I agree with retiring old tech, but my point was that I believe Japan has tried to hide the radiation risk. It’s all good crisis management, until people get sick years from now. See 9/11 https://secure.wikimedia.org/wikipedia/en/wiki/Health_effects_arising_from_the_September_11_attacks
“The lesson here is that 40 year old designs need to be retired and new plants built.”
Newer designs or not, a few more lessons might be:
Don’t falsify safety inspection reports at a nuclear power plant.
Maintain and test the backup systems.
Figure out a better solution for spent fuel.