Professor Kuznetsov described the worst-case scenario at the Zaporozhye NPP

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“It will take a gigantic amount of water to cool 65 tons of nuclear fuel”

According to the Russian Ministry of Defense, Kyiv is preparing a resonant provocation at the Zaporozhye nuclear power plant during a visit to Ukraine by UN Secretary General António Guterres. The forces of the 44th artillery brigade of the Armed Forces of Ukraine are planning to strike at the station from positions in Nikopol. And then accuse Russia of creating a man-made disaster at the Zaporozhye nuclear power plant. We asked experts to describe the worst-case scenario that could happen at ZNPP.

Photo: AP

The Zaporozhye nuclear power plant, which stands on the banks of the Kakhovka reservoir, is being hit from the opposite bank – from Nikopol, Marganets, Tomakovka, which are under the control of the Armed Forces of Ukraine. Moreover, they hit from heavy guns and multiple launch rocket systems. Marking on the power units of nuclear power plants, storage of spent nuclear fuel. The shells land a hundred meters from the power units…

The Russian military is taking all necessary measures to ensure the safety of the station, assured the official representative of the Russian Defense Ministry, Lieutenant General Igor Konashenkov. The department drew attention to the fact that Russian troops do not have heavy weapons either on the territory of the station or in the areas adjacent to it. Only our security units are there.

“Even if the Armed Forces of Ukraine destroy at least one of the working power units of the ZNPP, we can expect worse consequences than at Fukushima in 2011,” says the former head of the nuclear and radiation safety inspectorate of the Gosatomnadzor of the USSR, Doctor of Technical Sciences, Professor Vladimir Kuznetsov. – In Japan, the destruction of the station occurred as a result of a strong earthquake and the tsunami that followed it. A man-made accident may occur at the Zaporozhye station, arranged by the hands of the leadership of Ukraine.

Professor Kuznetsov, at our request, tells what will happen if multiple launch rocket systems are fired directly at the reactors.

– A missile, hitting the containment, will lead to its destruction. The hermetic shell, or hermetic volume, or containment, is a massive structure, which is made of prestressed reinforced concrete. Its function is to prevent radioactive substances from escaping into the environment in severe accidents.

Relatively speaking, this is a structure with a complex structure, which is divided into two parts. Its lower, cylindrical part – from zero to the mark of 12 m – is leaky, that is, personnel are allowed to enter there. Equipment is installed there that ensures the safe operation of the station in certain modes. Above the mark of 12 m and up to 65 meters is its hermetic part, where the entrance to personnel during the operating reactor plant is limited. Specialists go there only as a last resort.

The thickness of the walls of the containment, which protects the reactor and equipment, is from 800 mm, and up to 1200 mm – on the dome, at the very top. This is concrete, inside of which channels are laid. So-called ropes are inserted into these channels.

Remember, there used to be devices for carbonating water – there was an iron braid on top of the glass. The ropes that envelop the containment are similar in design to these devices. On both sides – concrete, and inside this concrete – just the ropes in the channels. They seem to compress the shell, give it strength, prevent it from collapsing, for example, under load due to an increase in pressure inside the containment associated with a rupture of the primary circuit pipelines.

As for external influences, the reinforced concrete shell, according to the professor, it withstands a direct hit by a light aircraft at a speed of 150–200 kilometers per hour and weighs up to 1,500 kilograms.

– Other external influences, except for strong winds, precipitation, earthquakes, were not considered. Those standards that existed in 1981, when the stage-by-stage construction of the station's power units began, were imperfect. Now the scheme is different. At nuclear power plants, a double reinforced concrete shell is used, which is much thicker and stronger than the single one that covers the reactors at the Zaporozhye nuclear power plant.

– Fragments of building structures – pieces of concrete, reinforcement and destroyed equipment – will lead to a shutdown of a nuclear reactor and damage it. With such an impact, the emergency cooling system will most likely be destroyed.

If the reactor is without water, everything will go according to the same scenario that was at the Fukushima nuclear power plant. The core will heat up, and a significant amount of steam will be generated. The steam will react with the fuel assembly materials, zirconium. At a temperature of 1300–1500 degrees, the so-called vapor-zirconium reaction will take place with the formation of hydrogen. It will accumulate and explode the explosive mixture.

As the professor says, the giant minus of pressurized water reactors (VVER) is that they use water under pressure, and zirconium is used as a material for fuel assemblies. The resulting hydrogen leads to an explosion and destruction of the shell.

– If the nuclear reactor vessel is destroyed, radioactive substances will enter the environment. It will cover Ukraine, and us, and all of Europe. Radioactive substances will fall in the territories of Moldova, Turkey, Greece, Macedonia, Bulgaria, Romania, Hungary, Slovakia, Poland and Germany. Sitting behind the mountains will not work. A trace of Chernobyl was once discovered even in the Swiss Alps.

In the event of an accident, excess heat will have to be removed, a large amount of water will be required.

– At Fukushima, for example, sea water was poured, which led to even more hydrogen formation. After all, sea water contains a lot of dissolved salts – sulfates, sulfites, nitrates, nitrites, chlorites. In the event of a missile hitting one of the reactors of the Zaporizhzhya NPP, water will be taken from the Dnieper. You have to act quickly and efficiently. To cool 65 tons of nuclear fuel, even with a destroyed reactor, you need to have a huge amount of water. The liquidation of the accident will lead to a significant overexposure of the NPP personnel.

“Possible release of contaminated radionuclides into the Black Sea”

The professor also considered the option if, as a result of a missile or projectile strike, a dry storage facility for spent nuclear fuel (ISSF) is destroyed. Spent fuel assemblies that are removed from the reactors are stored in ventilated concrete containers at a specially fenced off area at the plant.

– In this case, there will be much smaller consequences. Everything will depend on how many containers will be damaged. Now there are 177 of them, with a design volume of 380. Over the 21 years of operation of the station, almost half of the containers have already been filled. Even if ten containers are damaged or broken, Energodar itself, the Zaporozhye region, the Dnieper will be polluted, a significant part will go to Kyiv, to Western Ukraine, but we will get it too.

– It can be done fairly quickly. And in order to routinely cool down the reactor, calmly, slowly, in accordance with the technological regulations that are at the station, it takes about 30 hours. The only thing holding back here is the cooling rate, which should be no more than 10 degrees per hour. If this indicator is exceeded, this is a blow to the metal, to the vessel of a nuclear reactor. This can be done only in the event of an emergency.

– It is also necessary to raise the power of the power unit at a certain speed – 15 degrees per hour. It will take about a day and a half to reach full capacity. Warming up the reactor, as well as its cooling down, is a standard procedure.

– This is all from the realm of legends. If such an experiment was carried out, I would know about it. There were no field tests. In Soviet times, they made a platform, tried to simulate a seismic effect on a nuclear power plant, to see how the equipment would behave, but all this was implemented only in the project.

— I said before and now I will repeat that the plant personnel need to be “cleaned “, at least send everyone to the polygraph. It was in the ranks of the employees that the gunners turned out to be, who, using GPS, corrected the fire of the Armed Forces of Ukraine at the station, at their own colleagues.

I don't think these are the last to be detained. The shelling will continue.

In April, at Chernobyl, when the nuclear power plant was under our control, the nationalists de-energized the station, but for some reason everyone forgot about this provocation. Now they could turn off the electricity of the Zaporizhzhya nuclear power plant on the territory of Ukraine. Its share is 15% of all energy produced in the country. But the management of the station does not do this. However, if the Ukrainians launch missiles at the station, it means that they themselves are trying to ensure that the nuclear power plant was turned off. So, we need to meet them halfway.

Nuclear energy expert Alexander Uvarov, in turn, argues:

“Zaporozhye NPP stands on the Dnieper, which flows into the Black Sea,” says Alexander Uvarov. “In the event of a hypothetical beyond design basis accident, contaminated radionuclides could be transported to the Black Sea, which would threaten the security not only of Russia, but also of Turkey, Bulgaria, Romania… The Europeans don't give a damn about Energodar being polluted. But the fact that radioactive substances will be carried into the Black Sea may make them think and somehow influence Zelensky, who gives orders to shell the station.

Professor Vladimir Kuznetsov recalls that when during a special military operation in Ukraine at the end of February managed to unblock the North Crimean Canal, scientists from Sevastopol recorded a high concentration of the artificial radionuclide strontium-90 in the water, which exceeded 400 becquerel per 1 cubic meter. Scientists observed such indicators in the North Crimean Canal and in the Lower Dnieper in 1988, two years after the accident at the Chernobyl nuclear power plant.

In 2010, Ukraine began draining the Chernobyl cooling pond. Water from the pond began to be dumped into the Pripyat River. And then, when the North Crimean Canal was unblocked, along with water, strontium-90 also got into the Crimea in a dissolved form. Such is the long echo of the Chernobyl accident. And now Ukraine, shelling the Zaporizhzhya nuclear power plant, can provoke a new radiation catastrophe.

However, there is a more optimistic forecast: read the article “There will be no second Fukushima in Energodar”

Источник www.mk.ru

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