Nuclear power and the role of the government

My heart goes out to everyone in Japan after the earthquake, and the ensuing problems with the Fukushima reactor. Japan has long been my favourite country to visit and it is very sad to have to see the country and its people tested by an event of this magnitude.

Now I'll need to do a bit more research tomorrow to find out who owns TEPCO (I am pretty sure it is privately held with no or minimal government ownership), but the whole event got me thinking - what is the optimal ownership structure for something like a nuclear reactor or other piece of infrastructure whose failure could have a severe impact on the environment? Can and should such assets be privately owned? Or should the government retain some sort of ownership? Does government ownership imply such assets would be better operated and maintained?

Various allegations against TEPCO have emerged, including (i) basic safety and maintenance lapses prior to the earthquake, (ii) that when the earthquake happened, TEPCO delayed using seawater to cool the reactors because this action would have made the reactors unusable and inoperable (TEPCO was basically trying to prevent a write-off of its assets), and (iii) government civil defence and military forces were not called in until a fairly late stage, because they were not requested by TEPCO.

Now, could some of these problems and lapses have been avoided if the plant had been government owned and operated? The Japanese government reportedly helped cover up some of TEPCO's inadequate inspection and maintenance activities prior to the quake, though if the plant had been government owned and operated to begin with, perhaps these lapses wouldn't have occurred in the first place. Likewise, the decision to use seawater to cool the reactors may have been made earlier at a government owned plant, where profitability was not a concern.