1. Zaporizhzhia Nuclear Power Plant (NPP) continues to be occupied by Russia

Since Russia took over the Zaporizhzhia NPP in southeastern Ukraine in March 2022, which has the largest power generation capacity in Europe, we have regularly observed its situation in this section. In August and September of the same year, a series of shelling of unknown origin that both Ukraine and Russia accused of attacking the other side and raised concerns about large-scale leaks of radioactive materials due to damage to the reactors and spent fuels.[1] In June 2023, the Kakhovka Dam, located downstream of the Kakhovka Reservoir on the Dnipro River, which serves as a water source for cooling the reactors, collapsed, and after that, it was confirmed that the reservoir had been depleted, raising concerns about whether the nuclear fuels could be cooled to a safe level.[2]

The Zaporizhzhia NPP has caused a stir when the Russian state-owned nuclear company Rosatom announced its intention to restart the plant by the end of 2027 in accordance with Russian laws and safety standards.[3]

Although the International Atomic Energy Agency (IAEA) provides guidelines for safety standards for nuclear reactor operation, the actual licensing of operation is left to the safety standards set by the nuclear regulatory authorities in each country. Therefore, this case is not simply about putting a nuclear power plant back into operation but involves a change in the jurisdiction of the nuclear power plant. Jurisdiction means that the state or public entity has the authority to control a facility or area.[4] If the Zaporizhzhia NPP is restarted under Russian legislation, the plant will be controlled by Russian authority, which could lead to the fact that the plant and the region in which it is located belong to Russia. Russia unilaterally declared the annexation of four regions in southeastern Ukraine, including Zaporizhzhia state, in the fall of 2022, but international law does not recognize a change in the attribution of these regions, and Ukraine is vehemently opposed to Russia's policy.[5]

This article will assess the current status of the Zaporizhzhia NPP based on satellite imageries and IAEA reports and consider whether Russia's jurisdiction over the plant and its resumption of operation is justified from the perspective of international law, the IAEA charter, and other international conventions, while comparing the claims of both Ukraine and Russia.

2. Overview and current status of Zaporizhzhia NPP

The Zaporizhzhia NPP consists of six units of a type called Russian pressurized water reactor (VVER). This system was developed in the former Soviet Union. In a nuclear reactor, high-temperature, high-pressure water generated by the heat from the nuclear fuel is sent to a steam generator, where steam is generated and sent to a turbine to generate electricity. Each of the six reactors is capable of outputting 1,000 Mwe (megawatts) of electricity, for a total of 6,000 Mwe. This power generation capacity is the third largest in the world and the largest in Europe, after TEPCO's Kashiwazaki-Kariwa Nuclear Power Plant (7 units totaling 8,212 MWe) and another. Until the start of the Russian military invasion on February 24, 2022, it provided approximately 20% of Ukraine's electricity supply. After being occupied by Russian forces in March of the same year, shelling continued in the vicinity until September, and shells were confirmed to have landed on the site of the nuclear power plant, and in order to ensure safety, Unit 6, which was the only reactor in operation after the occupation, was shut down, and all reactors were suspended.

Satellite imagery 1：Panoramic view of the Zaporizhzhia NPP

Source: Maxar (7 September 2022)

In June 2023, the Kakhovka Dam, located in the lower reaches of the Dnipro River, the source of water for the Zaporizhzhia NPP, and located in Russian-controlled territory,[6] collapsed. The Dnipro River, which had lost its ability to regulate water flow and volume, began to flow all the way to the Black Sea. A comparison of satellite images taken just before the dam collapse and one month after the collapse shows that the Kakhovka reservoir was depleted in a short period of time.

Satellite imagery 2：Reservoir before the dam broke

Source: © Planet Labs

Satellite imagery 3：Reservoir after a dam breach

Source: © Planet Labs.

In September 2022, under an agreement between Russia and Ukraine, the IAEA dispatched an investigation team, including Director General Grossi, to the Zaporizhzhia NPP, and has since stationed two staff members at the plant to monitor it. Ensuring the safety of nuclear facilities in combat zones is not the IAEA's mission, but as a result, large-scale armed clashes between Ukraine and Russia in the vicinity of nuclear power plants have been avoided, although there have been sporadic attacks by drones and other means. In addition, according to the IAEA, the depletion of the Kakhovka reservoir has been met with a cold shutdown to indicate that another water source has been secured and that the six reactors are safely cooling the nuclear fuel.[7]

Photograph 1：IAEA personnel on their way to the Zaporizhzhia NPP

Source: IAEA “IAEA Report Highlights Two Years of Efforts to Prevent an Accident at Ukraine’s Zaporizhzhya Nuclear Power Plant” 4 September 2024.

Thus, the reactors at the Zaporizhzhia NPP are currently in stable condition. In addition, all six reactors and the nuclear fuels they are loaded with are Russian-made, so there are few technical difficulties for Russia to restart the plant.

3. Russia's Decree to Restart Zaporizhzhia NPP, International Covenant Perspective

(1) Legal basis for restarting nuclear reactors

If the technical problems can be overcome, the legal basis for restarting the reactors becomes a challenge. Reading the following process for restarting the reactors published by Rosatom, it is clear that Russia is aware of the legal basis.

1. For the Zaporizhzhia NPP, Russia currently has provisionally approved the license of the Authority for Nuclear Safety of Ukraine. The licenses issued by this authority for Units 2 and 6 of the plant will expire in February and October 2026, and the Ukrainian authority’s licenses for all six units will expire.
2. After the expiry of the Ukrainian authority’s license, the Russian Federal Atomic Energy Authority will issue operating licenses for all units by the end of 2027.
3. Thus, the Zaporizhzhia NPP could be restarted in accordance with Russian regulations. In that case, operations would begin with Units 2 and 6.[8]

On the other hand, Ukraine, which had jurisdiction over the Zaporizhzhia NPP before Russia's military invasion, is fiercely opposed. Energoatom, the country's power company, said that "ending the Russian occupation and conducting a safety review in accordance with Ukrainian laws is the only way to restart the Zaporizhzhia NPP”.[9] However, as Russia's occupation of the plant continues, it is impossible for the Ukrainian side to carry out the safety checks required to issue operating licenses.

(2) Grounds under the International Covenant for the Jurisdiction and Operation of a Militarily Occupied Nuclear Power Plant by the Occupying State

Since the occupation of the Zaporizhzhia NPP was the result of an act of war, the issue of restarting the plant cannot be examined solely by the laws and regulations of both Ukraine and Russia. In addition, as mentioned in the introduction, since the licensing of reactor operation is entrusted to safety standards set by the regulatory authorities of each country, which country's laws, regulations, and safety standards govern the operation of nuclear reactors has a significant impact on the jurisdiction of nuclear power plants and the issue of their regional attribution. These factors necessitate the perspective of international covenants, and we would like to discuss them by comparing the claims of Ukraine and Russia, and by listing the main international covenants to be considered.

• Charter of the United Nations
  Ukraine claims "Russia's actions are a use of force prohibited by the UN Charter."
  Russia's claim "To exercise the right of self-defense under the UN Charter."
  Article 2, paragraph 4 provides that "all Member States shall, in their international relations, refrain from the threat or use of force against the territorial integrity or political independence of any State, or in any other manner incompatible with the purposes of the United Nations”.[10] Interpretations exist that the clause could be one of the grounds for indicating that a military invasion of Ukraine by Russia is inherently prohibited.[11] By making the invasion itself a violation of the Charter, it leads to the idea that the occupation of the Zaporizhzhia NPP is also invalid. Russia, on the other hand, insists on exercising the right of self-defense under Article 51 of the UN Charter.
  At the UN Security Council meeting on February 25, 2022, immediately after the invasion, 11 out of 15 countries voted in favor of a resolution declaring Russia's actions in violation of Article 2.4, with three abstentions (China, India, and the United Arab Emirates), with only Russia opposing.[12]
• Budapest Memorandum
  Ukraine claims "the Memorandum promised respect for its borders and the non-use of force"
  Russia's claim "the Memorandum does not create rights or obligations under international law."
  It was concluded in December 1994 between the United States, the United Kingdom, and Russia, and the former Soviet republics of Ukraine, Belarus, and Kazakhstan. In exchange for these three countries, including Ukraine, abandoning nuclear weapons deployed during the former Soviet era and joining the Nuclear Non-Proliferation Treaty (NPT), the Memorandum stipulates that the United States, Britain, and Russia respect the sovereignty and existing borders of the three countries. The Memorandum with Ukraine clearly states that the first clause "respects Ukraine's independence, sovereignty and existing borders" and paragraph 2 "no threat or use of force against Ukraine".[13] From Ukraine's point of view, Russia's military invasion can be interpreted as a violation of the Memorandum, as is the case with Article 2.4 of the UN Charter.
  Russia, on the other hand, questions the legal validity of the Memorandum. In December 2024, 30 years after the signing of the Memorandum, a Russian Foreign Ministry spokesman said, "The Memorandum is not a treaty and does not give rise to any rights or obligations under international law".[14]
• Convention (IV) respecting the Laws and Customs of War on Land and its annex: Regulations concerning the Laws and Customs of War on Land (Hague Convention on Land Warfare: Russia and Ukraine are parties to the Convention[15])
  Ukraine claims: "Territorial integrity before the annexation of the Crimean Peninsula in 2014 is non-negotiable"
  Russia's claim "Four states in the southeast, including Zaporizhzhia, were annexed by Russia"
  Considering the ongoing situation in which Russia continues to effectively control parts of Ukraine's territory, it is necessary to refer to the laws of war. If we interpret the areas currently occupied by Russia, including the area where the Zaporizhzhia nuclear power plant is located, as "occupied territory”, we can refer to this Convention, which entered into force in 1910 and is still in force. Article 55 provides that “The occupying State shall be regarded only as administrator and usufructuary of public buildings, real estate, forests, and agricultural estates belonging to the hostile State, and situated in the occupied country. It must safeguard the capital of these properties, and administer them in accordance with the rules of usufruct”.[16] With regard to public buildings and real estate requisitioned by the war, the occupying country is only a manager of them, a right holder who can use them for a certain purpose (usufruct holders). As stated above, the Convention emphasizes the preservation of the original condition of the occupied territories, and Article 43 also provides for respect for the laws of the occupied territories.[17] For Ukraine, even though it is currently occupied by Russian forces, the interpretation is that Ukraine still has jurisdiction over the Zaporizhzhia NPP.
  As mentioned earlier, Russia initially provisionally approved the license of the Authority for Nuclear Safety of Ukraine. This fact suggests that Russia was conscious of Article 55, but the restart of the Zaporizhzhia NPP in accordance with Russian law can be seen as part of a movement to convert from “the areas occupied by Russia by force” to “Russian territory”. If the plant is restarted under Russian law when the license of the Ukrainian authority expires and the change in jurisdiction of the plant becomes a fait accompli, it may be possible to justify the fact that Russia declared the annexation of four southeastern Ukrainian regions, including Zaporizhzhia, in the fall of 2022, and to appeal to the international community for their belonging to Russian territory.
• Protocols Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts (Protocol I) (both Russia and Ukraine are parties to the Protocols)
  Ukraine's position: "Russia's actions violate the protection of nuclear power plants stipulated in the Geneva Conventions"
  Russia's position: "Russia has not harmed civilians by occupying the nuclear power plant, and it has not violated the Convention"
  Meanwhile, nuclear power plants are facilities that are granted "special protection" under international humanitarian law because of the risk of serious effects on the surrounding environment and human body in the event of an attack. Article 56 of the Additional Protocol lists “three facilities containing dangerous forces-Dam, levee, nuclear power plant" in paragraph 1 of the Protocol and stipulates that " shall not be made the object of attack, even where these objects are military objectives, if such attack may cause the release of dangerous forces and consequent severe losses among the civilian population". Russia's attack and occupation of the Zaporizhzhia NPP could constitute a violation of the treaty from Ukraine's point of view.
  On the other hand, Russia's position is weighted by the fact that the Additional Protocol does not provide that an attack on a protected facility under Article 56(1) would immediately constitute a violation of the Convention. Article 85(3)(c) adds a provision that " launching an attack against works or installations containing dangerous forces in the knowledge that such attack will cause excessive loss of life, injury to civilians or damage to civilian objects" constitutes a violation of the Convention.
  Since it is not possible to determine whether Russia was aware that the attack on the Zaporizhzhia NPP would cause undue damage to civilians, and because it did not cause serious damage to civilians, it is considered that it does not meet the requirements for a violation of the treaty.[18]
• IAEA Charter, Ukraine-IAEA Safeguards Agreement
  Ukraine's position "Ukraine has jurisdiction over the Zaporizhzhia NPP and nuclear facilities in the Crimea"
  Russia's position: "Russia has jurisdiction over nuclear facilities in areas annexed by Russia"
  The IAEA Charter provides for the peaceful uses of nuclear energy and does not envisage an act of war that will result in the occupation of a nuclear power plant or a change in its jurisdiction. The IAEA Agreement on Safeguards (IAEA’s inspections of nuclear facilities and nuclear materials) concluded separately with States Parties stipulates that all nuclear facilities within the territory of the country are subject to safeguards so that the nuclear facilities of the country are used for peaceful purposes. The safeguards agreement between Ukraine and the IAEA was concluded in 1998 after Ukraine renounced its nuclear weapons in the Budapest Memorandum, and its Article 1 specifies that all nuclear facilities located on the territory of Ukraine are subject to safeguards[19]. From the point of view of Ukraine, the Zaporizhzhia NPP is naturally targeted, and the focus will be on whether the IAEA recognizes the Zaporizhzhia NPP as a "facility on the territory of Ukraine."
  On the other hand, Russia objected to the IAEA's statement in its annual report that Ukraine still had jurisdiction over nuclear facilities in the Crimean Peninsula after the annexation in 2014. In June 2015, Russia sent a letter to the IAEA, claiming that "through the referendum procedure, the Crimean Peninsula has become Russian territory and is under Russian jurisdiction".[20]
  The IAEA has failed to implement safeguards in the Crimean Peninsula but has not changed its claims in its annual report since then.[21] In the case of the Zaporizhzhia NPP, Russia may make similar claims and use its position as a nuclear-weapon state that is not obliged to take safeguards to refuse to apply safeguards to the plant, but the IAEA is not expected to change its previous position.

Thus, while it is difficult to find a legal basis to justify Russia's jurisdiction over the Zaporizhzhia NPP and the restart of the reactor when reading the relevant major international conventions, it is also difficult to immediately recognize Russia's actions as a violation of the international conventions. If Russia resumes operations at the plant, it will become a fait accompli that the plant will be under its jurisdiction in accordance with Russian laws and safety standards, and it is likely to affect negotiations over the attribution of four southeastern Ukrainian regions, including Zaporizhzhia.

4. How should Japan respond?

How should Japan respond to Russia's move to restart the Zaporizhzhia NPP and make its jurisdiction a fait accompli? First of all, it is necessary to assume that a similar situation may occur in the vicinity of Japan. Unfortunately, if a Taiwan emergency breaks out, there is a risk that China will occupy Taiwan's nuclear power plants. Taiwan is not a state, but it has a separate safeguards agreement with the IAEA, which could be violated by the occupation. As a major premise for ensuring the safety of the peaceful uses of nuclear energy, it is essential that the regulatory authorities of each country comply with the safety standards stipulated according to their respective circumstances, and that the status quo is not changed by force, such as by force of arms. Therefore, Japan must start discussions on measures to exclude nuclear facilities from attack targets in wartime and clarify its position. On top of that, Japan needs to be aware of the fact that it always emphasizes the importance of the "rule of law" at international conferences and summit meetings with other countries. With regard to Russia's military aggression, Japan will not only continue to persistently advocate for an end to the war based on compliance with the UN Charter, but also protect nuclear facilities in wartime so that a second Zaporizhzhia NPP will not be created in the future, in light of the peculiarities of nuclear facilities that might have a serious impact on the environment and human body in the event of an attack. Japan should take the lead in international rule-making discussions. One proposal is to amend the Protocols Additional to the Geneva Conventions to specifically exclude nuclear facilities from the target of attack. In addition, in the case of the Zaporizhzhia NPP, the presence of IAEA staff at the plant has avoided large-scale fighting in the vicinity of the plant, so it is also essential to discuss the role of the IAEA in protecting nuclear facilities in or near the war zone.

(2) North Korea's Aims and Intention