3D modelling of long-term sulfide corrosion of copper canisters in a spent nuclear fuel repository

Self Cite

Reactive‐transport models (RTMs) have been an integral part of the safety case and design optimization for the nuclear waste repository in Finland. Such highly resolved, internally complex RTMs tend to be computationally demanding, thus their design is often a compromise between representativeness and computational efficiency. A modeling strategy is presented, demonstrating how a 2D simplified model can be constructed based upon and calibrated against a geometrically realistic 3D RTM. Key geometrical parameters of the 2D model are consistent with the 3D model, and the 2D model is verified by a series of benchmarks for various designs and conditions of the repository. Overall, the 2D model is proven suitable for fast scoping calculations, as (1) it reduces the mesh elements by 16 times and shortens the run time by about 40 times; (2) it has much more flexible remeshing possibilities; and (3) it provides highly consistent results with the 3D model.

Section: Model Descriptionmentioning

confidence: 99%

“…Case 1 is based on the reference model described in Ma et al [2] It involves fully saturated, isothermal conditions.…”

Section: Case 1: Reference Casesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Development of a 2D model for rapid estimation of sulfide corrosion of copper canisters in a spent nuclear fuel repository

Alt‐Epping

Pastina

et al. 2023

Self Cite

Reactive‐transport model for the production, transport, and consumption of sulfide in a spent nuclear fuel deep geological repository in crystalline rock

Hung

Briggs

et al. 2023

A 1‐D reactive‐transport model has been developed to describe the production and transport of sulfide in a deep geological repository in crystalline rock and the subsequent corrosion of the copper canister. The model accounts for various processes, including: (i) the microbial reduction of sulfate by organotrophic and lithotrophic sulfate‐reducing bacteria, (ii) the supply of sulfate from both the ground water and from the dissolution of gypsum present as an accessory mineral in the bentonite buffer, (iii) diffusive transport of reactants and products, and (iv) sequestration of a fraction of the microbially produced sulfide by precipitation as mackinawite. The results of a base case simulation and of sensitivity analyses indicate that the extent of uniform corrosion is approximately 0.2 mm after 1 million years and that the maximum flux of sulfide to the canister surface is below the threshold for localized corrosion or stress corrosion cracking.

Natural and archaeological analogues for corrosion prediction in nuclear waste systems

King¹,

Behazin

Keech

2023

Natural and archaeological analogues can be a powerful means to build confidence in the long‐term prediction of corrosion in nuclear waste systems. Analogues are meaningful to both experts and lay audiences. Useful analogues exist to support the long‐term behaviour for both copper and steel used fuel containers (UFC) and examples are given for the corrosion processes that are, and are not, expected to occur under repository conditions for both materials. The concept of kinetic versus thermodynamic stability is used to explain the persistence of such analogues. The use of analogues to support the prediction of the long‐term corrosion performance of the UFC in the safety case is also discussed. While there have been a wide range of analogue studies in the past, it is suggested that future studies should be focussed on addressing specific aspects of the treatment of corrosion issues in the safety case.