The attacks of russians on Ukraine's electricity grid revealed a safety feature of the convenient nuclear power plants (at least those operated in Ukraine) - they cannot produce electricity while being alone in the grid (or in isolated pieces of the grid). If inflow of electricity fails the nuclear power plant switches to diesel generators and gradually decreases its power output going effectively into hibernation. Attacks of November 23 caused exactly that, all three nuclear power plants (excluding ZPP which is on temporarily occupied territory) were shut down since they lost incoming power [1].