a nuclear power plant takes a decade or more to build

That's largely due to waste, not the actual process of safe construction. If there's public will, nuclear projects could be fast-tracked without compromising safety, though the costs would probably go up:

But those were far from the only costs. They cite a worker survey that indicated that about a quarter of the unproductive labor time came because the workers were waiting for either tools or materials to become available. In a lot of other cases, construction procedures were changed in the middle of the build, leading to confusion and delays. Finally, there was the general decrease in performance noted above. All told, problems that reduced the construction efficiency contributed nearly 70 percent to the increased costs.

By contrast, R&D-related expenses, which included both regulatory changes and things like the identification of better materials or designs, accounted for the other third of the increases. Often, a single change met several R&D goals, so assigning the full third to regulatory changes is probably an over-estimate.

So, while safety regulations added to the costs, they were far from the primary factor. And deciding whether they were worthwhile costs would require a detailed analysis of every regulatory change in light of accidents like Three Mile Island and Fukushima.

As for the majority of the cost explosion, the obvious question is whether we can do any better. Here, the researchers' answer is very much a "maybe." They consider things like the possibility of using a central facility to produce high-performance concrete parts for the plant, as we have shifted to doing for projects like bridge construction. But this concrete is often more expensive than materials poured on site, meaning the higher efficiency of the off-site production would have to more than offset that difference. The material's performance in the environment of a nuclear plant hasn't been tested, so it's not clear whether it's even a solution.

The above focuses on costs, but there's also some discussion about time as well (e.g. waiting for tools and materials).

nuclear waste

At least in the US, we have plenty of space for that. Most of Nevada is barren, and isn't likely to be used by people for anything important. There's also research into recycling spent nuclear fuel into new fuel:

Spent nuclear fuel from power plants still has 95% of its potential to produce electricity

I don't know much about water use though, so that could absolutely be an issue in many parts of the world. I am interested in looking into efficient ways to desalinize water, which is important for a whole host of reasons.

In conclusion, renewables are by far the best solution, not nuclear energy.

The best solution is a mixture of both. We need an inexpensive baseline energy production. Solar, wind, etc are bursty by nature, so we'd need a large amount of energy storage in order to go full renewable. Until I see a practical, inexpensive way to store energy, I'm going to push for nuclear since it's a clean, stable energy supply.

Renewables are a solution only in short term. The biggest issue with renewables is the relatively low power output. Our power demands will only grow in the future and eventually we're going to hit a wall with renewables. Long term nuclear is the way to go. Ideally we should be creating solar and wind parks and focus on making thorium reactors viable so we could switch from renewables to thorium.

Nuclear is the future, just not the kind of nuclear we're using right now.