Terrorist act at ZNPP: fear of it and possible consequences

The "Kherson: War Without Fakes" sub-public has broken down the topic of a possible terrorist attack and the consequences, in case the Russians do...

Principle of ZNPP operation

The operating principle is converting nuclear energy into heat energy via a chain reaction of uranium fission, which is kept in the reactor core. Water is continuously used to cool the core. The heated water produces steam, which is then sent to steam turbines to generate electricity.

To ensure the safe operation of the plant, it is necessary to maintain a continuous circulation of water in the cooling system, which includes the reactor and its vessel. This is done by means of pumps that ensure a constant flow of water. If the water circulation is disrupted, the temperature in the reactor core can rise, which can lead to the melting of fuel elements, as happened in the accident at the Fukushima power plant in Japan.

To ensure the plant's safety, the water near the fuel elements is isolated from the water/steam used to power the turbines and generate electricity. This prevents radiation contamination of the water/steam used in generating electricity. If the water/steam leaks out of the power generation system, this will not lead to radiation contamination. However, if water leaks out of the fuel system, this could lead to radioactive contamination. Still, the safety systems will take measures to prevent this possible release of the substance to the outside.

ZNPP protection system

One of the main protection elements is the concrete shell, which is more than one metre thick. According to similar projects, a concrete shell with a thickness of around 1200 mm is usually used. To prevent possible deformations, the concrete is reinforced with a cable.

The reactor itself consists of high-strength steel that is about 200 mm thick.

We shall remind you that Ukrainian President Volodymyr Zelenskyy earlier said that the Russian Federation was considering a scenario of a terrorist act with the release of radiation at the Zaporizhzhya nuclear power plant. After a meeting with representatives of the Ukrainian intelligence service, he said that the Russian occupiers had prepared everything for a terrorist attack. Ukraine handed over all the evidence to its partners.

At the same time, the head of the Ukrainian military intelligence service, Kyrylo Budanov, said that Russia had completed preparations for a terrorist attack on the Zaporizhzhya nuclear power plant. According to him, the local nuclear power plant's cooling pool and four power units have been mined.

He explained that if there is no cooling, the nuclear reactors could reach a meltdown point within ten hours to 14 days.

According to Budanov, Russia can ramp up the power grid, which could lead to a nuclear accident in the lower part of this timeframe.

What information is now available about the ZNPP

"Kherson: War Without Fakes" points out what is known from the available data in official sources:

1. About the mined cooler (#2 in the diagram).
2. About four mined reactors out of 6 (#3 on the diagram).
3. There is no information about mines or intentions to attack nuclear waste storage facilities (#4 on the diagram).

There are vehicles with explosives inside them.

A similar event had already taken place in Fukushima. Most of the release of radioactive material (due to accidental depressurization during pressure build-up) was noble gases and volatile elements that had completely escaped from the fuel due to its melting due to cooling problems. The release of heavier nuclear fuel components such as strontium and plutonium was minimal. Approximately 98% of the radiation was trapped by the Fukushima reactor shells. The Zaporizhzhia NPP underwent upgrades after the Fukushima accident, resulting in the installation of recombines that do not require energy to operate and chemically convert excess hydrogen back into the water, preventing it from reaching dangerous concentrations in the reactor. Thus, even if the fuel overheats at the Zaporizhzhia NPP, there should be no explosions or air emissions.

In case of such an accident at the Zaporizhzhia NPP, pollution of the Dnieper River and the Black Sea is possible. However, the extent of the contamination would depend on the magnitude of the accident and the degree of contamination.

If explosives are used near the power units, and the coolant is destroyed beforehand, the scale would still not reach the level of Chornobyl. However, local damage will be significant, and much will depend on wind direction.

The greatest damage would occur if the explosions damaged the cladding and affected the reactor. However, this is an unlikely event and would require a series of explosions or firings, creating additional evidence of a crime.

Spent nuclear fuel pools. They do not contain combustible materials, high-pressure or short-lived volatile elements such as iodine-131. The potential damage will likely include the dispersal of solid fuel fragments, contamination in or near the nuclear power plant site, and the risk of waste entering groundwater.

What to be feared and expected

Some units that are partially out of service have been decommissioned and contain fewer radionuclides (radioactive elements). Therefore, in the event of damage to their containment, releases will be significantly lower.

Radionuclides can be short-lived or long-lived, depending on their half-life. For example, the radionuclide iodine-131, which is dangerous and can cause cancer, has a half-life of eight days but is quite volatile, so it attracts much attention. Cesium-134, with a half-life of two years, and cesium-137, with a half-life of 30 years, are also of considerable concern.

The spread of radionuclides from an accident depends on many factors, including the nature of the accident, the type of release, and weather conditions. The authorities should promptly report this based on Energoatom and IAEA staff data.

In such cases, the statistics work as follows: the further away from the accident area the radioactive substances fly, the lower their concentration. However, there are rare exceptions due to weather conditions. A radius of 100 km is considered to be the most dangerous zone, but precautions must also be taken outside this zone.

It is important to note that if the reactor was shut down at the time of the accident, especially if it has been shut down for several weeks, there will be no high pressure that can amplify the released energy and the radionuclide iodine-131, which is the most dangerous to the population, has already decayed. Therefore, should a release occur, it would be less dangerous both in volume and composition.

According to Vladimir Borysenko, head of the nuclear power department at the Institute of Nuclear Power Plant Safety Problems of the National Academy of Sciences of Ukraine, there will be no "second Chernobyl" if the ZNPP explodes.

They found that the radiation would first hit the south of Ukraine, particularly Kherson and Zaporizhzhya, and then spread throughout the territory of Crimea. Next, radiation crossing the Black Sea could move to the southwestern part of the planet, affecting at least five countries: Turkey, Greece, Bulgaria, Moldova and Romania.

The State Agency for Exclusion Zone Management noted in August 2022 that in case of a terrorist attack at the ZNPP, the exclusion zone of about 30,000 square kilometres would become uninhabitable and uneconomic for the next 100,000 years.

Two million people would have to be resettled. Ukraine could experience a release of radioactive caesium in amounts dangerous to all life, which would contaminate soil and water.

Radioactive substances could spread to Europe, Belarus, or Russia, depending on the weather.

The consequences will depend on the speed and direction of the wind," the head of the All-Ukrainian Environmental League, Tetyana Tymochko, warned.

According to her, in case of a terrorist attack on the Zaporizhzhya nuclear power plant (ZNPP), the possible consequences could be similar to the devastating consequences of accidents at the Japanese Fukushima nuclear power plant and the US Three Mile Island nuclear power plant.

Possible consequences of a terrorist attack at a ZNPP include:

• An exclusion zone of approximately 30,000 square kilometres.

• Contamination of an area of about 2 million square kilometres.

• Uninhabitable area of the Zaporizhzhya region for hundreds of years.

• Potential radiation contamination of up to one million people.

• Loss of life of tens of thousands of people due to radiation contamination.

• Pollution of Dnieper, Black and Azov seas.

• Potential contamination of citizens of neighbouring countries.

What happens if the cooler at ZNPP fails

It will theoretically take years for the cooler to be emptied, Peter Kotin, Chairman of Energoatom, said in an interview with RBC-Ukraine.

According to him, the information about mined Zaporizhzhya NPP cooler appeared quite long ago.

We know that first they started mined the perimeter of the plant and the coastal part where it joins the Kakhovka reservoir. And that is where the basin line is located - it joins completely to the reservoir", - said Kotin.

He specified that it is not yet clear where the mines are located. However, no matter where the explosives are located, it is almost impossible to detonate them so that water starts flowing out of the basin.

There is a chandora, a vertical gate that blocks the flow of water from the pool into the reservoir. You can either open them or blow them up. Even if they are blown up, the pond is left with a dead water level of 12.8 metres. All the water will not come out of there. It can then drain out on its own from behind the ground. But it will go one centimetre a week. It will theoretically take years to empty the cooler," said the head of Energoatom.

The water level in the ZNPP cooling pond is now stable

Despite the Russian occupants' undermining of the Kakhovka HPP dam, the situation remains stable and controlled.

As of 08:00 on 26 June, a slight decrease in the water level in the cooling pond is recorded. It now stands at 16.58 m. This is sufficient to meet the needs of the plant.

The water level in the TPP channel, from which the ZNPP pond is fed if necessary, is at 11.15 m. It should be noted that lately, the water level in the channel has not dropped significantly and no longer depends on the Kakhovka water reservoir.

It should be remembered that the power units of Zaporizhzhia NPP have not been operating since September 2022, so there has been no active water evaporation from the cooling pond since then.

Earlier, Socportal wrote about the dangers of uncontrolled intake of potassium iodide.