A Reactive Transport Model for Oxidative Dissolution of Spent Fuel and Release of Nuclides Within a Defective Canister

2002 ◽  
Vol 137 (3) ◽  
pp. 228-240 ◽  
Author(s):  
Longcheng Liu ◽  
Ivars Neretnieks
Keyword(s):  
Reactive Transport ◽  
Transport Model ◽  
Spent Fuel ◽  
Oxidative Dissolution ◽  
Reactive Transport Model

Spent fuel alteration model integrating processes of different time-scales

MRS Advances ◽  
2020 ◽  
Vol 5 (3-4) ◽  
pp. 159-166
Author(s):  
O. Riba ◽  
E. Coene ◽  
O. Silva ◽  
L. Duro
Keyword(s):  
Reactive Transport ◽  
Transport Model ◽  
Beta Radiation ◽  
Comsol Multiphysics ◽  
Water Radiolysis ◽  
Spent Fuel ◽  
Subsequent Reduction ◽  
Reactive Transport Model ◽  
Safety Assessments ◽  
Different Time Scales

ABSTRACTA 1D reactive transport model has been implemented in iCP (interface COMSOL Multiphysics and PhreeqC) to assess the corrosion of Spent Fuel (SF), considered as homogeneous UO2(am,hyd) doped with Pd. The model couples: i) generation of water radiolysis species by alpha and beta radiation considering the complete water radiolysis system with the kinetic reactions involving: H+, OH-, O2, H2O2, H2, HO2-, HO2·, O·, O-, O2-, H·, ·OH and e- ii) processes occurring in the spent fuel surface: oxidative dissolution reactions of UO2(am,hyd) and subsequent reduction of oxidized fuel, considering H2 activation by Pd, and iii) corrosion of Fe(s) in oxic and anoxic conditions. Process i) has been implemented in COMSOL and processes ii) and iii) have been implemented in PHREEQC with their kinetic constants being calibrated with different sets of experimental data published in the open literature. The model yields a UO2(am,hyd) dissolution rates similar to the values selected in safety assessments.

scholarly journals Computational Efficiency of Decoupling Approach in Solving Reactive Transport Model: A Case Study of Pyrite Oxidative Dissolution

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Jixiang Huo ◽  
Fuheng Ma ◽  
Hanzhou Song
Keyword(s):  
Computational Efficiency ◽  
Reactive Transport ◽  
Building Materials ◽  
Transport Model ◽  
Chemical Species ◽  
Oxidative Dissolution ◽  
Direct Solver ◽  
Reactive Transport Model ◽  
Decoupling Approach

Pyrite existed widely in nature and its oxidative dissolution might lead groundwater to become acidic, which was harmful to the environment and indeed to artificial building materials. The reactive transport model was a useful tool to predict the extent of such pollution. However, the chemical species were coupled together in the form of a reaction term, which might lead the equations to be nonlinear and thus difficult to solve. A decoupling approach was presented: linear algebraic manipulations of the stoichiometric coefficients of the chemical reactions for the purpose of reducing the number of equation variables and simplifying the reactive source were used. Then the original and decoupled models were solved separately, by both a direct solver and an iterative solver. By comparing the solution times of two models, it was shown that the decoupling approach could enhance the computational efficiency, especially in situations using denser meshes. Using a direct solver, more solution time was saved than when using an iterative version.

Impact of iron released from steel components on the performance of the bentonite buffer: a preliminary assessment within the framework of the KBS-3H disposal concept

2006 ◽  
Vol 932 ◽  
Author(s):  
Paul Wersin ◽  
Lawrence H. Johnson ◽  
Margit Snellman
Keyword(s):  
Adverse Effects ◽  
Reactive Transport ◽  
Iron Sulfide ◽  
Transport Model ◽  
Spent Fuel ◽  
Preliminary Assessment ◽  
Reactive Transport Model ◽  
Bentonite Buffer ◽  
Simple Mass ◽  
Limited Process

ABSTRACTSteel components in the engineered barrier of HLW repositories have a potential to react with the clay buffer and induce adverse effects on its properties. These effects have been assessed within the KBS-3H disposal concept, which includes spent fuel in copper canisters surrounded by bentonite blocks and a steel supercontainer (SC), placed within tunnels in deep crystalline Olkiluoto-type host rock. Based on literature review and thermodynamic modeling, the SC is predicted to completely corrode within a minimum of a few thousand years. The resulting corrosion products are expected to be magnetite, and depending on groundwater compositions, also iron sulfide and perhaps siderite. Furthermore corrosion-derived Fe(II) may react with the clay to form non-swelling phyllosilicates, such as berthierine. From simple mass balance estimates and by applying a more realistic reactive transport model, it can be deduced, that the effect of iron from the SC on the integrity of the bentonite buffer is limited. However, large uncertainties in adequately quantifying this effect pertain due to limited process knowledge on Fe-bentonite interactions.

scholarly journals Reactive Transport Model of Sulfur Cycling as Impacted by Perchlorate and Nitrate Treatments

2016 ◽  
Vol 50 (13) ◽  
pp. 7010-7018 ◽  
Author(s):  
Yiwei Cheng ◽  
Christopher G. Hubbard ◽  
Li Li ◽  
Nicholas Bouskill ◽  
Sergi Molins ◽  
...  
Keyword(s):  
Reactive Transport ◽  
Transport Model ◽  
Sulfur Cycling ◽  
Reactive Transport Model
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