Swiss Waste Management Research Articles

ENHANCEMENT OF VALIDATION STUDIES FOR REACTOR DOSIMETRY AND ACTIVATION PREDICTIONS WITH THE NUCLEAR DATA SAMPLING METHODOLOGY

The CASMO/SIMULATE/MCNP/FISPACT-II calculation route has been established at the Paul Scherrer Institute (PSI) for reactor dosimetry and activation studies. Furthermore, the in-house tool NUSS is in use at PSI for nuclear data (ND) related uncertainties quantifications with Monte Carlo neutron transport calculations. The use of randomly sampled ACE-formatted ND files not only allows propagation of the ND uncertainties, but also can serve for assessing the applicability of different types of experimental data for validation of calculation predictions of parameters of interest. In the present work an application of the PSI calculation scheme for analysis of activation reaction rates and the fast neutron fluence (FNF), throughout the Swiss pressurised water reactor (PWR) and simplified containment building models, is demonstrated. As particular examples of potentially available experimental data, two kinds of the neutron flux monitors are considered: a) the reactor pressure vessel scraping samples and detectors placed in the dosimetry channels, mounted at the core barrel and designed for validation of FNF calculations, and b) the ex-vessel dosimeters, specifically used by the Swiss waste management organisation (NAGRA) for validation of bio-shield activation predictions. The calculations were done with the ENDF/B-VII.1 library. The obtained results demonstrate importance of the ND uncertainties for the dosimetry evaluations. The assessment of the applicability of the selected experimental information for validation of the bio-shield irradiation calculations was done based on evaluation of the ND-related Pearson correlation coefficients.

What constitutes agency? Determinants of actors’ influence on formal institutions in Swiss waste management

Institutional change is crucial for the transitions of socio-technical systems. This study addresses why some actors have strong agency by uncovering the determinants of their influence on formal institutions. We focused on a recent and major policy process in Swiss waste management as the empirical case. We carried out content analysis of consultation documents, expert surveys, online questionnaire and social network analysis. The resulting data were then analysed with Qualitative Comparative Analysis (QCA) to determine the necessary and sufficient conditions associated with large influence. Results suggest that only several actors have a major influence on the policy output. Possessing material or non-material resources is found to be necessary yet not sufficient, as actors need to exhibit high activity and embeddedness in social networks or articulate a discourse rich in various concepts. By elucidating the configuration of endowments critical for actors’ influence on formal institutions, this study yields novel insights into the ingredients of strong agency. The analytical approach we present can be applied to various settings and thus can be pursued for a systematic analysis on the determinants of actors’ influence and how it varies with political or organizational context.

The anoxic corrosion behaviour of carbon steel in anoxic alkaline environments simulating a Swiss L/ILW repository environment

AbstractThe Swiss waste management programme foresees that low‐ and intermediate‐level radioactive waste will be disposed of in a deep geological repository constructed in Opalinus Clay. Gas generation is expected in the repository due to the decomposition of organic materials and the corrosion of metals, with carbon steel being the primary source. The corrosion behaviour of mild steel under anoxic conditions has been studied over the course of several years to better understand the long‐term hydrogen evolution profile under anticipated repository conditions. Steel, either bare or encased within mortar, was tested in water vapour or immersed in electrolytes representative of aged cement waters at 50°C. The corrosion rate was measured indirectly through the hydrogen analysis using a solid‐state probe. The hydrogen evolution behaviour of grout was also monitored to more accurately determine the hydrogen generating from the corrosion of the embedded steel. For steel in water vapour or in alkaline environments, embedded in cementitious material or immersed in simulated aged cement pore water, corrosion rates were invariably <1 nm/year after several years of analysis.

Dry storage modeling activities at PSI: implementation and testing of a creep model for dry storage

Abstract According to the Swiss waste management policy, spent nuclear fuel is planned to be disposed in a deep underground repository. Prior to final disposal, spent nuclear fuel is stored at reactor sites and in a centralized dry storage facility. Since the operation dates of the final repository are unknown, extended periods of interim storage have to be considered. A research program to investigate the fuel rod integrity during long-term dry storage has recently been launched at Paul Scherrer Institute. In the context of the project, fuel rod performance simulations will be carried out with the code Falcon. Until now, an extensive literature survey concerning current trends in dry storage modelling has been written and first developments of Falcon’s capabilities towards dry storage modeling have been made. In this work, Falcon has been modified by implementing a long-term cladding creep model. The original and upgraded versions of Falcon have been used to simulate a demonstration case consisting of the base irradiation, wet storage, drying and dry storage. Results obtained with both versions have shown an important difference in the cladding hoop creep which justifies implementation of the new creep model.

A heuristic for conceptualizing and uncovering the determinants of agency in socio-technical transitions

There has been a growing interest in transition studies on the role of agency in bringing about disruptive change. Previous studies have examined how actors perform institutional work to create legitimacy and transform institutions. In doing so, they have provided insights into specific practices and strategies that actors follow. This paper seeks to complement existing studies by elucidating the foundations of agency that transforms institutions through institutional work. Drawing on institutional sociology and organizational studies, resources, discourses and networks of actors are identified as key elements enabling institutional work practices. The agency of each actor is conceived of as dependent on the configurations it possesses with respect to these elements. A heuristic is presented that helps to determine the configurations associated with a strong agency in empirical settings and use Swiss waste management as an illustrative case example. The heuristic enables a systematic analysis of agency across different organizational fields.

Modular life cycle assessment of municipal solid waste management

Life cycle assessment (LCA) is commonly applied to examine the environmental performance of waste management systems. The system boundaries are, however, often limited to either one tonne of material or to specific waste treatments and are, therefore, lacking a systems perspective. Here, a framework is proposed to assess complete waste management systems based on actual waste flows, assessed with a detailed material flow analysis (MFA) in a modular MFA/LCA approach. The transformation of the MFA into a product-process-matrix facilitates a direct link between MFA and LCA, therefore allowing for the assessment of variations in flows. To allow for an up-to-date and geographically specific assessment, 190 LCA modules were set up based on primary industrial data and the ecoinvent database. The LCA modules show where there have been improvements in different recycling processes over the past years (e.g. for paper recycling) and highlight that, from an environmental perspective, closed-loop recycling is not always preferable to open-loop recycling. In a case study, the Swiss municipal solid waste management system, of which there is already a detailed MFA, was modeled using the new LCA modules and applying the modular MFA/LCA approach. Five different mass flow distribution scenarios for the Swiss municipal solid waste management system were assessed to show the environmental impact of political measures and to test the sensitivity of the results to key parameters. The results of the case study highlight the importance of the dominant fractions in the overall environmental impacts assessment; while the metal fraction has the highest impact on a per kilogram basis, paper, cardboard, glass and mixed municipal solid waste were found to dominate the environmental impacts of the Swiss waste management system due to their mass. The scenarios also highlight the importance of the energy efficiency of municipal solid waste incineration plants and the credits from material substitution as key variables. In countries with advanced waste management systems such as Switzerland, there is limited improvement potential with further increases in recycling rates. In these cases, the focus of political measures should be laid on (i) the utilization of secondary materials in applications where they replace high-impact primary production, and (ii) an increased recovery of energy in waste-to-energy plants.

Discourse coalitions in Swiss waste management: gridlock or winds of change?

As a complex socio-technical system, waste management is crucially important for the sustainable management of material and energy flows. Transition to better performing waste management systems requires not only determining what needs to be changed but also finding out how this change can be realized. Without understanding the political context, insights from decision support tools such as life cycle assessment (LCA) are likely to be lost in translation to decision and policy making. This study strives to provide a first insight into the political context and address the opportunities and barriers pertinent to initiating a change in Swiss waste management. For this purpose, the discourses around a major policy process are analysed to uncover the policy beliefs and preferences of actors. Discourse coalitions are delineated by referring to the Advocacy Coalition Framework (Sabatier, 1998) and using the Discourse Network Analysis (Leifeld and Haunss, 2012) method. The results display an incoherent regime (Fuenfschilling and Truffer, 2014) with divergent belief clusters on core issues in waste management. Yet, some actors holding different beliefs appear to have overlapping interests on secondary issues such as the treatment of biogenic waste or plastics. Although the current political context hinders a system-wide disruptive change, transitions can be initiated at local or regional scale by utilizing the shared interest across different discourse coalitions.

Do We Have the Right Performance Indicators for the Circular Economy?: Insight into the Swiss Waste Management System

SummaryA material flow analysis of the 2012 Swiss waste management system is presented, highlighting the material content available from waste. Half of municipal solid waste (MSW) is materially recycled and the other half thermally treated with energy recovery. A key component of an industrial ecosystem is increasing the resource efficiency through circulating materials. Recycling rates (RRs), an indicator for the circulating behavior of materials, are often used as measure for the degree of circularity of an economy. This study provides an in‐depth analysis of the recycling of paper, cardboard, aluminum, tinplate, glass, and polyethylene terephthalate (PET) from MSW in Switzerland by splitting the RRs into closed‐ and open‐loop collection rate (CR) and RRs. Whereas CR refers to collected material that enters the recycling process, RRs measure the available secondary resources produced from recycling processes. For PET, the closed‐loop CR of 45% and the open‐loop CR of 40% compare to an RR of 31% and 37%, respectively (including exports and recycling of polyethylene and metals from collection). Official collection rates for paper and cardboard are very high (97%), whereas CR of 74% and 89% and RR of 59% and 81% for paper and cardboard, respectively, were found in the present study (including export). For a majority of the separately collected materials investigated, the rates that are determined are substantially lower than those that are officially communicated. Furthermore, given that official rates often do not provide information on the availability of secondary materials, the improvement potential for increased resource recovery is hidden.

The Swiss waste management program

In Switzerland, legislation and regulatory guidance are in place to ensure the implementation of deep geological repositories for all types of radioactive waste. A site selection process based on safety criteria, defined in the “Sectoral plan for deep geological repositories”, will be followed by a step-by-step licensing process under the responsibility of the Federal Government. Stage 1 of the Sectoral Plan has been successfully completed and geological siting regions identified. Stage 2, currently underway, has included the participation of a wide range of stakeholder to identify sites for the surface facilities. It will lead to the narrowing down of the number of geological siting regions by means of a safety-based comparison. Key factors for successful site selection include: (i) A clearly defined stepwise approach with the criteria defined before starting site selection with first priority given to safety; (ii) a process in which all stakeholders are prepared to commit themselves and work together, and are ready to accept the basic rules defined beforehand; (iii) for this purpose, it is important to have a strong process owner who keeps the process on track.

Problem structuring for transitions: The case of Swiss waste management

Transdisciplinarity is considered an appropriate approach in supporting transitions of complex socio-technical systems as such transitions demand highly contextualized real world knowledge and valuations. This holds especially true for the problem identification and structuring (initial) phase of a transition project, which aims at supporting goal formation based on a sound understanding and representation of the system's current state and its dynamics. Throughout this phase, it is important that all relevant perspectives in terms of expertise and interests are considered and adequately fed into a process of knowledge integration. This paper presents in its first part the structuring for complex transitions (SCT) procedure aiming at this requirement. The procedure has been specifically designed for problem structuring in socio-technical systems in the initial phase of a transition project. The results of the procedure provide sound inputs for the next project phases and the transition methods applied therein, but can themselves already be used as fruitful orientations in strategy development. The second part of the paper briefly outlines the application of the SCT procedure to Swiss waste management. This application involved 48 participants who reached consensus on relevant impact factors and developed a shared vision for managing a complex transition process in the area of waste management. The approach is marked by high feasibility and socially robust results.

Preliminary Safety Studies for Conventional Spent Fuel, MOX, and Vitrified High-Level Waste

This paper discusses the results of post-closure safety studies for two different waste streams that, according to current Swiss waste-management concepts, may be co-disposed in a single deep geological repository. The waste streams are:• directly disposed spent UO2 and mixed-oxide (MOX) fuel• vitrified high-level waste from the reprocessing of spent fuelThe inventories are based on a consideration of the anticipated arisings from nuclear power generation in Switzerland. A part (at least) of these arisings will be reprocessed, with the resultant vitrified high-level waste and long-lived intermediate-level waste returned to Switzerland. The Swiss electricity utilities have placed contracts with BNFL (UK) and COGEMA (France) for the reprocessing of about one third of the total arisings of spent fuel from nuclear power generation, assuming an electricity production scenario of 120 GWa(e). The decision as to whether to reprocess the remainder is currently left open, implying that up to two thirds of the arisings could be in the form of unreprocessed spent fuel for direct disposal. For the purposes of the present study, however, it is assumed that the arisings from the full 120 GWa scenario will be either directly disposed or reprocessed.

Battery-recycling as a part of the Swiss waste management concept

The efforts presently taken by the Federal Office of Environment, Forests and Landscape of Switzerland to control and reduce the environmental risk associated with battery waste, are described and evaluated in terms of efficiency and cost.

Nuclear waste management in Switzerland / Nukleare Entsorgung in der Schweiz

The Swiss waste management concept foresees geological disposal for all categories of radioactive waste. Two repositories are planned, one for short-lived low- and intermediate-level wastes (L/ILW), and one for high-level waste and long-lived intermediate-level waste (HLW/TRU) or spent fuel elements. The Wellenberg in Central Switzerland was proposed as the site for the L/ILW repository. There are three priorities for the current decade: providing centralised interim storage facilities, commencing construction of a L/ILW repository, and identifying a site for a HLW/TRU repository