Eh, the knowledge of how to construct a nuclear weapon has long been widely and publicly available. And it's not useful, not without weapons-grade fissile material. And if you could make weapons-grade fissile material you could figure out how to make a weapon if it wasn't already well-known.
In fact, we had a Supreme court decision on this with The Progressive v. United States, with the USSC ruling The Progressive had the right to publish the methods and details of constructing a nuclear weapon as it was in the public interest to know such things.
