Ukraine's Zaporizhzhya Nuclear Power Plant (ZNPP) has started to transfer reactor unit 4 from hot shutdown to cold shutdown today following detection of a water leak at one of its four steam generators located in the containment of unit 4, Director General Rafael Mariano Grossi said.
The ZNPP will place unit 4 into cold shutdown to determine the precise cause of the water leak that has been detected and to conduct maintenance to repair the affected steam generator. There was no radiological release to the environment. At the same time, over the next three days, ZNPP will move unit 6 to hot shutdown to continue steam production on site.
Unit 6 has been in cold shutdown since 21 April, to enable inspection and maintenance of the safety systems. During the week, the IAEA experts were informed that ZNPP has been conducting specific maintenance on parts of unit 6 safety systems and ZNPP has stated that this work and all tests of the safety systems were successfully completed before commencing the transition of unit 6 to hot shutdown. The IAEA team on the site will closely monitor the operations for the transition between the shutdown states of Units 4 and 6.
The other units at ZNPP remain in cold shutdown.
As previously reported, the Ukraine national regulator - SNRIU - has issued regulatory orders to limit the operation of all six units to a cold shutdown state.
The site uses the steam generated from one reactor unit in hot shutdown for various nuclear safety purposes including the processing of liquid radioactive waste collected in storage tanks. The IAEA continues to strongly encourage the installation of an external source of process steam, which, from a nuclear safety perspective, would provide the safest longer-term solution for the steam needs at the site.
Today, the 750kV Dniprovska power line disconnected twice. First for approximately twelve hours until 13:37 and then again at 16:13 local time. It remains disconnected.* These disconnections of the 750 kV power line mean that the ZNPP has had to rely on its only remaining off-site power line, the 330 kV backup line, to supply the electricity that is required, for example, to perform safety functions such as pumping cooling water for the plant. There was no total loss of off-site power to the site and there was no need to use the emergency diesel generators
ZNPP has been experiencing major off-site power problems since the conflict began in early 2022, exacerbating the nuclear safety and security risks facing the site currently located on the frontline.
"The repeated power line cuts underline the continuing precarious nuclear safety and security situation at the plant," Director General Grossi said.
The availability of cooling water remains relatively stable at ZNPP. While the height of the ZNPP cooling pond continues to drop by about 1cm per day, the height of the discharge channel from the neighbouring Zaporizhzhya Thermal Power Plant (ZTPP) is regularly being topped up by pumping water from the ZTPP inlet channel.
During the past week, the IAEA experts conducted multiple walkdowns in different parts of the site.
On 4 August, the team visited the dry spent fuel storage facility, where they were able to verify the integrity of the fuel casks stored there.
On 8 August, the team visited the unit 2 main control room, emergency control room and other safety-related rooms. They did not observe any mines or unusual objects in these areas. However, in the turbine hall of unit 2, the team noted the presence of a number of military trucks parked in an area reserved for vehicle maintenance.
While the team did not observe mines or explosives in any new locations during the past week, they did confirm the presence of the mines previously observed on 23 July 2023.
Today the IAEA experts visited one of the fresh fuel storage facilities. They confirmed that the fresh fuel was safely and securely stored.
Following the IAEA experts' visit to the unit 3 and unit 4 rooftops last week, the team continues to request access to conduct walkdowns on the rooftops of the other four units.
The IAEA experts were informed by ZNPP that a drone was spotted and intercepted near Enerhodar on 9 August, but this was not related to ZNPP, the neighbouring thermal power plant or the city. There was no impact on ZNPP's safety, and the IAEA experts confirmed that they did not hear or observe anything at the plant.
The IAEA experts at the Khmelnitsky, Rivne, and South Ukraine NPPs and the Chornobyl site reported several nationwide air-raid alarms yesterday. The teams all reported that the safety and security at the facilities was not affected. The IAEA is aware of reports of an attack last night in an area approximately 60 km from Khmelnitsky NPP and 150 km from the Rivne NPP.
* Status at 19:00 CEST
