On the night of 10 August, the Russian-occupied Zaporizhzhya nuclear power plant lost feed from the main 750 kV external power line, Ukraine's atomic energy operator Energoatom has said on Telegram.
After that, ZNPP had to switch to the only available backup line of 330 kV, the disconnection of which carries a risk of blackout.
"In case this scenario materialises, the main threat to nuclear and radiation safety is the continuing hot shutdown mode of Zaporizhzhya NPP Unit 4, which the occupiers operate in violation of the terms of the licence to operate NPP reactor units of the Ukrainian regulator (SNRIU)," the company said.
According to Energoatom's acting executive director Taras Tkach, in case of a complete loss of external power supply, the main circulation pumps of the plant will be shut down and the power unit will switch to the natural circulation mode.
"In this case, it would be necessary to urgently 'cool it down' in the absence of cooling pumps," said Tkach.
This mode is difficult for the reactor, its duration is limited by the design, and it can lead to a failure of the main equipment of the power unit.
"The further occupation of ZNPP by Russia, the operation of the plant by the illegitimate and ill-trained ruscist management, which bears no responsibility for the nuclear and radiation safety of the facility, will continuously lead ZNPP to a catastrophe," Energoatom warned.