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The IAEA said ten of the country’s 15 nuclear energy reactors are currently connected to the grid three at the Rivne Nuclear Power Plant (NPP), three at the South Ukraine nuclear power plant (NPP), two at the Khmelnytskyy NPP, and none at ZNPP. The IAEA continues to receive remote safeguards data from the sites of the four operational NPPs in Ukraine, as well as from the Chernobyl NPP.Update 100 – IAEA Director General Statement on Situation in Ukraine
No reactors are currently operating at ZNPP. Of its six reactors, only Unit 6 was recently operating , and all units are currently in cold shutdown.Update 101 – IAEA Director General Statement on Situation in UkraineA backup transmission connection is providing power to the plant, with another backup transmission line from a nearby thermal power plant in reserve.Update 101 – IAEA Director General Statement on Situation in UkraineEither grid connection provides sufficient power to support the on-site needs of ZNPP
The NPP has four high voltage (750 kV) transmission lines, plus one on standby that connects to the nearby TPP thermal power plant. The ZNPP is currently disconnected from the four main 750 kV power lines that normally would transmit power to the grid. The 330 kV power line that connects the nearby thermal plant to ZNPP was disconnected on September 5th and repaired on September 11th.Update 100 – IAEA Director General Statement on Situation in Ukraine During that time, the Unit 6 reactor was used to generate the power required at the plant.Update 100 – IAEA Director General Statement on Situation in Ukraine A second back-up 750/330 kV backup connection was restored on September 12th. The 750/33 kV connection is providing power to the plant, with the backup connection to the nearby thermal power plant held in reserve.Update 101 – IAEA Director General Statement on Situation in Ukraine No damage to nuclear safety systems was reported. The 330 kV line is sufficient to maintain the safety of the plant. The ZNPP has 20 emergency diesel generators available if needed. Each diesel generator has fuel for at least 10 days of operation.Update 100 – IAEA Director General Statement on Situation in Ukraine If grid connection is lost, only one diesel generator is needed for each reactor to maintain safety.Update 100 – IAEA Director General Statement on Situation in Ukraine
Site radiation levels remain normal, and spent nuclear fuel remains safely stored on the premises. A more detailed assessment of safety and security concerns is provided below:
Ukraine informed the IAEA that it had made “a change in” the regulatory license for the ZNPP, instructing the Ukrainian plant staff to maintain reactor units 1 and 2 in cold shutdown.Update 92 – IAEA Director General Statement on Situation in Ukraine Without a license to operate, the Ukrainian staff cannot start these reactors. Up to this point, Russia has said that the operation of the plant is under the control of the civilian Ukrainian staff. A restart of these reactors would require Russia to take control of reactor operations, which could be a violation of Protocol II of the Geneva Convention.
The mental stress of duty under duress since March 3, 2022, is of continued concern. Human error is a high contributor to risk in any industry. The mental and psychological stress of Russia’s hostile invasion of Ukraine, and the six-month occupation of ZNPP, are taking a tremendous toll on plant workers. This prolonged mental and psychological stress increases the potential for human error in operating and maintaining the plant.
On March 3, 2022, Russian military operations and shelling around the Zaporizhzhia nuclear power plant (ZNPP) resulted in fire damage to a training building. The fire was extinguished. Security footage supports claims by Ukraine's nuclear regulator of damage at three other locations: the Unit 1 reactor building, the transformer at the Unit 6 reactor, and the spent fuel pad which is used to store nuclear waste. The integrity of the used fuel storage canisters was maintained, evidenced by plant radiation levels, which remained normal.Update 10 – IAEA Director General Statement on Situation in Ukraine Security video footage also shows ordnance striking a high-voltage line outside the plant. According to the IAEA, two offsite transmission lines were damaged in the attack. The plant operator also reported shelling damage to an administrative building and a power transformer located on-site but separate from the power plant. No damage to any of the reactors or essential safety equipment was reported.
There are reports of further explosions at the ZNPP on March 14th. Indications are that Russian forces carried out the disposal of unexploded munitions at the site of the Zaporizhzhya NPP.Update 21 – IAEA Director General Statement on Situation in Ukraine The regulator had previously informed the IAEA about ongoing work to detect and dispose of unexploded munitions found at the damaged training center and elsewhere around the NPP site following the events of March 4, 2022, when Russian forces took control of the Zaporizhzhia nuclear power plant site.
Shelling on August 20 and 21 damaged ZNPP infrastructure, including laboratory and chemical facilities.Update 93 – IAEA Director General Statement on Situation in Ukraine The ZNPP is currently disconnected from the four main power lines that normally would transmit power to the grid. A backup power line from a nearby thermal plant to the ZNPP was disconnected on September 5th and repaired on September 11th.Update 100 – IAEA Director General Statement on Situation in Ukraine During that time, the Unit 6 reactor was used to generate the power required at the plant. No damage to nuclear safety systems was reported. A secure off-site power supply from the grid is essential for ensuring nuclear safety.
Concerns that shelling and other munitions might have compromised containment and the reactor core were unfounded and implausible. The nuclear reactors are housed within thick, steel-reinforced containment structures. After September 11, 2001, aircraft impact tests for similarly designed and constructed containment structures in the US revealed that these structures are highly resistant to damage from a direct hit by large aircraft. The reactors were never physically vulnerable to the military shelling. Absent an intentional effort to destroy the plant with bunker-buster munitions or similar weaponry, standard artillery and rocket-launched grenades were incapable of damaging the plant’s containment. The primary safety concern from military operations was a loss of electrical power to cooling and safety systems, which did not occur. Electrical power was continuously available to all safety systems. If that power had been lost, redundant emergency diesel generators would have supplied power to safety systems, ensuring safe shutdown and core cooling for operating reactors and the spent fuel pool, which are housed in containment structures.
Even in a worst-case scenario, there would be no release of radiation to the public. All reactors would have been shut down and ceased generating electricity, power would have been lost from the electrical grid, and all six emergency diesel generators would be either disabled or destroyed as a result of the battle to take control of the plant. Alternatively, the emergency generators would have eventually depleted their seven-day fuel oil reserves if grid power could not have been restored.
In this scenario, active cooling systems to the reactors would be lost, similar to the events that resulted in the meltdown of reactor cores at Fukushima Daiichi in 2011. Absent offsite or backup power for safety systems, which is highly unlikely, water in the reactors would eventually boil off and uncover the fuel within approximately 3-4 hours.https://doi.org/10.1016/j.anuc... If, in addition to the loss of all power, the reactor operators are unable to intervene to replenish coolant losses and continue other safety functions, the water would have boiled off and uncovered the fuel rods in approximately 1-2 hours.
In this event, recently off-loaded, irradiated (hot) fuel in the spent fuel pool would begin to heat up and, over time, fuel cladding would partially melt. In contrast to Fukushima Daiichi, however, where fuel melt resulted in build-up and explosion of hydrogen inside the containment structures and reactor buildings, the reactors at Zaporizhzhia feature a passive hydrogen safety system that does not require external power. Unlike the containment features at Fukushima Daiichi, the containment structures of VVER-1000 plants like Zaporizhzhia are leak-tight. As a result, even in a worst-case situation, any releases of radioactive gas from failed nuclear fuel cladding would be retained within the containment structure, preventing release to the public.
Five of the six reactors were already shut down when the firefight around the plant broke out, and heat loads were very low.
To date, military operations and shelling around the Zaporizhzhia plant have not caused a loss of power to the reactor or spent fuel pool cooling systems or to other safety equipment. But even if a sustained loss of power were to occur, a release of radiation even comparable to that which occurred at Fukushima Daiichi would be extremely unlikely, given the Zaporizhzhia plant’s differing design and more recent vintage. An intentional and deliberate attempt to blow up the plant and cause a major radiological event, with munitions far more powerful than those utilized by Russian troops as they seized control of the plant, would still fall far short of what is necessary to produce a release of radiation comparable to that which occurred at Chernobyl.
Military conflict frequently damages major infrastructure of all sorts, often with substantial public health consequences. Major industrial infrastructure, from refineries and petrochemical plants to dams, bridges, and roads, are frequently damaged in military conflicts, intentionally and unintentionally, and often have substantial public health and environmental consequences. Oil wells set afire during the first Gulf War, for instance, are estimated to have caused as much as $40 billion in environmental damage and as many as 1000 fatalities from respiratory ailments. In addition, many thousands of civilians have perished in dozens of commercial aircraft unintentionally shot down in military conflicts. Those consequences, however, are almost always vastly less significant than the suffering and damage associated with the conflicts themselves. Virtually no civilian infrastructure is designed to operate in a war zone. But modern light-water nuclear power stations, sheathed in concrete containment structures, supported by multiple redundant electrical and cooling systems, surrounded by large exclusion zones, and guarded by security forces, are better engineered to withstand military operations and attack than any other class of civilian infrastructure.
Eleven of the fifteen operational nuclear reactors in Ukraine are of the same model as Zaporizhzhia. Two reactors at the South Ukraine site are variations of the reactor design used at Zaporizhzhia. Two reactors at the Rivne site are older, smaller reactors that have confinement buildings instead of leak-tight containment buildings. These reactors provide less robust but adequate protection from radiation release than the larger models at other sites, and significantly more protection than the Chernobyl design.
Chernobyl Units 1, 2, and 3 were all shut down by 2000 and remain permanently shut down for decommissioning. Site radiation levels remain normal, and spent nuclear fuel remains safely stored on the premises. However, safeguards monitoring is degraded, which presents challenges to monitoring and accounting for nuclear material.
Russian forces took control of the site on February 24th and held the staff on site for 26 days. On February 25th, the Ukrainian regulator reported “elevated radiation levels at the Chernobyl site, possibly caused by heavy military vehicles churning up contaminated soil, but the IAEA assessed that the radiation readings remained low and did not pose any danger to the public.”Update 2 – IAEA Director General Statement on Situation in UkraineReports of Russian soldiers receiving high doses or suffering effects of radiation sickness are unlikely to be true and cannot be confirmed by the IAEA.Update 38 – IAEA Director General Statement on Situation in Ukraine
On March 20th, the Russian occupying force allowed some Chernobyl site workers to leave the site and other staff to replace them. The remaining staff were allowed to rotate on March 21st (except 13 who chose to stay and most of the Ukrainian guards).Update 28 – IAEA Director General Statement on Situation in Ukraine The Ukrainian nuclear regulator and Russian forces reached an agreement on how to organize future staff rotations; however, there has not been a shift change since March 20-21.Update 34 – IAEA Director General Statement on Situation in Ukraine
On March 31st, Ukraine informed the IAEA that the Russian forces that have been in control of Chornobyl Nuclear Power Plant (NPP) since 24 February had, in writing, transferred control of the NPP to Ukrainian personnel.Update 38 – IAEA Director General Statement on Situation in Ukraine Russian forces withdrew from Chernobyl on March 31.Update 46 – IAEA Director General Statement on Situation in Ukraine
On April 26, 2022, the IAEA and Ukraine agreed to establish a working group to coordinate IAEA assistance and support workers at Ukraine’s nuclear sites to maintain safe and secure operations.Update 64 – IAEA Director General Statement on Situation in Ukraine On April 28, 2022, IAEA Director General Grossi presented results of an IAEA mission to Chernobyl to deliver equipment and measure radiation levels around the Chernobyl site. Measurements confirmed that radiation levels around the site, including locations inhabited by Russian forces, remain well below radiation dose limits for plant workers.Update 66 – IAEA Director General Statement on Situation in Ukraine
A more detailed assessment of safety and security concerns is provided below:
On March 7, 2022, the State Nuclear Regulatory Inspectorate of Ukraine (SNRIU) reported shelling damage to the National Scientific Center “Kharkiv Institute of Physics and Technology” (KIPT), a nuclear research facility in Kharkiv, that produces radioisotopes for medical and industrial purposes.Updated information on the neutron source site | State Nuclear Regulatory Inspectorate of Ukraine (snriu.gov.ua) The research facility housed very low quantities of nuclear material, and damage did not result in radiation exposure to the public. SNRIU reported the radiological situation at the KIPT site is normal.
Rani Franovich is a Senior Policy Advisor for the Nuclear Energy Innovation team.
Adam is Director for Nuclear Energy Innovation at Breakthrough.
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