Splitting the Atom, Dividing the Union? Analysing Nuclear Energy’s role in EU Energy and Climate Policy-making

By Rutger Lievens

Promoted by Prof. Dr. Thijs Van de Graaf

[September 2025]

This paper explains why and how nuclear energy has been included in EU energy and climate decision-making. By drawing on the multiple streams framework, theories of European integration and EU decision-making, a comparative case study of three relevant policy processes is performed using process tracing, supported by media articles and semi-structured interviews. Findings suggest that policy entrepreneurship from France was necessary, but not sufficient to gain recognition for nuclear energy. Coalitions with other member states and their own preferred energy sources were needed. This diversity in preferences can be overcome by the Commission through strategic flexibility and package deals, at the risk of increased contestation and lower policy effectiveness.

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Introduction

In recent years, the European Green Deal (the EU’s decarbonisation strategy) has come under pressure. The Russian invasion of Ukraine and the resulting energy crisis have put energy security and affordability in the spotlight again over sustainability. At the same time, nuclear energy has again gained interest, because of its low carbon emissions during power production. In addition, it is seen as a reliable energy source that increases energy security.

Nuclear energy has long been a contested issue in the EU. The Euratom Treaty (1957) was one of its founding treaties and was created to develop nuclear technology for civilian use. Over time, nuclear energy has had its ups and downs in terms of popularity; in the 1970s it was seen as a way of increasing energy security after the oil crisis. However, several nuclear accidents caused some member states (MS) to outlaw any development of the technology (like Austria and Ireland), and some others to turn their back on nuclear by enacting phase-out policies (like Sweden and Germany). Today, the issue is still highly polarized in and between MS. This cleavage is reinforced by the fact that the two biggest MS – France and Germany – find themselves on opposite sides on this issue. In the last few years, nuclear energy has been the focal point of negotiations in several key energy and climate policy (ECP) files.

This paper focuses on three notable instances where nuclear energy played a central role in the decision-making process of key EU energy and climate legislation: the inclusion of nuclear energy in the EU Taxonomy for Sustainable activities (EUST), the recognition of nuclear-derived hydrogen in the most recent revision of the Renewable Energy Directive (REDIII) and the strategic label for nuclear technology in the Net-Zero Industry Act (NZIA). The paper intends to answer the question of how this inclusion of nuclear energy can be explained. Each case is studied through process tracing to uncover the causal links that lead to the observed outcome.

Nuclear energy in the EU has mostly been studied in MS context, for example regarding phase-out policies, or in the context of nuclear safety at EU level. The role of nuclear energy in EU ECP and specifically decarbonisation policies has only recently gained some attention (Elsner, 2024; Buzogány, et al., 2023). However, its increasing importance in decision-making has not yet been studied through the lens of public policy theory. To address this gap, the Multiple Streams Framework (MSF) is used as an analytical-heuristic framework to explain change during decision-making and to structure the case studies.

In addition, theories of European integration capture the trends on a longer time scale among and between EU institutions and MS. This includes liberal intergovernmentalism (LI), supranationalism, politicisation, Europeanisation and contestation. Finally, concepts of EU decision-making theory are needed to capture negotiation or bargaining dynamics. This includes new institutionalist approaches that describe how institutions shape decisions. 

Explaining change in EU ECP

The Multiple Streams Framework (MSF)

The Multiple Streams Framework (MSF) posits that policy change occurs when three independent streams in the political system (problems, policies and politics) are successfully coupled by entrepreneurial actors during a window of opportunity (Kingdon, 1984). This means that sometimes policy solutions can be legitimized by linking it to a certain problem from the problem stream (Zahariadis, 2008). This contrasts with the rational image of the policy cycle, which starts with a certain problem that gets attention, gets added to the political agenda, for which then a policy solution is formulated and implemented. In this context, proponents of nuclear energy have argued that it is a low-carbon energy source (thus useful for climate mitigation), can provide baseload power output (to account for variability of renewable power sources) and is beneficial for energy security (less susceptible to supply disruptions like gas).

The MSF emphasizes ambiguity, which makes it suitable to the complexity of EU policy-making (Ackrill et al., 2013). Ambiguity is manifested through the absence of clear policy goals, time constraints, and the fluidity of actor participation (Copeland & James, 2014). Compared to rational institutional approaches, MSF does not see problems as objective facts, but rather as social constructs. Consequently, for conditions to be considered problematic by policymakers, they need to be framed as such. The framing of a problem is thus crucial, also because it determines which solutions can be coupled to it. This constructive element allows for agency to become relevant. Policy entrepreneurs can thus use the problem stream by framing a condition as a problem that can be coupled with their policy proposal. Proponents of nuclear energy can exploit the ambiguity within the proposed policies by framing nuclear energy as being “sustainable”, “low-carbon”, or “strategic”.

The MSF was originally developed by Kingdon for the agenda-setting stage of the policy process at the federal level of the United States (Kingdon, 1984). For the research in this paper, the MSF will be applied to the decision-making stage in the EU policy process. This study builds on the modifications that (1) allow to distinguish between agenda and decision coupling, following (Herweg et al., 2015) and (2) is adapted to study the EU policy process, based on (Herweg, 2017).

EU integration and decision-making

Liberal intergovernmentalism (LI) emphasizes the role of MS as core actors in EU ECP who defend their (economic) interests by bargaining and coalition-building and posits that MS with higher bargaining power (especially the large MS) can shape negotiation outcomes more in line with their preferences (Moravscik & Schimmelfennig, 2019). Supranational approaches emphasize the policy entrepreneurship of the Commission (Maltby, 2013). However, more and more Europeanization of renewable energy policy led to contestation of EU authority over energy policy, since the Treaty of Lisbon did give the EU some competences in energy policy, but safeguarded MS’ right to determine their own energy mix (Solorio & Jörgens, 2020).

Rational-choice institutionalism (RCI) applies LI to the decision-making process. It still sees MS as the primary actors but does take formal institutional rules into account. Historical institutionalism (HI) acknowledges that MS are key to understanding European integration, but also holds that EU institutions must be adequately considered in explaining decision-making processes over time (Pierson, 1996). It expects that policy outcomes can be understood as a path-dependent outcome of existing rules, norms, values and ideas.

The three streams

The problem stream plays a minor role during decision-making, since the policy proposal is discussed regardless of developments in the problem stream. However, a supportive problem stream reinforces the necessity to deal with an issue, while an adverse problem stream dampens it (Herweg, 2017). Also, due to the length of EU policy processes, developments in the problem stream can open new windows of opportunity (Herweg & Zohlnhöfer, 2022). From a HI perspective, the Russian invasion of Ukraine and the resulting energy crisis might constitute a critical juncture for EU ECP. This would result in radical policy change in which decision makers decide to recognize nuclear energy towards the EU’s decarbonisation goals. Problem framing is a crucial coupling strategy for policy entrepreneurs (Knaggård, 2015). Proponents of nuclear energy need to frame the problem that nuclear energy is intended to address in such a way that nuclear energy can be linked as a solution to it. For example, by stressing it as a low-carbon power source, a cheap form of energy or crucial to ensure energy security.

The policy stream remains important during decision-making in so far as political entrepreneurs combine policies in a way which makes it possible to win a necessary majority (Herweg, 2017). But as decision windows in the EU policy process can remain open for quite a long time, it is possible that the policy stream develops, and new ideas arise (Herweg & Zohlnhöfer, 2022). From HI, it is expected that support for nuclear energy is constrained due to the centrality of renewable energy promotion in ECP. Additionally, the Fukushima nuclear accident led to an increase in phase-out policies (Wittneben, 2012). For nuclear energy to be considered viable to be included in the policy, the framing of nuclear needs to correspond to the proposed policy. For example, nuclear must be considered sustainable to be included in the EUST.

Next to that, the political stream is of prime importance during decision-making, because this stream contains the actors whose support is required to adopt a policy (Herweg, 2017). Since the main form of interaction in the political stream is bargaining and coalition building, it is expected that negotiation outcomes will reflect a compromise between the largest MS, France and Germany (in line with LI and RCI). Since both have opposing views on support for nuclear energy, any inclusion of nuclear energy in the adopted policies will be accompanied by concessions to Germany. LI also emphasizes that national energy industries will influence the negotiating position of their national governments (Ydersbond, 2018). Formal institutional rules will affect the strategies used by MS while their preferences stay the same. When QMV is applicable, pro-nuclear MS are expected to be more prepared to agree to compromises. However, since the Council often strives for consensus even if the formal rules do not require unanimity, this leaves room for MS (especially large ones) to extract further concessions.

Research design and methodology

To answer the research question, this study made use of a comparative case study of three EU policy processes to identify the causal mechanisms leading to the inclusion of nuclear energy. The cases were chosen (and limited to three) based on several criteria: (1) nuclear energy was an explicitly contested point during negotiations, (2) the adopted policies differ in some way from the initial proposal in terms of how nuclear energy is included, (3) the policy adoption process is fully concluded (that is, the political agreement reached after trilogue negotiations has been approved by the Council and the Parliament). The outcome for nuclear energy of the decision-making stage is the dependent variable in the analysis, which is structured according to the theoretical framework.

A process tracing method is used to analyse the sequence of events in the policy process (from policy proposal to adoption) for each case. The goal is to identify the causal chain of events leading to the specific policy outcome for nuclear energy. The general approach for each case study consists of several steps. First, the timeline of the decision-making process is reconstructed. As a starting point, the initial policy proposal by the Commission is taken, whereas the adoption of the agreed upon final text marks the end point. Second, the gaps in between are filled in by identifying key moments, the precise change they bring about and the actions of relevant actors. Third, the key factors that contributed to the final agreement are interpreted using the concepts from the theoretical framework.

The process tracing analysis was performed using multiple qualitative data sources. Initially, the policy process timelines were reconstructed using official EU documents and press releases, academic literature and articles from relevant EU media outlets such as (but not limited to) Euractiv, Politico and the Financial Times. Then, in a next phase of the research, seven semi-structured interviews were conducted with policy experts and actors either directly involved in or knowledgeable of the studies policy processes to complement the desk research. For each interview, questions were tailored to the interview subject’s role and experience with the selected cases. The list of questions was designed in such a way that answers can be linked to the key theoretical concepts from the framework, including identifying policy entrepreneurs and their impact, coupling strategies, and so on.

Case selection

Case 1: EUST

The EUST is the central part of the EU sustainable finance framework and a key tool of the Green Deal. Its core idea is to have a clear, science-based dictionary for investors that clearly states what economic activities can be considered sustainable, with the goal of scaling up sustainable investment and preventing greenwashing (European Commission, n.d.-c). The biggest challenge for decision-makers is to define what economic activities can be considered as sustainable. The main approach to this question is to define Technical Screening Criteria (TSC), which determine under which conditions a certain economic activity or technology is in line with the environmental objectives.

Case 2: REDIII

The original RED was adopted in 2009 to deliver a minimum 20% share of renewable energy sources in EU final energy consumption by 2020. The RED was substantially revised in 2018 to deliver the EU objective of a minimum 32% share of RES in final energy consumption by 2030. The ’fit for 55’ package, part of the EGD, included a significant revision of the RED. The Commission proposal for REDIII would increase the binding EU minimum share of RES in final energy consumption to 40% by 2030 (European Parliament, n.d.). The core debate around nuclear energy in this file is the fact that EU ECP only promotes RES by setting binding targets, instead of recognizing all low-carbon energy sources (which could be done by granting rebates to MS according to the carbon intensity of their electricity mix).

Case 3: NZIA

The NZIA is part of the Green Deal Industrial Plan, focusing on improving the competitiveness of EU net-zero industry, in a context of increased competition with the US and China. The NZIA aims to scale up the manufacturing capacity of net-zero technologies,. It does so by identifying goals for net-zero industrial capacity and providing a regulatory framework to allow faster permitting (European Commission, n.d.-d). The war in Ukraine and the ensuing energy crisis constituted a focusing event; Commissioner Breton said at the presentation of the Commission proposal: “Our dependency on Russian gas has taught us several lessons. Let’s not replace that dependency with a reliance on others to produce solar panels and other technologies we rely on.” (European Commission, n.d.-e)

Empirical research

EU Sustainable Taxonomy

Pro-nuclear advocates were successful in overturning an initial compromise between Council and Parliament that would practically exclude nuclear energy from the EUST into an adopted EUST that included nuclear energy as a transitional activity. There are several reasons explaining this outcome. First, pro-nuclear MS successfully formed a blocking minority in the Council in December 2019, forcing the presidency to renegotiate with the Parliament, postponing the decision on inclusion of nuclear energy. This success of the pro-nuclear MS coalition instigated closer cooperation under the informal Nuclear Alliance group (Interview 3).

Second, the publication of the JRC report in April 2021 reversed the policy stream to support nuclear energy’s inclusion. This was possible because of the complexity of evaluating nuclear energy against the sustainability criteria of the EUST and the JRC’s information advantage because of its expertise in nuclear safety and technology. In line with the MSF, this illustrates how policy entrepreneurs can exploit an imbalance in information in a case of high issue complexity and unclear technology (Saurugger, 2013). Additionally, the origins of the Commission’s scientific research body can be traced back to the Euratom Treaty. Whether this path dependency gave nuclear energy a crucial edge in the JRC conclusions was not evaluated in detail, although its importance in the eventual decision has been downplayed (Interview 1, 4).

Third, the lively scientific debate on what constitutes “green” or “sustainable” became dominated by political and interest groups that hijacked the discussion, which shifted to the question “what is needed to do the green transition” or even “what is feasible” (Interview 4). Importantly, a coordinated lobbying campaign by the nuclear and gas industry representatives with EU officials took place (Schreiber, 2020).

Fourth, the use of a Delegated Act (DA) gave the Commission a bigger role in decision-making than in the ordinary legislative procedure, allowing it to gain more control over the policy process and steering it in a decisive direction. The DA was published in the very last minutes of December 2021, indicating that the Commission anticipated backlash. The Commission ensured that an objection by the Council would be highly unlikely, by setting up the DA as a package deal between MS that wanted nuclear energy included (mainly France) on the one hand and natural gas (mainly Germany) on the other (Interview 1, 4, 5). The group of MS that were against the inclusion of both nuclear energy and natural gas consisted of only four, while a qualified majority was needed to object to the DA. Additionally, Germany could not take a firm position against the planned DA, because the issue of gas divided both its active government and ongoing coalition talks after parliamentary elections. This lack of unity provided France with an opportunity to lobby the Commission more in their favour (Interview 1, 7).

Fifth, a majority of the Parliament did not object to the inclusion of nuclear energy and natural gas in July 2022. The package deal again had its effect here, with the S&D group being split along national lines on natural gas inclusion. It must be stressed that this vote was necessary to include nuclear energy in the EUST and that this was largely outside of the control of both the Commission and pro-nuclear or pro-gas MS. Nevertheless, Commission President Von der Leyen warned that there would be no other DA if this one failed. This institutional manipulation is recognized as an entrepreneurial strategy in the MSF (Zohlnhöfer et al., 2016), (Herweg, 2017).

This letter was argued to be the decisive moment at which previously undecided MEPs took the decision not to veto the DA (Interview 5), although there is no real consensus on this (Interview 1, 4). However, it can be noted that the Finance Commissioner attempted to frame the inclusion of both energy sources as supporting Ukraine, by reading the letter from the Ukrainian energy minister to the EP the day before the vote.

Renewable Energy Directive

Nuclear-derived hydrogen has been recognized in the final adopted REDIII. MS can reduce the renewable hydrogen sub-target for industry by 20%, but under conditions that are impossible to meet, except for France and Sweden. There is also a preamble included with a Commission declaration where the EU executive said it would ”on a case-by-case basis ... not take into account these existing plants” for meeting certain 2030 green hydrogen targets, if these plants are already making efforts to move away from fossil-based hydrogen. These nods to France are generally interpreted as symbolic wins (Interview 2, 7).

Thus pro-nuclear advocates were unable to establish major policy change within the core EU Green Deal strategy; the RED is still centred around the promotion of renewable energy, rather than taking all low-carbon energy sources (like nuclear) into account. This despite efforts from the French government to establish a more coordinated pro-nuclear coalition of MS, spearheaded by the policy entrepreneurship from Energy Minister Pannier-Runacher. She was the leading protagonist in the pro-nuclear camp (Interview 1, 2, 3, 6), known as a tough negotiator (Interview 1, 2, 7) and persistent in being present “everywhere where there was something to do with nuclear” (Interview 6).

Several factors explain this outcome. First, there was a lack of coherence in the Nuclear Alliance in terms of interests in this file. While France and the Nordic countries are generally in favour of both nuclear and renewable energy, the Central and Eastern European MS are more sceptical of renewable energy targets, and climate action more generally (Interviews 2, 6, 7). Other studies have shown the importance of coherence in the interpretation of problems and possible solutions by a coalition of policy entrepreneurs to bring about radical policy change (Saurugger & Terpan, 2016).

Second, the Commission exercised its agenda-setting power (supported by the Parliament) by coupling an increased renewables target in the RED to the problem of import dependence on Russian fossil fuels. As a result, it successfully connected the sustainability agenda to the energy security frame that became dominant after the Russian invasion of Ukraine.

Third, being the MS with most interest in counting nuclear energy towards renewable energy targets, France was constrained in influencing the Council’s position on the Commission proposal, because it held the Council presidency during the first half of 2022 (Interview 6). French representatives changed to a more vocal stance to push their own nuclear interests, but by then it had become quite hard to turn negotiations in their favour.

Net-Zero Industry Act

Pro-nuclear advocates managed to recognize all nuclear energy technology (including existing nuclear power plants) as strategic, as opposed to the Commission proposal, which only included emerging technologies (like SMRs and next generation reactors). However, most links to financial support were kept out of the agreement.

Again, several factors can explain this outcome for nuclear energy. First, contrary to the other two cases, the Commission proposal already recognized some nuclear technology as strategic, which gave pro-nuclear policy entrepreneurs in the Parliament and the Council a foot in the door during negotiations. This nod can be attributed to the assertiveness in the College by Commissioners from pro-nuclear MS; French Commissioner Breton was supported by Central and Eastern European Commissioners. They faced opposition from other powerful members, notably Danish Commissioner Vestager. The inclusion of emerging nuclear technology in the Commission proposal should be understood as a compromise pushed by President Von der Leyen (Interview 3).

Second, the Parliament position was surprisingly accommodating to the pro-nuclear group. It reflected a package deal, mainly between pro-nuclear MS and MEPs on the one hand, MS and MEPs favourable towards sustainable fuels on the other. The list of strategic technologies was thus expanded, including all types of nuclear energy, in addition to e-fuels and biogas. The latter two ensured that the rapporteur’s report also received support from the full Renew and Socialist groups, leaving only Green MEPs in opposition because of nuclear’s inclusion. Additionally, the position removed the distinction between ”strategic” and ”net-zero” technologies. The Council position reflected the expansion of the strategic list but maintained the distinction.

Third, the original Commission proposal also included easier access to financing for the strategic net-zero technologies, including EU funds. This provision was scrapped during negotiations, which was the main priority of anti-nuclear MS (Interview 7). In the end, all MS were essentially left free to choose which technologies they wanted to consider strategic. Similarly to the case of the EUST, it is widely recognized that this agreement weakened the effectiveness of the NZIA, because the range of technologies covered by the strategic label was too long.

Discussion: cross-case comparison

Similarities

All three cases can essentially be boiled down to the same discussion; the pro-nuclear camp wants nuclear energy to be recognized on the same footing as renewable energy in EU ECP to be eligible for more financing opportunities (either private investment, EU funds or state aid), while the anti-nuclear camp wants to prevent financial resources being diverted away from renewable technologies and EU budget going into the development or maintenance of nuclear power generation. The EUST is an informational instrument meant to guide private investment, the REDIII gives a political signal to investors and the NZIA was originally meant to be tied to EU funding (which was strongly limited after trilogues).

According to the MSF, pro-nuclear advocates need to frame the problem they face (financial resources for nuclear power) in a way that justifies EU action. The framing most used by pro-nuclear advocates (mainly MS), is the low-carbon nature of nuclear as a power source, referring to the EUs decarbonisation goals. However, the case studies have shown that the framing is adjusted to developments in the problem stream. For example, pro-nuclear MS framed nuclear energy as a cheap energy source at the very beginning of the energy crisis in late 2021. President Macron and Commissioner Breton pushed the energy security frame by arguing that nuclear energy is needed for energy independence around the same time.

MS coalitions played an important role in all three cases. In the EUST, the initial compromise between Council and Parliament was blocked by the same group of MS that would form the core of the Nuclear Alliance, which was established some years later during the negotiations on the REDIII and the NZIA. However, despite this closer cooperation than during the EUST file, the Nuclear Alliance was less successful in extracting concessions for nuclear energy in the REDIII. This can be explained due to the different interests of France and the Central and Eastern European MS regarding the RED. In contrast, blocking the TR compromise in the EUST case left the door open for both nuclear energy (priority for France) and natural gas (priority for CEE members of the Nuclear Alliance). The clear reflection of MS interests supports the LI expectation of decision-making.

Another common trend that can be observed is that the nature of policy change is more incremental rather than radical, because pro-nuclear advocates have had to concede to considerable constraints. From an MSF perspective, the policy change studied is typically enacted by policy entrepreneurs that want to get their own proposal onto the governmental agenda. This research focused on how nuclear energy was included in already existing policy proposals tabled by Green Deal policy entrepreneurs. This put pro-nuclear entrepreneurs already on the backfoot. From a HI perspective, radical policy change can be enacted in critical junctures. Even though the Russian invasion of Ukraine is a good candidate for such a critical juncture, the response from the Commission was mainly to double down on the existing Green Deal strategy by promoting a higher renewables target under the REDIII. This also illustrates path dependency in EU ECP: Since renewable energy promotion has been placed central to EU ECP, putting nuclear energy on an equal footing would defeat the purpose of the directive. For the EUST, there arguably was an effect on the vote in the EP, although more research is needed to make a more accurate assessment.

The observed incremental policy change also confirms literature findings, which state that contestation of EU authority can be managed by strategically offering flexibility to advance increased ambition (Herranz-Surrallés et al., 2020;Solorio & Jörgens, 2020). It should be noted that incremental change can lead to more radical policy change later on, which is described in the MSF literature as “salami tactics” (Zahariadis, 2008). This means that policy entrepreneurs can agree to concessions that lead to small policy change only, if that makes larger-scale change possible later on. For example, the Commission proposal for the new multiannual budget includes financing of new nuclear energy capacities through the Competitiveness Fund, since the Fund refers to the technologies included in the NZIA (European Commission, n.d.-b).

Differences

From an MSF perspective, the element of ambiguity is crucial for political entrepreneurs to be able to influence the agenda (and make changes to proposals). This ambiguity could be exploited more in the EUST and the NZIA cases than in the REDIII. The ambiguous nature of the sustainability aspect of nuclear energy allowed the Commission to justify involving the JRC to formulate an answer to the issue. The conclusions of the JRC report allowed the Commission to justify the inclusion of nuclear energy on a scientific basis, which made it easier to dismiss objections to the inclusion from certain MS and MEPs and prevent a public consultation round for the DA (as was standard practice for earlier DAs). The NZIA was in that sense comparable to the EUST; the ambiguous nature of what can be considered “strategic” again allowed for proponents of nuclear energy to frame the technology as strategic, in the context of high concerns of energy dependence on Russia in the wake of Russia’s invasion of Ukraine.

In contrast, the REDIII did not contain that element of ambiguity that could be exploited. First, there is little ambiguity on what the RED is about; targets for increasing renewable energy deployment. Although France stressed the importance of all low-carbon energy sources to fight climate change over only one type of low-carbon source (renewables), the RED proved to be the wrong policy file to use this framing strategy.

An important difference is the formal institutional rules by which nuclear energy was included. While the REDIII and NZIA cases followed the OLP, the decision in the EUST case was made through a DA. This gave the Commission an opportunity to exercise more agency in decision-making than it can during the OLP. From an MSF perspective, the Commission still acted as an agenda-setter, gathering input from the policy stream (expert groups on sustainable finance and the JRC). But in addition, it could now play the role of political entrepreneur, actively looking for a majority for its policy proposal (the DA). By using the package deal strategy, the Commission ensured there was not enough support to object to the DA in the Council. One could argue that the DA reflects the preferences of the big MS France and Germany, with nuclear being a nod to the former and gas to the latter. However, the constraints imposed against the requests of both MS indicate a certain agency of the Commission. This case thus illustrates how DAs can empower the Commission. At the same time, it causes significant contestation of its authority, illustrated by a legal challenge filed by Austria and Luxemburg against the DA at the ECJ.

Nuclear was not included in the Commission’s proposals for the EUST or the REDIII, but it was partially included in the NZIA proposal. This can be explained by the fact that French Commissioner Breton was more closely involved in the drafting of the NZIA proposal, as Commissioner for the Internal Market, while his DGs weren’t involved in the drafting of the EUST proposal (was not Commissioner at the time) and the REDIII. The NZIA involved more institutional ambiguity (Ackrill & Kay, 2011) than the other cases, illustrated by the fact that multiple DGs and Commissioners provided input into the proposal, including Energy Commissioner Simson and Competition Commissioner Vestager. This institutional ambiguity allowed Commissioner Breton to put more weight behind nuclear inclusion in the Commissioner College.

Conclusion

The study in this paper has performed a comparative case study of three policy processes using a process tracing approach to explain why and how nuclear energy has been included in recent EU ECP. Making use of the multiple streams framework, European integration and decision-making theories, the research has identified multiple necessary conditions for nuclear energy to be given (some) recognition.

France, motivated by domestic policy choices regarding nuclear, was the key driver behind these developments. It could count on political entrepreneurs in different parts of the political stream; its ministers in the Council, MEPs leading a pro-nuclear group in the Parliament and an influential Commissioner position. Additionally, it exploited its large MS status and the informal consensus rule in the Council and in the Commission to push for concessions in an isolated position, in line with the bargaining theory from LI.

However, the most notable policy change for nuclear energy could only be brought about by allying with other MS that are also pro-nuclear, but whose priority in ECP is to defend the role of natural gas and resist too ambitious climate targets. In addition, a lack of policy coordination in the German government prevented them from lobbying more effectively against the inclusion of nuclear power, confirming findings from the literature (Roth, 2011). The result for both considerations is that nuclear energy is rarely included without provisions for other controversial energy sources, like natural gas.

The research has also shown that the Commission can act as a political entrepreneur in decision-making through its delegated authority. This expands upon the literature that applies the MSF to the EU context, in which mainly the agenda-setting power of the Commission is studied. In addition, when the Commission uses its delegated authority, it anticipates by designing its proposal in a way that it will receive sufficient support to pass (Bürgin, 2015). In case of a DA, this means pleasing as much MS as possible and the number of MS (mainly in CEE) supportive of nuclear, makes the Commission more inclined to take nuclear energy into account. This observation supports the idea of strategic flexibility, as shown already for the REDIII (Buzogány et al., 2023). However, unlike the provisions for nuclear energy in REDIII, the nuclear inclusion in the EUST affects all MS equally, which leads to contestation of EU authority. This shows the limits of the strategic flexibility approach to accommodate MS preferences.

The issue of nuclear energy illustrates the tension between the EU’s current approach to increasing climate ambition and the right of MS to determine their own energy mix. The Commission has chosen to ease this tension by offering flexibility to outlier countries (notably France) or by forging / allowing package deals between MS with different preferred energy sources (notably France and Germany). This strategy has succeeded in keeping the Green Deal agenda on the rails. However, by trying to please everyone (and large MS in particular), the Commission risks undermining the effectiveness of its own policy proposals. In addition, forging package deals between large MS at its own initiative (by DA) increases contestation of its authority by smaller MS when such a package deal affects all MS. Thus, it is questionable whether this strategy is sustainable for further rounds of increasing climate ambition.

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