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        <title>Frontiers in Nuclear Engineering | Radioactive Waste Management section | New and Recent Articles</title>
        <link>https://www.frontiersin.org/journals/nuclear-engineering/sections/radioactive-waste-management</link>
        <description>RSS Feed for Radioactive Waste Management section in the Frontiers in Nuclear Engineering journal | New and Recent Articles</description>
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        <pubDate>2026-05-15T17:55:03.866+00:00</pubDate>
        <ttl>60</ttl>
        <item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2026.1840901</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2026.1840901</link>
        <title><![CDATA[The safety case for a deep geological repository in Switzerland: concepts for waste disposal and methodology for safety assessment]]></title>
        <pubdate>2026-05-15T00:00:00Z</pubdate>
        <category>Methods</category>
        <author>Paul Smith</author>
        <description><![CDATA[This paper describes the deep geological repository concept considered by Nagra in support of its recent general licence application and the methodology used by Nagra to demonstrate its post-closure safety. The concept presented is for a deep geological repository for high-level waste (HLW) and for low- and intermediate-level waste (L/ILW) located in the Opalinus Clay host rock in Switzerland. The safety and repository concept is based on geological and engineered barriers which together perform a range of different high-level safety functions. The safety case is built on an assessment basis that is defined as the evidence, knowledge, assessment tools, and methodologies developed or acquired in support of the safety assessment. The safety assessment itself consists of four main steps or processes: i) performance assessment, in which arguments are developed and evidence presented to show that the safety functions of the repository are upheld and that the system will evolve as expected in most reasonably foreseeable situations, ii) safety scenario development, which defines a set of safety scenarios that capture alternative ways in which the repository system could evolve over time, taking uncertainty into account, iii) the analysis of radiological consequences, which uses quantitative models to evaluate annual individual dose rates or risks for these safety scenarios and compares the results with regulatory guidelines, and iv) the demonstration of post-closure safety, which synthesises the various lines of argument and evidence to produce the safety case. The paper provides an overview of the safety assessment methodology. Detailed aspects of performance assessment, safety scenarios development and the analysis of radiological consequences are provided in separate papers within this special issue.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2026.1760157</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2026.1760157</link>
        <title><![CDATA[Transformation of discrete fracture networks into equivalent continuum models for sparsely fractured rocks: comparing flow-based and geometry-based upscaling for flow and transport]]></title>
        <pubdate>2026-04-22T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Caroline Darcel</author><author>Quentin Courtois</author><author>Urban Svensson</author><author>Romain Le Goc</author><author>Benoît Pinier</author><author>Jan-Olof Selroos</author><author>Philippe Davy</author>
        <description><![CDATA[In this study, we analyze the impact of transforming a discrete fracture network (DFN) model to an equivalent continuum model (ECM) on flow and solute transport characteristics. The analysis was conducted in a setting derived from – though simplified relative to – in-situ fracturing conditions at the Forsmark site. The geometrical structure of the DFN model considered is combined successively with a highly simplified transmissivity model (single constant value) in order to isolate spatial and structural effects, and with a more realistic model in which transmissivities depend on both fracture size and orientation (indirectly reflecting mechanical stress conditions). Two upscaling methods are considered: a simplified geometry-based method and a numerical flow-based method, in which local ECM cell properties are directly informed by local flow and transport simulations. For both approaches, we quantify the impact of ECM resolution. Specifically, we assess the sensitivity of local properties as well as local and global flow and transport indicators, to both the upscaling method and the ECM grid resolution. The results demonstrate that the transformation from DFN to ECM overestimates hydraulic conductivity, underestimates the geometric porosity but to a lesser extent and overestimates the transport porosity. This also artificially reduces flow path variability and tortuosity, except at very high resolutions. Consequently, average transfer times are shorter in ECMs than in DFNs, with discrepancies increasing as grid resolution coarsens. Similar trends are observed for first arrival times and mode (the peak of the distribution), but to a lesser extent. DFNs are also more likely to have very long transport times. Finally, we show that ECMs derived from geometry-based upscaling are highly sensitive to grid resolution, whereas flow-based upscaling exhibits significantly lower sensitivity.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2026.1798989</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2026.1798989</link>
        <title><![CDATA[Activity release calculation from the near-field of a repository for spent fuel]]></title>
        <pubdate>2026-04-22T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Ping Chen</author><author>Qi Zhang</author><author>Chengming Shang</author>
        <description><![CDATA[It is essential for the safety assessment of a repository to analyze the release and transport of radionuclides from the near-field to the geosphere and subsequently to the surface environment. A new model has been developed in COMSOL Multiphysics based on input data from the safety case for the disposal of spent nuclear fuel at Olkiluoto. Complex processes, for example, nuclide decay, material corrosion, diffusion, sorption, and advection, are coupled in COMSOL Multiphysics. Under reasonable assumptions, the release rates of C-14, Cl-36, I-129, Cs-135, and Ni-59 are compared with results from simulations by GoldSim. Higher release rates are observed for these five isotopes. This discrepancy may arise from two factors. On the one hand, an excessively coarse grid in GoldSim enhances nuclide transport properties, leading to a greater accumulation of nuclides in the buffer in areas below the failed canister. On the other hand, important information is omitted in the 2D model. This suggests that the release rates calculated by GoldSim may require reconsideration. Although higher release rates were confirmed in this 3D model, the release rates of Tc-99, Np-237, Pu-239, and Pu-242 remain at low levels after 106 years (the timeframe for safety assessment in Finland and Sweden). Further development is possible in COMSOL Multiphysics, such as the replacement of spent fuel with vitrified glass and the implementation of a chemical reaction module. With this new model, greater confidence is achieved in the calculation of radionuclide release and transport. This is crucial for the safety assessment of repositories.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2026.1836941</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2026.1836941</link>
        <title><![CDATA[Editorial: Advanced modeling techniques in radioactive waste disposal]]></title>
        <pubdate>2026-04-07T00:00:00Z</pubdate>
        <category>Editorial</category>
        <author>Yuankai Yang</author><author>Tao Wu</author>
        <description></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2026.1787346</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2026.1787346</link>
        <title><![CDATA[Identification of safety-relevant radionuclides for performance assessment modeling]]></title>
        <pubdate>2026-03-09T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Stefan Finsterle</author><author>Michael J. Hannon</author><author>Jesse Sloane</author>
        <description><![CDATA[We propose, apply, and verify a screening approach for the selection of safety-relevant radionuclides that should be tracked in models assessing the performance of geologic repositories for the disposal of spent nuclear fuel and high-level radioactive wastes. Starting with a comprehensive list of radionuclides present in the waste form, a multi-step down-selection process evaluates each isotope’s potential relative contribution to the total peak exposure dose, which is a surrogate metric for overall repository safety. In the first screening step, only basic, readily available characteristics of a radionuclide are needed, such as its inventory, half-life, specific activity, and dose coefficient. In the second step, the radionuclide’s transport time from the repository to the accessible environment is estimated based on factors affecting its mobility and retardation. By adjusting the screening threshold, the number of radionuclides considered potentially safety-relevant can be changed, thus yielding a larger or smaller (more or less conservative) set of radioisotopes being tracked in the performance assessment model, as warranted by the stage of repository development. We exercise the proposed screening approach for a particular waste form—spent nuclear fuel assemblies—and two disposal pathways—deep horizontal and vertical borehole repositories. An integrated performance assessment model is then used to simulate the migration of a considerably larger set of radionuclides from the disposal canisters to the land surface. The acceptably small difference in peak dose calculated with the comprehensive and reduced set of radionuclides indicates the appropriateness of the proposed screening approach.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2025.1765005</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2025.1765005</link>
        <title><![CDATA[Editorial: EURAD: state of the art in research and development on radioactive waste management and disposal]]></title>
        <pubdate>2026-02-25T00:00:00Z</pubdate>
        <category>Editorial</category>
        <author>Tara Beattie</author><author>Bernd Grambow</author>
        <description></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2026.1795642</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2026.1795642</link>
        <title><![CDATA[A future design approach to nuclear waste repository siting: activating futurability and cultivating pride]]></title>
        <pubdate>2026-02-19T00:00:00Z</pubdate>
        <category>Perspective</category>
        <author>Tatsuyoshi Saijo</author>
        <description><![CDATA[Nuclear waste repository siting presents an unprecedented intergenerational challenge: decisions made today will affect approximately 5,000 future generations over 100,000 years. Contemporary approaches in Finland, Sweden, and France rely almost exclusively on present-generation perspectives in societal decision-making. While achieving varying degrees of local acceptance through institutional trust and economic compensation, these processes implement no systematic exercises where current residents adopt future generations’ temporal viewpoints. Future Design (FD) offers a complementary framework by activating futurability—the capacity to experience present happiness through pursuing future generations’ wellbeing. FD employs dual perspective-taking: temporal (through integrated Past Design, Present Design, and Future Design exercises) and spatial (host-beneficiary dialogue). This cultivates three forms of pride: achievement pride from confronting civilization’s waste challenge, collective pride in community contribution, and anticipatory pride imagining descendants’ evaluation. Unlike compensation-based acceptance, pride-based acceptance emerges intrinsically through perspective-taking. Rigorous pilot testing comparing FD and non-FD deliberations is essential, with ethical safeguards ensuring transparency and genuine openness to rejection. Integrating FD into repository siting can help demonstrate what current generations owe future generations: not merely engineered safety, but proven concern.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2025.1738676</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2025.1738676</link>
        <title><![CDATA[First evaluation of geopolymer encapsulation of simulated alkaline aluminum-rich liquid waste from Mo-99 production]]></title>
        <pubdate>2026-02-11T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Whitney Talavera Ramos</author><author>Adrián Tellería Narváez</author><author>Lucas Dos Santos</author><author>Daniel Arcone</author><author>Ayelén Manzini</author>
        <description><![CDATA[This study investigates the synthesis and characterization of metakaolin-based geopolymers for the immobilization of simulated aluminum-containing radioactive liquid waste. Two kaolin precursors with different Si/Al ratios and purities were calcined between 700 °C and 900 °C. Geopolymers were prepared using a sodium silicate–NaOH activating solution (10 M NaOH) with and without sand, and cured at 60 °C. The effects of curing time and simulated liquid waste incorporation (10–40 wt%) on mechanical strength and microstructural development were evaluated through compressive strength tests, XRD, and SEM analyses. The results showed that curing time influenced strength development. Incorporation of simulated liquid waste generally reduced compressive strength, probably due to increased porosity and decreased metakaolin (MK) dissolution; however acceptable performance was achieved at a 20 wt% addition for MKSR-based geopolymers. XRD analyses confirmed the formation of an amorphous band between 25° and 35° typical of geopolymer structures. In contrast, MKS-based geopolymers exhibited lower mechanical strength and incomplete gel formation under the tested conditions. These findings demonstrate the potential of local precursor MKSR metakaolin-based geopolymers as promising matrices for the immobilization of aluminum-bearing radioactive liquid waste.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2025.1736818</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2025.1736818</link>
        <title><![CDATA[Adsorption of Pb(II) and brilliant green dye onto geopolymer/zeolite hybrid composites]]></title>
        <pubdate>2026-01-09T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Hammad R. Khalid</author>
        <description><![CDATA[Geopolymers, aluminosilicate materials formed by alkali activation, have drawn interest because of their unique mechanical, chemical, and thermal characteristics. They are interesting for adsorption applications due to their similar chemical structure to zeolite. This study investigates the synthesis and characterization of hybrid geopolymer/zeolite composites to remove lead ions (Pb(II)) and brilliant green (BG) dye from aqueous solutions. Sodium hydroxide and sodium silicate were used to activate fly ash and blast furnace slag blends. This was followed by hydrothermal treatment to encourage the conversion of amorphous geopolymeric gel to crystalline zeolites. Several variables were systematically changed, such as foaming agents, alkali molarity, and bead size to compare adsorption performance. The formation of zeolite phases was confirmed by structural and morphological investigations, such as XRD, FT-IR, SEM, and BET, which also shed light on the porous character of the composite. The geopolymer/zeolite composites demonstrated notable removal efficiency for Pb(II) (up to 123 mg/g) and BG dye (up to 115 mg/g) in adsorption studies. Importantly, this work reveals that average pore diameter plays a more critical role than surface area in determining adsorption capacity of bulk-type adsorbents, contrasting conventional assumptions in the field. The work provides possibilities for creating long-lasting, efficient adsorbents for the treatment of water by highlighting the roles that pore size and surface area play in the adsorption mechanism. Given the structural similarity between heavy metals and certain radionuclides, these findings have broader implications for developing geopolymer-based materials for radioactive waste treatment applications.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2025.1729916</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2025.1729916</link>
        <title><![CDATA[Modeling glass degradation and release of radionuclides from vitrified waste for performance assessment simulations]]></title>
        <pubdate>2026-01-05T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Stefan Finsterle</author><author>Jeffrey R. McLachlan</author><author>Michael J. Hannon</author><author>Jesse Sloane</author><author>Rebecca J. Abergel</author><author>Per F. Peterson</author>
        <description><![CDATA[The release of radionuclides initially encapsulated in a slowly degrading solid waste form and contained in an eventually corroding canister defines the source term for numerical simulations for the assessment of a geologic repository for high-level radioactive waste. While the details of waste degradation, canister corrosion, and dissolution and mobilization of the radionuclides in pore water include complex chemical reaction and transport processes that are coupled to the thermal, hydrological, microbiological, and mechanical conditions in the repository, the source-term model suitable for use in a numerical performance assessment model should be a defensible abstraction of these mechanisms. We developed a radiological source-term model and implemented it into a non-isothermal flow and transport simulator. While the proposed source-term model is applicable to various waste forms, canister systems, and disposal concepts, we specifically considered radionuclide releases from vitrified high-level waste placed in a cylindrical canister disposed in a deep vertical borehole repository. In this model, waste degradation is a function of temperature, and it can be adjusted to evaluate the influence of and propagate uncertainties in pH, passivation reactions, and chemical conditions as well as geometrical factors. The time-dependent, congruent release of safety-relevant radionuclides present in the decaying inventory is then calculated. Finally, the radionuclides are mobilized by diffusive and advective transport according to the thermo-hydraulic conditions prevailing in the near field of the repository, from where they migrate through the geosphere to the accessible environment. We examine the influence of the source-term model’s parameters on performance assessment calculations through sensitivity and uncertainty propagation analyses, identifying influential factors and confirming the upper bound of their impact. These considerations align with the overarching goal of repository design, which is to demonstrate that engineered and natural barriers can collectively delay radionuclide migration for timescales far exceeding human planning, thereby providing multiple, redundant barriers against environmental contamination.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2025.1693242</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2025.1693242</link>
        <title><![CDATA[Mesoscale phase-field modeling of silver dissolution in Cast Stone with AgM granules]]></title>
        <pubdate>2025-11-24T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Shenyang Hu</author><author>Yulan Li</author><author>R. Matthew Asmussen</author>
        <description><![CDATA[A mesoscale model is developed to study silver (Ag) dissolution in Cast Stone (CS) matrix containing silver mordenite (AgM) particles. The model captures microstructure-dependent thermodynamic and kinetic properties, including multispecies diffusion, redox reactions, and Ag precipitation. Simulations show that Ag-rich precipitate formation at the AgM/CS interface slows dissolution by reducing chemical potential gradients and diffusivity, while oxidation reactions enhance Ag release by increasing retention around unreacted reagents (e.g., slag, cement). Smaller AgM particles dissolve more rapidly due to shorter diffusion paths. This model offers a mechanistic framework to assess how microstructure and redox chemistry influence Ag retention and can be integrated with geochemical speciation models for multiscale performance evaluation of nuclear waste forms.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2025.1689795</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2025.1689795</link>
        <title><![CDATA[Generation and dissipation of corrosion gas in a deep horizontal borehole repository for radioactive waste]]></title>
        <pubdate>2025-11-20T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Stefan Finsterle</author><author>Matthew Waples</author><author>Mengzhu Yang</author><author>Karl P. Travis</author>
        <description><![CDATA[The performance of a deep borehole repository for the disposal of radioactive waste may be affected by the generation of hydrogen gas produced by the corrosion of the steel canisters and the borehole casing. In particular, the evolution of a free gas phase may lead to high overpressures within the borehole and near field of the repository, displacing radionuclides dissolved in pore water, and facilitating the transport of volatile radionuclides. These processes are analyzed by numerical modeling of non-isothermal, multiphase flow and transport of hydrogen gas and water in a generic deep horizontal borehole repository completed in an argillaceous host rock. The near-field submodel addresses gas generation within and outside the canister and the effect of canister breach on near-field pressure and saturation distributions; a repository-scale model examines the effect of gas generation in a long disposal section. The models support canister and design decisions for deep borehole repositories. The simulations reveal the significance of the repository design on gas flow, both on the local scale of the components of the engineered barrier system, and on the larger scale of the repository layout. It can be concluded that for a typical design of a deep horizontal borehole repository, corrosion gases are contained within the disposal section of the borehole, or effectively dissipate into the repository’s near field without generating excessive overpressures that affect the integrity of the engineered barrier system or the overall performance of the repository.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2025.1699785</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2025.1699785</link>
        <title><![CDATA[Electron irradiation effects on Vickers hardness of potassium-based geopolymers: the role of water content]]></title>
        <pubdate>2025-11-19T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Thi-Mai-Dung Do</author><author>Yang Yaru</author><author>Takashi Kikuchi</author><author>Tadachika Nakayama</author><author>Gordon James Thorogood</author><author>Hisayuki Suematsu</author>
        <description><![CDATA[Potassium-based geopolymers were synthesized with varying initial water content (7–10 mol %). Samples were initially cured under tight-lidded conditions at different temperatures (room temperature, 40 °C, and 60 °C) for the initial 24 h and then transitioned to ambient curing without lid. Analysis of the pore size distribution revealed that higher initial water content generally led to larger pores, while higher curing temperatures resulted in smaller pores. Vickers hardness measurements showed a dependence on both initial water content and curing temperature. The electron beam irradiation was processed up to 16 kGy by pulsed linear electron accelerator at Nagaoka University of Technology and up to 992 kGy by electron beam irradiation at the Takasaki Institute of Advanced Quantum Science. The Vickers hardness of a selected sample remained largely unchanged even after electron beam irradiation up to a high dose.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2025.1654080</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2025.1654080</link>
        <title><![CDATA[An empirical model linking solution volume-to-surface area ratio to the dissolution kinetics of oxides in aqueous systems]]></title>
        <pubdate>2025-11-10T00:00:00Z</pubdate>
        <category>Hypothesis and Theory</category>
        <author>Jianwei Wang</author>
        <description><![CDATA[Understanding how environmental variables influence the dissolution rate of nuclear waste materials in aqueous systems is crucial for developing durable nuclear waste forms. In experiments to estimate dissolution rates, the amount of aqueous solution reacting with the material surface is often used as a convenient variable to control the solution saturation state, which then controls the dissolution rate. An exponential function between the dissolution rate and the solution volume-to-surface area ratio was derived, based on an empirical relation of a power function between the Gibbs free energy of dissolution and the volume-to-surface ratio. The relationship was employed to model the dissolution rates of several oxide minerals. The results suggest that the relationship is robust in numerically describing the dissolution rates as a function of the volume-to-surface ratio. Applying the relationship to the dissolution datasets of a nuclear glass and a ceramic nuclear waste form demonstrates its applicability to nuclear materials, providing important insights into the saturation state of the experimental conditions and the chemical durability of these materials. The proposed empirical relationship provides a convenient tool to help design dissolution experiments and offers important insights into the dissolution behavior of materials.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2025.1664370</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2025.1664370</link>
        <title><![CDATA[Foundations of site selection procedures for deep geological repositories: an argument-based model to explain how site rejection decisions can be justified by inaccurate operationalizations and assessments of long-term protection]]></title>
        <pubdate>2025-09-05T00:00:00Z</pubdate>
        <category>Hypothesis and Theory</category>
        <author>Martin Navarro</author>
        <description><![CDATA[Site selection procedures for deep geological repositories are driven by the rejection of candidate sites whose degree of long-term protection is insufficient or less sufficient. If long-term protection is defined in relation to future exposures, it has to be operationalized, that is, translated into measurable indicators, such as dose or degree of containment, which, again, have to be evaluated by safety assessments. Site selection procedures, therefore, depend on the quality with which long-term protection is operationalized and assessed. Although it is widely acknowledged that operationalizations and assessments of long-term protection are inherently inaccurate, little attention has been paid to the question whether these inaccuracies prevent site selection procedures from improving long-term protection. Still, there is no theory of site selection that could specify the conditions under which site selection procedures are rational with regard to the target of long-term protection. To contribute to such a theory, a conceptual model is presented that explores how site rejection decisions can be justified by inaccurate operationalizations and safety assessments. The model rests on the assumption that site rejections are justified by logical arguments. By explicating what is needed to support the arguments, the model displays the complex structure of the justification, which, amongst others, rests on the quality of operationalization, safety assessment and system understanding. The presented argument-based approach is novel in the context of site selection. However, it is not meant as an alternative to multi-criteria decision-making, but as a necessary complement to understand the potential and limitations of safety-related decision criteria. The presented model identifies which types of errors are tolerable in the context of site selection and it explains why error tolerance is lowest for safety comparisons. The model points out that the frequently used assessment strategy of conservatism is not suitable for rejecting sites for reasons of insufficient or lower safety. It also shows that consensual requirements for the conditions under which long-term protection is achieved may be powerful tools for site selection.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2025.1436087</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2025.1436087</link>
        <title><![CDATA[EURAD state-of-the-art report: thermo-hydro-mechanical behaviour of clay buffers at high temperatures]]></title>
        <pubdate>2025-07-31T00:00:00Z</pubdate>
        <category>Review</category>
        <author>María Victoria Villar</author><author>Katerina Cernochova</author><author>Jaime Cuevas</author><author>Antonio Gens</author><author>Natalia Gimeno</author><author>Caroline Graham</author><author>Jon Harrington</author><author>Vlastislav Kašpar</author><author>Stephan Kaufhold</author><author>Olivier Leupin</author><author>David Mašín</author><author>Jan Najser</author><author>Markus Olin</author><author>Heini Reijonen</author><author>Šárka Šachlová</author><author>Sergey Sayenko</author><author>Daniel Svensson</author><author>Jiri Svoboda</author><author>Gianni Vettese</author><author>Janne Yliharju</author><author>Borys Zlobenko</author>
        <description><![CDATA[Most safety cases for radioactive waste disposal consider a temperature limit of 100°C for the clay buffers. Given that being able to tolerate higher temperatures would have significant advantages, the work package HITEC of the EURAD project aimed at determining the influence of temperature above 100°C on buffer properties, trying to establish if the safety functions are unacceptably impaired. A synthesis of the state of knowledge on the thermo-hydro-mechanical and chemical behaviours of different buffer materials at different temperatures is presented, along with the progress made in this area during HITEC. The changes in the properties of the preheated material and the hydromechanical properties of bentonite at high temperatures were assessed. To cover the first instance, bentonite was heated at 150°C in dry and wet conditions for different periods of time up to 2 years. The clay mineralogy was significantly preserved. The slight changes observed in the other properties were opposite depending on the heating conditions: in the case of evaporation, the cation exchange capacity, specific surface area, sorption coefficients, and sometimes swelling pressure decreased. These changes likely resulted from the strong drying induced by the elevated temperatures. Bentonite was also subjected to hydration under a thermal gradient in field and laboratory tests. No post-mortem structural modifications of the smectite were observed; however, dissolution and precipitation of species occurred, conditioned by the type of bentonite and hydration water. These processes were accompanied by the modification of the exchangeable cation complex. Determination of the hydromechanical properties of expansive clay at elevated temperatures is challenging owing to experimental and interpretation issues. In most cases, a reduced swelling pressure was obtained when the temperature increased, particularly at higher dry densities. These results may have been affected by the experimental protocols, use of bentonite or purified smectite, and exchangeable cations. Even at the highest temperatures, bentonite can fill voids and develop large swelling pressures at high densities. Thermo-hydro-mechanical models were developed or upgraded during the project to include thermal phenomena and dependencies and were applied to the simulation of new laboratory thermo-hydraulic tests in cells.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2025.1436490</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2025.1436490</link>
        <title><![CDATA[EURAD state-of-the-art report: thermo-hydro-mechanical behaviour at high temperature of host clay formations]]></title>
        <pubdate>2025-03-28T00:00:00Z</pubdate>
        <category>Review</category>
        <author>María Victoria Villar</author><author>Pierre Bésuelle</author><author>Frédéric Collin</author><author>Robert Cuss</author><author>Christophe de Lesquen</author><author>Arnaud Dizier</author><author>Ginger El Tabbal</author><author>Antonio Gens</author><author>Caroline Graham</author><author>Dragan Grgic</author><author>Jon Harrington</author><author>Christophe Imbert</author><author>Olivier Leupin</author><author>Séverine Levasseur</author><author>Asta Narkūnienė</author><author>Eric Simo</author><author>Alexandru-Bogdan Tatomir</author>
        <description><![CDATA[Most safety cases for radioactive waste disposal concepts consider a temperature limit of 90°C in the clay host rock. Being able to tolerate higher temperature would have significant advantages. For this reason, part of the EURAD-HITEC project aimed at determining the influence of temperature above 90°C on clay host rock properties, trying to establish the possible extent of elevated temperature damage in the near and far field of clay host rock formations and the consequences of any such damage. Three clay formations considered to host radioactive waste repositories in Europe were the focus of the studies: the Boom Clay, the Callovo-Oxfordian claystone and the Opalinus Clay. A summary of the background knowledge about the thermo-hydro-mechanical behaviour of these clay host rocks is first presented. Then, the experimental and modelling activities carried out in the framework of the EURAD-HITEC project concerning these materials have been synthesised. The laboratory tests analysed the impact of temperature on the short- and long-term behaviour of the clay host rock and the self-sealing processes. Hydro-mechanical couplings between peak pore water pressure, temperature, permeability and confining stress were identified. The results confirmed that the claystone keeps its good mechanical and retention properties even when heated up to 100°C. Provided that the clay content of the samples is high enough, self-sealing was an efficient mechanism whatever the experimental conditions, although temperature may have a delaying effect. Poro-elastic models were used to model generic cases of a high-level waste repository, and consistent results were obtained by the different codes and teams, which shows the robustness of the modelling approach used to design the repositories. Two heating tests, performed in the HADES (Belgium) and MHM (France) underground research laboratories, were selected as benchmarks for the modelling activities. The evolutions of temperature and pore pressure were well modelled in the far field with a poro-elastic approach, but more advanced models are needed to take into account the processes occurring around the tunnels (e.g., modification of hydraulic properties within the EDZ, creep). The modelling of laboratory experiments showed the importance of a good understanding of the tests setup and of the boundary conditions.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2024.1433247</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2024.1433247</link>
        <title><![CDATA[EURAD State-of-the-Art Report: ACED assessment of the chemical evolution at the disposal cell scale—part I—processes at interfaces and evolution at disposal cell scale]]></title>
        <pubdate>2025-01-20T00:00:00Z</pubdate>
        <category>Review</category>
        <author>Erika Neeft</author><author>Guido Deissmann</author><author>Diederik Jacques</author>
        <description><![CDATA[Within the framework of the European Joint Programme on Radioactive Waste Management, the work package ACED–Assessment of chemical evolution of intermediate level (ILW) and high level (HLW) waste at disposal cell scale–used combined experimental and modelling methods in a multi-scale approach with process integration to improve the long-term modelling and assessment of the chemical evolution at the disposal cell scale. Part I provides the relevance of the assessment of the chemical evolution for safety, performance, and optimization. It further describes the main characteristics of disposal cells for ILW and vitrified HLW waste in European disposal programmes. From that, a number of interfaces between different types of material are identified that are highly relevant for many national disposal programs: glass-steel, steel-concrete, steel-clay, steel-crystalline, concrete-clay, and concrete-crystalline. Based on literature review, the main processes and consequences occurring at these interfaces are described. The key element is the narrative of the evolution at the disposal cell scale based on process understanding. In part II, tools to obtain process understanding–experiments, analogues, modelling–are discussed in detail.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2024.1433257</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2024.1433257</link>
        <title><![CDATA[EURAD State-of-the-Art Report: Assessment of the chemical evolution at the disposal cell scale – part II – gaining insights into the geochemical evolution]]></title>
        <pubdate>2025-01-20T00:00:00Z</pubdate>
        <category>Review</category>
        <author>Guido Deissmann</author><author>Erika Neeft</author><author>Diederik Jacques</author>
        <description><![CDATA[Long time frames are to be considered in the safety and performance assessment of deep geological disposal of intermediate and high level radioactive waste. Geochemical conditions will change in the waste, conditioning matrix, waste package, engineered barriers and the host rock–all components present at the disposal cell scale. This aspect of geological disposal was the focus of the work package ACED (Assessment of chemical evolution of intermediate level (ILW) and high level (HLW) waste at disposal cell scale) in the EURAD project (the European Joint Programme on Radioactive Waste Management). The first part of this review provided a narrative of the geochemical evolution of the disposal cell. In this second part, an overview is given about methods and approaches that can be used to gain further insights into the processes driving the geochemical evolution, more in particular (i) laboratory and in-situ experiments, (ii) archaeological and natural analogues, and (iii) modelling tools. The review concludes with a short discussion on the consequences on material properties, waste forms and radionuclide mobility.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fnuen.2024.1416508</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fnuen.2024.1416508</link>
        <title><![CDATA[Opportunities for the further development of the Safety Case for deep geological repositories by transdisciplinary research – FEP catalogs and scenario development]]></title>
        <pubdate>2025-01-03T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Marcel Ebeling</author><author>Martina Heiermann</author><author>Klaus-Jürgen Röhlig</author>
        <description><![CDATA[In the TRANSENS research project (2019–2025), large-scale transdisciplinary research on nuclear waste management is being conducted for the first time in Germany. Transdisciplinary in this context means that non-specialists and practice actors are systematically involved in developing and addressing research questions. One out of four TRANSENS research topics is addressing optimization potential for the Safety Case (SC) for Deep Geological Repositories (DGR) for nuclear waste. Seven workshops on this topic were held with three working groups, which differed from one another in terms of their types of knowledge. The work focused on the area of FEP (features, events, and processes) and scenarios. It also shows how objections and optimization proposals for safety cases differ between the various transdisciplinary working groups. Accessibility of SC content was identified as a fundamental area for improvement. Summaries of the report that are appropriate for various target audiences were called for, as was the inclusion of experts from outside the established SC community. The use of digital presentations and communication options was examined in detail. Regarding FEP processing, matrix forms of representation were discussed which, in addition to representing general dependencies, can also depict the strength of these dependencies. There were also proposals for the use of a morphological box to achieve this goal and to be able to create scenarios from FEP. Suggestions were made as to when FEP should be excluded from catalogs, when scenarios can be discarded and how these processes could be documented. To find previously unknown FEP, ideas were put forward regarding a reward system through which the general public could contribute to the completeness of the FEP catalog. In all workshops, promising and valuable results (e.g., criticisms, ideas) were achieved through transdisciplinary research. In TRANSENS, it was proven that the participation of non-experts in research can lead to substantive and in-depth suggestions for improvement. This also means that meaningful contributions based on participatory research are possible in broad participatory processes such as the German site selection procedure. It remains to be seen to what extent the results obtained in TRANSENS will be considered in the preparation of the future German Safety Cases.]]></description>
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