The Nuclear Waste Management Organization (NWMO) is responsible for implementing Canada’s plan for the long-term management of used nuclear fuel. Canada’s plan, termed Adaptive Phased Management, emerged from a multi-year study of options and dialogue with Canadians conducted between 2002 and 2005. Adaptive Phased Management is designed to be responsive to the values and expectations of Canadians and consists of both a technical method and a management system that includes the sustained engagement of people and communities throughout the phased process of decision and implementation. Adaptive Phased Management has as its end point the centralized containment and isolation of Canada’s used nuclear fuel in a deep geological repository (DGR) situated within a suitable rock formation.
The NWMO is currently working with a number of communities interested in learning more about the project and that are exploring their interest in becoming potential hosts for the deep geological repository. Ten communities have entered the site selection process: Ignace, Ear Falls, Hornepayne, Schreiber and Wawa, Nipigon and Red Rock in the province of Ontario, and English River First Nation, Pinehouse Village and Creighton in the province of Saskatchewan. All except Nipigon and Red Rock have successfully completed initial screenings and are considering taking the next step in the process (a feasibility study). Nipigon requested an initial screening in mid-November; Red Rock was discounted on geological reasons. There is no fixed timetable for implementing Adaptive Phased Management. Nor is there a fixed deadline for entering the site selection process. The NWMO has committed to giving six months notice before closing off siting process entry.
As Canada’s used fuel inventory is currently stored at seven nuclear sites across four provinces, transportation of the material to a centralized facility is a necessary component of Adaptive Phased Management.
Figure 1: Canadian spent nuclear fuel storage sites
The NWMO recognizes that people have questions and concerns about the transport of used nuclear fuel. However, Canadian and international experience demonstrate that used nuclear fuel can be safely transported.
Fuel type
Canada’s inventory of used nuclear fuel consists almost entirely of CANDU-type fuel made with unenriched, natural uranium. As with light water reactor fuel, it is a solid ceramic material encased in corrosion-resistant metal tubes of a zirconium alloy. However, the CANDU fuel elements are significantly smaller than their light water counterparts. Typically, 28 or 37 tubes are arranged into a cylindrical array called a fuel bundle. Each CANDU fuel bundle is roughly the size of a fire log and weighs approximately 24 kilograms.
Fuel discharged from the country’s commercial nuclear generating reactors is stored at the sites where it is produced. In addition, small amounts of fuel are present at the Chalk River and Whiteshell research facilities, and at university research reactors in Alberta, Saskatchewan, Ontario and Quebec. Canada’s existing inventory of used fuel amounts to approximately 2.3 million used fuel bundles, currently being safely stored in water-filled pools or dry storage containers, silos or vaults.
For the purpose of developing conceptual used fuel transportation systems and studies, a used fuel inventory of 3.6 million bundles was assumed based on planned nuclear reactor operation and refurbishment activities in Canada.
As the Adaptive Phased Management approach is built around a centralized repository facility, used fuel transport to this facility from the current sites will be required. Land modes of transport—road and rail (that is, truck and train)—are currently being investigated. Rail transport will require additional intermodal transport due to limitations of existing transport infrastructure.
Potential site location, available transport infrastructure in the vicinity and societal preferences must be carefully considered in mode selection. Presently, a number of communities have publicly expressed interest in learning about Canada’s plan for managing used nuclear fuel over the long term and are each at different stages of building their understanding.
Radioactive materials transport is a well-established practice in Canada. As a major supplier of the world’s medical isotopes, Canada ships about one million packages of radioactive materials each year. The transport of used fuel, however, has been much more limited in scale. Since the 1960s, more than 500 used nuclear fuel shipments have occurred, including the movement of 360 CANDU bundles from a demonstration reactor at the Bruce reactor site in Ontario to the Atomic Energy of Canada Limited’s (AECL) Whiteshell Laboratories in Pinawa, Manitoba. There are also periodic shipments of small numbers of used nuclear fuel bundles each year from the nuclear generating stations to AECL’s Chalk River Laboratories for research and post-irradiation examination.
The Canadian Nuclear Fuel Waste Management Program initiated in the 1970s included the design, testing, construction and certification of a transportation package to demonstrate the ability to transport large volumes of used fuel. The Irradiated Fuel Transportation Cask (IFTC) consists of a solid stainless steel box with walls nearly 30 centimetres thick and a lid attached by 32 bolts. It was designed to meet a series of severe performance requirements specified by the federal transportation regulations (based on international standards) to demonstrate the ability to withstand severe impact, fire and immersion in water. The package can contain 192 used fuel bundles, weighs almost 35 tonnes when loaded, and can be carried by all surface modes of transport without the need for special oversize permits (see Figure 2).
The IFTC was certified for used fuel transport in the 1980s and has been regularly recertified by the Canadian Nuclear Safety Commission since that time. The IFTC, shown above in Figure 2, provides the basis upon which existing used fuel transport planning is established.
Used fuel stored at the commercial nuclear electricity generating sites accounts for about 99% of Canada’s used fuel inventory. Three of these sites (Pickering, Darlington and Gentilly) are located on rail lines, and the remaining two sites (Bruce and Point Lepreau) are within 75 kilometres of existing rail infrastructure. Transport logistics will be largely dependent on the location of the repository site. Used fuel transported to the repository site is assumed to be cooled for a minimum of 30 years out-of-reactor, so the radioactivity and heat output of the fuel will have reduced considerably.
Figure 3 is a flow diagram of potential transport options by mode to a generic deep geological repository. Due to the limited inventory of used fuel at the Whiteshell site, road mode transport is assumed in all cases.
Figure 3: Proposed fuel flow diagram
Based on a processing capacity of 120,000 bundles per year at the deep geological repository, approximately 630 IFTCs will be received annually at the facility. In general terms, the shipment frequency by transport mode are about two road shipments per day or five rail shipments per month. Additional intermodal transport is required to support rail transport due to existing transport infrastructure limitations.
For a reference inventory of 3.6 million bundles, the Canadian used fuel transportation programme will require an operating period of 30 years. The programme is not expected to begin operation until 2035, the earliest assumed date for start of repository operation.
The existing used fuel transportation system is based upon a reference design of the deep geological repository. Much effort is currently being focused in the optimization of the reference repository design, including the design of the used fuel container for long-term management in the repository.
Optimization of the used fuel container design may influence fuel handling logistics at the interim storage facilities and at the repository site, potentially leading to changes to the transportation package design. The used fuel container design will be updated within the next few years, and used fuel handling and transport logistics will be clarified. Changes to the transportation system, including transport package design, will be addressed through a similar optimization programme.
Stakeholder engagement
Two federal laws govern the transport of radioactive materials in Canada today: the Transportation of Dangerous Goods Act, and the Nuclear Safety and Control Act. However, as road transport falls under provincial jurisdiction, provincial Highway Traffic and Transport of Dangerous Goods acts also apply. A large number of regulations based on international standards have been issued under these laws, which stipulate licensing, certification and safety requirements. The NWMO will work with federal and provincial authorities to ensure a common understanding of transportation policies, regulations, roles and responsibilities, and address any questions regarding Adaptive Phased Management transportation plans and processes.
Going forward, the NWMO will be identifying preferred transportation modes and potential routes for communities in the siting process. This will involve identifying existing transport infrastructure and calculating transport distances between the interim storage sites and a potential candidate site. In addition to working with the potential host communities, the NWMO will welcome communities along potential transportation routes as a large group with a shared interest to raise questions or concerns to be addressed in the process.
Conclusion
With over 500 used fuel shipments made since the 1960s, Canada has and continues to demonstrate its ability to safely transport used fuel. Regulations governing used fuel transport based on international standards are appropriate and in place.
The NWMO is developing a framework for a reference used fuel transportation programme. Further technical development of the programme will proceed over the next few years in parallel with developments in the siting process. Mode and routing decisions will require input from a broad range of stakeholders beyond those in the potential host community.
The NWMO acknowledges the concerns of many citizens about the transportation of used nuclear fuel and the need to demonstrate the safety of any transportation system to the satisfaction of citizens prior to the start of operations. On the basis of the work that the NWMO has conducted and the discussions it has had with nuclear waste management organizations in other countries, the NWMO believes used nuclear fuel can be transported safely.
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This article first appeared in the December 2011 issue of Nuclear Engineering International magazine (p21-22)
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