Canada's path to nuclear weapons is getting shorter, experts warn

Canada remains officially opposed to nuclear weapons, but experts say the country has one of the world's easiest technical paths to building them if the political will ever existed.

The reason lies in the design of Canada's CANDU reactors, which use unenriched natural uranium and can produce weapons-grade plutonium while concealing that production from international monitors in ways that light water reactors cannot. "The only thing that inhibits Canada is the will to do it, the political decision to do it," said Steve Fetter, a nuclear weapons expert at the University of Maryland who served in the White House Office of Science and Technology Policy.

Canada designed CANDU reactors to operate differently from most of the world's 440-odd reactors. While typical light water reactors require fuel enrichment and are refuelled infrequently—making it easy to track what goes in and out—CANDU reactors use online refuelling, meaning fuel can be swapped continuously while the reactor runs. That continuous process makes it harder for the International Atomic Energy Agency to monitor production, according to Ed Lyman, director of nuclear safety for the Union of Concerned Scientists.

Canada was a major participant in the Manhattan Project during World War II. After the war, the U.S. and U.K. were cut off from American nuclear cooperation, prompting Canada to develop its own completely indigenous program—which it ultimately chose not to weaponize, unlike the U.K.

Technological changes expected in coming years will likely make Canada an even more significant threshold nuclear power, whether or not the country crosses that threshold. For now, Canada remains a non-nuclear weapons state with no stated plans to change that policy.