Ukraine's Zaporizhzhya Nuclear Power Plant (ZNPP) has completed the planned transition of its reactor unit 5 to cold shutdown while moving reactor unit 4 to hot shutdown, Director General Rafael Mariano Grossi said today.
The ZNPP conducted this change in reactor status in order to carry out maintenance activities at unit 5 that are only possible in cold shutdown. Unit 5 was transitioned into cold shutdown yesterday morning, three days after unit 4 shifted to hot shutdown, its steam now being used to treat wastewater at the ZNPP. The other units remain in cold shutdown.
The IAEA experts at the site have been encouraging the ZNPP to investigate all possible options to install an external boiler instead to generate the steam required, which would enable the site to bring all units into a cold shutdown state. As reported previously, the Ukraine national regulator - SNRIU - had issued regulatory orders to limit the operation of all six units to a cold shutdown state.
Yesterday, the IAEA team visited reactor unit 5 where they observed the reactor vessel, spent fuel pool and the steam generator. The team noted that all equipment seemed to be in normal condition. There were no restrictions during the visit and the team did not observe any mines or explosives.
However, during a walkdown within the site's perimeter on Thursday, the team confirmed that the mines that they observed on 23 July were still in place. The IAEA is also continuing to request access to the roofs of the ZNPP's reactors and their turbine halls.
Over the last few days the IAEA team has heard occasional detonations; some at a distance away from the plant, and some apparently closer. Director General Grossi again stressed the paramount importance of adhering to the five basic principles for the protection of the ZNPP that he established on 30 May at the United Nations Security Council, stating that there should be no attack from or against the plant and that it should not be used as storage or a base for heavy weapons - multiple rocket launchers, artillery systems and munitions, and tanks.
"An increased risk of military activities near the Zaporizhzhya Nuclear Power Plant could potentially endanger nuclear safety and security at this major facility. I call on all sides to refrain from any action that could lead to a nuclear accident with potential consequences for public health and the environment," Director General Grossi said.
"Now more than ever, these five basic principles designed to ensure the protection of Europe's largest nuclear power plant must be strictly observed. It should be in everybody's interest to help prevent a nuclear accident," he said.
The IAEA experts at the ZNPP are continuing to closely monitor the situation regarding the availability of water for cooling the ZNPP's six reactors and other essential nuclear safety and security functions, following the destruction of the downstream Kakhovka dam in early June and the subsequent depletion of the huge reservoir near the plant.
The IAEA team reported that the available water supply remains relatively stable, with the water level in the site's large cooling pond decreasing by around 1 centimetre per day due to usage and evaporation. Submersible pumps have been periodically used to pump water from the Zaporizhzhya Thermal Power Plant (ZTPP) inlet channel to the ZTPP discharge channel. The combination of the pumping and heavy rain experienced during the week has seen the height of the ZTPP discharge channel increase by around 25 centimetres. The site continues to have sufficient water for some months.
On 27 July, the IAEA team conducted a walkdown of the cooling pond area, visiting a pilot well that has been built near the port. Testing of the quality of the water and the flow rate which will determine if the location meets the site's requirements for the well are ongoing, the team reported.
The IAEA experts also went to the cooling tower area, and the isolation gate of the discharge channel of the nearby ZTPP. During the walkdown, the team did not see any mines or explosives. However, the team could not go to the cooling pond retention gate to see progress of the construction of an additional barrier being put in place. The team was informed that the construction was completed but access was not authorised.
One of the off-site radiation monitoring stations, which had been damaged by military activity in the past, was restored earlier this week and put back into operation. However, the online data transmission to the SNRIU is still not working. As an interim measure, the data from the off-site radiation monitoring stations is manually provided to the IAEA team, which also regularly conducts independent radiation monitoring at the site. The off-site data and the team's own measurements are uploaded by the IAEA to the IAEA's International Radiation Monitoring Information System (IRMIS).
The IAEA teams at the Chornobyl, Rivne, Khmelnitsky and South Ukraine NPPs did not report any issues related to nuclear safety or security over the past week and have observed nothing unusual at the sites. Rotations of IAEA teams were completed this week at the Rivne, Khmelnitsky and South Ukraine NPPs.
As previously reported, the IAEA conducted a Support and Assistance Mission on the Safety and Security of Radioactive Sources in Ukraine over the past week. The fact-finding mission collected information that will provide the basis for identifying future needs and priorities in this area. A strategy for technical support and assistance in the area of nuclear safety and security of radioactive sources will also be developed.
