Chernobyl power supply cut but IAEA says no imminent safety threat UN’s nuclear watchdog voices concern over ‘worsening’ situation for staff at defunct Ukrainian plant

Ukrainian authorities have said the power supply has been cut to the defunct Chernobyl power plant, but the UN’s atomic watchdog said the spent nuclear fuel stored there had cooled down sufficiently for it not to be an imminent safety concern.

Ukraine’s nuclear regulator said the power supply to the Chernobyl plant failed on Wednesday morning, and the national power company Ukrenergo said it was impossible to restore the power lines because of fighting in the surrounding areas.

The nuclear energy company Energoatom said in a post on the Telegram messaging app: “Emergency diesel generators are switched on at the site to supply power to safety-critical systems. In case of trouble-free operation, the stock of diesel fuel on diesel generators will be enough for 48 hours.”

Ukraine’s foreign minister, Dmytro Kuleba, said that after the 48 hours were up, “cooling systems of the storage facility for spent nuclear fuel will stop, making radiation leaks imminent.”

However, the International Atomic Energy Agency (IAEA) said there was enough water in the spent fuel pools for the fuel rods to cool sufficiently to avoid an accident. It referred back to a statement the agency made on 3 March which said that due to the amount of time since the Chernobyl disaster in 1986, the spent fuel had cooled down enough that “the pool is sufficient to maintain effective heat removal without the need for electrical supply”.

The IAEA voiced concern that the site had stopped transmitting data on ambient radiation and other variables, and expressed concern for the staff, who were under Russian guard and had not been able to change shifts. The situation for the staff was worsening, the IAEA said, citing the Ukrainian nuclear regulator.

James Acton, a co-director of the nuclear policy programme at the Carnegie Endowment for International Peace, said: “The loss of power at Chernobyl is concerning but it is extremely unlikely that spent fuel pools there will empty because of evaporation (which could lead to fuel melting). This process is slow and mitigations should be straightforward.”

Acton said the risks at Ukraine’s operational nuclear power plants were much higher than at Chernobyl.

One of Ukraine’s four functioning nuclear power plants, Zaporizhzhia, the largest in Europe, is under Russian control after it was fired on with artillery. The operating staff are being held under armed guard and forbidden from taking any action without getting the approval of the Russian officer in charge.

The IAEA director general, Rafael Grossi, has said the situation at Zaporizhzhia violates basic safety principles.”


Now 19,442 fuel assemblies are stored in the “wet” repository for spent nuclear fuel (SNF repository-1) in the Chernobyl NPP zone. This makes about 8,500 tons of spent nuclear fuel with a total activity of up to 2.5×1020 Bq (as of 2001) which was unloaded from the 1, 2, 3 Chernobyl power units. The Unit 3 was shut down on December 15, 2000. Currently, the risk of an uncontrolled nuclear reaction is really low. During 20 years, most short-lived isotopes have decayed. The temperature inside the assemblies does not exceed 250 oC and the assemblies can be kept for a long time without cooling.

However, as it is published in IAEA documents and scientific papers, hydrogen is released during the spent nuclear fuel storage as a result of radiochemical reactions [Gayazov AZ, Komarov SV, Leshchenko AYu, Revenko KE, Smirnov VP, Zvir EA, Ilyin PA, Teplov VG (2019) Study of hydrogen generation and radionuclide release during wet damaged oxide spent fuel storage. Nuclear Energy and Technology 5(1): 61–66.; HYDROGEN EFFECTS ON DISSOLUTION OF SPENT NUCLEAR FUEL IN REDUCING REPOSITORY CONDITIONS—LITERATURE REVIEW AND LABORATORY EXPERIMENTS: Prepared for U.S. Nuclear Regulatory Commission Contract NRC–02–07–006 Prepared by Pavan K. Shukla, Tae Ahn, Jude McMurry, Michael J. Rubal, Darius Daruwalla Yi-Ming Pan: Center for Nuclear Waste Regulatory Analyses San Antonio, Texas; U.S. Nuclear Regulatory Commission Washington, DC; Southwest Research Institute® San Antonio, Texas: May 2015; EURAD State of the Knowledge (SoK) Report Spent Nuclear Fuel Domain 3.1.1 Kastriot Spahiu SKB, Stockholm and Chalmers University of Technology, Gothenburg, Sweden Version : 1.0 ; 09 November 2021].

Under normal conditions, the gas emissions are discharged through a forced ventilation system. Due to the absence of electricity supply, the ventilation system stops working and hydrogen accumulates in the premises. At a ratio 2 : 1 of hydrogen : oxygen, an explosive mixture is formed which can be exploded by just one spark.

At present, the content of the most dangerous from the medical and biological point of view radionuclides 137Cs and 90Sr in the SNF repository-1 at the Chernobyl NPP (taking into account the decay) is about 2.0 × 1019 Bq and 1.5 × 1019 Bq, respectively. This is 60-80 times higher than there was accumulated in the 4th Chernobyl power unit at the time of the accident. And it is from 240 (137Cs) to 1500 (90Sr) times more than was released into the environment due to the Chernobyl catastrophe.

As it is known, it was as a result of accumulation of an explosive mixture that the Chernobyl and Fukushima reactors exploded causing global nuclear catastrophes. If the Chernobyl energy supply will not be restored in 24 hours, the threat of an explosion would become a reality.

A terrorist attack at the Zaporizhzhia NPP can lead to a global nuclear catastrophe as well because the dry storage facility for spent nuclear fuel accumulates radioactivity 1,000 times higher than that at the moment of the Chernobyl explosion, as it was published earlier:

“For 20 years from 2001, the Zaporizhzhia NPP has been used as a dry storage facility. Each year from the VVER-1000 (PVR of 1000 MVt capacity) reactor, 42 fuel assemblyis unloaded, which makes 17 tons. The specific activity of one assembly after 3-year exposure is 3 • 1016 Bq/T. During one year, 5.1 • 1017 Bq of radioactive materials come from each of the six reactors.

From this activity 8.16 • 1016 Bq accounts for 137Cs and 5,95 • 1016 Bq for 90Sr.

Simple calculation shows:

The SNF from the 6 VVER-1000 reactors of the Zaporizhzhia NPP accumulated in thedry repository during 20 years, contains more than 6 • 1019 Bq of long-lived radionuclides including 9 • 1018 Bq 137Cs and 7 • 1018 Bq 90Sr.

This is over 30 times more than it has been accumulated in the IVth power unit of the Chornobyl NPP at the time of the accident.

This is 100 times more than the amount of 137Cs and 700 times more than that of 90Sr that was released from the Chernobyl NPP emergency unit as a result of the accident in 1986.”


Are IAEA experts aware of this? Are the authorities of the NATO aware that there is no protection and salvation from the radioactive cloud that might cover our planet?

To protect the world from the global nuclear threat, the IAEA must initiate the deployment of UN troops to the territory of critical nuclear facilities in Ukraine to ensure their safe operation in wartime.

Prof. Oleksandr Kopylenko

Head of NCRPU
Academician of the National Academy of Sciences

Prof. Anatolii Nosovskii

Head of NCRPU Committee
for Comprehensive Safety Analysis
of Nuclear and Radiation Technologies
Academician of the National Academy of Sciences
Director of Institute for Safety Problems of Nuclear Power Plants

Prof. Viktor Dolin

Head of NCRPU Committee
for Integrated Safety Analysis of Radiation Waste
and Spent Fuel Management
Research Director of Institute for Environmental Geochemistry
Expert of IAEA (2009)