I stumbled onto a documentary about this on TV this evening - first I have ever heard of it. Did an atomic bomb fall in Canada?
http://www.portaec.net/library/peace/1950_bomber_crash_in_bc.html
http://www.cowtown.net/proweb/brokenarrow2.htm
http://www.portaec.net/library/peace/1950_bomber_crash_in_bc.html
http://www.cowtown.net/proweb/brokenarrow2.htm