Editorial note. This piece is written against Argentina’s regulatory framework, Law 24,804 and the ARN’s licensing standards. The stages described are largely common across countries, but the specific requirements and legal references follow the Argentine case.

Building a nuclear power plant demands years of work and an enormous amount of human, technical and economic resources. This article traces that path, from site selection to commissioning, to show why a project of this scale cannot be resolved by a single overnight decision.

Before going further, a word on scope is in order. For the purposes of this piece, the focus is on a power reactor generating between 300 and 1,000 MWe, the case for which the siting, licensing and construction process is best documented.

Two ideas frame everything that follows. The first is that a nuclear project plays out across three dimensions at once: the technical, the economic and the sociopolitical. No stage of the project belongs to only one of these. The second is that, with the exception of the licensing chain, the stages do not run in sequence but overlap.

Left for other pieces are discussions that are central in their own right but belong to a different plane, such as the choice of technology and fuel type, decades of commercial operation, life extension and final decommissioning. Each deserves its own treatment.

Framework

Three dimensions

Throughout a nuclear power plant construction project, every technical decision has an economic counterpart and a sociopolitical reading, and the three dimensions feed back into one another. Siting is the clearest example of how these three dimensions interact, since a geologically suitable site can become unviable due to community opposition or a municipal ordinance banning the activity. This article therefore first works through the project’s technical backbone, then revisits it through an economic lens and finally through a sociopolitical one.

Once that distinction is made, the overlap becomes visible. The only part of the project that follows a rigid order is the chain of four licences granted by the regulator: Construction, Commissioning, Operation and Decommissioning, each a prerequisite for the next. Everything else does not wait its turn. Engineering, supplier development and financing start early, often before the Construction Licence is granted, and continue as the work advances.

Programme and project

Two concepts are often conflated. Planning a nuclear programme is one thing; developing a nuclear project is another. The International Atomic Energy Agency (IAEA) draws a clear line between them in its guide on the development of national nuclear infrastructure.¹ The programme is the national infrastructure that makes nuclear energy possible: the legal framework, the regulator, financing, industry, siting policy and technology choice. The project is the specific plant that gets contracted and built. This is why this piece does not discuss which reactor or fuel is best, since those are programme-level definitions rather than construction-project ones, and merit their own treatment.

A caveat is in order regarding siting. This piece treats it as a technical aspect of the project, but identifying candidate sites is a task that a mature nuclear programme resolves in its early phases.

A country can have a programme underway, with a national position, a legal framework and a regulator in place, while its siting work remains at the level of a suitable region rather than a specific closed-off site, which is to be expected of a young programme. In Argentina’s case, most projects still gravitate toward the same site, which exposes how far the definition of new sites has lagged in a nuclear programme that is already half a century old.

I. The technical aspects

The starting point is the project’s backbone: the sequence of stages that turns a plot of land into a plant ready to operate. Siting, engineering, licensing, supplier development, construction and commissioning.

1. Siting

The first thing to define is the location. As noted, identifying the regions where nuclear plants could be sited is, strictly speaking, a matter of state policy that a country resolves, or at least sets in motion, before a specific project is even conceived. It belongs to the programme. The project inherits that groundwork and carries it to the level of detail, characterizing and licensing the specific site.

The selection methodology runs from determining a suitable region to the final siting report, and is generally structured in the following steps:

1. Determination of regions suitable for nuclear facilities.
2. Establishment of priorities among those regions.
3. Preliminary siting studies within the chosen region (identification of possible sites, pre-selection, and studies of the pre-selected sites).
4. Assessment of each site’s potential and recommendations.
5. Final siting report.

Within this framework, the preliminary studies weigh a range of factors spanning the three dimensions mentioned above:

• Environmental effects. Physical environment factors (geology and soil characteristics, atmosphere, hydrology) and living environment factors, such as ecology and potential public exposure.
• Technical factors. Access to cooling water, ground conditions, access and transport, availability of labour and equipment, logistical support, integration with the national grid, high-consumption facilities, nuclear safety, communications and proximity to industrial hubs.
• Socioeconomic factors. Water, soil and natural resources; existing infrastructure, services and industrial capacity; and effects on the human environment, both psychological and prospective (cultural, tourism, commercial and residential).

Once the region has been established, a detailed review of factors and sub-factors follows, with an analysis that leaves out none considered relevant. This weighing process takes years and must be carried out with specialists from different fields, transparently enough to avoid stoking public suspicion, and with a scope that provides technical grounding for the subsequent stages of design, construction and operation.

As already noted, siting is the clearest case of a stage that entangles all three dimensions. A site can be technically optimal and still stall over community opposition, a municipal ordinance, or difficulties in acquiring the land.²

2. Engineering

Once the site framework is defined, the project must work through its engineering, one of the pillars that determines whether the work can proceed on time. A plant’s engineering runs through three linked stages. Conceptual engineering sets the baseline definitions, basic engineering develops the main systems, and detailed engineering translates the design into the drawings and specifications actually used to build the plant and procure its components.

How much of that engineering is resolved locally and how much arrives already developed depends on where the reactor design originates, a definition that, as noted, belongs to the programme. In any scenario, however, the local effort always includes site adaptation and detailed engineering, carried out in dialogue with the regulator. In every case, this is years of work that overlaps with both licensing and construction.

3. Licensing

Argentina’s regulatory regime rests on Law 24,804 (National Nuclear Activity Law), which empowers the Nuclear Regulatory Authority (ARN) to issue radiological and nuclear safety, licensing and oversight standards for nuclear facilities. Building on that law, the ARN developed a framework that is performance-based rather than prescriptive. This means the licensee³ must demonstrate that its proposed technical means meet the safety objectives, rather than having the regulation dictate the specific means to be used.

The standard that structures the process is AR 0.0.1 (Licensing of Class I Installations), which organizes the path into four sequential licences: Construction, Commissioning, Operation and Decommissioning. This is the strict chain mentioned earlier. This piece covers the stretch from the Construction Licence to the Operating Licence.

The first requirement, then, is the Construction Licence, for which the ARN requires a Preliminary Safety Report.⁴

The Preliminary Safety Report

The Preliminary Safety Report is the core document of the Construction Licence application. In it, the party responsible for the facility describes the plant’s design and demonstrates that it meets the safety objectives. The number and ordering of chapters vary with the reactor and the guide adopted, but a report of this kind typically spans about twenty chapters, including:

• Introduction and general plant description.
• Site characteristics (geology, seismology, hydrology, meteorology and demographics).
• Design of structures, systems and components, and their design bases.
• Reactor and coolant circuit systems.
• Safety systems and accident mitigation.
• Radiation protection and waste and effluent management.
• Accident analysis and safety assessment.
• Operational conduct, organization and human factors.
• Quality assurance and emergency plans.

Producing this documentation typically takes years and requires large teams: engineers from different specialties, experts in probabilistic and deterministic safety analysis, radiation protection and regulatory affairs, among others.

In parallel, the ARN must review this documentation, which tends to extend the timeline further. A regulatory body’s responsiveness is directly tied to its level of professionalism and to having qualified staff equal to the project. The process is therefore iterative between applicant and reviewer, not a linear procedure.

That responsiveness, moreover, is tested anew with each new technology. Regulatory frameworks were designed for large power reactors, and adapting them to more recent designs, such as SMRs, remains an open challenge for regulatory authorities worldwide, Argentina included.

Environmental Impact Assessment

Added to these requirements is an Environmental Impact Assessment (EIA), governed by national legislation and required before the Construction Licence application. The EIA is a full procedure comprising the following essential steps:

1. The Environmental Impact Study, also prepared by the licence holder where applicable.
2. Review of the Environmental Impact Study, conducted by the competent environmental authority.
3. A public participation stage.
4. The Environmental Impact Declaration, issued by the competent environmental authority.

The public participation stage, listed here as a procedural step, is also one of the points where the project is fully exposed to the sociopolitical front. This is taken up again below.

4. Supplier development

A component destined for a nuclear power plant cannot be compared to an ordinary industrial input. The supplier must be qualified, and pre-qualification assesses whether it has the technical, financial and quality management capacity required by the project, examining its track record, organization and management system. When a supplier does not appear on the licensee’s approved list, an audit and qualification process for its quality management system must be completed before it can be awarded any work.⁵

Many of these components must also meet nuclear-grade quality standards. These are critical parts, equipment and systems, pressure vessels, piping, pumps, valves, designed to operate under extreme conditions of temperature, pressure and radiation. Their design and manufacture are governed by codes stricter than those of other industries, such as Section III of the ASME code or its equivalents under other technologies, which ensure the traceability and integrity of each part throughout its service life.⁶

Supplier development takes time and must be planned years in advance, which makes it one of those cross-cutting activities that start early and do not wait for construction to begin. How much of the supply chain is resolved through local industry and how much is imported is, in turn, an economic and strategic decision, addressed further in the following section.

5. Construction

Once the Construction Licence is granted, the actual construction phase begins. Construction covers both civil works (earthworks, foundations and the large concrete structures that house the reactor) and the electromechanical assembly of systems and components. This is a years-long stage, employing thousands of workers at peak activity, marked by construction milestones along the way.

Strict quality control applies throughout construction. Every structure, system and component relevant to safety is manufactured, assembled and verified according to qualified procedures, with the ARN maintaining oversight of the work as it proceeds. Traceability and supporting documentation are an essential part of the work. As construction advances, other workstreams continue in parallel: detailed engineering keeps being resolved and the regulator continues reviewing safety documentation, so construction, design and licensing coexist over time.

The project’s management model shapes both its timeline and its dynamics. A turnkey scheme, in which a main contractor assumes overall responsibility, is not the same as a split-package model, in which the owner coordinates multiple contractors, nor is either the same as a hybrid model combining both logics.⁷ Each arrangement distributes responsibilities, risks and coordination burdens differently.

Another decision made at the outset is whether the party building the plant will also operate it, or whether the operator takes over the facility once it is finished. This is a decision where the technical and the political intersect. On one hand, it shapes how knowledge will be transferred to the future operator and how commissioning is approached. On the other, it determines who ends up in charge of operating the plant, a question that goes beyond technical matters and touches on how the country’s nuclear sector is organized.

6. Commissioning

Once assembly is complete and the Commissioning Licence granted, this stage’s testing and verification work begins, checking that every system performs as designed before commercial operation starts. It follows a gradual, staged sequence:

1. Cold tests, verifying systems without fuel and without operating conditions.
2. Hot tests, bringing systems up to operating pressure and temperature.
3. Fuel loading into the reactor core.
4. First criticality, the first start-up of a controlled chain reaction.
5. Ascending power tests, raising power in steps and verifying plant behaviour at each level.

Each stage is cleared only once the plant is shown to behave as expected, ensuring that it enters service with its safety verified. In parallel with these tests, the Operating Licence is processed, which authorizes the plant to run commercially. To obtain it, the licensee must submit and keep updated an extensive body of documentation, including the Final Safety Report, the Technical Operating Specifications, the Operations Manual, the Emergency Plan and the Probabilistic Safety Assessment, among many others.

With that licence in hand, the construction project comes to an end and the plant is authorized to feed power into the grid. What follows is decades of commercial operation and, at the end of its service life, decommissioning, which opens a chapter of its own beyond the scope of this piece.

II. The economic aspects

Having worked through the technical backbone, it is worth revisiting it through the lens of money, since the greatest challenge of a nuclear power plant remains the cost of building it.

A nuclear power project requires investment on a large scale, with the particularity that most of it is concentrated in the initial stage, before the plant generates a single MWh, and is recovered over a service life measured in decades. This gives nuclear economics an asymmetric profile: a high upfront cost combined with a low operating cost. An estimated 70% to 80% of the total lifetime cost of nuclear electricity comes from construction and the interest on debt taken on for that stage. Once the plant is operating, fuel and maintenance costs are comparatively low.

This feature calls for financial engineering to match it, capable of defining funding sources, the disbursement schedule across the years of construction, and the conditions that make a project with such a long maturation period sustainable. This planning accompanies the project from the outset and is updated as engineering gains definition and budgets move from preliminary estimates to increasingly refined figures.

The cost structure is not limited to construction. It includes engineering, supplier qualification, nuclear-grade components, initial fuel, insurance and provisions for eventual decommissioning. Added to this are the costs associated with regulation and safety, and the effort required to build social licence. Above all, risk weighs heavily: still-immature supply chains, loans that must be repaid on strict schedules, and cost overruns or delays, which in the nuclear sector are often decisive.

This landscape has pushed the industry to explore schemes that reduce financial risk, such as standardization and serial manufacturing of components. Small modular reactors (SMRs) are the avenue most explored along these lines.⁸

Finally, there is an economic decision rooted in the technical: how much of the supply chain is resolved through local industry and how much is imported. Argentina’s industrial supply chain today is not the one it had in 1974, when the country undertook its first plants. Much of a nuclear project’s strategic value lies precisely in that transfer of capabilities to local industry, which is at once a development bet and a factor of cost and schedule.

III. The sociopolitical aspects

What remains is the third lens, the one most often underestimated and the one that in practice derails as many projects as the numbers do.

The starting point is social acceptance. A plant is not sited on technical permits alone; it needs the acceptance of the population that will live near it. This is why work on risk perception accompanies the project from the siting study onward, through information that is transparent and sustained over time. An opaque process feeds the suspicion that later hardens into opposition.

The Lemóniz plant, in the Basque Country, illustrates the weight of this front to its full extent.⁹

That acceptance depends, in large part, on how the plant affects local life. A nuclear power plant is both a piece of infrastructure and an advanced technological industry that brings employment and development, but it also changes the surrounding environment and the life of the community that lives alongside it. Much of a project’s acceptance or rejection is decided within that tension, between what it brings and what it disrupts.

Added to this dimension is the provincial and municipal regulatory framework. Across the country, various provincial laws and municipal ordinances restrict or outright ban nuclear activity. A technically suitable site can be ruled out by a local regulation, and clearing that obstacle is political and legal work, not engineering.

Another aspect is land tenure. If the site chosen does not belong to the national government, the licensee must decide whether to purchase the land or resort to expropriation. Negotiations, costs and timelines all hinge on that decision and feed directly into the schedule, since a delay in acquiring the land pushes back everything that follows.

Above all of this lies an underlying condition: long-term energy policy. A project measured in decades needs a state policy that outlasts individual governments, regardless of whether the plant is built by the public sector or a private one. That continuity is what sustains financing, contracts and schedules over time. When it is missing, construction stalls and resumes at the pace of each administration, and that intermittency is itself one of the greatest sources of cost overruns. The history of Atucha II shows this starkly.

Finally, a matter that outlasts the plant’s own lifetime but remains part of its public discussion is radioactive waste. Argentina stores it on-site, in facilities designed for that purpose, but these are interim storage solutions. The final destination of high-level waste is still undefined, and that definition is a political question that goes beyond any individual project.

In summary

What emerges from this overview is the idea running through the whole piece. Building a nuclear power plant is not impossible, but it is a decades-long commitment that plays out across the technical, economic and sociopolitical planes at once.

Argentina’s own numbers help convey the scale of the challenge.¹⁰

In the end, what determines the fate of a nuclear project is neither engineering alone nor money alone. It is the ability to sustain, over years, an energy policy that outlasts governments and a social consensus that stands behind it.

This is why, before the question of how, there is a prior question worth asking in earnest: what does the country want a larger nuclear fleet for, and at what cost? Is the goal to increase generation and energy security, to gain technological autonomy, or to fold nuclear energy into a broader energy transition programme? The answer determines whether nuclear energy is part of a development agenda conceived in decades, or merely a window of opportunity opened by a global moment demanding more energy. More than any technical stage, that definition determines whether a project reaches port.

Understanding that scale, of time, resources and agreements, is only a first step toward discussing seriously what place a new plant might occupy in the country’s energy future.

Notes

1. The milestones approach is developed in the IAEA guide “Milestones in the Development of a National Infrastructure for Nuclear Power” (Nuclear Energy Series NG-G-3.1, Rev. 1). It sets out the three phases, the three milestones and the nineteen infrastructure issues in detail.
2. Within this framework there is no stand-alone “siting licence.” Siting is resolved as part of the technical documentation submitted for the Construction Licence, administratively subordinate to that stage, though it is governed by its own underlying technical standard (AR 10.10.1 “Siting Evaluation of Nuclear Power Reactors”).
3. The party responsible for the project, accountable to the regulator.
4. Comparable to the PSAR under the US regulatory framework.
5. Suppliers are held to quality management standards stricter than those of other industries, such as ASME NQA-1 or ISO 19443.
6. The IAEA has codified these good practices in materials such as the Nuclear Contracting Toolkit and in Nuclear Energy Series publication NP-T-3.21 “Procurement Engineering and Supply Chain Guidelines.” These materials also warn about risks specific to the nuclear supply chain, such as the appearance of counterfeit, fraudulent or suspect items, which call for strict traceability controls.
7. The IAEA describes these arrangements and the distribution of responsibilities among project partners in its classic guide on nuclear power project management (Technical Reports Series No. 279).
8. One alternative being explored is SMRs, precisely because of their business model, a smaller, staged upfront investment and modular serial manufacturing that reduces the risk associated with large-scale construction.
9. The Lemóniz plant, in the Basque Country, illustrates the weight of this front. Construction was nearly complete, but strong social opposition, a tense political climate and a nuclear moratorium (a legally mandated suspension of nuclear development) imposed by the Spanish government in the 1980s led to the project’s abandonment. It was viable both technically and economically; it was the sociopolitical front that brought it down.
10. Summary of construction times (start of works to commercial operation). Atucha I, 1968 to 1974, about 6 years (turnkey, Siemens/KWU). Embalse, 1974 to 1984, nearly 10 years (project without interruptions). Atucha II, 1982 to 2014, about 32 years start to finish, but with the project halted between 1994 and 2006, so the effective construction time was considerably shorter.