Mark HibbsUkraine: ZNPP Reactor Restarts

On February 10, the International Atomic Energy Agency (IAEA) published a statement from Ukraine’s nuclear regulator spelling out that, unless Ukraine has resumed control of the station and safety examinations had been carried out, none of the six power reactors at the Zaporizhzhia Nuclear Power Plant (ZNPP) will be permitted to generate electricity:

“The State Nuclear Regulatory Inspectorate of Ukraine (SNRIU) informed the IAEA that it would only permit ZNPP to resume power-generating operations after it has been returned to the control of Ukraine and a thorough inspection program and the implementation of any measures deemed necessary to restore the plant to safe working conditions have been completed.”

The release of the Ukraine statement was timely and it may not have been coincidental: On February 6, on this website I raised issues concerning the future operational status of the ZNPP reactors under Russian occupation, having been informed that for specific reasons, decision makers might aim to restart reactors during 2023, and that doing so might significantly affect the risk profile of the plant. 

During most of 2022 Ukraine and Russia responded to Russian invasion and occupation by intentionally limiting reactor operation; in September and October all six reactors were put into “cold shutdown” in response to shelling attacks and ongoing personnel conflict threatening the station. After a few weeks, management began taking actions to permit two shuttered units, Z-5 and Z-6, to resume operation. Aside from the stated aim of generating local heat and steam, operating the reactors might protect their licenses and avoid equipment damage and safety challenges that prolonged outages would incur. Separately, Ukraine has objected that Russia aims to restart the reactors in order to connect ZNPP to the Russian power grid. In addition, under an IAEA-proposed “nuclear safety and security protection zone” for ZNPP, it has not been publicly disclosed whether reactors would be permitted to operate and under what conditions. 

For as long as the war continues, operational factors may figure significantly in decision making of line managers. Long reactor outages at ZNPP could result in conflict between safety authorities and operator organizations. According to regulators in one European country operating Russian-design VVER power reactors, after a prolonged outage, the plant operator would have to justify the safety of the plant and demonstrate that safety systems are operable. This justification may require additional testing of the safety systems at a level that had been required at the time the plant was initially commissioned for operation. The intensity of such safety examinations would “strongly” depend on “how the systems are kept operable during the shutdown period.” 

The statement from Ukraine published on February 10 would imply that, for as long as Russia occupies and controls ZNPP, the plant will not generate any electricity, and that ZNPP will not be connected to Russia’s power grid. The statement does not expressly exclude operation of reactors under “hot shutdown” conditions without power generation. Prior to Russia’s invasion of Ukraine, ZNPP routinely produced about 20% of Ukraine’s electric power.