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Refurbishment and life extension

Nuclear power plant refurbishment

The life of a nuclear power plant can be extended for several decades through refurbishment, by modernizing and enhancing major equipment and systems to support long-term operation.

In addition to component maintenance, replacement and/or modifications, refurbishing a facility also provides opportunities to enhance safety, by modernizing and updating technology and knowledge.

The CNSC oversees refurbishment projects from the initial planning before shutdown to the return-to-service.

Safety note

If an important safety-related improvement is identified, we do not wait for a refurbishment to take place!

Many improvements and upgrades are completed during regularly scheduled maintenance outages, throughout the normal operating life of the reactor.

Preparing a refurbishment

As part of its licensing process, the CNSC requires a technical assessment to be completed before authorizing a refurbishment project.

Two important components of the technical assessment are the environmental assessment (EA) and the integrated safety review (ISR).

Environmental assessment

An environmental assessment (EA) is completed as part of the licensing process for the refurbishment of a nuclear power plant.

Units 1 and 2 at the Bruce A Nuclear Generating Station were returned to service in 2013 and 2012 respectively, following their refurbishment.

The EA addresses the impacts of the refurbishment work and of extending the facility’s operation for several decades on the environment, including human health.

For the CNSC to allow refurbishment to proceed, the project proponent must demonstrate that adequate provisions for the protection of the environment and the health and safety of people will be made.

Comprehensive in nature, the EA also looks at the expansion of the facility (to accommodate waste from refurbishment and continued operations).

A large number of studies are completed as part of an EA – each looking at a different aspect, such as the impact on water, animals, plants, air quality and people.

Public participation opportunities are provided through the licensing process, which may involve EA-specific consultation activities and information sessions.

The CNSC offers funding to help stakeholders and Aboriginal groups participate in those opportunities.

Public hearings are conducted at the end of the licensing process, to publicly examine the findings.

The hearings allow the Commission to hear from everyone involved, including the project proponent, CNSC staff, technical experts and the public.

Integrated safety review

Completed in parallel with the EA, the integrated safety review (ISR) identifies all practicable safety improvements that could be made during the refurbishment.

Reactor work at NB Power's Point Lepreau Generating Station, which was returned to service in November 2012, following refurbishment.

The ISR provides for a rigorous review of the reactor’s systems, structures and components against modern standards, experience, best practices and research findings.

The ISR considers a wide range of safety-related topics (including plant design, environmental qualification, and probabilistic safety analysis).

Building on international best practices, the ISR identifies additional backup systems which enhance the facility’s ability to prevent accidents and mitigate their consequences, should they occur. The ISR enables determination of reasonable and practical modifications that should be made to enhance the safety of the facility to a level approaching that of modern plants, and to allow for long-term operation.

This measure is also part of the CNSC’s post-Fukushima action plan to deal with very low probability events.

As with the EA, the ISR is subject to public scrutiny and open hearings are held to examine findings.

Licensing decision

The CNSC will only approve the project if it is satisfied that the project proponent identified all practicable safety improvements to bring the facility up to modern standards.

The licence that covers the facility’s refurbishment identifies the conditions that must be met before the operator is allowed to refuel and power up the reactor, to return to service.

Project execution

During project execution, the CNSC verifies that the work is done according to plan, and that safety improvements are designed to codes, installed and commissioned.

As is the case during regular operation, a team of onsite CNSC inspectors is present throughout the project, to verify safety and compliance with the licence.

CNSC staff also include technical specialists in various disciplines, who review project execution on a regular basis, to make sure regulatory requirements and licence conditions continue to be met.

The CNSC reports publicly on the results of its inspections.

Refurbish a virtual nuclear power plant

Refurbish a virtual nuclear power plant and learn about the planning and licensing process.

Safety note

During refurbishment, the reactor is defueled, drained of coolant and some of the normally inaccessible systems are opened to allow parts to be inspected and replaced, if necessary.

Waste minimization

The principles of "reduce, reuse, recycle" are followed throughout refurbishment to minimize the amount of disposable waste.

During the initial planning, the licensee identifies what parts can be reconditioned and reused safely for another 25 to 30 years.

After reconditioning, these parts are thoroughly tested and inspected before being reused in the reactor.

Most of the waste produced during refurbishment is non-radioactive, and can be recycled.

Reduction is another aspect of radioactive waste management.

The radioactive waste is divided carefully by type and nature, to minimize quantities.

For instance, bulky, low-activity waste such as clothing and wipes can be incinerated in specially designed facilities to reduce volume, and metal pieces can be cut and compressed for storage in special containers.


Once all the refurbishment activities are finished and the inspections are completed, the CNSC closely monitors the facility’s refueling and return to service.

The restart is done very gradually, over several months, to allow for the safety testing of all systems.

The process of returning to service includes progressing to regulatory hold points. The licensee requires CNSC approval to move on after each stage (hold point) is completed. Some of the main steps requiring CNSC approval to restart a nuclear reactor include reloading fuel, approach to criticality and increase of power above 50%.

Each step ensures verification that all required testing had been properly done, to ensure that systems function as planned in safe condition.

Regulatory experience

The CNSC has an extensive experience regulating refurbishment projects.

To date, five reactors have been refurbished in Canada:

  • Pickering Unit 1
  • Pickering Unit 4
  • Bruce A Unit 1
  • Bruce A Unit 2
  • Point Lepreau

All the lessons learned from these projects are integrated into future refurbishment projects.


The CNSC is committed to continuous improvement, and exchanges information with other national nuclear regulators and international organizations (such as the International Atomic Energy Agency, a body of the United Nations).

The CNSC works closely with other CANDU regulators.


Nuclear power plant operators fund several research initiatives in support of refurbishment and life extension projects.

For instance, issues such as obsolescence or aging of structures and components are being examined by the industry, along with state-of-the-art studies to assess risk from both internal (e.g., fire) and external events (e.g., high winds or earthquakes).

The findings and results of these projects form part of assessing safe long-term operation by CNSC experts.

Integrating the best available science with its decision making, the CNSC independently funds its own research initiatives and programs.

Research is carried out on a wide range of topics, from health studies on nuclear workers and host communities, to detailed technical studies on reactor component aging and reliability.

This research is often completed with the support of independent third-parties, and/or in collaboration with national and international partners, providing access to valuable expertise, modern facilities and the best available data.

The CNSC values the use of independent peer reviews, and encourages technical staff to submit articles for publication in scientific journals.

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