Modelling of the Degradation of Cement in a Nuclear Waste Repository

1988 ◽  
Vol 127 ◽  
Author(s):  
A. Haworth ◽  
S. M. Sharland ◽  
C. J. Tweed
Keyword(s):  
Nuclear Waste ◽  
Transport Model ◽  
Thermodynamic Description ◽  
Nuclear Waste Repository ◽  
General Corrosion ◽  
Chemistry Transport Model ◽  
High Ph ◽  
Preliminary Model ◽  
Waste Repository ◽  
Aqueous Species

ABSTRACTThe current UK concept for a low- or intermediate-level nuclear waste repository includes a largely cementitious backfill. The cement provides a high pH environment in which the general corrosion rate of the metal canisters is reduced and the solubilities of many nuclides low. It has previously been assumed that this high pH will exist for a period of 107 years, however cement will degrade due to leaching of the solid components and attack from aqueous species in groundwater. In this paper we describe the preliminary stages of a model of the degradation of cement in a repository. The modelling involves the incorporation of a thermodynamic description of cement[2] into the static code PHREEQE[5]. This is then used in a coupled chemistry-transport model of simple leaching of cement using the code CHEQMATE[4]. This preliminary modelling also provides a useful verification of CHEQMATE as a direct comparison with a THCCDM (a coupled code based on CHEMTRN) model is possible. Results from this preliminary model suggest that the fall in pH due to leaching is slow. The model is sufficiently flexible to form the basis of more detailed investigations of the effect of groundwater interactions on the degradation of cement.

Modeling Alloy 22 general corrosion in the Yucca Mountain nuclear waste repository

JOM ◽  
2008 ◽  
Vol 60 (1) ◽  
pp. 52-57 ◽  
Author(s):  
Kevin G. Mon ◽  
Brvan E. Bullard ◽  
Fred Hua ◽  
Gopal C. De
Keyword(s):  
Nuclear Waste ◽  
Yucca Mountain ◽  
Nuclear Waste Repository ◽  
General Corrosion ◽  
Alloy 22 ◽  
Waste Repository

Corrosion Behavior of Alloy 22 and Ti Grade 7 in a Nuclear Waste Repository Environment

CORROSION ◽  
2004 ◽  
Vol 60 (8) ◽  
pp. 764-777 ◽  
Author(s):  
F. Hua ◽  
G. Gordon
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Nuclear Waste ◽  
Crevice Corrosion ◽  
Nuclear Waste Repository ◽  
General Corrosion ◽  
Corrosion Rates ◽  
Significant Difference ◽  
Alloy 22 ◽  
Waste Repository

Abstract Alloy 22 (UNS N06022) and Ti Grade 7 (UNS R52400) are the current corrosion-resistant materials of choice for fabricating the waste package outer barrier and the drip shield, respectively, for the proposed high-level nuclear waste repository at Yucca Mountain. In this work, the general and crevice corrosion behavior of annealed and welded Alloy 22 and Ti Grade 7 exposed in basic saturated water (BSW-12) for four and eight weeks at 60°C to 105°C were evaluated using the ASTM G78 method combined with surface analysis and statistical analysis of corrosion rate. The general corrosion rates for Alloy 22 and Ti Grade 7 were found to increase linearly with temperature but decrease with the exposure time. The mean corrosion rate was found to be 0.003 mpy (0.075 μm/y) at 60°C and 0.010 mpy (0.25μm/y) at 105°C for Alloy 22 and 0.008 mpy (0.20 μm/y) at 60°C and 0.022 mpy (0.56 μm/y) at 105°C for Ti Grade 7. No significant difference in corrosion behavior between the annealed and welded materials was observed. For both materials the surface imperfections inherited from materials processing did not seem to deteriorate the excellent corrosion resistance of the materials but might serve as the “traps” for corrosion products. The apparent activation energies for the temperature dependence of corrosion rates of Ti Grade 7 and Alloy 22 in BSW-12 environment were obtained as 25.3 (±5.5) KJ/mol and 23.7 (±4.5) KJ/mol, respectively. Although none of the materials was found susceptible to crevice corrosion under the test conditions, to conclude that these materials are immune to crevice corrosion in BSW-12 would require longer-term testing.

Effects of Heavy Metal Ions on Corrosion of Titanium Grade 7 In Concentrated Groundwaters

2002 ◽  
Vol 713 ◽  
Author(s):  
April L. Pulvirenti ◽  
Karen M. Needham ◽  
Mohammad A. Adel-Hadadi ◽  
Charles R. Marks ◽  
Jeffery A. Gormana ◽  
...  
Keyword(s):  
Nuclear Waste ◽  
Heavy Metal Ions ◽  
Yucca Mountain ◽  
Nuclear Waste Repository ◽  
General Corrosion ◽  
Reasonable Approximation ◽  
Waste Repository ◽  
Concentrated Solution ◽  
Titanium Grade ◽  
Service Environments

ABSTRACTA Titanium Grade 7 (Ti-7) drip shield is being considered for use in the potential nuclear waste repository at Yucca Mountain, Nevada. The purpose of the drip shield is to keep water from reaching the surfaces of the canisters containing nuclear waste. Among the species that may be expected to be present in the water are heavy metals. This paper explores the effects of five species, lead, mercury, cadmium, tin and sodium, on the dissolution rate of Ti-7. The results of these tests indicated that lead, mercury, cadmium and tin ions do not significantly accelerate the general corrosion of Ti-7 under the conditions studied. A highly concentrated solution of NaOH was found to cause significant dissolution of Ti-7. Such a solution is a reasonable approximation of possible service environments.

Chemical, Physical and Engineering Characterization Of Candidate Backfill Clays and Clay Admixtures for a Nuclear Waste Respository-Part I

1981 ◽  
Vol 6 ◽  
Author(s):  
Sudesh K. Singh
Keyword(s):  
Nuclear Waste ◽  
Morphological Changes ◽  
Deionized Water ◽  
Engineering Properties ◽  
Nuclear Waste Repository ◽  
Exchange Cation ◽  
Mineral Components ◽  
Waste Repository ◽  
Mineralogical Compositions

ABSTRACTFourteen Canadian clays and clay admixtures were subjected to simulated nuclear waste repository environments. The present work is concerned with the montmorillonite-dominant materials only. The montmorillonite-dominant samples showed significant leaching on interaction with deionized water. On heating the samples at 200°C for 500 hours, montmorillomites lost intermicellar water completely and acquired cusp-like to cylindrical morphologies. The loss of water and the morphological changes in montmorillonites significantly altered the engineering characteristics. Permeability, shrinkage limits, compactability and shear strength varied in response to the dominant exchange cation in the structure of montmorillonites and the presence of other mineral components in the materials. The synthetic granite water reacted with montmorillonites and led to changes in chemical and mineralogical compositions, crystalline state and engineering properties.

Modelling of thermal rock mass properties at the potential sites of a Swedish nuclear waste repository

2009 ◽  
Vol 46 (6) ◽  
pp. 1042-1054 ◽  
Author(s):  
Jan Sundberg ◽  
Pär-Erik Back ◽  
Rolf Christiansson ◽  
Harald Hökmark ◽  
Märta Ländell ◽  
...  
Keyword(s):  
Rock Mass ◽  
Nuclear Waste ◽  
Nuclear Waste Repository ◽  
Rock Mass Properties ◽  
Mass Properties ◽  
Waste Repository
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