> The problem is that this is not necessarily good for the grid as a whole
I agree. Average electricity prices seem to be higher the more renewables are available in a given area.
It seems to me that this, in part, is due to the pricing mechanisms available. Let's say a nuclear based energy company could sell power to its customers at a fixed price, where the customer would commit to buying this even when the spot price went lower.
Now, let's also assume that the customer would only pay for the grid capacity needed to transfer this power from the local power plant. If companies selling wind power needed a grid capable of transmitting the power from the other side of the continent, that extra cost would be slapped on top of the wind power, NOT other power sources.
In sum, this should make it possible to sell the nuclear power to consumers at prices moderatly above the production cost (plus taxes, local grid costs and reasonable profits).
For old nuclear plants (or those built at the prices available in Korea or China), this would make the price to the consumer quite competitive, if not outright cheaper than energy mixes based on renewables and natural gas.
Also, there is nothing technical that prevents us from building nuclear plants at the safety standards of those plants, with designs from about 1970 not only at the same price (inflation adjusted) as back then, but even much cheaper, due to technological developments. If so, I would expect production costs below $20/MWh. This would still cause less total harm per TWh than any other stable power mix available today.
What prevents this seems to be regulations at every level, where nuclear is burdened with all sorts of extra costs, ranging from insane security requirements and other red tape, limits on pricing in many markets, having to pay for the extra grid capacity required by renewable sources, excessive taxes or deposits for externalities that is not required for other energy sources.
Now let's say all power sources were held to the same standards when it comes to externalities such as safety/harm caused.
This would mean that wind would have to deposit enough funds to ensure proper recycling of blades at end-of-life (or at the very least, safe storage). Ditto for solar. Hydrocarbons have the same allowances for toxic substances as nuclear, in terms lives lost and diseases caused. The harm from greenhouse gases could also be priced in this way. Grid costs would be allocated proportionally to grid capacity requirements.
If we do this, I'm convinced Nuclear would come out as the cheaper than renewables combined with enough hydrocarbon plants (or batteries) to even out the variability of the production capacity. If all power source were punished the same as nuclear for any risks, they would be impossibly expensive. If the demands on nuclear were reduced to the same levels as other sources, it would become dirt cheap.