HELLO COMRADES!
New hotfix (1.0.1176.0) is live,
From now on if the game saves the radiation on a high level, it will be automatically lowered, so you'll be able to survive after loading the save file with the high amounts of it.
In addition, you'll be able to invert Y-axis in the Controls menu.

Sorry for the inconvenience.
Good luck in the Institute ventures…