International Atomic Energy Agency director general Rafael Grossi reported on 29 July (Update 176) that Ukraine’s Zaporizhzhya nuclear power plant (ZNPP) had completed the planned transition of its reactor unit 5 to cold shutdown while moving reactor unit 4 to hot shutdown.
ZNPP made this change in order to carry out maintenance activities at unit 5 that are only possible in cold shutdown. Unit 4 was shifted to hot shutdown on 25 July. Its steam is now being used to treat wastewater at ZNPP. The other units remain in cold shutdown.
IAEA experts at the site have been encouraging 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. The Ukraine national regulator – SNRIU – had previously issued regulatory orders to limit the operation of all six units to a cold shutdown state.
On 28 July the IAEA team visited reactor unit 5 where they assessed the reactor vessel, the spent fuel pool and the steam generator, and noted that all equipment seemed to be in normal condition. There were no restrictions during the visit and the team did not observe the presence of mines or explosives.
However, on 23 July during a walk round IAEA experts observed directional anti-personnel mines on the periphery of the Zaporizhzhya site. They were located in a buffer zone between the site’s internal and external perimeter barrier in a restricted area that operating plant personnel cannot access, and they were facing away from the site. The team did not observe any within the inner site perimeter at that time.
During a walkdown within the site’s perimeter on 27 July, the team confirmed that the mines that they observed on 23 July were still in place. In connection with this the IAEA is continuing to request access to the roofs of the ZNPP’s reactors and their turbine halls.
During the week of 23 July the IAEA team had heard occasional detonations, some at a distance 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 … Zaporizhzhya … 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,” said Mr Grossi.
“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 is 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 reducing by around 1 cm day owing to usage and evaporation. Submersible pumps have been periodically used to bring water from the Zaporizhzhya thermal power plant 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 cm. The site still has 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, damaged by military activity, has been back into operation, but the online data transmission to the SNRIU is not. 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. This data is uploaded to the IAEA’s International Radiation Monitoring Information System (IRMIS).
The IAEA conducted a Support and Assistance Mission on the Safety and Security of Radioactive Sources in Ukraine over the week of 23 July. The information collected 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.
- Update: Following repeated requests, on 4 August the IAEA was allowed access to the rooftops of Unit 3 and Unit 4 reactor buildings and the turbine halls but found no mines or explosives. The team had unimpeded access to the rooftops of the two reactor units and could also clearly view the rooftops of the turbine halls. IAEA will continue its requests to visit the roofs of the other 4 units at ZNPP.
Image courtesy of Ukrinform