When Astute is fully commissioned as a hunter-killer she will be fitted out with Tomahawk missiles which can be equipped with nuclear warheads for TLAM operations though they are more commonly used with conventional explosives for anti-ship use. So yes she is technically a nuke ship.

"Navy Larkers" will recall the exchanges between Philips and Goldstein usually ended with a cry of "Everybody Down!" followed by a rending crunch.