The official output is classified. It's enough to drive more than a thousand/two thousand tons of metal at better than 30 knots through water, though, plus various electronics including an active sonar capable of killing fish too close to it when it's on, so you have to figure it's perhaps half as powerful as a civilian plant. This means at least 20 megawatts, possibly more.
The thing is, yes, we've not had something crash an airplane, but you have to remember, submarines have been sunk with active reactors aboard. The Scorpion and the Thresher, and the Russians have lost a few too. As far as is possible to determine, none of them breached their containment vessels. The Scorpion and Thresher were both lost in deep water in the mid-Atlantic, and neither of them was capable of diving deeper than about 900 feet. (Furthermore, they wouldn't be that deep willingly, because that deep you can't tell what's going on on the surface because the thermocline layer over your head is in the way.) The water where they were lost was at least five times that. What is often forgotten about ships sinking is that they more or less fall the rest of the way to the ocean floor. It's not like dropping them from equivalent altitude, maybe a quarter of that. A ship hitting a rock bottom can look every bit as crumpled as if it had fallen onto a concrete surface from the air.
Scorpion's reactor containment vessel was confirmed to be undamaged when it was found...because the sub had hit the bottom hard enough it more or less pancaked and the reactor was forced out the top of the hull. Scorpion was, of course, brand new, and it is known that after ten years or so reactor containment vessels become very brittle because of constant radiation exposure. Nonetheless, it effectively fell the surface equivalent of 1000+ feet onto a rock surface without sustaining damage sufficent to breach the containment vessel.
