[chimera]

According to publicly available assesments of potential terrorist threats to nuclear facilities, it is not the reactor that is most vulnerable. It is the stored spent nuclear fuel. This stuff is secured such that a car or truck bomb would not likely get to it, but an aircraft would have a clear shot. In the case of a jumbo jet going into one of the known storage facilities, it is considered to be one of the worst possible scenarios. Worse by far than the WTC.

I don't see how it could be worse. The fuel storage pool is a quite robust structure. Not as strong as the containment building but no pushover. Sure, it contains spent fuel, but in general it has undergone quite a bit of decay. I may be wrong, but it is my sense that the source term for a storage pool release has got to be orders of magnitude smaller than for a core that has reached equilibrium burnup.

Impact would be the primary mechanism for storage pool damage. Fuel elements have very high melting temperatures. The zircalloy cladding would not weaken even at sustained high temperatures like you would have in a jet fuel fire.

Plus, it would be just damn hard to hit the thing head-on. You're talking about targeting a specific structure within the overall plant, not just plowing into the side of a building or smashing into the general area of the plant layout. Its possible, sure, but a cut above the difficulty of landing in the Pentagon.

[TKEman]

I agree with you. The Pentagon is a fairly large target. In order to hit it, even as large as it is, the terrorists had to circle around to lose some speed and drop altitude. These big airliners can't turn on a dime.

I doubt even an experienced pilot could pick out a specific small building within a complex such as Three Mile Island. And then hit it head on.