Nuclear energy (from fission) has a very large number of disadvantages. Here are just a few:
- It's inherently and obviously risky --- even its greatest proponents know that, but they just choose to minimize the importance of that risk and its deadly consequences. There have been more than enough nuclear reactor disasters already, yet some people just don't learn. Even with better designs, accidents will happen from geophysical causes and through human failure, as well as by deliberate action. You can't prevent this from happening, so don't create such deadly installations (and juicy targets) in the first place.
- Radioactive waste from fission accumulates a massive liability for future generations. It forces our own chosen risk onto our descendents without giving them any choice in the matter. This is unethical even in the best of cases, but in the worst case it's downright criminal because some of those radioactive stores will unavoidably release their contents (even explosively with human help) and result in human casualties and suffering --- maybe your own descendents. Don't gamble with the lives of others.
- Nuclear energy is out of step with a world that is rapidly converting to clean, inexhaustible energy harnessed from the environment. Nuclear is not just unclean but deadly unclean, and it's very demanding on the planet's resources as well. It adds to our debt on the planet instead of reducing it.
- According to a growing number of climatologists who are witnessing first-hand the unfolding climate disaster in the Arctic and Antarctic, our existing several hundred nuclear reactors could quite possibly be the direct cause of our extinction in the decades ahead, after the indirect cause (CO2 and methane) lead to death by starvation of billions and make the world's economies collapse. Nuclear reactors can't be rapidly turned off and made non-radioactive --- the full process of decommissioning takes some 50 to 60 years as an industry average, and it takes a LOT of money. There will be no money available under conditions of economic collapse, cooling will be interrupted, and many will go into meltdown. Even if you choose to disbelieve the warnings of specialists, the risk remains. Knowing what we already know about rising sea levels and epic storms, we should not be adding to the risk.
Dr. Brice Smith of the Institute for Energy and Environmental Research summarized this very well:
"Nuclear power is a very risky and unsustainable option for reducing greenhouse gas emissions. Trading one potentially catastrophic health, environmental and security threat for another is not a sensible energy policy." --- Source.
The whole idea of adding more nuclear power is hazardous and ill-considered, and it's also unnecessary.