I have read that most of the first-generation nuclear power plants (installed in the late 1950’s, early 60’s ) are now at the end of their design life. One such planr (Yankee Rowe, in Rowe, Ma) was shut down a few years ago. I believ that the reactor core was removed, cut up, and buried in a secured land fill-but what about the containment dome? These things are 2-3’ thick, reinforced concrete-what do you do with them? ARE they simply filledup with concrete and left? Just how radioactive is a spent nuclear plant? Are they something that will be hazardous for 100-10,000 years? Rowe Yankee was a small plant…what about the giant nukes built in the 1980’s?
Finally, when are we going to see high temperature nuclear (ie gas-cooled, high-efficiency plants)? The old plants were mostly low-efficiency boilng water plants-I thought by now that we would have some new designs.
Here’s a good site about the decommisioning of Maine Yankee:
The reactor pressure vessel will be buried at Barnwell, SC (in progress). The dome will be taken down and the radioactive parts taken to Barnwell. The fuel will remain onsite in dry storage until the facility at Yucca Mountain is open. Eventually, the site of Maine Yankee will be returned to a “green field” state (but still suitable for another power plant 
).
The next generation nuclear power plants are simply evolutionary designs based on existing plants. They’re pretty efficient as is. High temperature gas cooled plants were tried in a few places (Fort Saint Vrain, Peach Bottom 1, I think), but proved to be difficult to keep operating because of material degradation and just generally being a hassle to operate.
They give it a gold watch and a pat on the back?