In terms of software, there are plenty of options but I use Fusion 360 for anything CAD. It is a professional tool that you can use for free for personal use. Blender works well for more artistic things, or organic shapes, and is also free.
In terms of hardware, I don’t have enough knowledge or experience to help you. I’m running a Creality CR-10 V3 and very happy with the results, but I’m not sure it is your ideal printer.
What you should definitely do is figure out what kind of materials you want to use, and how large you want the print bed to be. Those are going to influence your choice a lot, and it will help someone with more knowledge to recommend something 😀
There is a difference between contaminated water, like in Fukushima, and regular non-contaminated cooling water. There should be no radioactive contaminants in the water that the French nuclear power plants release.