In Situ Decommissioning of the Whiteshell Reactor #1

Canadian Nuclear Laboratories (CNL) is proposing to decommission the Whiteshell Reactor #1 (WR-1 Reactor), a former nuclear research reactor that operated until 1985. The WR-1 Reactor is located at the Whiteshell Laboratories (WL) site in Pinawa, Manitoba, which is situated approximately 100 kilometres northeast of the city of Winnipeg and located near the towns of Lac du Bonnet and Seven Sisters.

CNL is proposing an in situ (leaving in place) decommissioning approach. In situ decommissioning of the WR-1 Reactor involves preparing systems and structures for grouting whereby the below-grade sealed structure will encapsulate and contain radiological sources and hazardous materials for a defined period of institutional control.

The following activities are being proposed:

  • preparation for in situ decommissioning
  • grouting of below-grade (underground) structures and systems
  • removal of above-grade structures and systems
  • installation of engineered cover over grouted area
  • final site restoration
  • long-term care and maintenance activities

Some temporary infrastructure – such as construction trailers and equipment paddocks, as well as an increase to the electrical services – would also be required in order to facilitate decommissioning. Additional groundwater monitoring wells would be installed, as required, to monitor the performance of the in situ decommissioned facility.

Under the Nuclear Safety and Control Act, CNL's proposal requires an amendment to its existing Decommissioning Waste Facility Licence issued by the Canadian Nuclear Safety Commission (CNSC). An environmental assessment conducted under the Canadian Environmental Assessment Act, 2012 is required, and an EA decision affirming that the proposed activities will not cause significant adverse environmental effects, before the CNSC can make a licensing decision on this proposal.


This map is for illustrative purposes. The markers represent the approximate locations based on available data. More than one marker may be identified for a given assessment.


Latest update

April 30, 2020 - On March 27, 2020, Canadian Nuclear Laboratories (CNL) submitted a revised draft environmental impact statement (EIS) for the proposed In Situ Decommissioning Of the Whiteshell Reactor #1 Project to the Canadian Nuclear Safety Commission (CNSC), which included an updated EIS, updated technical supporting documents, and consolidated responses to all federal and provincial information requests. CNSC staff conducted a completeness check and determined that insufficient information was provided to enable the federal and provincial review team to proceed with the EIS technical review. CNL is expected to provide additional information and resubmit the revised EIS and supporting documents at a later date. More information can be found in the April 30th letter to CNL, and the subsequent completeness check table.


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Canadian Nuclear Safety Commission
Aimee Rupert, Environmental Assessment Officer
280 Slater Street
Ottawa, Ontario K1P 5S9
Telephone: 613-316-2087 or 1-800-668-5284

  • Location

    • Pinawa (Manitoba)
  • Nature of Activity

    • Nuclear Energy
  • Assessment Status

    In progress
  • Start Date

  • Proponent

    Canadian Nuclear Laboratories
  • Authorities

    • Canadian Nuclear Safety Commission
  • Assessment Type

    Environmental assessment under CEAA 2012
  • Reference Number


Nearby assessments

..within 200 kilometres
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