Decommissioning of the Gentilly‑2 facilities

Project overview

What is decommissioning?

Decommissioning is the process that leads to the final shutdown of a nuclear facility and restoration of the site to a predetermined final condition. The process includes putting the reactor in a guaranteed shutdown state, and decontaminating and dismantling the facility. It refers to administrative and technical actions taken to allow the removal of some or all of the regulatory controls from a facility.

The Gentilly‑2 facilities belong to Hydro‑Québec. They are located on the south shore of the Fleuve Saint-Laurent (St. Lawrence River), in the municipality of Bécancour, about 15 km east of the city of Trois-Rivières. The site hosts the old Gentilly‑2 nuclear generating station and waste storage facilities.

On September 20, 2012, the Québec government announced that it would not be refurbishing the Gentilly‑2 generating station and would begin the definitive shutdown of the plant, which had reached the end of its service life.

Gentilly‑2 generating station had an installed capacity of 675 MW and is equipped with a CANDU (CANada Deuterium Uranium) reactor. Commissioned in 1983, it ceased operation on December 28, 2012, after 29 years of meeting the most exacting security and safety standards with respect to protection of the environment, workers and the general public.

The decommissioning of the Gentilly‑2 power plant is a four‑step process: preparation for storage with surveillance, which covers unloading the reactor and deactivating the systems; storage with surveillance, in which spent (irradiated) fuel is put into dry storage for more than 40 years; dismantling the facilities; and, finally, final site restoration.

Complete decommissioning schedule



Complete defueling of the reactor core and gradual lay up of nuclear systems.


Storage with surveillance and fuel transfer preparation

Progressive transfer of spent fuel to dry storage (completed in December 2020). Ongoing lay up of systems that are no longer required during decommissioning. Reconfiguration of services (e.g., power supply, ventilation) to simplify future maintenance and monitoring during dormancy years.


Storage with surveillance

Dormancy period at the site. Activities will include surveillance of the site, infrastructure aging management and carrying out minimal maintenance of systems still needed during decommissioning. 


Transfer of spent fuel to a permanent site

Hydro-Québec’s access to a deep geological repository under the responsibility of the Nuclear Waste Management Organization for storage of spent fuel bundles.


Preparation and dismantling

Preparation and planification of work package. Detailed decommissioning plan, regulatory approvals, resources and equipment acquisition, modifications and upgrades before dismantling. Initiation of chemical and radiological characterization on site.

Dismantling of all systems, structures and components with a level of radioactivity exceeding the applicable clearance criteria in accordance with current regulations.


Final site restoration

Conventional demolition of buildings, structures, and foundations, backfilling of excavations with clean materials, levelling and soil vegetation.


Environnemental monitoring

10‑years environmental monitoring following the site restoration phase.

Key milestones

  • Final shutdown of the nuclear power plant
    December 2012
  • Complete transfer of spent fuel bundles from the reactor core into a pool for about seven years
    September 2013
  • Abolition of the Plan des mesures d'urgence nucléaire externe de Gentilly‑2 (Gentilly‑2 external nuclear emergency response plan) by the Organisation régionale de la sécurité civile Mauricie–Centre-du-Québec (regional civil security organization)
    May 2016
  • Issuance of a 10-year nuclear power plant decommissioning licence by the Canadian Nuclear Safety Commission
    June 2016
  • Storage of all spent fuel bundles in dry storage modules
    December 2020

Prevention and safety

The Canadian Nuclear Safety Commission (CNSC) regulates the nuclear sector in Canada. It applies an approval regime that requires applicants and licensees to prove that their activities are in compliance with nuclear safety standards, as well as legislative and regulatory requirements.

As it does for all of its facilities, Hydro‑Québec drew up and keeps up to date an emergency response plan for the Gentilly‑2 generating station, which was updated following the announcement of the generating station’s closure. The plan calls for a permanent liaison between the Organisation régionale de la sécurité civile (ORSC) and Hydro‑Québec to coordinate actions at the Gentilly‑2 facility and those off site, whenever necessary. Since May 2016, the ORSC Mauricie–Centre-du-Québec abolished their external nuclear emergency response plan since the Gentilly‑2 facilities no longer posed a risk to neighbouring populations.

Site security

The Gentilly‑2 site is and will continue to be managed in accordance with strict safety and security standards. The CNSC approved the security program and oversees its implementation in accordance with regulations.

Regulatory oversight

The Canadian Nuclear Safety Commission regulates the entire life cycle of nuclear power plants. It ensures that decommissioning complies with regulatory requirements in order to protect workers, the public and the environment.

CNSC inspectors also oversee operations at the Gentilly‑2 site, even during decommissioning.

To reach us

Info-Project line

1 866 388‑1978


Véronique Trépanier
Advisor – Community Relations