What do you consider acceptable? https://en.wikipedia.org/wiki/High-voltage_direct_current#Ad... puts the loss for HVDC at 3.5% per 1000km. That would imply 4000km with 15% loss, which is pretty good considering that wind and solar are significantly more than 15% cheaper than nuclear.

Specifically, https://en.wikipedia.org/wiki/Cost_of_electricity_by_source#... puts the cost of wind/solar at roughly 1/3rd the cost of nuclear, so it's more (cost) efficient to spend as much on transmission as you do on generation and build a really well connected massive grid than to use nuclear.

We can transport it a fair bit further than that, but only under ideal circumstances that are rarely met, and its very rare the grid is built for it, its never been needed after all. For instance, regulatory issues usually mean that every country border crossed tends to have a transformer station, which makes minor changes at a 10% or so efficiency loss.

Europe. Same grid. 8% losses