CANDU 6 Fuel
Natural uranium fuel ore is mined in the Canadian Shield in Saskatchewan and northern Ontario. The uranium ore is converted to yellow cake (U308) at the mine. It is then taken to the uranium refinery in Port Hope, Ontario where it is refined to uranium dioxide (UO2), a black powder. At the fuel fabrication plant, the powder is compressed to form pellets, which are then baked in an oven to harden and give them properties of ceramic material.
Fuel received from the manufacturer is referred to as "new fuel". It is perfectly safe but must be handled very carefully because a fuel bundle cannot be used if it is damaged. The fuel arrives in ordinary transport trucks. Normally about one year's supply of new fuel is kept at the plant.
As it is required new fuel is loaded into the reactor using a fuelling machine. A sister fuelling machine is used simultaneously to remove the irradiated fuel from the other end of the channel being fuelled. On-power refueling is one of the unique features of the CANDU system. Staff in the Fuel Handling group are responsible for operating and maintaining the computer-controlled equipment that loads new fuel into the reactor and removes irradiated fuel.
As a result of becoming irradiated in the reactor, irradiated fuel is stored under water. Water is a good radiation shield and the water carries the heat away from the fuel bundles. After having been water-cooled for approximately seven years, the irradiated fuel is then stored in the on-site dry fuel canisters.
Starting in 1991, additional storage on site at Point Lepreau Generating Station was provided by concrete canisters in which the irradiated fuel is stored in the dry state. When fuel is first discharged it is very radioactive but it decays very rapidly. Within 1 hour of being removed from the reactor, the used fuel bundles have lost over 60% of their radioactivity and after 10 years 99.9% of the radiation has decayed away.
Although it would be possible to continue to store the irradiated fuel indefinitely at Point Lepreau Generating Station, it is intended to be moved to a permanent repository in the future. The Whiteshell Laboratory of Atomic Energy of Canada Limited (AECL) in Manitoba is responsible for developing Canada 's long-term storage arrangements.
Federal Legislation on Long-Term Management of Nuclear Fuel Waste
In April 2001, the Government of Canada introduced new legislation regarding the long-term management of nuclear fuel waste.
The new legislation mandates nuclear utilities to form a waste management organization that would provide recommendations to the Government of Canada regarding the long-term management of nuclear waste. The new legislation requires the utilities to establish a trust fund to cover the financial requirements for long-term storage.
Ontario Power Generation, Hydro Quebec, NB Power and AECL are working together to plan their next steps and implementation protocols. The legislation is undergoing committee review.
Proposed Long-Term Solution
Canada has undertaken research and development on the long-term management of nuclear waste. Under a plan developed by AECL, the spent fuel would be stored in corrosion resistant containers and permanently disposed of deep in the stable rock of the Canadian Shield . The containers would rest at a depth of 500 to 1,000 meters. The spent fuel would continue to lose its radioactivity safely shielded from human contact and the biosphere.
Another important component of the proposal involves transporting the spent fuel to the disposal site. Special transport casks have been developed which are able to withstand various types of accidents. The transport casks will withstand being dropped onto a hardened surface, exposed to a 800 degrees Celsius fire for 30 minutes, or immersed in water for a period of 8 hours. These tests ensure the casks will maintain their longevity and protection from the Canadian public and the biosphere.