-- First of all, complaints about the capex of nuclear make little sense if you are trying to argue for wind/solar; as the only reason you could plausibly make a case that solar/wind enjoy a comparable marginal levelized cost as fossil fuels is assuming that the cost of capital is insanely low thus making the large upfront capital expenditures on solar/wind infrastructure look like a better tradeoff than the cheaper upfront cost of fossil fuel and higher ongoing maintenance/fuel to run a fossil fuel plant.
If you are making that assumption for wind/solar it stands to reason you can make the same assumptions for nuclear as well. Of course, in the "real world" only super rich countries can afford to make those tradeoffs in the first place and given that nuclear usually requires access to cheap capital (i.e. government loans) it stands to reason wind/solar have the same problems; and to use an example I will return to later Germany has considerable subsidies for wind/solar compared to fossil fuels as expected.
-- Secondly, no utility uses the marginal cost of producing electricity for a power source that is inherently variable. The economic costs of failing to produce enough power for a regional or national utility outweigh any hypothetical marginal advantage for wind/solar. Essentially every wind/solar power source has to have a reliable backup source that can step in to ensure the utility can meet the demand for electricity. In most cases this just means you build cheap combined cycle gas plants. If you are a rich country like germany you can afford to overbuild your power generation capacity.
Countries like germany also have the advantage of being able to purchase energy from neighboring countries to make up shortfalls in demand. The german energy program relies on the availability of french nuclear power for precisely this reason. Of course, some days you can trumpet that some gigantic % of total production is supplied by wind/solar but this is mostly irrelevant from the financial perspective of the utility.
-- Finally, energy storage for wind/solar simply doesn't make sense with current technology. To take one example, Hydropower can already be expensive; now add in the cost of producing enough renewable energy to power all the original power produced by hydro cycle AND the cost of machinery to somehow replicate the operation of gravity. Basically you are looking at 2.5 to 3x the cost of your original investment to make your variable energy source reliable. Current lithium battery technology is totally unworkable at scale as another alternative.
To top it off I think the levelized cost figures often trumpted on this site for wind/solar are off anyway. Basically, unless you get a bunch of subsidies from the government it almost never makes sense unfortunately.