Introduction

International nuclear law has a significant influence on the United Kingdom’s electricity policy because nuclear power is simultaneously an electricity-generation technology, a radiation-risk activity, a source of nuclear material, and an area of international security and non-proliferation law. The UK therefore cannot formulate nuclear-electricity policy solely through domestic energy legislation. Its nuclear programme operates within a network of international treaties, safeguards arrangements, nuclear-liability conventions, environmental obligations and international regulatory standards.

This relationship has become particularly important since Brexit. The UK left the European Atomic Energy Community (Euratom) framework alongside its withdrawal from the EU and consequently developed a domestic nuclear-safeguards system administered by the Office for Nuclear Regulation (ONR). The UK nevertheless continues to participate in international nuclear institutions and treaties, including the International Atomic Energy Agency (IAEA) framework and the Convention on Nuclear Safety. (GOV.UK)

As of 2026, the UK's nuclear policy also forms part of a broader electricity strategy involving existing nuclear stations, new nuclear construction, advanced nuclear technologies and long-term decarbonisation. The international legal framework consequently affects not only nuclear safety but also investment, electricity-market design, environmental protection, nuclear fuel supply, liability and cross-border nuclear cooperation.

1. Meaning and Scope of International Nuclear Law

International nuclear law is not contained in one comprehensive treaty. It consists of several overlapping legal regimes dealing with:

nuclear safety;

nuclear security;

nuclear safeguards and non-proliferation;

liability for nuclear damage;

radioactive waste and spent fuel;

transboundary environmental impacts;

nuclear material transfers and trade;

emergency notification and assistance;

international nuclear cooperation; and

peaceful use of nuclear technology.

For the UK electricity sector, the most important institutions and instruments include the IAEA, the Convention on Nuclear Safety, the Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management, the Convention on Early Notification of a Nuclear Accident, the Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency, and the nuclear third-party-liability conventions.

The UK government states that the UK is party to these major nuclear-safety conventions and that they establish legally binding obligations concerning domestic nuclear safety regimes and international accountability. (GOV.UK)

2. Convention on Nuclear Safety and UK Electricity Generation

The Convention on Nuclear Safety (CNS) is particularly important for electricity-generating nuclear installations.

Its central purpose is to promote a high level of nuclear safety through national measures and international peer review. The Convention addresses matters including:

legislative and regulatory frameworks;

regulatory bodies;

responsibility of operators;

financial and human resources;

safety assessment;

quality assurance;

radiation protection;

emergency preparedness;

siting;

design and construction;

operation of nuclear installations.

The UK has participated in the CNS reporting process since its entry into force. Its latest national report, published in August 2026, explains how the UK complies with the Convention and discusses operating nuclear stations as well as new-build design and licensing activities. (GOV.UK)

Effect on electricity policy

The Convention means that the UK's objective of increasing nuclear generation cannot be separated from safety obligations. Electricity policy may encourage construction of nuclear plants, but nuclear projects remain subject to independent safety regulation.

The practical consequence is that energy-security and decarbonisation objectives do not replace nuclear-safety requirements.

3. IAEA and UK Nuclear Electricity Policy

The IAEA provides an important international institutional framework.

Its functions include:

developing nuclear safety standards;

facilitating safeguards;

supporting peaceful nuclear cooperation;

promoting nuclear security;

providing technical assistance;

encouraging international information-sharing.

The UK has stated that its nuclear and radiological safety policy is consistent with the IAEA Fundamental Safety Principles. (GOV.UK)

The UK therefore operates through a combination of:

international standards → domestic legislation → independent regulation → licensing → operational compliance.

The ONR is particularly important because it regulates nuclear safety and security and also performs safeguards functions under the UK's post-Euratom system.

4. Euratom and the UK's Electricity Sector

Before Brexit, Euratom played an important role in the UK's civil nuclear sector.

Euratom was relevant to:

nuclear safeguards;

nuclear material accounting;

nuclear research;

nuclear cooperation;

radioactive materials;

nuclear safety;

nuclear fuel arrangements.

The UK formally left the Euratom framework as part of Brexit. This created a legal problem because many of the UK's safeguards arrangements with the IAEA were linked to Euratom membership.

The Nuclear Safeguards Act 2018 established the legal foundation for a domestic UK safeguards regime. The legislation empowered the UK to replace the previous Euratom-based framework and enable the ONR to fulfil UK safeguards obligations. (Legislation.gov.uk)

The domestic regime became operational at the end of the Brexit transition period in December 2020. (GOV.UK)

Importance for electricity policy

This was crucial for nuclear electricity because operating nuclear power stations requires continuing access to:

nuclear fuel;

nuclear material;

international supply chains;

nuclear technology;

international cooperation.

Safeguards therefore have an economic and electricity-policy dimension as well as a non-proliferation dimension.

5. Nuclear Safeguards and Electricity Generation

Nuclear safeguards seek to ensure that civil nuclear material is not diverted to prohibited purposes.

For the UK's electricity industry, safeguards involve:

accounting for nuclear material;

reporting;

inspections;

verification;

record keeping;

international cooperation.

The Nuclear Safeguards Act 2018 expressly connects the domestic safeguards system with the UK's international safeguards obligations. (Legislation.gov.uk)

The UK therefore has to maintain a safeguards system capable of supporting its civil nuclear industry while satisfying international non-proliferation commitments.

This becomes increasingly important if the UK expands nuclear generation through new reactors, advanced reactors or small modular reactors.

6. International Nuclear Liability and UK Electricity Policy

One of the most important connections between international nuclear law and electricity policy concerns third-party liability.

Nuclear accidents can produce extremely large economic and environmental losses. International nuclear-liability conventions therefore establish special rules governing:

operator liability;

jurisdiction;

compensation;

insurance;

financial security;

limitation of liability;

international compensation mechanisms.

The UK is party to the Paris Convention on Third Party Liability in the Field of Nuclear Energy and the Brussels Supplementary Convention. These arrangements are implemented domestically principally through the Nuclear Installations Act 1965. (GOV.UK)

The 2004 amendments substantially increased liability and compensation levels. UK legislation was amended in preparation for implementation of those changes, with the revised regime taking effect in 2022. (Legislation.gov.uk)

Importance for investors

The liability framework performs two competing functions:

Victim protection: ensuring compensation following nuclear damage.

Investment certainty: preventing unlimited and unpredictable liability from making nuclear investment commercially impossible.

This balance is highly relevant to UK electricity policy because nuclear power plants require very large long-term investments.

7. Convention on Supplementary Compensation for Nuclear Damage

The UK has also expanded its international nuclear-liability participation.

According to the UK's current civil-nuclear policy framework, the UK acceded to the Convention on Supplementary Compensation for Nuclear Damage (CSC) on 1 January 2026. (GOV.UK)

The CSC provides another international mechanism for compensation following nuclear damage.

Its significance for UK electricity policy includes:

greater international compensation capacity;

improved cross-border legal coordination;

increased clarity concerning liability;

greater protection for victims;

improved predictability for nuclear operators.

Thus, international nuclear liability forms part of the institutional infrastructure supporting civil nuclear electricity generation.

8. Environmental Law and Nuclear Electricity

Nuclear power is low-carbon during operation, but nuclear facilities create environmental-law issues throughout their lifecycle.

These include:

radioactive discharges;

radioactive waste;

spent fuel;

cooling-water impacts;

biodiversity;

land use;

decommissioning;

accidental releases.

International environmental principles can therefore affect nuclear electricity policy.

The precautionary principle, polluter-pays principle, environmental impact assessment and transboundary environmental principles can all become relevant.

The European Court of Justice's Hinkley Point litigation illustrates this intersection particularly clearly.

9. Case Law: Austria v Commission – Hinkley Point C

Republic of Austria v European Commission, Case C-594/18 P, 2020

This is one of the most important cases concerning nuclear energy and electricity policy.

The case concerned the European Commission's approval of UK state aid supporting Hinkley Point C.

The financing package included mechanisms designed to provide long-term revenue certainty for nuclear electricity generation. Austria challenged the Commission's approval.

The Court of Justice confirmed that EU State-aid rules could apply to nuclear energy because the Euratom Treaty did not exclude application of the relevant FEU Treaty rules. (curia)

The Court also recognised that the UK was entitled, under EU law as it then applied, to determine its own energy mix. (curia)

Legal significance

The case demonstrates that nuclear policy operates at the intersection of:

energy sovereignty;

electricity markets;

state aid;

environmental law;

competition law;

nuclear policy.

It also shows that legal support mechanisms for nuclear electricity can be examined under general economic and environmental rules.

10. Case Law: Commission v Council, C-29/99

Commission v Council, Case C-29/99, 2002

This case concerned Euratom's participation in the Convention on Nuclear Safety.

The Court examined the scope of Euratom's competence concerning nuclear safety.

It held that Euratom possessed competence in several important fields, including:

nuclear-safety legislative and regulatory frameworks;

safety assessment and verification;

emergency preparedness;

nuclear installation siting;

design, construction and operation. (curia)

Importance for the UK

Although this was an EU/Euratom case rather than a modern UK domestic electricity case, it is important historically because the UK was formerly within the Euratom system.

It illustrates why Brexit required the UK to construct a separate domestic safeguards and regulatory framework while maintaining international nuclear commitments.

11. Case Law: R (Greenpeace Ltd) v Secretary of State for Trade and Industry

R (Greenpeace Ltd) v Secretary of State for Trade and Industry, [2007] EWHC 311 (Admin)

This is a particularly important UK case.

Greenpeace challenged the government's decision to support nuclear new-build as part of the future UK electricity-generating mix.

The challenge focused substantially on the consultation process.

The High Court found that the consultation concerning nuclear policy was legally defective because important matters, particularly the economics of nuclear construction and nuclear-waste issues, had not been adequately presented for consultation. (Bailii)

Principle

The case demonstrates that nuclear electricity policy is not simply a matter of political preference. Government must comply with applicable administrative-law requirements, including procedural fairness where consultation duties arise.

Importance today

The case remains relevant to major nuclear policy decisions because new nuclear projects involve:

very long-term commitments;

substantial public policy consequences;

environmental questions;

waste-management questions;

significant financial arrangements.

12. Case Law: British Nuclear Group Sellafield Ltd v Gemeinschaftskernkraftwerk Grohnde GmbH

[2007] EWHC 2245 (Ch)

This case concerned contractual disputes involving nuclear-fuel reprocessing at THORP at Sellafield.

The litigation involved detailed evidence concerning the design, capacity and operation of the reprocessing facility and contractual obligations associated with nuclear-fuel reprocessing. (Bailii)

Importance

The case illustrates the commercial dimension of nuclear law.

The nuclear-electricity industry depends upon an extensive contractual chain involving:

uranium → fuel fabrication → reactor operation → spent fuel → storage/reprocessing → waste management → decommissioning.

International nuclear law therefore interacts with ordinary contract law and commercial arrangements throughout the nuclear fuel cycle.

13. Case Law: Sellafield Environmental Regulation

UK nuclear policy also generates judicial-review litigation concerning environmental regulation.

For example, in Bennett (on behalf of Lakes Against the Nuclear Dump) v Environment Agency [2026] EWHC 778 (Admin), the claimant challenged aspects of an Environment Agency decision concerning a water-abstraction licence associated with the Sellafield site. (Bailii)

Although the case is not directly about electricity-market regulation, it demonstrates the broader legal principle that nuclear facilities remain subject to environmental regulatory controls and judicial review.

Sellafield itself is subject to regulation by the Environment Agency and ONR, covering radioactive waste, discharges and nuclear safety. (GOV.UK)

14. International Nuclear Waste Obligations

Nuclear electricity policy must account for the entire lifecycle of nuclear facilities.

The Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management is particularly relevant.

It requires states to establish appropriate legal, regulatory and organisational arrangements concerning:

spent fuel;

radioactive waste;

storage;

disposal;

safety assessment;

institutional responsibility.

This means that the UK's decision to expand nuclear electricity generation necessarily creates long-term legal responsibilities extending beyond the operational lifetime of individual reactors.

15. Emergency Notification and International Assistance

Nuclear accidents can have effects beyond national borders.

The UK is party to:

the Convention on Early Notification of a Nuclear Accident; and

the Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency. (GOV.UK)

These instruments facilitate:

rapid information exchange;

international notification;

technical assistance;

emergency cooperation.

For UK electricity policy, this means nuclear emergency planning has an international dimension.

A serious nuclear incident cannot be treated solely as an internal domestic electricity-sector matter.

16. Nuclear Security and Electricity Infrastructure

Modern nuclear electricity policy increasingly involves critical-infrastructure security.

Nuclear facilities must protect against:

terrorism;

sabotage;

cyber threats;

unauthorised access;

theft or diversion of nuclear material;

hostile interference.

International nuclear-security principles therefore complement domestic regulatory requirements.

The importance of security is particularly significant because nuclear power stations are simultaneously:

electricity-generating facilities;

critical national infrastructure; and

facilities containing nuclear and radioactive materials.

17. International Trade and Nuclear Cooperation

Nuclear electricity generation requires international supply chains.

The UK therefore maintains nuclear cooperation arrangements with international partners.

Following Brexit, the UK established arrangements designed to ensure that nuclear trade and cooperation could continue outside the Euratom framework. Government guidance covers nuclear cooperation agreements, nuclear-material reporting and export licensing. (GOV.UK)

This affects electricity policy because nuclear reactors require access to internationally sourced:

fuel;

components;

specialist technology;

engineering services;

research;

nuclear materials.

Consequently, nuclear electricity policy is partly dependent upon international trade law and diplomatic cooperation.

18. Brexit and the Transformation of UK Nuclear Law

Brexit did not eliminate international nuclear obligations.

Instead, it changed their institutional implementation.

Before Brexit

The framework substantially involved:

UK → Euratom → EU institutions → IAEA

After Brexit

The UK moved toward:

UK Government + ONR → domestic safeguards → IAEA/international agreements

The Nuclear Safeguards Act 2018 was central to this transformation. (Legislation.gov.uk)

The UK subsequently developed a domestic safeguards regime intended to preserve international standards and cooperation. The government has stated that the post-Euratom framework was designed to maintain robust safeguards rather than weaken them. (GOV.UK)

19. Relationship Between International Law and UK Electricity Policy

The relationship can be summarised as follows:

20. Impact on Future UK Nuclear Electricity Policy

International nuclear law is likely to remain important as the UK develops its civil nuclear programme.

The legal challenges will include:

A. New nuclear construction

New reactors require international standards concerning safety, design, safeguards and liability.

B. Small Modular Reactors

SMRs may require regulatory frameworks capable of dealing with different reactor designs while maintaining international safety commitments.

C. Advanced nuclear technologies

Advanced reactors may involve new fuel cycles and therefore additional safeguards and international cooperation requirements.

D. Nuclear waste

Expansion of nuclear generation increases the importance of long-term spent-fuel and radioactive-waste governance.

E. Nuclear financing

International liability rules and domestic compensation arrangements affect investment structures.

F. Supply-chain security

International cooperation is increasingly important for uranium, fuel fabrication, reactor components and specialist services.

G. Energy security

Nuclear generation is increasingly considered within broader UK energy-security planning, but security objectives remain subject to nuclear-safety and safeguards requirements.

21. Key Legal Principles

Several principles emerge from the interaction of international nuclear law and UK electricity policy.

1. Principle of international cooperation

Nuclear risks can cross borders, making international cooperation indispensable.

2. Principle of independent regulation

Nuclear safety should be regulated independently from commercial electricity-generation interests.

3. Precautionary principle

Potentially serious nuclear and environmental risks justify preventive regulatory measures.

4. Polluter-pays principle

The economic consequences of environmental damage should not simply be transferred to the public.

5. Operator liability

Nuclear liability regimes generally channel liability toward the nuclear operator while providing structured compensation mechanisms.

6. Non-proliferation

Civil nuclear electricity must remain compatible with international safeguards and peaceful-use obligations.

7. Intergenerational responsibility

Nuclear waste and decommissioning create obligations extending far beyond the period in which electricity is generated.

Conclusion

International nuclear law provides an essential legal framework within which the UK's electricity policy operates. The UK remains free to pursue nuclear generation as part of its electricity and decarbonisation strategy, but that freedom is constrained and structured by international obligations concerning safety, safeguards, non-proliferation, environmental protection, liability, radioactive waste, emergency response and international cooperation.

The post-Brexit legal framework is particularly significant. The UK replaced the Euratom-based safeguards structure with a domestic regime centred on the ONR while retaining international safeguards and cooperation commitments. (Legislation.gov.uk)

The case law demonstrates the breadth of the legal relationship. Greenpeace v Secretary of State illustrates the importance of lawful consultation in nuclear policy; Austria v Commission demonstrates the relationship between nuclear generation, electricity markets, state support and environmental principles; Commission v Council illustrates the historical importance of Euratom's nuclear-safety competence; and British Nuclear Group Sellafield v Grohnde demonstrates the contractual and commercial dimensions of the nuclear fuel cycle. (Bailii)

Accordingly, UK nuclear electricity policy should be understood not as an exclusively domestic energy-policy field but as a multi-layered legal system connecting domestic electricity regulation with international nuclear safety, environmental law, liability, trade, safeguards and non-proliferation law.

Important cases to cite

R (Greenpeace Ltd) v Secretary of State for Trade and Industry [2007] EWHC 311 (Admin). (Bailii)

Republic of Austria v European Commission (Hinkley Point C), C-594/18 P, EU:C:2020:742. (curia)

Commission v Council, C-29/99, EU:C:2002:734. (curia)

British Nuclear Group Sellafield Ltd v Gemeinschaftskernkraftwerk Grohnde GmbH [2007] EWHC 2245 (Ch). (Bailii)

Bennett v Environment Agency [2026] EWHC 778 (Admin). (Bailii)