Work is ongoing at Ukraine’s Zaporizhzhya Nuclear Power Plant (ZNPP) to ensure it has maximum amounts of cooling water in reserve, in case it can no longer access the nearby Kakhovka reservoir which is continuing to drop after its downstream dam was damaged earlier this week, Director General Rafael Mariano Grossi of the International Atomic Energy Agency (IAEA) said today.
The reservoir’s water level has so far declined by around 2.8 metres since the dam was breached early on Tuesday, reaching 14.03 metres by 6 pm local time today, Director General Grossi said.
However, the hourly loss rate has slowed slightly, to between 5 and 7 centimetres per hour from a peak of around 11 cm/hour yesterday, he added, citing information from the IAEA’s experts present at the ZNPP.
If the level falls below 12.7 metres, the ZNPP will no longer be able to pump water from the reservoir to the site. As the full extent of the dam’s damage remains unknown, it is not possible to predict if and when this might happen. If the current drop rate were to continue, however, the 12.7 metre level could be reached within the next two days (the heights used are relative to the Baltic Sea – known as the Baltic Heights System).
Preparing for such a possibility, the ZNPP is continuously replenishing its water reserves – including the large cooling pond next to the plant as well as its smaller sprinkler cooling ponds and the adjacent channels – by fully utilizing the water of the Kakhovka reservoir while this still remains possible.
When full, these water sources will be sufficient to provide the plant with the water it needs to cool its six reactors as well as its spent fuel for several months. Even though the ZNPP’s six reactors are all in shutdown mode, they still require cooling water to prevent fuel melt and a possible release of radioactive material, Director General Grossi said.
The possible lack of access to the Kakhovka reservoir has underlined the need to keep the ZNPP’s other water sources intact, particularly the large cooling pond near the site, as well as the discharge channel of the nearby Zaporizhzhya Thermal Power Plant (ZTPP) which is used to bring water from the reservoir to the ZNPP site.
“It is essential that the integrity of both the ZNPP cooling pond and of the ZTPP discharge channel is maintained. This is critical so the plant has sufficient water to provide essential cooling to the site for the months ahead,” Director General Grossi said.
Director General Grossi will travel to the ZNPP next week to assess the situation there following the damage to the dam and to monitor compliance with the five basic principles for protecting the ZNPP that he presented to the United Nations Security Council on 30 May.
In view of the IAEA’s intensifying activities under the newly established principles, he will also strengthen the IAEA’s presence at the site, replacing the current team with a larger group travelling with him across the frontline.
“Now more than ever, the IAEA’s reinforced presence at the Zaporizhzhya Nuclear Power Plant is of vital importance to help prevent the danger of a nuclear accident and its potential consequences for the people and the environment at a time of increased military activity in the region. The possible loss of the plant’s main source of cooling water further complicates an already extremely difficult and challenging nuclear safety and security situation,” he said.
Five of the ZNPP’s six reactors are in cold shutdown. One unit remains in hot shutdown to produce process steam on site for operations such as the treatment of liquid radioactive waste which is collected from the six reactors even during the shutdown state of the reactors.