CBC Radio's story today - updated link - on the possibility a US serviceman may have been exposed to nuclear radiation at Argentia raises the issue of American nuclear weapons and Newfoundland and Labrador.
While the idea of nuclear weapons at Argentia would have been controversial a decade or more ago, there is enough research to conclude that nuclear weapons were present there for most of the Cold War although the presence of fissionable materials would most likely have been of very limited duration.
Mk 7, Lulu and Betty depth bombs, based on the original atomic weapons designs were introduced to the US navy in the 1950s and remained in service into the late 1960s and early 1970s. It is reasonable to assume that nuclear weapons components for these systems were either temporarily stored at Argentia or transitted through there on various American naval vessels and aircraft.
Components include the bomb casing, the firing and ranging systems and the high-explosive charge used to trigger a fission explosion. Fissionable material (the core) was legally in the hands of the US Atomic Energy Commission unless specifically released to the military. That normally happened in North America for frontline deterrent units.
At Argentia, fissionable material was deployed during the Cuban Missile Crisis and for a short period afterward, as far as I have been able to determine. This was not routine and certainly would not have involved large numbers of cores. Long term storage would have produced a detectable radiation signature and to the best of my knowledge there has never been such a signature detected at or near Argentia.
Here's the single most detailed account published recently. Here's another commentary that makes reference to the same book.
In short:
1. The US military routinely moved nuclear weapons around its various bases and stored them at many overseas bases throughout the Cold War.
2. These weapons often did not contain the nuclear cores needed to make them true nuclear weapons. What they did consist of was the casing, the high explosive detonating device and any electronics that go with the weapon.
3. The Canadian and American governments agreed on the deployment of nuclear weapons to Canada on many occasions and in the post-Cuban Missile Crisis period, the federal government understood and approved what was occurring. Nuclear weapons and their nuclear cores were stored on Canadian soil with the full knowledge of the Canadian government from time to time. There was a specific agreement for Argentia signed in 1968.
4. There have never been any tests of biological, chemical or radiological weapons at Argentia or anywhere else in Newfoundland and Labrador.
5. Project SHAD was a series of tests, some of which were conducted at Argentia, in which materials were released to study the distribution of radioactive particles and biological agents in the atmosphere. The tests also served to evaluate decontaminating procedures. No radioactive particles were used; rather the tests involved inert agents that simulated the behavior in the air of radioactive and biological particles.
A specific project summary for the COPPER HEAD test can be found here.