Can you point me towards what you read on this outside of the article? Not doubting you it's just been like 500 years since I studied nuclear chem and I'm not sure what literature you're talking about.

A good introduction is Eric Schlosser's Command and Control. For the points here the concept of one-point safe is the idea of if a nuclear device is likely to detonate in an uncontrolled situation. A good definition I found was[0]:

> What is one-point safe?

> Apart from preventing unauthorized use, it is equally important to ensure that the weapons do not explode accidentally. For example, if it is accidentally dropped dur­ing transportation (such incidents have occurred), it should not explode. A nuclear weapon is one-point safe if, when the High Explosive inside the weapon is initiated and detonated at any single point, the probability of producing a nuclear yield exceeding 4 pounds TNT equivalent is less than 1 in one million.

A surprising number of early nuclear devices were not one-point safe.

[0] http://www.nucleardarkness.org/nuclear/nuclearandconventiona...