Events, practices, and processes in managing nuclear power often have both an exceptional and a mundane side to them. As Hecht (2009, 2014) and many others have shown, nuclear technology has simultaneously profited from regulatory, political, and cultural processes that mark it as requiring exceptional treatment while also being characterized as everyday, safe, under control, and comparable to other technologies and materials. Examples include struggles around negative environmental and health effects of nuclear disasters and uranium mining (Kuchinskaya, 2014; Makhijani, 2000; Jacobs, 2022), social cleavage due to conflicts between the state and anti-nuclear activism (Chandra, 2021; Masco, 2006, 2021), or deep time requirements of nuclear waste storage and communication of knowledge about nuclear waste into the far future (Joyce, 2021; Ialenti, 2020; Keating and Storm, 2023).

This special issue's focus is on the mundane in nuclear energy cultures as a site of nuclear politics in its own right. Lewis Mumford noted already a century ago that planning, as an exercise of power, is mostly a boring activity. Richard White further expanded on this: Power does not have to be exercised behind the scenes. It can be open. The audience is asleep. The modern world is forged amidst our inattention (White, 1995:64). The same can be said of nuclear power and radioactive waste management: even though it is prone to the extraordinary or spectacular (like Chernobyl, Fukushima, or the anti-nuclear movement) and often shrouded in secrecy, most processes behind it are mundane and sometimes even boring. Furthermore, these processes take place openly. However, they require specialized technical and scientific knowledge and are subject to the long decision-making timeframes of legal regulation and political action. This may lead to societal negotiation processes being bogged down in an overwhelming number of documents, often difficult to access and understand.

Yet, incorporated in procedures of planning approvals (e.g. of final disposals), safety inspections (in running power plants or above-ground disposal sites), and radioactive dose measurements (around nuclear facilities and of waste from decommissioning), to name just a few, are classifications and standards that consolidate socio-political and socio-scientific narratives (Bowker and Star, 2000). Once set, these become norms not to be questioned and difficult to change. Norms, categories, and legal frameworks, however, are acts of silencing, whereby the exceptional of the nuclear becomes negotiated in mundane acts of power. A closer look at who is being silenced and how this affects the ability to scrutinize routine processes opens up questions of justice and eventually even leads to potential safety issues.

Trustworthy numerical simulations are irreplaceable for model-based safety analyses in nuclear waste management. From model conceptualization to model validation, various aspects of confidence building with respect to process models and performance assessment models have to be considered in this context. This is particularly true as soon as significant safety-oriented decisions are involved – and if public participation is at stake.

Therefore, the present issue of SaND explores the following question: "what do we need to trust in models?" The individual papers discuss, from a modeller's perspective, measures to strengthen the confidence in numerical models.

Confidence building in models is a complex issue which has to be examined from different perspectives. Only then can research and development needs be identified. The present "Trust in Models" issue focusses on the following aspects of confidence building:

• technical aspects, such as code verification, the consistency of input data, and other measures of quality measurement;
• safety analysis aspects, such as adequacy of models, handling of uncertainties, and the complexity of demonstration strategies;
• organizational aspects, such as maintenance of competence and the installation of a safety culture.

The individual contributions to this SaND special issue are the results of the workshop series "Trust in Models", which has been organized by BASE annually since 2022.

We invite you to contribute to this format either by commenting on the present manuscripts while public peer review is ongoing or by taking part in one of the "Trust in Models" workshops and/or this special issue of SaND by submitting your own manuscript.

Events, practices, and processes in managing nuclear power often have both an exceptional and a mundane side to them. As Hecht (2009, 2014) and many others have shown, nuclear technology has simultaneously profited from regulatory, political, and cultural processes that mark it as requiring exceptional treatment while also being characterized as everyday, safe, under control, and comparable to other technologies and materials. Examples include struggles around negative environmental and health effects of nuclear disasters and uranium mining (Kuchinskaya, 2014; Makhijani, 2000; Jacobs, 2022), social cleavage due to conflicts between the state and anti-nuclear activism (Chandra, 2021; Masco, 2006, 2021), or deep time requirements of nuclear waste storage and communication of knowledge about nuclear waste into the far future (Joyce, 2021; Ialenti, 2020; Keating and Storm, 2023).

This special issue's focus is on the mundane in nuclear energy cultures as a site of nuclear politics in its own right. Lewis Mumford noted already a century ago that planning, as an exercise of power, is mostly a boring activity. Richard White further expanded on this: Power does not have to be exercised behind the scenes. It can be open. The audience is asleep. The modern world is forged amidst our inattention (White, 1995:64). The same can be said of nuclear power and radioactive waste management: even though it is prone to the extraordinary or spectacular (like Chernobyl, Fukushima, or the anti-nuclear movement) and often shrouded in secrecy, most processes behind it are mundane and sometimes even boring. Furthermore, these processes take place openly. However, they require specialized technical and scientific knowledge and are subject to the long decision-making timeframes of legal regulation and political action. This may lead to societal negotiation processes being bogged down in an overwhelming number of documents, often difficult to access and understand.

Yet, incorporated in procedures of planning approvals (e.g. of final disposals), safety inspections (in running power plants or above-ground disposal sites), and radioactive dose measurements (around nuclear facilities and of waste from decommissioning), to name just a few, are classifications and standards that consolidate socio-political and socio-scientific narratives (Bowker and Star, 2000). Once set, these become norms not to be questioned and difficult to change. Norms, categories, and legal frameworks, however, are acts of silencing, whereby the exceptional of the nuclear becomes negotiated in mundane acts of power. A closer look at who is being silenced and how this affects the ability to scrutinize routine processes opens up questions of justice and eventually even leads to potential safety issues.

Trustworthy numerical simulations are irreplaceable for model-based safety analyses in nuclear waste management. From model conceptualization to model validation, various aspects of confidence building with respect to process models and performance assessment models have to be considered in this context. This is particularly true as soon as significant safety-oriented decisions are involved – and if public participation is at stake.

Therefore, the present issue of SaND explores the following question: "what do we need to trust in models?" The individual papers discuss, from a modeller's perspective, measures to strengthen the confidence in numerical models.

Confidence building in models is a complex issue which has to be examined from different perspectives. Only then can research and development needs be identified. The present "Trust in Models" issue focusses on the following aspects of confidence building:

• technical aspects, such as code verification, the consistency of input data, and other measures of quality measurement;
• safety analysis aspects, such as adequacy of models, handling of uncertainties, and the complexity of demonstration strategies;
• organizational aspects, such as maintenance of competence and the installation of a safety culture.

The individual contributions to this SaND special issue are the results of the workshop series "Trust in Models", which has been organized by BASE annually since 2022.

We invite you to contribute to this format either by commenting on the present manuscripts while public peer review is ongoing or by taking part in one of the "Trust in Models" workshops and/or this special issue of SaND by submitting your own manuscript.