Top secret until 2073 is no less than a cover up.
One sure wonders what it is that is so embarrasing/frightening that it has to be kept hidden until there is nobody left alive that can take an interest.
It must have been a major ****up not directly related to the accident itself.
I guess a major part of the civil servants got there hands dirty to an extent that, if it were to become public, all hell would have broken loose.
Things were quite smelly back in the days of the RLD, the competent authority.
There are things with a heavy odour right now with the successor, ILENT, as my recent dealings with them confirmed.