Dire warning: It will only last seven days, and then it will explode worse than Chernobyl

Ukraine's power grid is at "increased risk of catastrophic failure" following a Russian missile and drone attack on Sunday, the organization warned, raising safety fears for the country's three operating nuclear power plants.

Moscow's recent strikes targeted electrical substations "critical to the operation of Ukraine's nuclear power plants" and there is a possibility that the reactors could lose power and become unsafe, according to a Greenpeace briefing that was subsequently provided to Britain's Guardian.

• It has begun - America has closed the embassy, ​​there is information about a major attack

Sean Burney, a Greenpeace nuclear energy expert in Ukraine, said it is clear that Russia is using the threat of a nuclear disaster as the main military lever to defeat Ukraine.

"But by launching attacks, Russia risks a nuclear disaster in Europe, comparable to Fukushima in 2011, Chernobyl in 1986 or worse," he warned.

The International Pressure Group called on Russia to immediately stop attacks on Ukraine's power grid and the International Atomic Energy Agency (IAEA) to deploy permanent monitors at substations critical to Ukraine's nuclear power plants.

The Guardian reminds that in 1986 Ukraine was the site of the world's worst nuclear disaster, when faulty design led to the explosion and destruction of the Chernobyl reactor. Thirty people died within a month, and radioactive material spread to Ukraine, Belarus and Russia, and to a lesser extent Scandinavia and Europe.

On Sunday evening and early morning, Russia launched more than 210 missiles and drones aimed at power generation and transmission targets across Ukraine. Hours later, Ukrenergo, the country's main electricity supplier, announced nationwide rationing to help the system recover.

Explosions were heard in Kyiv, Odessa and Mykolaiv in the south, in Kryvyi Rih, Pavlograd, Vinnytsia in central Ukraine and Rivne and Ivano-Frankivsk in the west.

Explosions were also heard near Ukraine's border with Moldova, where Ukraine's grid connects to the neighboring country and the rest of Europe.

While the attacks are not believed to have directly targeted Ukraine's three remaining operational nuclear power plants, in Rivne and Khmelnytskyi in the west, as well as a plant in southern Ukraine, Greenpeace said Russia was deliberately trying to increase the stress on Ukrainians by targeting substations which are related to nuclear plants.

On Sunday, the IAEA reported that the main transmission lines from four substations leading to three nuclear power plants were cut, and that a "heavy explosion was heard" at the Khmelnytskyi nuclear plant.

Two transmission lines to Rivne became unavailable, and production was reduced at six of the nine operating nuclear reactors at three sites. By the way, the Guardian explains, about two-thirds of Ukraine's electricity goes to those three mentioned locations because previous attacks by Russia destroyed most of the country's coal and oil power plants, while some of the country's hydroelectric plants were also damaged.

Of particular concern is that "serious damage to the Ukrainian power system, including substations, is causing great instability," according to Greenpeace, which could mean a prolonged loss of external power supply to the reactors. Cooling the reactor and spent fuel requires electricity, the stable supply of which is threatened, the environmental group added.

In the event of a supply outage, Ukraine's reactors have on-site diesel generators and batteries to provide a basic power supply with enough fuel for seven to 10 days, but if the fuel cannot be maintained or power restored, the consequences could lead to a nuclear disaster.

"Loss of cooling function in one or more reactors would inevitably lead to nuclear fuel meltdowns and large-scale radiological releases," Greenpeace said in its report.

"The people and environment of Ukraine are most at risk, but there is the potential for much of Europe and beyond to be seriously affected, depending on the wind direction at the time," the report said.