That's incredibly short sighted. And not just the measure of 'centuries' (even if that were true, it's still arguably just postpone the problem). Energy demand is going up, sharply, as more countries join our standard of living. We will, definitely, need technologies that are as clean as possible to meet the demand, eventually. No amount of pollution that is avoidable is acceptable at the scale we are going to witness. Which brings us to
> the overall environmental impact is better than that of renewables
I've stopped buying this argument and I'm sick of seeing it again and again - it's complete and utter Bullshit. The only way we have come up in terms of "dealing" with the highly toxic waste that nuclear energy produces (letting alone the often brushed over but equally horrifying ecological cost of mining the fuel) is to store it away "somewhere". The kicker is: We have not figured out that "somewhere". In Germany, there is exactly one site that is being developed for this. We literally ship the containers there and they sit in a holding facility above the salt mine because we have not even figured out how to get the fuel from the shipment containers into the storage containers. Oh, and the storage containers haven't been fully developed either. This is a catastrophe just waiting to happen.
Years and years of politics playing nice with (and pushing money into) the nuclear industry have produced no results that a reasonable person could support. What the government had done was basically doubling down on what is often - in this thread as well - requested: To let the market figure it out. Oh they have figured it out alright. Just not the part about it also being reasonable. Or even sane.
And this is only for the waste that was produced so far. The technology and storage capacity for centuries of waste simply doesn't exist. At all.
Story time: They actually did have the "solving" of this in mostly private hands for a long time - a semi-government agency (under strong, yet curiously absent oversight) conducted "experiments" on how to store the waste in a different salt mine [1]. They "experimented" with things like whether they roll or "throw down" barrels into caves. When they "noticed" that they had a problem with huge amounts of radioactive water rising up everywhere, they "solved" it by pumping it down into a deeper cavity. That whole agency was abolished and replaced and put under proper (and horrified) oversight when the extent of the disaster came to light in a huge scandal.
They have been "working on" trying to clean up this mess since nineteen frigging ninety five. They haven't even figured out how to drill into the closed off cavities to get the improperly stored fuel out of there, for crying out loud! All while cancer rates are going off around the site.
So yeah, great environmental impact. Go sell your snake oil somewhere else.
Very few things piss me off as much as nuclear defenders selling their technology as reasonable. Zero Carbon Emissions, Woo! Give me a break.
[1] http://en.wikipedia.org/wiki/Schacht_Asse_II - the German version is a lot more in-depth: http://de.wikipedia.org/wiki/Schachtanlage_Asse - the English version seems to brush over much of the issues.