If I have this story straight, back in (I think) the 1970s there was going to be some kind of nuclear reactor built at Jervis Bay (don't know if it was for power, more research or what). It got to the stage where they had poured at least part of the slab before it got canned.
I just had a look on Maps at where I thought I had previously seen it (in the flesh), and it seems to me it must have been at Murrays Beach, right at the southern tip.
Google Maps
Zoom out and check this horrible part of the world - definitely worthy of a nuclear bomb! Or not.