The risk of an accident at the Zaporizhzhia nuclear power plant in southern Ukraine is more linked to a succession of equipment failures and errors – catalyzed by the war – than to the possibility of a direct shot hitting a reactor. Despite this, the impact of a nuclear accident would be so high that the international community dramatically increased pressure this week on Russia, which controls the nuclear facility.
For the first time in history, a large nuclear power plant is in the middle of the battlefield in a high-intensity war. It is the largest plant in Europe and is located in the city of Enerhodar, in the oblast (state) of Zaporizhzhia. It accounts for 19% of Ukraine’s electricity supply.
The complex was invaded by Russian forces on March 4. The action set off a fire in non-essential facilities and sparked a wave of international criticism. The takeover of the plant was part of a rapid advance by the Russian army that resulted in the capture of a large swath of southern Ukraine in the first week of the war.
The battlefront soon advanced towards the northeast, towards the city of Zaporizhzhia, capital of the oblast. Thus, the region of the plant, in occupied territory, began to enjoy relative tranquility.
A part of the approximately 10,000 employees continued to operate the plant, but forced to do so by the Russians. It began operating at minimum capacity, with only two of the six reactors operating, but it continues to supply power to regions under the Ukrainian government’s control.
Even with the fighting taking place about 60 kilometers from the plant, the possibility of a missile hitting one of the six nuclear reactors has always terrified residents of the region. I witnessed this on the morning of April 26, when the city of Zaporizhzia was bombed. Reports quickly spread across the region of people who saw cruise missiles fly over the plant. Panic spread through the city, but there was no damage to the nuclear facility.
However, reports of explosions at the plant reoccurred in August. A fire station and radiation measurement stations were destroyed. Russia and Ukraine blamed each other for the attacks.
These events began to occur after the start of a major Ukrainian counteroffensive to try to retake part of the Kherson oblast, which lies about 180 kilometers southwest of Enerhodar along the Dnipro River. Until then, the biggest fighting of the war had been concentrated in the north and east of the country.
At least 20,000 Russian fighters were redirected south to thwart the Ukrainian counteroffensive. Russian artillery units were then positioned between the plant’s six reactors to fire primarily at the city of Nikopol or at Ukrainian troops attempting to cross the Dnipro River. In other words, the plant was used by Moscow as a kind of shield, allowing the Russians to fire freely without the threat of a counterattack.
Russia has accused Ukraine of acts of terrorism, for allegedly shooting at the plant. Ukrainian officials say they have evidence that the Russians are faking false attacks to try to blame the government of President Volodymyr Zelensky for facilitating a catastrophe.
According to the Ukrainians, a Russian film crew had been caught staging a fake Ukrainian attack. The footage would be used in information warfare.
It is not possible to independently verify for the moment which is the correct version of these facts.
Real risks to the plant
Russia and Ukraine are known to fight in the Zaporizhzhia region mainly using artillery fire. These include mortar and howitzer fire (which are types of cannons that fire grenades in a parabola trajectory) and rockets. These armaments can destroy armored vehicles and fortifications.
However, all the nuclear reactors and pools of radioactive material discarded at the Zaporizhzhia plant are protected under concrete and steel structures about 1.2 meters thick. They are sufficient to withstand accidental artillery impacts from a large aircraft collision.
However, there is the possibility of radioactive leakage caused by failures in the nuclear fuel cooling systems.
The Enerhodar plant was built in the 1980s and uses VVER (pressurized water nuclear reactor) technology. According to engineer Dagoberto Lorenzetti, a specialist in nuclear energy, the system is similar to the technology used in the Angra plants in Brazil.
“Water in this type of reactor is, at the same time, a moderating element and a coolant fluid,” he said.
This means that, as a moderating element, water is able to reduce to adequate levels the energy of the neutrons that are emitted in each nuclear fission of uranium 235. This causes these neutrons to generate new nuclear reactions, creating a chain reaction and producing energy.
This energy heats up another hydraulic system. In it, water turns into steam and drives a turbine that generates electricity.
In addition, water is also used to cool reactors and a series of pools where discarded nuclear fuel is placed. This entire cooling system works from pumps powered by electricity.
disaster scenario
According to a report by the NGO Greenpeace released in March of this year, in a hypothetical scenario, the fighting could destroy the electrical cables that bring energy from other sources into the nuclear plant. It is this energy that sustains the operation of the plant’s water pumps.
After the release of the report, three of the four lines that supply the plant were damaged by bombing.
Thus, if the external energy is completely cut off, the plant’s entire water pump system would operate on an emergency basis, with electricity supplied by diesel generators that exist within the complex.
In the event that one set of these generators fails and is not replaced quickly, there is a possibility that the entire system will overheat.
Even before the war, some of these diesel generators already had problems due to lack of parts and maintenance, according to a 2020 investigation by the Ukrainian regulatory agency.
To make matters worse, many technicians and plant personnel involved in the emergency response process may find it difficult to reach the site – due to fighting and restrictions imposed by Russian troops. This could delay the emergency response.
In reactors, with partial vaporization or complete drying of the water, the nuclear chain reaction would be extinguished and the equipment would automatically shut down. But even turned off, both the reactors and the spent fuel pools still need refrigeration – to remove the heat generated by the decay of nuclear fission products.
In the scenario raised by the study, if the cooling stops completely, there is a chance of meltdown of one or more nuclear reactors.
“We would not have a catastrophe the size of Chernobyl (1986), but even so, an accident with serious consequences could occur. This sequence of events is possible, but unlikely’, assessed Lorenzetti.
Another possibility, with a little more chance of occurring, is a fire in the pools of used nuclear material, due to lack of water. This event could cause radioactive material to leak into the atmosphere, even if the reactor’s protective structure has not been compromised.
In other words, the possibility of a nuclear accident in Zaporizhzhia depends on the occurrence of a series of successive factors and not on a single event. However, the level of stress to which the Ukrainian employees of the plant are subjected, under the control of the Russians, can facilitate the occurrence of accidents.
The organization Greenpeace also pointed out the possibility of flooding and consequent failure of the plant’s cooling systems if the dikes containing the nearby Dnipro River are damaged by artillery fire.
The report also warned of a minor nuclear accident scenario, in which a heavy weapon fire could lead to the destruction of part of the 160 concrete barrels that store spent nuclear fuel (of lower radioactive content) in a plant yard.
diplomacy and energy
The realization of a nuclear accident in Zaporizhzhia would not be good for either Ukraine or Russia – even for war propaganda purposes. Until now, the persistence of fighting in the region seems to be motivated by the belief, especially of the Russians, that the plant’s structure will withstand eventual miscalculations in military operations.
The Ukrainian government has accused Moscow of wanting to redirect energy production from the Zaporizhzhia plant to occupied territory. Russia denies this possibility. But, if it happens, it could create a scenario of energy shortages in Ukraine, due to the importance of the plant.
In theory, the country could be helped by neighbors, as its electricity grid was connected to that of the European Union at the beginning of the war, precisely to mitigate this type of risk. But Europe itself is at risk of electricity shortages if Russia cuts off supplies of natural gas – which is used to power many power plants on the continent.
Moscow announced on Friday that it would cut off supplies for three days for alleged maintenance work on the Nord Stream 1 pipeline.
The UN Secretary General, António Guterres, defended last week, with the support of the Ukrainian government, the creation of a demilitarized zone in Enerhodar. But the proposal was rejected by Putin.
On the other hand, in a conversation with French President Emmanuel Macron, the Russian said he would agree to the entry into the plant of a delegation from the International Atomic Energy Agency (IAEA). The visit is scheduled for September and will be led by the head of the organ, Rafael Grossi.
He had said that any further escalation of violence in the region related to the six reactors at Zaporizhzhia “could lead to a severe nuclear accident with potentially serious consequences for human health and the environment in Ukraine and elsewhere.”
The UN has already managed to sew an agreement to resume grain exports in Ukraine and facilitate the flow of Russian production. The idea was to lessen the possibility of a global food crisis.
Now, Guterres says he believes that with behind-the-scenes negotiations, it will be possible to reach an agreement to prevent a nuclear disaster that could affect much of Europe and even Russia.
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