At that time, Sweden had a secret program to acquire nuclear weapons. They intended to either buy them from America or manufacture their own, with the intent of defending themselves from the Soviet Union. America decided not to support this, so Sweden wound down the program in the 60s and 70s and exported the plutonium they had produced to America.

That seems pretty short-sighted of him - atomic shelters come in useful if you're trying to survive your neighbors fighting without getting involved!