Chalk River Decommissioning and Environmental Remediation

Our strategy at CNL is to accelerate decommissioning to restore and protect the environment by reducing our nuclear waste footprint to uphold our science and technology mission for the benefit of all Canadians. Within the secure Controlled Area at Chalk River Laboratories, there are many buildings that have been used for a variety of purposes including office space, laboratories, nuclear processes, nuclear materials storage, and waste processing.   These buildings are typically made of wood and metal frames with concrete foundations and range from 30 to 60 years in age. Today, many have reached the end of their useful life and need to be decommissioned.

The NRX Reactor was Canada’s first large-scale research reactor. NRX began operation on July 22, 1947. The NRX design was conceived at the dawn of the nuclear era. It was a robust and versatile design that allowed the reactor to be operated for over four decades in support of:

• Fundamental nuclear physics research on materials using neutrons.
• Production of medical and industrial isotopes.
• Applied nuclear physics and chemistry research of reactor operation, including heavy water moderation and uranium and thorium fuels.
• Development and testing of reactor fuels and materials, known as the loop test equipment.

NRX permanently ceased operation on April 8, 1993, and a three-phased decommissioning began:

Phase 1 – establish safe, sustainable shutdown

Phase 2 – storage with surveillance

Phase 3 – final decommissioning

Workers completed Phase 1 activities in 1996 when the facility was placed in a safe shutdown state and formally turned over to the Facilities Decommissioning team. The Facilities Decommissioning team at Chalk River kept the facility in storage with surveillance until 2019, when the Canadian Nuclear Safety Commission granted CNL regulatory permission to begin final decommissioning work on NRX.

The final decommissioning phase has been split into two distinct stages.  The first stage includes the following scope of work:

• Engineering preparatory and enabling works
• hazard abatement and building clean-out
• scoping and characterization
• strategies and work plan development
• decommissioning of reactor experiments, loops, and support systems as well as targeted isolations

The second stage includes:

• remaining isolations
• removal of the new and old storage blocks
• reactor block
• chimney
• final building demolition followed by site restoration

The team is currently safely reducing the liability presented by NRX and completing characterization.

The 200 Series buildings include three large buildings in a laboratory complex, also used for nuclear materials storage and handling. The complex is structurally connected and consists of a former Thorium Fuel Reprocessing Facility/Bay De-ionization plant, a former plutonium plant, and former fuel rod storage and handling bays. The work that was formerly conducted in all three of the buildings involved work with fuel from the NRX reactor. The complex has a footprint of 38,545 Sq ft and was erected in the 1940s. Considerable progress has been made in all three buildings, each in a different decommissioning stage. The former Thorium Fuel Reprocessing Facility is the furthest ahead as the building has been isolated and contaminated systems have been removed while the former plutonium plant is expected to be the last of the three to be considered “Demolition-Ready” due to the high hazards within the facility.

Building 250 is a large multi-purpose laboratory with a footprint of 13,500 Sq ft. It was built over the course of three years, from 1950 to 1953. The laboratory formerly housed a hot cell facility and a tritium facility, as well as the Analytical Chemistry and Chemical Engineering branches. Due to its age, construction, and history, including the type of work and the materials involved, the decommissioning of Building 250 is a vital part of CNL’s environmental remediation goals.

In 2019, the Canadian Nuclear Safety Commission (CNSC) approved the final version of the Detailed Decommissioning Plan for B250. From a regulatory perspective, this approval permits the CNL team to proceed with the decommissioning and demolition of the building. The team has begun characterization and hazard abatement in the facility, including the removal of asbestos and dismantling of contaminated building components. Due to the age and state of the building, CNL will complete decommissioning on Building 250 as soon as practical.

To ensure future growth in Canada’s science and technology capabilities, CNL must reduce environmental liability and create space for modern buildings through the replacement and removal of deteriorating infrastructure in the Supervised Area at Chalk River Laboratories.

The Supervised Area at Chalk River Laboratories contains several older buildings that were utilized for office space, manufacturing, maintenance support, and supply storage functions that were not directly involved in nuclear operations. The buildings are typically of wood and metal frame construction on concrete slab foundations, ranging from 40 to 60 years in age, and are ready for decommissioning. The decommissioning and demolition of these redundant buildings and structures not only reduces hazards and liabilities but also supports the revitalization of Chalk River Laboratories.

The project to remove and replace redundant buildings in the Supervised Area began in 2016 and many facilities have already been removed.

Minimizing the nuclear liabilities at Chalk River Laboratories is of utmost importance to CNL and supports Canada’s commitment to a clean and healthy environment for all. Environmental Remediation is the removal, reduction, or control of contaminants from water (both groundwater and surface water) and sediment to protect human health and the environment. The Environmental Remediation program will progressively reduce the nuclear risks and liabilities at Chalk River Laboratories through prudent management and the cleanup of legacy contamination and affected sites. This work is a key part of our Environmental Remediation Management mission, ensuring the site is ready for next land use assessments in consideration of public and Indigenous perspectives.

Right now, the Environmental Remediation team is conducting site assessment and characterization activities to support remedial decision-making for affected lands and historic non-operational Waste Management Areas at Chalk River Laboratories. Ultimately, the team will clean up the land and groundwater to meet end land uses and cleanup criteria at Chalk River Laboratories. CNL determines what specific actions to take on a project site-specific basis. Options for impacted sites range from full retrieval and appropriate dispositioning of wastes and contaminated soils to in situ management.