One thing people often turn to in discussing nuclear energy a clean energy source is the Hanford Site along the Columbia River in central Washington. Here, you’ll learn about what happened at Hanford, why there’s a large cleanup project today, and that it is largely unrelated to commercial nuclear energy.
During the Manhattan Project in World War 2, American scientists knew of two potential ways to make materials that would explode as nuclear weapons: enriching uranium to nearly 100% 235U or producing plutonium in special nuclear reactors. Since they didn’t know which one would work, they tried both. Enrichment facilities were built in Oak Ridge, Tennessee, and special plutonium-producing reactors were built at Hanford, WA. Both approaches ended up working. After that and into the Cold War, weapons production capabilities grew at Hanford, and at least 9 weapons production reactors operated there through the years.
The plutonium-production process that occurred at Hanford involved irradiating nuclear fuel in a reactor, melting it down in a big acid vat, using chemistry to extract just the plutonium, and fabricating the plutonium into weapons. The giant vats of liquid radioactive acid were a waste product and dealing with them was not the priority of the Cold War (keeping up with the USSR was). So instead of implementing a nice waste-treatment process, the vats just sat there and the sludge was left for later generations. That’s what we’re dealing with now.
Of course not. Rather than melting down spent fuel and putting it in a vat, today’s commercial nuclear plants put their irradiated fuel in extremely solid and safe dry cask storage where there is no risk of anything radioactive leaking out. The spent fuel is solid, after all. The leaks at Hanford are unrelated to commercial nukes.
There are some benefits to recycling used commercial nuclear fuel, such as reducing the total amount of nuclear waste and using our resources more efficiently. To do this, you do need to melt the fuel down and do some degree of purification, similar to what happened at Hanford. The difference is, well-designed reprocessing facilities like La Hague in France include a stable waste form (e.g. vitrification) from the beginning. If you think it through, you can reprocess cleanly and safely. In haste of WW2 and the Cold War, waste forms were an afterthought.