Nuclear Power Plants in Wartime

The brazen Russian invasion and bombardment of Ukrainian cities poses the most serious threat to European security and the global order since World War II. Nuclear-armed Russia’s invasion of a country with 15 nuclear reactors, which generate half its electricity, and its shelling of a training centre, not far from the six reactors of the  Zaporizhzhia nuclear complex has raised the spectre of a massive radioactive leak from a damaged reactor, reviving memories of the 1986 Chernobyl disaster.

The six Zaporizhzhia nuclear reactors supply a quarter of Ukraine’s total electricity, and the near-accident caused by the Russian military’s aggressive brinkmanship has demonstrated the inadequacy of existing international instruments such as the Additional Protocol I to the Geneva Conventions. The protocol states that

works or installations containing dangerous forces, namely dams, dykes and nuclear electrical generating stations, 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.

However, these special protections do not apply to a nuclear power plant, which is considered a legitimate target “if it provides electric power in regular, significant and direct support of military operations and if such attack is the only feasible way to terminate such support.” The primary aim of the non-proliferation treaty of 1970 is the prevention of the spread of nuclear weapons, not the protection of nuclear power plants during warfare.

This is worrying. Large civilian populations reside near nuclear reactors. There is a distinct possibility that China may launch a land invasion of Taiwan involving combat operations in the vicinity of its three nuclear reactors. In addition, an errant airstrike, drone strike or misdirected missile test might hit a nuclear power plant at any time, especially in a contested region like the India–Pakistan or North Korea–South Korea border. Under these circumstances, Additional Protocol I’s limited protections seem inadequate.

The United Nations International Atomic Energy Agency (IAEA) has never undertaken a detailed, scenario-based risk assessment of the threats to nuclear power plants nor issued recommendations for multilateral agreements to prevent deliberate strikes or targeting errors from causing a catastrophic radioactive release from a nuclear plant. This puts at risk a significant fraction of the global nuclear reactor fleet of 440 nuclear reactors, operational in 32 countries (including potential conflict zones) and producing 10% of the world’s electricity. (A single nuclear reactor can produce enough electricity to power 760,000 American homes.)

Sceptics may question the utility of agreements in ensuring the safety of nuclear power plants during war, given the inherent difficulties involved in controlling the scale and scope of armed conflicts. There is also a risk that the communication breakdowns and miscommunications resulting from the fog of war would render such agreements useless or ineffective. However, given the risks to the civilian population near nuclear reactors—both from the direct impacts of lethal radiation and the psychological impacts of the panic caused by news of radioactive release—guidelines, norms and agreements are a good place to start.

Let’s look at why nuclear power plants are at higher risk of catastrophic accidents during combat.

A conventional nuclear reactor uses neutrons to split natural or enriched uranium fuel atoms, packed into compact fuel rods, in a process known as nuclear fission, which produces enormous amounts of heat. The fission process occurs in a thick steel container called a reactor pressure vessel.

A reinforced concrete outer containment building prevents radioactivity from leaking out of the reactor during an accident and is also supposed to protect the reactor from natural disasters such as earthquakes, as well as from airstrikes. However, pressure vessels and concrete containment buildings are not designed to withstand sustained attacks from heavy explosive munitions.

The heat released from splitting the uranium fuel is used to boil water into steam, which drives turbines that generate electricity. Water is continuously circulated in the reactor vessel using electric pumps or diesel-powered backup pumps, in order to keep the fuel rods cool and help control or moderate the pace of the fission reaction. Control rods comprised of neutron-absorbing materials are inserted or removed from the reactor to manage the pace of fission and can be fully inserted to shut down the nuclear reaction.

Military conflict poses multiple threats to reactors. Explosive ordnances and projectiles can damage the containment building and the reactor pressure vessel resulting in a loss of coolant accident (LOCA), in which the circulation of water through the reactor core is disrupted and water levels cannot be replenished because of damage to electric pumps or backup diesel generators. The reactor then loses coolant water and the exposed radioactive fuel heats up, melts and burns through the pressure vessel and concrete containment to release massive amounts of radioactivity. The accidents at Three Mile Island and Fukushima both involved core meltdowns caused by loss of coolant water.

In conflict situations, the reactors’ cooling systems not only need to remain functional until they have been safely shut down, but must remain operational after the shutdown, until the residual heat from the fuel has been cooled by sufficient amounts of water. At Fukushima, an earthquake knocked out the grid connections supplying the electric pumps that circulated coolant water though the reactor and the ensuing tsunami submerged the backup diesel generators. Even though the reactors had been shut down, the loss of coolant meant that the residual heat in the radioactive fuel was sufficient to cause a core meltdown.

The risks don’t end here. The nuclear fission process also produces highly radioactive spent fuel, which must first be cooled in pools of circulating water and then isolated in a permanent underground waste repository, such as the one in Finland. These spent fuel pools are often located in or near the reactor complex and structural damage and loss of cooling capacity due to a power outage caused by a military strike can release radioactivity.

If China were to invade Taiwan, heavy artillery or airstrikes near Taiwan’s three nuclear reactors could damage the cooling systems. In the event of a war in the Korean peninsula, the North Korean army and artillery could similarly damage one of South Korea’s twenty-four nuclear power plants.

An errant missile strike could pose an even more serious risk. On 9 March 2022, India accidentally launched its nuclear-capable, supersonic BrahMos cruise missile deep into Pakistani territory, allegedly due to a technical malfunction. The missile hit a village about 120 km from the Indian border, but luckily there were no casualties. However, there was a small but not negligible chance that it could have hit a Pakistani nuclear facility, potentially triggering an escalatory spiral. That the missile was unarmed may not matter much, given the velocity of the projectile. In addition, the atmosphere of mistrust between the two nations could have led Pakistan to construe the accidental missile hit as a deliberate attack. The threat of an accidental missile strike on a nuclear facility in South Asia cannot be ruled out, especially as both India and Pakistan are constantly testing missiles.

There is also the risk that a deliberately provocative missile launch might accidentally hit a nuclear facility. North Korea recently test fired an intercontinental ballistic missile that landed in Japan’s exclusive economic zone. This is not the first time North Korea has launched a missile over Japan—a country with thirty-three nuclear reactors. That a North Korean missile might accidentally hit a Japanese nuclear facility is a remote—but not unimaginable—possibility. Likewise, an errant Chinese air or drone strike might accidentally hit a Taiwanese nuclear reactor due to the kind of targeting errors that are a constant feature of modern warfare—the mistaken targeting of civilians by US drone strikes in Iraq and Afghanistan provided a sobering example of this—thereby posing serious safety risks to nearby civilians.

Even if a nuclear reactor itself is not structurally damaged, artillery shells, missiles and bullets can kill or injure plant personnel or create a panic fuelled-exodus of workers, creating huge challenges for continued normal operations at the plant. War-related disruptions to supply chains could delay the arrival of crucial spare parts needed for the continued operation of the reactors and delay the arrival of replacement personnel. The 1986 Chernobyl disaster was not just the result of design flaws, but also due to operator error. In conflict situations, nuclear plant operators are under extreme psychological stress: they may have to endure high ambient noise levels caused by nearby exploding ordnance, may be coerced by an invading army that takes over the plant and will suffer from anxiety and insomnia—all of which heighten the risk of accidents.

Nuclear reactors not only threaten to release dangerous levels of radioactivity if there is a structural failure, but there is also the risk of a panic-induced mass exodus from surrounding areas at the news of an attack on a nuclear power plant—even if the attack is unsuccessful. Institutions such as the UN and the IAEA need to initiate detailed deliberations on non-binding guidelines and binding agreements that commit parties to creating buffer zones around nuclear plants, where combat operations are forbidden. They should also formulate norms and rules that ensure that nuclear plant personnel are not seen as legitimate targets of military attack. India and Pakistan regularly share a list of nuclear power plants, under the bilateral Agreement on the Prohibition of Attack Against Nuclear Installations and Facilities. This needs to become standard global practice, in order to minimize the chances of a test missile hitting a nuclear facility. We need to establish hotlines between countries in conflict zones and such hotlines should be used during conflict, to direct the course of the war away from large nuclear complexes. We can start with non-binding guidelines, but the ultimate aim should be to institute global treaties that insulate the large and vulnerable civilian nuclear complex from military disruptions that could cause catastrophic radioactive release, leading to the loss of human life and the permanent contamination of large tracts of land.