Decommissioning and legacy management
Sellafield nuclear site in Seascale, UK that is under decommissioning. Photo: Sellafield Ltd.

As many nuclear power plants will reach the end of their operating lives over the next 20 years, decommissioning is an increasingly important topic for governments, regulators, industries and the public, among other stakeholders. Decommissioning activities must be carried out at the end of life of the nuclear facilities and sites. Examples include nuclear power stations, fuel processing facilities, research reactors, and nuclear and radiological laboratories with a wide range of applications.

Some countries are further challenged with the decommissioning of legacy (i.e. complex) sites. These sites comprise different levels of uncertainty, such as a lack of clear governance (e.g. policy, regulation), limited funding or unclear disposal routes for the contained waste. The sites and facilities in question serve a wide range of uses, resulting in varied radiological characteristics and levels of complexity with regard to decommissioning. A multiplicity of approaches are therefore required for each decommissioning project.

Generally speaking, the decommissioning process can be separated into three phases when considered from a project and regulatory perspective, as the infographic shows.

  • prior phase: includes planning and other preparatory actions for decommissioning, followed by the permanent shutdown and the potential transition period required to grant authorisation to undertake decommissioning activities
  • active phase: refers to implementation of decommissioning, including a possible transition period and activities such as decontamination, dismantling and removal of structures/systems/components, demolition of buildings, remediation of any contaminated ground, and removal of radioactive and non-radioactive waste, among other
  • end phase: includes actions for authorities to authorise the termination of the licence and further use of the sites, including any associated activities required to do so

Nuclear decommissioning and legacy management seek to apply all required considerations towards achieving the goal of carrying out all administrative, technical and societal actions to allow the removal of a nuclear site from regulatory control.

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Publications and reports
NEA work on this topic

Work on decommissioning and legacy management is conducted by the NEA Committee on Decommissioning of Nuclear Installations and Legacy Management (CDLM). The CDLM provides a forum for experts from NEA member countries to facilitate the exchange of experience, practices and information, as well as to address various issues and advance the state of the art. Additional information about the committee, its associated working parties and expert groups, and their activities can be found on the CDLM webpage.


The first NEA programme on decommissioning began in 1978 as part of the work carried out by the Radioactive Waste Management Committee (RWMC). The NEA Co-operative Programme for the Exchange of Scientific and Technical Information on Nuclear Installation Decommissioning Projects (CPD) was then established in 1985 to encourage information sharing and exchange based on operational experience in decommissioning nuclear installations that might prove useful for current and future projects.

The Working Party on Decommissioning and Dismantling (WPDD)  was established in 2001 to properly address the rising decommissioning concerns of member states. This working party provided a focus for the analysis of decommissioning policy, strategy and regulation, including the related issues of materials management, release of buildings and sites from regulatory control, and associated cost estimation and funding. Beyond policy and strategy considerations, the WPDD also reviewed practical considerations for implementation such as techniques for characterisation of materials used in decontamination and dismantlement. The WPDD brought together senior experts in decommissioning from 21 NEA countries, and solicited involvement from other international organisations such as the European Commission (EC) and the International Atomic Energy Agency (IAEA).

The CDLM was established in 2018 in recognition of the need to address a broader range of decommissioning and legacy management issues based on the work achieved by the WPDD over the years.