Several nuclear facilities in Ukraine have been attacked by the Russian military over the past fortnight: a nuclear research facility at Kharkiv; two radioactive waste storage sites; the Chernobyl nuclear site (which no longer has operating reactors); and the operating Zaporizhzhia nuclear power plant.
Thankfully there have not been any significant radiation releases … yet.
The operating nuclear power plants pose by far the greatest risks. Ukraine has 15 power reactors located at four sites. Eight of the reactors are currently operating.
The Zaporizhzhia plant — the largest nuclear power plant in Europe, with six reactors — is under the control of the Russian military. At least one reactor is operating at each of the other three plants. The Russian military might fight to take control of these plants over the coming days and weeks.
Zaporizhzhia nuclear power plant
The military assault on the Zaporizhzhia nuclear power plant on March 4 damaged the "reactor compartment building" of reactor #1, two artillery shells hit the dry storage facility containing spent nuclear fuel (without causing significant damage), a fire severely damaged a training building, and a laboratory building was damaged.
The State Nuclear Regulatory Inspectorate of Ukraine (SNRIU) reported that the reactor #6 transformer had been taken out of service and was undergoing emergency repair after damage to its cooling system was detected following the attack.
Two people were injured in the fire, the International Atomic Energy Agency (IAEA) said, while Ukraine's nuclear utility Energoatom said that three Ukrainian soldiers were killed and two wounded.
The European Nuclear Safety Regulators Group said that it is "extremely disconcerting" that "damage has been reported to have occurred to unit 1 building, the gallery and grid infrastructure".
The military assault on Zaporizhzhia drew worldwide condemnation. To say that it was reckless would be an understatement. Dr Edwin Lyman from the Union of Concerned Scientists summarised the risks:
"There are a number of events that could trigger a worst-case scenario involving a reactor core or spent fuel pool located in a war zone: An accidental — or intentional — strike could directly damage one or more reactors. An upstream dam failure could flood a reactor downstream. A fire could disable plant electrical systems. Personnel under duress could make serious mistakes. The bottom line: Any extended loss of power that interrupted cooling system operations that personnel could not contain has the potential to cause a Fukushima-like disaster."
Lyman notes that a Chernobyl-style catastrophe — a massive steam explosion and long-duration fire — is implausible, but that the "consequences of a nuclear accident at one of the four operational Ukrainian nuclear plants could be similar to that of Fukushima".
The risks from the military attack were all the greater because one of the six reactors at Zaporizhzhia was operating at the time. SNRIU listed three reactors as operating on March 3 at 8am local time. The military attack began at 1am on March 4. SNRIU listed one reactor as operating on March 4 at 8am local time, with two reactors listed as operating from March 6 onwards.
Was Ukraine operating reactors because the electricity they produced was absolutely essential? Was the Ukrainian government hoping that continuing to operate reactors would minimise the risk of a military attack on the nuclear plant? How will the lessons learned from the Zaporizhzhia experience play out at the other three nuclear power plants?
Currently, Russian troops are using the Zaporizhzhia plant as a military base, presumably on the assumption that it won't be attacked by Ukrainian forces. Energoatom said on March 9 that there were 50 units of heavy Russian equipment, 400 military staff and "lots of explosives and weapons" at the Zaporizhzhia plant. SNRIU said the Russian military is turning the Zaporizhzhia nuclear plant "into a military facility, deploying heavy weapons in this territory to blackmail the entire world".
Zaporizhzhia staff are currently operating the nuclear plant under Russian control: any action, including measures related to the technical operation of the reactors, requires approval from the Russian commander. IAEA Director General Rafael Grossi noted that the arrangement violates one of the seven indispensable pillars of nuclear safety and security, that "operating staff must be able to fulfil their safety and security duties and have the capacity to make decisions free of undue pressure".
Dr Najmedin Meshkati, a nuclear safety expert at the University of Southern California, commented: "War adversely affects the safety culture in a number of ways. Operators are stressed and fatigued and may be scared to death to speak out if something is going wrong. Then there is the maintenance of a plant, which may be compromised by lack of staff or unavailability of spare parts.
"Governance, regulation and oversight — all crucial for the safe running of a nuclear industry — are also disrupted, as is local infrastructure, such as the capability of local firefighters. In normal times you might have been able to extinguish the fire at Zaporizhzhia in five minutes. But in war, everything is harder."
Zaporizhzhia staff are operating in three daily shifts according to SNRIU. There are problems with food availability and supply, SNRIU said. Ukrainian energy minister Herman Galushchenko said managers at the nuclear plant were being forced to record an address to be used as propaganda. "The employees of the station are physically and psychologically exhausted," Galushchenko said.
The IAEA reported on March 9 that the Zaporizhzhia site has four high-voltage (750 kilovolt, kV) offsite power lines plus an additional one on standby, but that it had been informed by the Ukrainian operator that two lines have been damaged and thus there are now two operating lines plus one on standby. The operator said that power requirements could be maintained with one line. "Nevertheless, this is another example of where the safety pillar to secure off-site power supply from the grid for all nuclear sites has been compromised," Grossi said.
If grid power is lost, the adequacy of backup power generators to maintain essential cooling of reactors and spent fuel will depend on factors such as the integrity of the diesel fuel store, and the viability of securing further diesel fuel. The inability to run generators was one of the causes of the Fukushima disaster.
Meshkati said: "My biggest worry is that Ukraine suffers from a sustained power grid failure. The likelihood of this increases during a conflict, because pylons may come down under shelling or gas power plants might get damaged and cease to operate. And it is unlikely that Russian troops themselves will have fuel to keep these emergency generators going — they don't seem to have enough fuel to run their own personnel carriers."
SNRIU said that its nuclear safety inspectors are not allowed to access the Zaporizhzhia plant due to the Russian troops deployed in the area.
SNRIU said that phone lines, email and fax were not functioning at Zaporizhzhia, with only some poor quality mobile phone service possible, so "reliable information from the site cannot be obtained through normal channels of communication".
Grossi said that the "deteriorating situation regarding vital communications" between the regulator and the nuclear plant is a "source of deep concern, especially during an armed conflict that may jeopardise the country's nuclear facilities at any time”.
“Reliable communications between the regulator and the operator are a critical part of overall nuclear safety and security."
The IAEA said on March 11 that "[i]t was not currently possible to deliver necessary spare parts, equipment and specialized personnel to the site to carry out planned repairs, and maintenance activities at Unit 1 had been reduced to the minimum level required by the plant operational procedures".
No reactors have operated at the Chernobyl site since the year 2000, but the site still has a large quantity of spent nuclear fuel, as well as the radioactive mess left by the 1986 disaster in reactor #4.
The Russian military took control of the Chernobyl site on February 24. Radiation levels were elevated due to heavy military equipment disturbing the contaminated dust around the site.
Russian occupiers have kept around 210 plant operators and guards at the Chernobyl site since February 24 without a new shift to relieve them. A relative of one worker told the BBC that the Russian military was willing to let them swap shifts, but that they could not guarantee their safety on the journey home, nor of workers travelling to take their place.
"All the staff are super exhausted and desperate. They doubt that anyone cares about them. Right now they don't see anyone doing anything to rescue them," the relative said.
According to the Ukrainian government, workers are being subjected "to psychological pressure and moral exhaustion" with "limited opportunities to communicate, move, and carry out full-fledged maintenance and repair work".
Electricity supply lost
The European Nuclear Safety Regulators Group warned on March 6 about the "current fragility of the electrical supplies to the site, with only one supply line out of three available and back-up diesel power having sufficient fuel supplies for only 48 hours".
The situation worsened with the loss of power from a 750 kV high-voltage line to the area on March 9, thus disconnecting the site entirely from the grid. On-site emergency diesel generators were activated "to power systems important to safety".
Energoatom said a loss of power made "it impossible to control the nuclear and radiation safety parameters at the facilities", adding that repairs to restore the area's power supply could not happen at the moment because of "combat operations in the region".
Whether the spent fuel at Chernobyl is at risk due to the loss of power is debated. Energoatom said there are about 20,000 spent fuel assemblies at Chernobyl that could not be kept cool during a power outage and warned of the release of radioactive substances into the environment. The IAEA is less concerned, saying that it saw "no critical impact on safety" due to the low heat load and the volume of cooling water.
SNRIU said on March 10 that in the event of a total blackout, including loss of emergency power supply, staff responsible for spent fuel pools will lose the possibility of remote monitoring of the radiological situation in the storage facility rooms; remote control of the water level and temperature in the cooling pool; makeup of the cooling pool and its water treatment; fire alarm monitoring; and maintenance of required temperature in spent fuel buildings.
The IAEA said on March 10: "If emergency power was also to be lost, the regulator said it would still be possible for staff to monitor the water level and temperature of the spent fuel pool. But they would carry out this work under worsening radiation safety conditions due to a lack of ventilation at the facility. They would also not be able to follow operational radiation safety procedures."
Ukraine's Foreign Minister Dmytro Kuleba said that Russia must observe a temporary ceasefire to enable repairs at the Chernobyl plant.
Reports on March 11 indicate that off-site power may have been restored to the Chernobyl site — the IAEA is seeking confirmation.
Grossi said: "From day to day, we are seeing a worsening situation at the Chernobyl NPP, especially for radiation safety, and for the staff managing the facility under extremely difficult and challenging circumstances."
Grossi also said that in recent days the IAEA has lost remote data transmission from its safeguards systems at Chernobyl and also the Zaporizhzhia nuclear plant.
Why was Chernobyl seized?
Why was Chernobyl seized by the Russian military? Timothy Mousseau from the University of South Carolina writes: "The reactor site's industrial area is, in effect, a large parking lot suitable for staging an invading army's thousands of vehicles.
"The power plant site also houses the main electrical grid switching network for the entire region. It's possible to turn the lights off in Kyiv from here, even though the power plant itself has not generated any electricity since 2000, when the last of Chernobyl's four reactors was shut down.
"Such control over the power supply likely has strategic importance, although Kyiv's electrical needs could probably also be supplied via other nodes on the Ukrainian national power grid.
"The reactor site likely offers considerable protection from aerial attack, given the improbability that Ukrainian or other forces would risk combat on a site containing more than 5.3 million pounds (2.4 million kilograms) of radioactive spent nuclear fuel."
Radioactive waste storage and disposal sites
"SNRIU said that all radioactive waste disposal facilities of the State Specialized Enterprise Radon were operating as usual, and the radiation monitoring systems did not indicate any deviations from normal values. On 27 February, the SNRIU informed the IAEA that missiles had hit the site of such a facility in the capital Kyiv, but there was no damage to the building and no reports of a radioactive release."
The Kyiv radioactive waste storage site appears to be at least 1km from any other human structures, suggesting the possibility of a deliberate strike.
Also on February 27, an electrical transformer was damaged at a radioactive waste storage site in Kharkiv, also without any reports of a radioactive release. According to SNRIU, a research reactor at the site has been shut down.
Grossi said: "These two incidents highlight the very real risk that facilities with radioactive material will suffer damage during the conflict, with potentially severe consequences for human health and the environment.
“I urgently and strongly appeal to all parties to refrain from any military or other action that could threaten the safety and security of these facilities."
The Kyiv and Kharkiv facilities typically hold disused radioactive sources and other low-level waste from hospitals and industry, the IAEA said, but do not contain high-level nuclear waste. However the Kharkiv site may also store spent nuclear fuel from the research reactor.
Other nuclear facilities
An oncology centre in Kharkiv was destroyed by Russian shelling, jeopardising the safety and security of high-level radiation sources. Ex-Soviet states have been at the centre of global networks of nuclear theft and smuggling since the break-up of the Soviet Union, and there will undoubtedly be incidents of lost, stolen and smuggled nuclear materials arising from Russia's war on Ukraine and the breakdown of national and international security arrangements.
SNRIU said on March 6 that there continued to be no communication with enterprises and institutions using Category 1‒3 radiation sources in the eastern port city of Mariupol, including its oncology centre, and that the safety and security of the radiation sources could not be confirmed. Such material can cause serious harm to people if not secured and managed properly, the IAEA noted.
SNRIU reported that a “Neutron Source” — a subcritical assembly with 37 nuclear fuel elements, controlled by a linear electron accelerator — at Kharkiv's Institute of Physics and Technology was subjected to artillery fire on March 6. Ukraine claimed that the Russian military fired missiles from truck-mounted “Grad” launchers, which do not have precise targeting."Radiation condition on the playground is ok," according to a reassuring — if imprecise — automatic translation of an SNRIU statement.
The European Nuclear Safety Regulators Group said in a March 6 statement that it is "very concerned about the safety of several research reactors as well as sites holding highly radioactive sources."
SNRIU's Acting Chair Oleh Korikov said on March 8: "I have to state that so far, despite the active initiatives of the Ukrainian party, unfortunately, no diplomatic efforts of the IAEA and other international partners have led to real results in reducing or eliminating military risks at Ukraine's nuclear facilities.
“It is no exaggeration to note that today in Ukraine, due to the military aggression of the Russian Federation, the risks not only of radiation accidents of various scales, loss of control over radiation sources, but also unprecedented risks of global nuclear catastrophe have been created."
In a letter to the IAEA, European Union Energy Commissioner Kadri Simson criticised Russia's ongoing role on the IAEA's Board of Governors. "I find it unacceptable that Russia can continue its privileged role at the IAEA in view of its irresponsible military actions on the ground in Ukraine," she said.