All European countries have, to a greater or lesser extent, anchored stepwise procedures in laws and/or policies to ensure that decision-making advances and continues over time. In countries like Finland and Sweden, these procedures are mainly tied to licensing requirements. France and Germany, facing stronger opposition, have introduced new laws to anchor milestones and principles. Switzerland has adapted an existing spatial planning instrument to allow for flexibility and regional participation (Kuppler and Hocke 2019). Experiences in these countries suggest that getting commitment on stepwise procedures by embedding them in laws or policies helps to resolve political and public debates on the decision-making process, and can enhance stakeholder cooperation and acceptance (Ferraro and Martell 2015b; Kuppler and Hocke 2019).

However, a smooth search for a repository is by no means guaranteed, highlighting the need for procedures that are both flexible and actionable. In Spain and Italy, for example, shifting political and public support as well as mistrust in institutions, stalled site selection progress (Di Nucci and Prontera 2023; Espluga-Trenc and Prades 2023). Germany had to revise its 2031 site selection milestone as it was too ambitious, and the UK faced delays due to unsuitable geology (Di Nucci and Brunnengräber 2023; Thomas 2023). All these countries had to adjust their procedures accordingly. Similarly, the Netherlands is now updating its approach to decision-making because setting a milestone as far out as 2100 for site selection reduced the urgency to act now (Dekker et al. 2023).

Many countries adopt additional guiding principles for democratic and effective decision-making, either in laws, policy or by the waste operator. For instance, Germany emphasizes participation, science-based decisions, transparency, and learning (Di Nucci and Brunnengräber 2023), Spain voluntarism, transparency and openness (Espluga-Trenc and Prades 2023), and France and the Netherland highlight reversibility (Dekker et al. 2023; Lehtonen 2023). Belgium is in the process of setting its guiding principles, informed by a public debate (Koning Boudewijnstichting 2024). The importance of such as debate is highlighted by Lehtonen (2023), stating that the debate about the principle of reversibility contributed to the advancements made in France in decision-making, as it came up as a public requirement. Translating principles into concrete procedures and institutions, however, often remains a work in progress. For instance, the Netherlands lacks mechanisms to execute the reversibility principle (Dekker et al. 2023).

As part of adopting a stepwise procedure, all countries also define roles and responsibilities, including those of waste operators, regulators, parliaments, and decide on topics such as whether local communities receive veto rights. Who has the main responsibility for RWM varies per country. In Finland and Sweden, the nuclear industry takes the lead, while in Switzerland, both the industry and government share responsibility. In France, Germany, Spain, the UK, Italy, Belgium, and the Netherlands, public organizations independent of the waste producers are responsible. A clear division of roles and responsibilities, is considered important for increasing transparency and trust in decision-making (van Est and Arentsen 2023). In the Netherlands and Italy, for example, establishing independent regulators enhanced accountability and oversight (Dekker et al. 2023; Di Nucci and Prontera 2023).

All European countries integrate participatory procedures in their stepwise approaches and adjust them to the phase of decision-making. Once sites are selected, for example, countries direct their participatory procedures towards the regional and local level (Ferraro and Martell 2015b). The degree and type of participation depends on the national political culture. For example, Finland’s minimum approach worked well due to high trust in the nuclear industry and a voluntary site selection process (Vehmas et al. 2023). Countries like Germany, Switzerland, and the UK have restarted decision-making with a white map to break stalemates, ensuring key steps, like site selection approaches, are first publicly debated (Ferraro and Martell 2015a). Such participatory procedures often exceed minimum legal participatory requirements and take place before repository implementation. Experience shows that stepwise, participatory procedures can still be undermined by RWM politicization and its strategic use by political parties, as seen in Germany and Spain (Di Nucci and Brunnengräber 2023; Espluga-Trenc and Prades 2023).

The principles of participation and the protection of future generations are present in all European countries, in part as a result of EU regulation (Arentsen and van Est 2023). However, experiences show that organizing ‘good’ participation remains challenging, prompting scholars to suggest to include extra guiding principles, such as deliberative quality (Lehtonen 2010), experimental mindsets (Parotte 2020), intergenerational justice (Schwarz 2022) and phased decision-making, formal and informal participation, intergovernmental relations, local partnerships, resources as capacity building and compensation (Ferraro and Martell 2015a). However, these principles are not yet explicitly reflected in the European countries studied.

In most European countries, institutions for public participation have been developed, in addition to basic legal requirements like consultations on permits. Many countries assign responsibility for participation to specific actors, such as RWM organizations, federal bodies, or independent committees (Dekker et al. 2024). Temporary organizational set-ups, like dialogue boards, regional conferences, and local partnerships, are also common for key decision-making steps. Experiences in Germany show that (legally) required periodic reviews can be essential for participation. For example, one such evaluation led to the institutionalization of the Forum Endlagersuche to better sustain public engagement (Di Nucci and Brunnengräber 2023). A lack of trust in actors or institutions, or their independence, can hinder the effectiveness of participatory procedures, as seen in Italy and Spain (Di Nucci and Prontera 2023; Espluga-Trenc and Prades 2023).

In most European countries knowledge agendas are aligned with RWM-policies and the decision-making phase (NEA 2004; NRC 2003). In Sweden, France and Switzerland, for example, research agendas are updated every three and five years to support decision-making (Kuppler et al. 2023; Lehtonen 2023; Swahn 2023). Additionally, all countries have waste management organizations that, in their own way, develop so-called safety cases (IAEA 2012). This is a standard, iterative procedure that facilitates decision-making, research, and public participation by conducting safety assessments of repository concepts at each stage of repository development. In some countries, such as Germany, evaluating alternatives is a mandatory part of this procedure (IAEA 2012). In Belgium and the Netherlands, research programs have been criticized for lacking sufficient connection to decision-making. This raises concerns that research organizations, by focusing on a single option for decades, may take over decision-makers’ roles by determining the disposal method and even the host rock (Dekker et al. 2023; Schröder et al. 2015).

In some countries, such as Germany, evaluating alternatives is a mandatory part of this procedure.

Many countries also develop procedural and substantive principles for research and development. Procedural principles ensure that knowledge production adheres to a good scientific practice (IAEA 2012). Moreover, inter- and transdisciplinary knowledge is increasingly valued. France and Belgium integrate social sciences into RWM-organizations, and Germany coordinates a socio-technical agenda. The joint research program EURAD promotes similar efforts at the European level. Nevertheless, socio-technical research, such as related to site selection challenges, remains rather limited. Most safety cases also prioritize technology development over broader societal considerations. Substantive principles are often the result of political and societal discussions. For example, Switzerland, France, Germany, and the Netherlands require retrievability before repository closure, while the UK does not. They all use the same argumentation: to avoid burdening future generations.

In most EU countries, waste management organizations play a key role in aligning R&D with the stepwise, participatory approach (Dekker et al. 2024). Some countries also strengthen stakeholder knowledge through forums, long-term local partnerships, and advisory bodies, enabling them to ask questions, fund research, and share expertise (Ferraro and Martell 2015b). Sweden allowed NGOs to access research funds from the Nuclear Waste Fund (Swahn 2023). Switzerland distributes knowledge across national, regional, and local levels, involving science, civil society, and politics (Kuppler et al. 2023). These efforts help to distribute and diversify knowledge, which contributes to the trustworthiness of knowledge and empowerment of diverse actors in decision-making (van Est and Arentsen 2023).

Most countries established procedures for assuring adequate funding for long-term RWM (IAEA 2022). However, according to IAEA (2022), the main challenge is to ensure that these funds remain viable, secure and available. This is difficult due to uncertainties regarding social and political developments, the lack of experience with deep geological repositories and the long-time frames involved (EURAD 2021; IAEA 2022). Countries therefore require procedures to periodically review and assess funds and their management (IAEA 2022).

In general, the financial governance of RWM is guided by two principles: the polluter pays principle and intergenerational justice (EURAD 2021). The first ensures that waste producers are responsible for covering all disposal costs, which is also required by the European 2011/70/Euratom directive. Intergenerational justice requires that current and past generations do not leave financial burdens to future generations. This makes long-term RWM rather unique, since unlike most long-term issues, discounting has little impact on its financing; otherwise, disasters 100,000 years from now would have negligible present-day value (Hansson 2023).

Radioactive waste producers are thus responsible for the funding of RWM. It depends on the country, however, whether this only counts for costs involved directly in RWM, or whether this also counts for activities like decision-making and participation. In Belgium and the Netherlands, for instance, the question of who pays what is still being discussed as part of the initiation phase (Dekker et al. 2024; Koning Boudewijnstichting n.d.). Finances are managed differently between countries: they can be managed by a dedicated body, within an organization, or as part of the state budget, but they are often subject to government oversight (IAEA 2022). Some countries like Belgium and Finland set up specific funds, like for short- and long-term RWM and for RWM and research (Lehtonen 2023; Schröder et al. 2015).