“There are alternative sources of water supply”
The water level in the Kakhovka reservoir after the APU blast of the dam of the Kakhovskaya hydroelectric power station has reached a level below the “dead” point — it has dropped to seven meters, the acting governor of the Kherson region said Vladimir Saldo. Zaporozhye Nuclear Power Plant can no longer take water into the cooling pond. According to the head of the IAEA, Rafael Grossi, who visited the station on a mission, the situation with nuclear safety remains unstable and potentially dangerous there. We asked Alexander Uvarov, director of the AtomInfo Center, to assess the situation.
Photo: DENAMAX COMMONS.WIKIMEDIA.ORG
“Here you should immediately pay attention to one fundamental point — there are two types of water at the nuclear power plant,” explains Alexander Uvarov. — The first type is water, which directly cools the reactors. It is contaminated with radiation and spins in a closed circuit, that is, this water does not go anywhere outside. Sometimes it needs a little nourishment, but, in general, it is there.
In order for it to circulate, you need a pump. For the pump to work, electricity is needed. She is on the site. This is the first type of water. It spins, passes through the reactor, cools it, and itself, of course, also heats up.
This water, as the expert says, must be cooled somehow, otherwise it will eventually boil.
“And this is done with the help of the second type of water. It is no longer contaminated with radiation, it does not come into direct contact with the first type of water, which is called the coolant. It passes through special devices, in this case a steam generator, contacts through the walls with hot water of the first type, heats up and goes further. Water of the second type can be safely drained into the same river. It is only slightly warm and clean. Its volumes are not very large to «evaporate» the river.
Alexander Uvarov recalls the situation when last year the Armed Forces of Ukraine shelled the Zaporozhye nuclear power plant and damaged the high-voltage power line. Due to the loss of power, an emergency start of diesel generators occurred, which ensured the operation of the fuel cooling pumps.
— It concerned just water of the first type. Now the problem is with water of the second type. Previously, water was taken from the Kakhovka reservoir, which now, due to the explosion of the APU of the dam of the Kakhovskaya hydroelectric power station, has begun to shallow. But water was not taken directly from the reservoir, because engineers are smart people. In the Kakhovka reservoir, a certain area was fenced off, a dam was built around it. This is how the cooling pond was formed. It is in contact with the reservoir, where certain channels are laid in the dam. But this tank largely lives on its own, as it can be isolated with special closures. Which, in fact, was done.
The nuclear worker notes that the Kakhovka reservoir is getting shallower, and the water level in the cooling pond remains at the same level of 16.67–16.66 meters. There is no water flowing out of the pond.
—There is no danger at the moment. I repeat, for now. This cooling pond provides the second type of water.
— That's right, so the head of the IAEA Grossi says that the pond can perform its functions for several months. That is, it is not a problem of tomorrow. But nevertheless, it must be solved.
Rosatom is now providing alternative sources of water supply. There is an option of pumping water from artesian wells. Near the nuclear power plant there is a thermal power plant, which has its own canal, you can take water from there. There are other options, which, for obvious reasons, I will not expand on. Work is underway, measures are being taken.
The representative of Rosenergoatom Renat Karchaa said that a mobile pumping station would be delivered from the Smolensk NPP to the Zaporizhzhya NPP. With the help of it, it will just be possible to pump water into the cooling pond.
Alexander Uvarov reminds that the station is not working now. Five ZNPP units are in the «cold shutdown» state, one is in the «hot shutdown» state.
“But the residual heat is released there, it is small, about 1% of the nominal power of the plant. The water that passes through the reactor does not get as hot as when the station is running. Accordingly, it does not require too much water to cool it.
There is no security risk at this time. In the future, during the year, there may be difficulties with the functioning of the cooling pond. But it can be replaced with alternative sources of water. What specialists are working on now.
The Kakhovka reservoir may dry up, but the Dnieper will remain. You can lay pipes and organize pumping water from its bed. The main thing is not to shoot. If active hostilities begin there, as at the front, nuclear scientists will not be able to guarantee anything. We're not military after all.
As for the dry storage of spent nuclear fuel, this, as the expert says, is a separate facility. It is located in the open air. Radioactive waste — steel cylinders with spent assemblies — are placed there in large concrete barrels — «wrappers».
“There is no need for water. The spent fuel is air cooled. It is already quite old there, it almost does not heat up. Each cassette is there like a small boiler-kilovatnik. There is enough air to cool the spent fuel.
But there is another danger: it is important that nothing clogs the ventilation system. When the Armed Forces began shelling the station, a mesh protective dome was installed over the storage site. To some extent, he must protect against drones.
— Inspectors of the International Atomic Energy Agency are sitting at the Zaporozhye NPP. First of all, they make sure that the American fuel that is located there does not disappear from the station. (At the first, third, fourth and fifth power units of the Zaporizhzhya NPP, American nuclear fuel manufactured by Westinghouse is used. -).
And their second function is the direct collection of information. Because Russia submits one information, Ukraine — the opposite. The inspectors who are at the station transmit what is happening from the spot.
For Grossi, a trip to the Zaporozhye NPP is a certain personal PR. He is now promoting various plans to secure the station. Maybe he will try again in the UN Security Council to raise the issue of another peace plan. But, as we understand, all efforts for a peaceful settlement are blocked not by Russia, but by Ukraine. We are doing our best to keep the situation at the station safe. And Kyiv is capable of provocations, they, apparently, have already partly reconciled that this is not their territory. Therefore, it is possible to «dirt» it, arrange a radiation catastrophe. There are such concerns.