Nuclear power has emerged as a controversial yet potentially crucial technology in addressing the global challenge of climate change. As the global push to reduce greenhouse gas emissions intensifies, nuclear power represents a low-carbon, high-capacity-factor, security-of-supply-enhancing option that can strengthen energy independence, while providing firm and ancillary services that complement variable renewables. However, nuclear power cannot be fully understood, nor effectively governed, if treated merely as a technical endeavour for decarbonisation. For this reason, I adopted the Large Technical System (LTS) lens to deal with the complexity of an infrastructure that evolves over decades, embedded in political economies, regulatory frameworks, and public perceptions. From an LTS’s perspective, I investigated two interrelated paths that are increasingly recognised as essential: the construction of new nuclear capacity (new build) and the operation’s safeguarding of existing infrastructure (preservation). While new build is necessary to meet future electricity demand and replace fossil fuel dependency, preserving existing capacity allows for the continued delivery of low-carbon electricity in the short and medium-term, leveraging already decades-old power plants and established operational knowledge. However, the nuclear-related literature presents several gaps. Regarding new build, the literature treats nuclear power primarily as an isolated technical object or project, neglecting nuclear LTSs where institutional alignment, path dependence, and historical evolution shape durable results. Regarding preservation, the literature lacks systematic accounts, beyond purely engineering studies, of i) how nuclear LTSs are maintained and reconfigured when dealing with exogenous and endogenous pressures and ii) the nuclear LTSs' dynamics after a preservation failure leading to phase-out. Against this background, the aim of my PhD Thesis is to investigate how nuclear LTSs are built and preserved. I achieve this aim through a collection of four papers addressing four interdependent objectives. I employ a qualitative, multi-method approach, focusing on Western countries as an empirical setting. My Thesis is theoretically enriched by the LTS lens, the System of Provision approach and the Theory of Social Representation. The Thesis shows that new build must be conceived as a systemic endeavour: projects and programs represent the building blocks of the nuclear LTS and enable the LTS to generate outcomes, value, and impacts for society. Projects should be properly assessed to ensure that their outputs generate nuclear LTS synergies and complementarities, rather than merely on project-specific performance (e.g., costs, time). As such, projects act as vectors of change, shaping trajectories of nuclear LTS, also enabling transitions between LTS lifecycle phases. However, I also show that, empirically, Western countries struggle with new builds, so the near-to-medium-term strategic lever is the preservation of the existing nuclear LTSs. Focusing on preservation, first, I explain divergent national responses to exogenous events (e.g., Chernobyl). I claim that events function as amplifiers of pre-event momentum, which I understand and describe as a configuration of several factors identified. Where momentum is strong, exogenous events are absorbed via reconfiguration; where it is weak, they foster decline. Second, I reframe long-term operations as a preservation strategy to face the endogenous pressure of ageing, identifying promoting and hindering factors. I highlight that licence renewal functions as a low-cost real option, postponing life-extension capital investments and reducing revenue uncertainties. Finally, I conceptualise “dormancy” as a post-decline LTS phase in which infrastructural, institutional, capability, and symbolic residues persist, creating time-bounded opportunities for path revival. In fact, investigating the symbolic residues, I empirically observed that social acceptance in communities around old nuclear power plants in a phase-out country is generationally patterned with a substantial collective memory impact.
Il nucleare rappresenta una tecnologia controversa, ma potenzialmente cruciale, per affrontare la sfida globale del cambiamento climatico. Con l’intensificarsi degli sforzi per ridurre le emissioni di gas serra, il nucleare si distingue come opzione a basse emissioni, ad alto fattore di capacità, capace di rafforzare la sicurezza degli approvvigionamenti e l’indipendenza energetica, fornendo al contempo servizi di capacità ed ancillari che complementano le rinnovabili non programmabili. Tuttavia, questo “rinascimento nucleare” non può essere compreso né governato efficacemente se trattato come un mero intervento tecnico per la decarbonizzazione. Per questo adotto la lente dei “Large Technical Systems” (LTS) per gestire la complessità di un’infrastruttura che evolve su decenni, incorporata nelle economie politiche, nei quadri regolatori e nelle percezioni pubbliche. In un’ottica LTS, indago due percorsi interrelati e oggi considerati essenziali: la costruzione di nuova capacità (new build) e la salvaguardia dell’infrastruttura esistente attraverso l’operatività di lungo periodo (preservation). Il new build è necessario per soddisfare la domanda crescente e ridurre la dipendenza dai combustibili fossili, mentre la preservation consente di mantenere un approvvigionamento di elettricità a basse emissioni nel breve-medio periodo, valorizzando gli asset già ammortizzati e le conoscenze operative consolidate. La letteratura, tuttavia, presenta alcune lacune: sul new build prevale una lettura tecnologica o progettuale che trascura il nucleare come LTS, dove allineamento istituzionale, percorsi evolutivi e traiettorie storiche determinano risultati durevoli; sulla preservation mancano quadri sistematici i) su come i LTS nucleari vengano mantenuti e riconfigurati sotto pressioni esogene ed endogene e ii) sulle dinamiche successive a un fallimento della preservation (phase-out). Su queste basi, la tesi mira a indagare come i LTS nucleari si costruiscono e si preservano, attraverso quattro studi qualitativi in paesi occidentali, teoricamente arricchiti dalla lente dei LTS, System of Provision e Theory of Social Representations. La tesi mostra che il new build va concepito come un impegno sistemico: progetti e programmi sono i mattoni costitutivi dell’LTS nucleare e abilitano l’LTS a generare outcomes, value e impacts per la società. I progetti dovrebbero essere valutati in modo appropriato per garantire che i loro output producano sinergie e complementarità a livello di LTS nucleare, anziché limitarsi alla performance specifica del progetto (ad es., costi, tempi). In tal senso, i progetti agiscono come vettori di cambiamento, plasmando le traiettorie dell’LTS nucleare e abilitando anche le transizioni tra le diverse fasi del ciclo di vita dell’LTS. Evidenzio tuttavia che, empiricamente, i paesi occidentali faticano ad avviare i new build; pertanto, nel breve-medio periodo, la leva strategica è la preservazione dei LTS esistenti. Sul fronte della preservazione, in primo luogo, spiego le risposte divergenti dei LTS nucleari nazionali a shock esogeni (es. Chernobyl) mostrando che gli eventi agiscono da amplificatori del momentum pre-evento, inteso come configurazione di fattori politici, industriali, regolatori e socioculturali. Dove il momentum è forte, gli shock vengono assorbiti attraverso la riconfigurazione; dove è debole, innescano il declino. In secondo luogo, riconsidero l’operatività di lungo periodo come strategia di preservazione rispetto all’invecchiamento endogeno dei LTS nucleari, identificando fattori abilitanti e ostacolanti. Fra questi, è importante evidenziare il rinnovo di licenza come opzione reale a basso costo che posticipa gli investimenti per l’estensione della vita dell’asset e attenua le incertezze sui ricavi. Infine, concettualizzo la “dormancy” come fase post-declino in cui residui infrastrutturali, istituzionali, di capacità e simbolici persistono, creando opportunità temporaneamente disponibili di riattivazione. Indagando i residui simbolici, rilevo empiricamente che l’accettazione sociale nelle comunità attorno a ex siti nucleari in un Paese in phase-out è generazionale, con un marcato effetto di memoria collettiva.
Nuclear power as a large technical system: the dual challenge of new build and preservation
DEI, GIACOMO
2025/2026
Abstract
Nuclear power has emerged as a controversial yet potentially crucial technology in addressing the global challenge of climate change. As the global push to reduce greenhouse gas emissions intensifies, nuclear power represents a low-carbon, high-capacity-factor, security-of-supply-enhancing option that can strengthen energy independence, while providing firm and ancillary services that complement variable renewables. However, nuclear power cannot be fully understood, nor effectively governed, if treated merely as a technical endeavour for decarbonisation. For this reason, I adopted the Large Technical System (LTS) lens to deal with the complexity of an infrastructure that evolves over decades, embedded in political economies, regulatory frameworks, and public perceptions. From an LTS’s perspective, I investigated two interrelated paths that are increasingly recognised as essential: the construction of new nuclear capacity (new build) and the operation’s safeguarding of existing infrastructure (preservation). While new build is necessary to meet future electricity demand and replace fossil fuel dependency, preserving existing capacity allows for the continued delivery of low-carbon electricity in the short and medium-term, leveraging already decades-old power plants and established operational knowledge. However, the nuclear-related literature presents several gaps. Regarding new build, the literature treats nuclear power primarily as an isolated technical object or project, neglecting nuclear LTSs where institutional alignment, path dependence, and historical evolution shape durable results. Regarding preservation, the literature lacks systematic accounts, beyond purely engineering studies, of i) how nuclear LTSs are maintained and reconfigured when dealing with exogenous and endogenous pressures and ii) the nuclear LTSs' dynamics after a preservation failure leading to phase-out. Against this background, the aim of my PhD Thesis is to investigate how nuclear LTSs are built and preserved. I achieve this aim through a collection of four papers addressing four interdependent objectives. I employ a qualitative, multi-method approach, focusing on Western countries as an empirical setting. My Thesis is theoretically enriched by the LTS lens, the System of Provision approach and the Theory of Social Representation. The Thesis shows that new build must be conceived as a systemic endeavour: projects and programs represent the building blocks of the nuclear LTS and enable the LTS to generate outcomes, value, and impacts for society. Projects should be properly assessed to ensure that their outputs generate nuclear LTS synergies and complementarities, rather than merely on project-specific performance (e.g., costs, time). As such, projects act as vectors of change, shaping trajectories of nuclear LTS, also enabling transitions between LTS lifecycle phases. However, I also show that, empirically, Western countries struggle with new builds, so the near-to-medium-term strategic lever is the preservation of the existing nuclear LTSs. Focusing on preservation, first, I explain divergent national responses to exogenous events (e.g., Chernobyl). I claim that events function as amplifiers of pre-event momentum, which I understand and describe as a configuration of several factors identified. Where momentum is strong, exogenous events are absorbed via reconfiguration; where it is weak, they foster decline. Second, I reframe long-term operations as a preservation strategy to face the endogenous pressure of ageing, identifying promoting and hindering factors. I highlight that licence renewal functions as a low-cost real option, postponing life-extension capital investments and reducing revenue uncertainties. Finally, I conceptualise “dormancy” as a post-decline LTS phase in which infrastructural, institutional, capability, and symbolic residues persist, creating time-bounded opportunities for path revival. In fact, investigating the symbolic residues, I empirically observed that social acceptance in communities around old nuclear power plants in a phase-out country is generationally patterned with a substantial collective memory impact.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/249517