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The destruction of the Kakhovka dam has consequences for the cooling system of the Ukrainian nuclear power plant Zaporizhia, but for now an alternative cooling system offers salvation, says the international nuclear watchdog IAEA. Cooling water is currently being drawn from the reservoir behind the dam, but the water level there is dropping rapidly. It’s enough for a few days, says the IAEA. After that, a switch must be made to an alternative cooling water reservoir. It is currently estimated that this is enough for several months of cooling, says IAEA director-general Rafael Grossi.
For the time being, there is therefore enough cooling water available, but Grossi emphasizes its importance for the safety of the plant. “If there is no cooling water left in the cooling systems for a longer period of time, this will lead to the failure of the emergency diesel generators and the melting of fuel rods”, he says.
Joost van den Broek, nuclear expert at NRG Petten, also points to the importance of cooling in a nuclear power plant. “As soon as one or more fuel rods melt, it can lead to the release of nuclear material, if other safety barriers also fail.”
Fill reservoirs to the maximum
The blowing up of the dam mainly affects the ‘normal’ cooling system of the nuclear power plant. Due to the break in the dam, the water in the reservoir near the power station drops at about 5 centimeters per hour. Early this morning the water level there was 16.4 meters. If it drops below 12.7 meters, it can no longer be pumped to the plant.
“At the moment they are trying to fill all the storage facilities of the cooling system to the maximum,” says Mark van Bourgondiën of the Authority for Nuclear Safety and Radiation Protection – the Dutch regulator for nuclear power plants. “If the water in the reservoir drops below the intake point, then they have to switch to other cooling water sources, such as water from the cooling pond.” That cooling pond is currently well filled, according to Van Bourgondiën.
The dam is about 120 kilometers from the nuclear power plant as the crow flies and pushes up the water in the Dnieper River. That is the main cooling system. The backup is an elevated pond with cooling water next to the power plant. That reservoir is about 16.6 meters deep, according to the Ukrainian energy agency Energatom.
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Cooling pond at Zaporizhia Nuclear Power Plant -
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Zaporizhia nuclear power plant is located about 120 kilometers from the Kakhovka dam as the crow flies
The amount of water in the cooling pond should therefore be enough for several months, especially since the nuclear power plant currently generates relatively little heat. Four of the six reactors were shut down more than a year ago, requiring far less cooling than operating reactors. “This is less than 1 percent of the cooling demand compared to reactors that are fully operational,” says Van Bourgondiën.
Until recently, two other reactors were in a so-called hot shutdown, so that they could still provide steam and heat for use in the nuclear power plant itself and in homes in nearby Energodar. The last two reactors have also been shut down.
IAEA chief Grossi has called on warring parties to leave the cooling alone: ”It is vital that the pond remains intact.” Van den Broek of NRG also sees the vulnerability there. “The reservoir is now becoming very crucial. If it leaks in any way, then you have to rely on real emergency resources.”
He mentions, for example, the supply of water by truck. According to Van den Broek, the situation is also so precarious because safety is being challenged in other areas. “The power supply has been attacked, there are far fewer people working, there is fighting around the power plant. Several layers are built into a nuclear power plant to guarantee safety, which are peeled off layer by layer in this way. That is extremely undesirable.”
2023-06-06 17:54:51
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