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This rocket fire has put Europe on high alert and the situation is still critical: These photos released by the Russian Defense Ministry on Sunday are said to show rocket parts in outbuildings of the Zaporizhia nuclear power plant in southeastern Ukraine.
For the second time since the beginning of Russia's war against Ukraine, the nuclear power plant has been shelled.
It has not been finally clarified who is responsible for the incident.
Sebastian Stransky, engineer:
"Rockets hit there, but not in the interim storage facility itself, but in the vicinity of support buildings, technical buildings.
And these building structures have been compromised.
Windows have probably been broken and, as far as we know, radiological measuring stations in the vicinity of the camp have also failed.
We don't know to what extent they have failed.
This means that the safety-related facilities of the power plant or the interim storage facility for fuel elements have not been adversely affected by the military actions."
Sebastian Stransky heads the International Projects department at the Society for Plant and Reactor Safety, and his team has been there several times.
The Zaporizhia NPP is the largest of the four active power plants in Ukraine, with only two of its six reactors currently in operation.
The most important components of the nuclear power plant are housed in the so-called containment, a safety container made of a steel layer one and a half meters thick.
Inside is the reactor with the radioactive fuel elements.
A chain reaction takes place here, with which the heat is generated.
Steam is produced, which drives a turbine that generates electricity.
The cooling, pumps and valves ensure that the reactor is safely cooled even in a so-called emergency.
And the security container can withstand a lot.
Sebastian Stransky, engineer:
»A shot at the containment with an artillery shell or a small rocket would not damage the containment to such an extent that an incident would automatically occur.
Even if the containment were damaged or even partially broken, that does not automatically mean that a core meltdown accident will occur.
A core meltdown accident only occurs when they are no longer able to maintain cooling, i.e. to dissipate the decay heat from the reactor.
«
A high-voltage power line was also hit during the shelling of the area.
The head of Ukraine's nuclear power company Energoatom, Petro Kotin, expressed concern.
Petro Kotin, head of Ukrainian nuclear power company Energoatom:
»Most of the power lines connecting the power plant to the Ukrainian power grid were damaged.
As a result, the power plant works only through a power line and transmits electricity to the Ukrainian power grid.
This is very dangerous because if this power line gets damaged, the power plant will go into blackout mode.
And the cooling of the active areas continues at the expense of the diesel generators.«
The Zaporizhia nuclear power plant has 20 of these diesel generators – which, according to engineer Stransky, should initially be sufficient for emergencies.
Sebastian Stransky, engineer:
»What is not said in Mr. Kotin's communication is that only one diesel generator is required to safely supply a block and maintain aftercooling.
That means they must have at least six diesels running.
Per block, when all diesels are available, you have two diesels in reserve.
If you now extrapolate this to the operating time: Ultimately, the Ukraine has enough electricity to be able to supply all diesel for seven days.
«
During this time, the power plant would have to be brought back into a safe operating mode.
In addition, since retrofitting in response to the reactor accident in Fukushima in 2011, the Zaporizhia nuclear power plant has had an additional separate cooling water line, a valve for pressure equalization and a filter for the radioactive substances.
According to the Ukrainian nuclear authority, Russia currently wants to disconnect the nuclear power plant from the Ukrainian power grid, connect it to the Russian one and thus supply Crimea directly.
This is complicated because: Ukraine has been connected to the European energy grid since mid-March and no longer to the Russian and Belarusian ones as before.
Sebastian Stransky, engineer: »The bottom line is that they have to have at least one reactor running so that the plant can continue to operate and be started up again, and at least one reactor in power mode so that it can supply the site. And then you could disconnect the site from the Ukrainian network and then try to connect to the Crimean network. But this is not possible. You cannot connect the power plant to the grid as a single power plant, but you would have to disconnect part of the Ukrainian grid, for example in eastern Ukraine, in southern Ukraine from the general country grid. That's doable.«
Only when Zaporizhia is running stably with the help of other power plants could it be synchronized with the Russian grid.
In addition to the technology, the staff is also crucial for the safe operation of the power plant.
But 500 Russian soldiers have been occupying it for five months.
The head of the International Atomic Energy Agency (IAEA), Rafael Grossi, warned that workers under pressure and constant stress could make dangerous operating errors.
That is why the G7 foreign ministers are calling for an independent IAEA mission on the ground.
Ukraine and Russia have agreed to it, but so far no one wants to guarantee the security of such a mission.
