Firefighters take part in a joint tactical and special exercises of the Ukrainian Ministry of Internal Affairs, the Ukrainian National Guard and Ministry Emergency in a ghost city of Pripyat, near Chernobyl Nuclear Power Plant on February 4, 2022. | AFP
VIENNA 鈥� The announcement on Wednesday that electricity had been cut to Ukraine鈥檚 Chernobyl nuclear plant has revived concern over the effect Russia鈥檚 invasion may have on it鈥檚 neighbor鈥檚 nuclear installations.
But experts have cautioned that for now the lack of electricity at Chernobyl 鈥� the site of the world鈥檚 worst nuclear disaster 鈥� does not pose a major security risk at the plant itself.
But last week鈥檚 shelling at Zaporizhzhia nuclear power plant 鈥� Europe鈥檚 largest 鈥� was a reminder that the stakes could get much higher if one of Ukraine鈥檚 four active nuclear installations is hit.
What happened?
On February 24, Russia invaded Ukraine and seized the defunct Chernobyl plant, site of the world鈥檚 worst civil nuclear disaster in 1986, which killed hundreds and spread radioactive contamination west across Europe.
According to a statement from Ukraine鈥檚 energy operator Ukrenergo on Wednesday, 鈥渂ecause of military actions of Russian occupiers鈥�, the plant at Chernobyl 鈥渨as fully disconnected from the power grid鈥�.
Ukrenergo added that military operations meant 鈥渢here is no possibility to restore the lines鈥�.
The country鈥檚 nuclear inspection body SNRIU said 鈥渆mergency diesel generators have been activated in order to power important security systems鈥� and should be able to last for 48 hours.
However, after this period 鈥渃ooling systems of the storage facility for spent nuclear fuel will stop鈥�, Ukrainian Foreign Minister Dmytro Kuleba said in a tweet.
The Chernobyl site comprises four decommissioned reactors 鈥� including one encased in a giant sarcophagus 鈥� as well as stores of nuclear waste.
More than 200 technical staff and guards remain trapped at the site, now working under Russian guard.
Telephone communications with the site are no longer possible.
The UN atomic watchdog, the International Atomic Energy Agency (IAEA) has called on Russia to make sure that staff are able to rest and rotate through shifts as normal.
What is the risk?
The reactor involved in the accident doesn鈥檛 itself pose a problem, Karine Herviou, deputy director general of France鈥檚 nuclear safety institute IRSN told AFP.
鈥淭hat reactor core does not need a cooling system,鈥� she explained.
But what of the 20,000 rods still in the plant鈥檚 spent fuel pool?
Given the time that has passed since the accident in 1986, the heat load and the volume of the cooling pools are together 鈥渟ufficient for effective heat removal without need for electrical supply鈥�, says the IAEA.
The agency said on Wednesday it saw 鈥渘o critical impact on safety鈥� at Chernobyl thus far.
Even if electricity isn鈥檛 re-established after 48 hours, Herviou says that 鈥渇rom what we know of the installations there isn鈥檛 a danger of radioactive emissions鈥�.
In such a scenario, she points to studies done after the 2011 Fukushima accident in Japan which indicate there would be 鈥渁 slow rise in temperature to around 60 degrees Celsius but no uncovering of the fuel rods鈥�.
鈥淭he water will not be brought to boiling point鈥�, she says.
What about the active plants?
A power outage would 鈥渃ause more problems鈥� at Ukraine鈥檚 four active power plants, says Herviou.
鈥淭here you would absolutely have to ensure the cooling of the fuel in the reactor core or in the cooling pools,鈥� she says.
鈥淭he heat that needs to be removed is much greater鈥� than in Chernobyl, she explains.
Generators could support the systems for seven to 10 days.
But beyond that a lack of electricity would risk 鈥渁 Fukushima-type scenario with a meltdown in the core reactor鈥�.
Since the beginning of the Russian invasion IAEA Director General Rafael Grossi has called for the utmost caution around Ukraine鈥檚 nuclear sites.
He has offered to go to Ukraine in order to negotiate with both sides on a way of securing the safety of the country鈥檚 nuclear installations.
鈥淭his time, if there is a nuclear accident, the cause will not be a tsunami brought on by Mother Nature,鈥� he told an IAEA meeting earlier this week, alluding to the cause of the Fukushima accident.
鈥淚nstead, it will be the result of human failure to act when we knew we could, and we knew we should.鈥�
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