The Fukushima Daiichi Plants 1–4 accident 10 years ago was a catastrophe inside a far larger catastrophe created by a huge tsunami that engulfed a large region of the eastern coast of Japan.
More than 20,000 people were killed by the flood, none by the radiation and radioactivity from the core meltdowns of reactors 1–3. The core of reactor 4 was totally out and in the fuel pool during a routine maintenance operation there.
Those reactor plants are the same design as Vermont Yankee's was, but that is irrelevant. The whole plant layout for units 1–4 - built on the lowest elevation on the site - was locally customized, putting the electrical distribution in the basement. Reactors 5 and 6 on the site were built later, higher up, with a different electrical arrangement. The basements of units 1-4 were flooded, causing a loss of all electrical power, leading to the meltdowns. Units 5 and 6 were not disabled by the tsunami, and their emergency diesel worked.
The Units 1–3 containments held for more than a day, allowing an evacuation per plan, which all nuclear plants have.
From the beginning, international assistance has used lessons learned from the Three Mile Island accident and other events. Spread of contamination was stopped, plans were made, and temporary enclosure buildings were built around the damaged reactor buildings. Fuel has been removed from units 2, 3, and 4 fuel pools, and will be from Unit 1 in the next year or so.
A large area was contaminated to a level requiring evacuation and cleanup, which was done by removing a surface layer of soil. People can come back to most of the area, and Fukushima rice and vegetables are on sale again! The soil will be able to be reused when the radioactivity decays to a normal level, as all radioactivity does.
Most of the stored contaminated water has been cleaned up to an acceptable level and will be discharged to the sea, which is naturally radioactive, as is the Connecticut River.
Safety throughout the entire process is the first requirement. Each step will have to be planned based on what is learned in previous steps. Timelines such as 30 to 40 years are only speculative.
The Chernobyl accident was 35 years ago. With international assistance and funding, the plant was covered by a containment building, with the expectation it will be there for 100 years until radiation levels decrease to safe levels, before removal can begin.