Effects of Container Material on PCT Leach Test Results for High-Level Nuclear Waste Glasses

1993 ◽  
Vol 333 ◽  
Author(s):  
Shi-Ben Xing ◽  
Ian L. Pegg
Keyword(s):  
Stainless Steel ◽  
Nuclear Waste ◽  
Atmospheric Carbon Dioxide ◽  
Aqueous Corrosion ◽  
Solution Ph ◽  
Leach Rate ◽  
Wide Range ◽  
Consequent Reduction ◽  
The Usa ◽  
High Level

ABSTRACTA glass-based waste form used for the immobilization of high-level nuclear wastes should exhibit good resistance to aqueous corrosion since typically this is the primary process by which radionucleides could be released into the environment upon failure of other barriers. In the USA, the Waste Acceptance Product Specifications (WAPS) provides a set of requirements to ensure the consistency of the waste forms produced and specifies the Product Consistency Test (PCT) as a measure of relative chemical durability. While the PCT procedure permits usage of both Teflon and stainless steel vessels for testing of simulated development glasses, Teflon is not permitted for testing of production glasses due to radiative degradation. The results presented in this paper indicate that there are very significant differences between tests conducted in the two types of vessels due to the well-known permeability of Teflon to atmospheric carbon dioxide which results in lowering of the solution pH and a consequent reduction in the leach rate of silicate glasses. A wide range of nuclear waste glass compositions was subjected to the PCT procedure using both Teflon and stainless steel vessels. The magnitude of the effect (up to a factor of four for B, Na, Li concentrations) depends strongly on glass composition, therefore the isolated checks performed previously were inconclusive. The permeability to CO2 of two types of Teflon vessels specified in the PCT procedure was directly measured using buffer solutions: ingress of CO2 is linear in time, strongly pH-dependent, and was as high as 100 ppm after 7 days. In actual PCT tests in Teflon vessels, the total CO2 content was 560 ppm after 87 days and 1930 ppm after one year.

Methodologies for Predicting the Performance of Ni-Cr-Mo Alloys Proposed for High Level Nuclear Waste Containers

1999 ◽  
Vol 556 ◽  
Author(s):  
D. S. Dunn ◽  
G. A. Cragnolino ◽  
N. Sridhar
Keyword(s):  
Nuclear Waste ◽  
Current Density ◽  
Localized Corrosion ◽  
Passive Current Density ◽  
Aqueous Corrosion ◽  
Wide Range ◽  
Anionic Species ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Passive Current

AbstractFor the geologic disposal of the high level nuclear waste (HLW), aqueous corrosion is considered to be the most important factor in the long-term performance of containers, which are the main components of the engineered barrier subsystem. Container life, in turn, is important to the overall performance of the repository system. The proposed container designs and materials have evolved to include multiple barriers and highly corrosion resistant Ni-Cr-Mo alloys, such as Alloys 625 and C-22. Calculations of container life require knowledge of the initiation time and growth rate of localized corrosion. In the absence of localized corrosion, the rate of general or uniform dissolution, given by the passive current density of these materials, is needed. The onset of localized corrosion may be predicted by using the repassivation and corrosion potentials of the candidate container materials in the range of expected repository environments. In initial corrosion tests, chloride was identified as the most detrimental anionic species to the performance of Ni-Cr-Mo alloys. Repassivation potential measurements for Alloys 825, 625, and C-22, conducted over a wide range of chloride concentrations and temperatures, are reported. In addition, steady state passive current density, which will determine the container lifetime in the absence of localized corrosion, was measured for Alloy C-22 under various environmental conditions.

scholarly journals Does Fully Radioactive Glass Behave Differently than Simulated Waste Glass?

1992 ◽  
Vol 294 ◽  
Author(s):  
X. Feng ◽  
J. K. Bates ◽  
C. R. Bradley ◽  
E. C. Buck
Keyword(s):  
Radiation Field ◽  
Nuclear Waste ◽  
Potassium Feldspar ◽  
Waste Glass ◽  
Solution Ph ◽  
Static Tests ◽  
Leach Rate ◽  
Nuclear Waste Glass ◽  
Surface Alteration ◽  
Leach Behavior

ABSTRACTStatic tests at SA/V (ratio of surface area of glass to solution volume) 20,000 m−1 on SRL 200 glass compositions show that, at long test periods, the simulated nuclear waste glass (nonradioactive) leaches faster than the corresponding radioactive glass by a factor of about 40, although comparative tests, done through 560 days, at lower SA/V, 2000 m−1, indicate little difference in the leach behavior of the two types of glasses. The similarity in leach behavior between radioactive and simulated glasses at SAN of 2000 m−1 or lower is also observed for SRL 165/42 and 131/11 compositions. The accelerated glass reaction with the simulated glass 200S is associated with the formation of crystalline phases such as clinoptilolite (or potassium feldspar), and a pH excursion. The radiation field generated by the fully radioactive glass reduces the solution pH. This lower pH, in turn, may retard the onset of increased reaction rate. The radiation field generated by the radioactive glasses does not directly affect the stability of the glass surface alteration layer under those conditions where the radioactive and simulated glasses react at the same rate. These results suggest that the fully radioactive nuclear waste glass 200R may maintain a much lower leach rate than the simulated 200S, if the lower pH in the 200R leachate can be sustained. Meaningful comparison tests between radioactive and simulated nuclear waste glasses should include long-term and high SA/V tests.

Dissolution of Synroc in Deionised Water at 150°C

1996 ◽  
Vol 465 ◽  
Author(s):  
Katherine L. Smith ◽  
Michael Colella ◽  
Gordon J. Thorogood ◽  
Mark G. Blackford ◽  
Gregory R. Lumpkin ◽  
...  
Keyword(s):  
High Level Waste ◽  
Solution Ph ◽  
Dissolution Study ◽  
Leach Rate ◽  
Elemental Concentrations ◽  
Icp Ms ◽  
Before And After ◽  
High Level ◽  
Periodic Replacement ◽  
Simulated High Level Waste

ABSTRACTSynroc containing 20 wt% simulated high level waste (HLW) was subjected to two sets of leach tests at 150°C where the leachant was and was not replaced during the test (replacement and non-replacement testing). The leachant was a KH-phthalate buffered solution (pH 4.2). Samples were characterised before and after leach testing using SEM, AEM and SIMS. Elemental concentrations in leachates were measured using ICP-MS. In concert with the findings of i) a dissolution study of perovskite in a flowing leachant and ii) a previous Synroc dissolution study (wherein Synroc containing 10 wt% simulated HLW was subjected to periodic replacement, leach testing in deionised water at 150°C), the results of this study show that when the leachant replacement frequency is varied from 7 d to the duration of the test, there is no effect on leach rate or leaching mechanisms.

Condiment: Source Code for Risk Assessment of French Nuclear Waste Repository

1988 ◽  
Vol 127 ◽  
Author(s):  
J. P. Mangin ◽  
E. Mouche ◽  
P. Lovera ◽  
H. Nguyen Ngoc
Keyword(s):  
Risk Assessment ◽  
Nuclear Waste ◽  
Source Code ◽  
Computer Code ◽  
Nuclear Waste Repository ◽  
Single Element ◽  
Aqueous Corrosion ◽  
High Level ◽  
Diffusion Convection ◽  
Waste Repositories

ABSTRACTCONDIMENT is the source code used in MELODIE, the overall French computer code for risk assessment of nuclear waste repositories in geological formations. This code models the diffusion-convection of elements released by a waste package, up to a distance of a few meters from the package. Two versions have been developed simultaneously:- CONDIMENT2 deals with the case of a single element. This version is more specifically designed for vitrified high-level wastes. The boundary conditions are furnished by studies on aqueous corrosion of French nuclear glass R7T7.- CONDIMENT3, deals with two ions that are liable to precipitate. This version is more specifically designed for wastes immobilized in cement.CONDIMENT3 is verified in a configuration for which an analytical solution exists.

The Development and Testing of Synroc C as a High Level Nuclear Waste Form

1981 ◽  
Vol 6 ◽  
Author(s):  
K.D. Reeve ◽  
D.M. Levins ◽  
E.J. Ramm ◽  
J.L. Woolfrey ◽  
W.J. Buykx
Keyword(s):  
Stainless Steel ◽  
Research And Development ◽  
Nuclear Waste ◽  
Thermophysical Properties ◽  
Atomic Energy Commission ◽  
Current Status ◽  
Fast Neutrons ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Storage Times

ABSTRACTThe current status of SYNROC C research and development by the Australian Atomic Energy Commission is reviewed. A non-radioactive fabrication demonstration line designed to produce 10 cm o.d., 90 cm long, cylinders of SYNROC canned in stainless steel by the method of in-can hot pressing is being commissioned. Leach tests are proving the excellent leach resistance of SYNROC. Accelerated radiation damage testing using fast neutrons has simulated storage times of up to 6.7×105 years. Thermophysical properties of SYNROC have been measured over the temperature range 20–650°C.

Thermodynamic Modelling of the Pd-Te-Ru System for Nuclear Waste Glasses Application

2010 ◽  
Vol 1265 ◽  
Author(s):  
Stephane Gossé ◽  
Sophie Schuller ◽  
Christine Guéneau
Keyword(s):  
Thermodynamic Properties ◽  
Nuclear Waste ◽  
Fission Products ◽  
Solubility Limit ◽  
Calphad Method ◽  
Borosilicate Glasses ◽  
Isothermal Sections ◽  
Metallic Particles ◽  
Wide Range ◽  
High Level

AbstractThe waste management process of the French nuclear spent fuels is managed by a new vitrification conditioning step. High level radioactive borosilicate glasses are melted by induction in a cold crucible to accommodate a wide range of minor actinides and fission products. Among the fission products, platinoids precipitate in the form of (Pd-Te, Ru-Rh, Ru) metallic particles in the glass. The microstructure of these phases can affect the physicochemical properties of the melt during the vitrification process. To predict the thermodynamic properties of these alloys in the glass, a database is being developed on the Pd-Rh-Ru-Te system using the Calphad method. The binary (Pd-Te, Pd-Ru, Ru-Te) and ternary (Pd-Te-Ru) systems have been modelled. The Pd-Te-Ru ternary system built by extrapolation from the binaries enables to calculate ternary isothermal sections and thermodynamic properties of the platinoid phases between 873 K and 1573 K. Solidification paths are also calculated for Pd-Te alloys representative for those observed in the glasses. The phase composition at equilibrium and the Ru solubility limit in Pd-Te alloys are also calculated.

Non-Linearity in Glass Composition Dependence of Dissolution Rates: Effect of Solution pH

1993 ◽  
Vol 333 ◽  
Author(s):  
Shi-Ben Xing ◽  
Isabelle S. Muller ◽  
Ian L. Pegg
Keyword(s):  
Nuclear Waste ◽  
Glass Composition ◽  
Ph Dependence ◽  
Solution Ph ◽  
Ph Values ◽  
Waste Vitrification ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Soluble Components ◽  
Glass Compositions

ABSTRACTIn our previous studies on the optimization of glass compositions for high-level nuclear waste vitrification it was found that, over certain composition ranges, PCT leachate concentrations increased dramatically with very small changes in glass composition. The large differences that are observed between the leachate pH values for the “durable” and the “less-durable” glasses is one possible cause for this strongly non-linear glass composition effect; conversely, the pH difference may be merely another symptom. In this study, four simulated nuclear waste glasses (two of the less-durable and two of the durable types), were leached in both zwitterionic and inorganic buffer solutions, at fixed pH-values in the ranges of 7 to 12. The very different leaching behaviors of the two types of glasses persisted and, furthermore, different pH-dependence was found despite their very similar glass composition. This study suggests that the leachate pH difference observed between the less-durable and the durable glasses under uncontrolled pH conditions is not the major cause of the large difference of leaching behavior between those glasses. The normalized release ratios of soluble components (B, Li, Na) to Si show significant differences for the two types of glasses.

The Salton Sea Geothermal Field as a Natural Analog for the Near-Field in a Salt High-Level Nuclear Waste Repository

1984 ◽  
Vol 44 ◽  
Author(s):  
Wilfred A. Elders ◽  
Judith B. Moody
Keyword(s):  
Nuclear Waste ◽  
Near Field ◽  
Geothermal Field ◽  
Salton Sea ◽  
High Level Waste ◽  
Nuclear Waste Repository ◽  
Natural Analog ◽  
Naturally Occurring ◽  
Wide Range ◽  
High Level

AbstractThe Salton Sea Geothermal Field (SSGF), on the delta of the Colorado River in southern California, is being studied as a natural analog for the near-field environment of proposed nuclear waste repositories in salt. A combination of mineralogical and geochemical methods is being employed to develop a three dimensional picture of temperature, salinity, lithology, mineralogy, and chemistry of reactions between the reservoir rocks and the hot brines. Our aim is to obtain quantitative data on mineral stabilities and on mobilities of the naturally occurring radionuclides of concern in Commercial High-Level Waste (CHLW). These data will be used to validate the EQ3/6 geochemical code under development to model the salt near-field repository behavior.Maximum temperatures encountered in wells in the SSGF equal or exceed peak temperatures expected in a salt repository. Brines produced from these wells have major element chemistry similar to brines from candidate salt sites. Relative to the rocks, these brines are enriched in Na, Mn, Zn, Sr, Ra and Po, depleted in Ba, Si, Mg, Ti, and Al, and strongly depleted in U and Th. However the unaltered rocks contain only about 2–3 ppm of U and 4–12 ppm of Th, largely in detrital epidotes and zircons. Samples of hydrothermally altered rocks from a wide range of temperature and salinity show rather similar uniform low concentrations of these elements, even when authigenic illite, chlorite, epidote and feldspar are present. These observations suggest that U and Th are relatively immobile in these hot brines. However Ra, Po, Cs and Sr are relatively mobile. Work is continuing to document naturally occurring radionuclide partitioning between SSGF minerals and brine over a range of temperature, salinity, and lithology.

High-Level Nuclear Waste Transportation: Political Implications of the Weakest Link in the Nuclear Fuel Cycle

1988 ◽  
Vol 6 (3) ◽  
pp. 311-322 ◽  
Author(s):  
A M Kirby
Keyword(s):  
Nuclear Waste ◽  
Public Perception ◽  
Fuel Cycle ◽  
The Political ◽  
State Institutions ◽  
Weakest Link ◽  
Political Implications ◽  
The Usa ◽  
High Level Nuclear Waste ◽  
High Level

By focusing primarily on the USA but also drawing upon examples from Europe and Australia, the author examines the technical, political, and constitutional issues which surround the question of high-level nuclear waste transportation. It is revealed that there are major questions of safety and public perception which are not being addressed by state institutions, and there is a discussion of the ways in which state and professional actors have attempted to limit the political discourse on these and related policy-relevant issues.

scholarly journals RELATIONSHIP BETWEEN CANADA AND THE UNITED STATES: ASYMETRY AND INTERDEPENDENCE

2018 ◽  
pp. 13-24
Author(s):  
I. Derevianko
Keyword(s):  
United States ◽  
Soft Power ◽  
The United States ◽  
Scientific Methods ◽  
Wide Range ◽  
The Usa ◽  
The Asymmetry ◽  
High Level ◽  
Political Economic ◽  
High Degree

The article analyze the nature and content of bilateral Canadian-American asymmetric relations with uses the general scientific methods of empirical knowledge. The asymmetry of quantitative and qualitative parameters of Canada and the USA, which is caused by historical, geographical, political, economic, demographic and cultural factors, is revealed. It is proved that in the conditions of interdependence, the asymmetry of military potentials is not a determining factor in relations between the two North American countries. It found that the existing asymmetry of indicators between Canada and the United States does not create opportunities for the strong side to dictate its conditions and does not allow these relations to be turned into a one-sided relationship. Key Canadian strategies aimed at reducing asymmetry in relations with the United States are identified. It is indicated that “soft power” is an important factor in strengthening Canada’s political position in the asymmetric model of coexistence with the United States. The Relations between Canada and the United States are characterized not only by the high level of asymmetry and the wide application of regulatory mechanisms, but also by the high degree of interdependence that is particularly noticeable in the economic and cultural spheres. The asymmetric relationship between Canadian-American is evident in terms of reaching consensus in a wide range of activities. Key words: USA, Canada, Canadian-American Relations, Asymmetry, Interdependence, Potential.

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