total System ◽  
Humid Air ◽  
Determine Parameter ◽  
Glass Dissolution ◽  
A Value ◽  
License Application ◽  
Parameter Values

ABSTRACTThis paper describes how the results of vapor hydration tests (VHTs) are used to model the corrosion of waste glasses exposed to humid air in the glass degradation model for total system performance assessment (TSPA) calculations for the proposed Yucca Mountain disposal system. Corrosion rates measured in VHTs conducted at 125, 150, 175, and 200°C are compared with the rate equation for aqueous dissolution to determine parameter values that are applicable to glass degradation in humid air. These will be used to determine the minimum for the range and distribution of parameter values in calculations for the Yucca Mountain disposal system license application (TSPA-LA). The rate equation for glass dissolution is rate = kE • 10 η • pH • exp(–Ea/RT). Uncertainties in the calculated rate due to the range of waste glass compositions and water exposure conditions are taken into account by using a range of values for the rate coefficient kE. The parameter values for the pH dependence (η) and temperature dependence (Ea) and the upper limit for kE are being determined with other tests. Using the values of η and Ea from the site recommendation model, the VHT results described in this paper provide a value of log kE = 5.1 as the minimum value for the rate expression. This value will change slightly if different pH-and temperature-dependencies are used for the TSPA-LA model.

scholarly journals Corrosion of Glass-Bonded Sodalite and its Components as a Function of ph and Temperature

2002 ◽  
Vol 713 ◽  
Author(s):  
Seung-Young Jeong ◽  
Lester R. Morss ◽  
William L. Ebert
Keyword(s):  
Dissolution Rate ◽  
Hot Isostatic Pressing ◽  
Waste Form ◽  
High Level Waste ◽  
Model Parameters ◽  
Dissolution Rates ◽  
Degradation Model ◽  
Modified Binder ◽  
Ph Range ◽  
High Level

ABSTRACTA glass-bonded sodalite ceramic waste form (CWF) has been developed to immobilize electrorefiner salt wastes from electrometallurgical treatment of spent sodium-bonded reactor fuel for disposal. A degradation model is being developed to support qualification of the CWF for disposal in the federal high-level waste disposal system. The parameter values in the waste form degradation model were previously determined from the dissolution rates measured in MCC-1 tests conducted at 40, 70, and 90°C. The results of several series of tests that were conducted to confirm the applicability of the dissolution rate model and model parameters are presented in this paper: (1) Series of MCC-1 tests were conducted in five dilute buffer solutions in the pH range of 4.8 – 9.8 at 20°C with hot isostatic pressing (HIP) sodalite, HIP glass, and HIP CWF. The results show that the model adequately predicts the dissolution rate of these materials at 20°C. (2) Tests at 20 and 70°C with CWF made by pressureless-consolidation (PC) indicate that the model parameters extracted from the results of tests with HIP CWF can be applied to PC CWF. (3) The dissolution rates of a glass made with a composition corresponding to 80 wt. % glass and 20 wt. % sodalite were measured at 70°C to evaluate the sensitivity of the rate to the composition of binder glass in the CWF. The dissolution rates of the modified binder glass were indistinguishable from the rates of the binder glass.

scholarly journals The fate of Si and Fe while nuclear glass alters with steel and clay

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
C. Carriere ◽  
P. Dillmann ◽  
S. Gin ◽  
D. Neff ◽  
L. Gentaz ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Protective Layer ◽  
Glass Dissolution ◽  
A Value ◽  
Waste Forms ◽  
Controlling Mechanism ◽  
Geological Repository ◽  
The Mean ◽  
High Level ◽  
Initial Dissolution Rate

AbstractThe French concept developed to dispose high-level radioactive waste in geological repository relies on glassy waste forms, isolated from the claystone host rock by steel containers. Understanding interactions between glass and surrounding materials is key for assessing the performance of a such system. Here, isotopically tagged SON68 glass, steel and claystone were studied through an integrated mockup conducted at 50 °C for 2.5 years. Post-mortem analyses were performed from nanometric to millimetric scales using TEM, STXM, ToF-SIMS and SEM techniques. The glass alteration layer consisted of a crystallized Fe-rich smectite mineral, close to nontronite, supporting a dissolution/reprecipitation controlling mechanism for glass alteration. The mean glass dissolution rate ranged between 1.6 × 10−2 g m−2 d−1 to 3.0 × 10−2 g m−2 d−1, a value only 3–5 times lower than the initial dissolution rate. Thermodynamic calculations highlighted a competition between nontronite and protective gel, explaining why in the present conditions the formation of a protective layer is prevented.

scholarly journals The initial dissolution rates of simulated UK Magnox–ThORP blend nuclear waste glass as a function of pH, temperature and waste loading

2015 ◽  
Vol 79 (6) ◽  
pp. 1529-1542 ◽  
Author(s):  
N. Cassingham ◽  
C.L. Corkhill ◽  
D.J. Backhouse ◽  
R.J. Hand ◽  
J.V. Ryan ◽  
...  
Keyword(s):  
Dissolution Kinetics ◽  
Intrinsic Rate ◽  
Waste Glass ◽  
High Level Waste ◽  
Dissolution Mechanism ◽  
Dissolution Rates ◽  
Forward Rates ◽  
Glass Dissolution ◽  
High Level ◽  
Kinetics Of

AbstractThe first comprehensive assessment of the dissolution kinetics of simulant Magnox–ThORP blended UK high-level waste glass, obtained by performing a range of single-pass flow-through experiments, is reported here. Inherent forward rates of glass dissolution were determined over a temperature range of 23 to 70°C and an alkaline pH range of 8.0 to 12.0. Linear regression techniques were applied to the TST kinetic rate law to obtain fundamental parameters necessary to model the dissolution kinetics of UK high-level waste glass (the activation energy (Ea), pH power law coefficient (η) and the intrinsic rate constant (k0)), which is of importance to the post-closure safety case for the geological disposal of vitreous products. The activation energies based on B release ranged from 55 ± 3 to 83 ± 9 kJ mol–1, indicating that Magnox–THORP blend glass dissolution has a surface-controlled mechanism, similar to that of other high-level waste simulant glass compositions such as the French SON68 and LAW in the US. Forward dissolution rates, based on Si, B and Na release, suggested that the dissolution mechanism under dilute conditions, and pH and temperature ranges of this study, was not sensitive to composition as defined by HLW-incorporation rate.

Assessing the durability of nuclear glass with respect to silica controlling processes in a clayey underground disposal

2006 ◽  
Vol 932 ◽  
Author(s):  
Laurent De Windt ◽  
Stéphanie Leclercq ◽  
Jan van der Lee
Keyword(s):  
Host Rock ◽  
Reactive Transport ◽  
Transport Model ◽  
Glass Block ◽  
High Level Waste ◽  
Residual Rate ◽  
Glass Dissolution ◽  
Underground Disposal ◽  
High Level

ABSTRACTThe long-term behaviour of vitrified high-level waste in an underground clay repository was assessed by using the reactive transport model HYTEC with respect to silica diffusion, sorption and precipitation processes. Special attention was given to the chemical interactions between glass, corroded steel and the host-rock considering realistic time scale and repository design. A kinetic and congruent dissolution law of R7T7 nuclear glass was used assuming a first-order dissolution rate, which is chemistry dependent, as well as a long-term residual rate. Without silica sorption and precipitation, glass dissolution is diffusion-driven and the fraction of altered glass after 100,000 years ranges from 5% to 50% depending on the fracturation degree of the glass block. Corrosion products may limit glass dissolution by controlling silica diffusion, whereas silica sorption on such products has almost no effect on glass durability. Within the clayey host-rock, precipitation of silicate minerals such as chalcedony may affect glass durability much more significantly than sorption. In that case, however, a concomitant porosity drop is predicted that could progressively reduce silica diffusion and subsequent glass alteration.

Doe Progress in Assessing the Long Term Performance of Waste Package Materials

1986 ◽  
Vol 84 ◽  
Author(s):  
A. Berusch ◽  
E. Gause
Keyword(s):  
Site Characterization ◽  
The United States ◽  
High Level Waste ◽  
Design Studies ◽  
Waste Package ◽  
License Application ◽  
High Level ◽  
Long Term Performance ◽  
Term Performance

Summary:Each of the projects has made significant progress toward the eventual operation of a repository for the disposal of high-level radioactive wastes in the United States. Although much has been accomplished, much remains to be done. For example, the Site Characterization Plans for BWIP and NNWSI are nearing completion to be followed by initiation of site characterization activities. The Site Characterization Plan for the selected salt site is scheduled for completion later in 1987. Waste package advanced conceptual design studies are currently scheduled to begin at each project before the end of FY 1987. These efforts will lead to selections of concepts to be detailed in the license application design phase. Compliance with the NRC criteria that require long-term waste package performance will be demonstrated by DOE by performing all of the aforementioned activities. In doing so, the DOE will also be assured that its plan for the safe disposal of high-level waste will be satisfactorily implemented.

Chemical durability of high-level waste glass in repository environment: main conclusions and remaining uncertainties from the GLASTAB and GLAMOR projects

2006 ◽  
Vol 932 ◽  
Author(s):  
P. Van Iseghem ◽  
K. Lemmens ◽  
M. Aertsens ◽  
S. Gin ◽  
I. Ribet ◽  
...  
Keyword(s):  
Near Field ◽  
Chemical Durability ◽  
High Level Waste ◽  
Model Parameters ◽  
Residual Rate ◽  
Geological Disposal ◽  
Glass Dissolution ◽  
Geologic Disposal ◽  
High Level

ABSTRACTThis paper reviews the main conclusions of two European Commission funded projects, GLASTAB and GLAMOR, on the durability of HLW glass in geological disposal, and the remaining uncertainties. The progress in GLASTAB relates to the characterization of the alteration layer, the modeling of glass dissolution, the interaction of glass with near field materials, the behaviour of radionuclides, and the calculation of HLW glass dissolution as part of geological disposal. The GLAMOR programme was focused on the decrease of the glass dissolution rate upon achieving silica saturation in solution. Two conclusions from this programme are the importance of the residual rate measured beyond silica saturation and the need to reduce the uncertainties in model parameters. The overall conclusion from the two projects is that strong progress has been achieved on basic dissolution mechanisms and interaction with disposal environments - HLW glass will act as a good barrier to the release of radionuclides in geologic disposal.

Sensitivity Studies of Waste Package Performance in High-Level Waste Management

2002 ◽  
Vol 757 ◽  
Author(s):  
N. Rivera-Feliciano ◽  
T. Bloomer ◽  
T. Ahn ◽  
O. Pensado
Keyword(s):  
High Frequency ◽  
The United States ◽  
Localized Corrosion ◽  
High Level Waste ◽  
Total System ◽  
Manufacturing Defects ◽  
Alloy 22 ◽  
The Mean ◽  
Long Life ◽  
High Level

ABSTRACTAn important attribute of the high-level waste (HLW) disposal program in the United States (U.S.) is the estimated long life of waste packages (WPs). The outer container of the WP is proposed to be constructed of a nickel-based alloy, Alloy 22 (58Ni-21Cr-14Mo-3W-4Fe), which is highly corrosion resistant. Under nominal conditions of the proposed repository at Yucca Mountain (YM), Nevada, WPs are anticipated to have a long life because of their extremely slow uniform corrosion rate. The technical basis for this expected long life of geological scale is still subject of discussion. In this paper, the NRC Total-system Performance Assessment (TPA) Code is used to evaluate uncertainties associated with the WP performance within a 10,000-year period. Early WP failure may occur due to localized corrosion or high frequency of manufacturing defects. Localized corrosion may occur under mixed salt deposits on the WP surface at temperatures above 100°C. High frequencies of WP juvenile failure are considered to account for the limited industrial experience with Alloy 22 and uncertainty in the long-term performance of Alloy 22 as container material. The localized corrosion and the high frequency of manufacturing defects were simulated with the TPA code by lowering the critical relative humidity for the onset of aqueous corrosion, RHc, and increasing the fraction of initially defective WPs. By sampling RHc from various normal distributions, the mean annual total effective dose equivalent (TEDE) approached 1 mrem/year at 10,000 years. Assuming a fixed fraction of initially defective WPs (1 percent), the mean annual TEDE approached 0.07 mrem/year at 10,000 years.

Sign in / Sign up

Export Citation Format

Share Document