09.06.2020

Protection of water bodies after the Chernobyl accident

Measures to protect water bodies from radionuclides

Photo and video

 

Another severe headache after the Chernobyl accident was the fear that the first rain would wash all the radioactive dust into the river, and later in the spring of 1987, due to floods, radionuclides could also get into water bodies. To prevent this from happening, a large list of countermeasures was compiled on the territory of the Chernobyl exclusion zone and beyond. For a better understanding, consider what water sources surround the Chernobyl nuclear power plant. Their use and their pollution after the accident.


So, let's begin. There are three large reservoirs around the nuclear power plant: a cooler pond, the Yanovsky Zaton, and the Pripyat River. There are several lakes, but in this context they are not important to us. The cooling pond is an artificial pond with an area of ​​22 km2 designed to remove heat from the reactor. It is connected to the Pripyat River through a dam where the onshore pumping station is installed. The pond itself has a certain aspect - the water level here is 5-6 m above the water level in the Pripyat River. For this reason, water was very actively leaking through the bulk dam, and therefore it must be replenished with an amount of water that is almost equal to the size of the reservoir. Yanovsky Zaton is a part of the old channel of the Pripyat River. On the map you can see that the river used to bend, and then it washed itself a direct path. Before the accident, the backwater was connected to the river, but after that it was separated by a bulk dam so that the radioactive bottom sediments would not fall into the river. A cargo port was built on the banks of the Yanovsky Zaton.


Pripyat River - flows 2 km from the Chernobyl nuclear power plant. Then it flows into the Dnieper River. The Dnieper itself enters the Kiev reservoir, and it is not difficult to imagine what will happen if the Pripyat river is contaminated with radionuclides. The central part of Ukraine will be left without drinking water.


After the explosion, the reactor gave birth to two traces of radioactive contamination - western and northern. Thanks to the wind that blew in two directions on April 26, 1986, north and west, the city of Pripyat found itself in the delta of these two radioactive traces. But where they passed even now, the level of radiation is high. A lot of precipitation fell precisely in the reservoir of Yanovsky Zaton and on the left bank of the Pripyat River. The pond cooler, although it was not so damaged, but radioactive water was pumped into it from underground utilities. It is the water that was used to extinguish the fire on the night of April 26. It is the water that spilled from the torn primary circuit. It is the water that was used to cool the already existing reactor.

 

Immediately after the accident, the liquidators began to work with storm sewers in the city of power engineers. The exhaust manifold going to the Pripyat River was blocked, and the drains were moved towards the cooler pond. Due to the fear of groundwater contamination with radionuclides from the reactor, it was decided to separate the industrial site from the Pripyat River by constructing a filtration wall in the soil. To do this, with the help of the Soviet milling machines SVD-500P and the Casagrande drilling machines acquired in Italy, deep but narrow trenches filled with clay were dug. The width of the trench was only 60 cm, the average depth was 30 m. In the end, the groundwater, slowly moving to the Pripyat River, rested against such a wall and could not go further.


Radionuclides that could get into the Kiev reservoir with mud were captured in various ways. At the bottom of the Dnieper and Pripyat rivers, as well as in a cooler pond, traps for bottom sediments were built, one of which was dug at the bottom by a quarry almost 1 km long. The flow of water passed through the depression, slowed down, and sediment from the radioactive sludge fell to the bottom of this depression. Over time, new deposits fell on top of the old ones and covered themselves with radioactive particles, burying them under themselves.


In 1992-93 A complex of flood dams was built on the left bank of the Pripyat River, which prevented radionuclides from entering the river. On the smaller rivers of the zone, dams filled with zeolite were built. Zeolite is a type of mineral that traps cesium and holds it tightly in its crystalline network. A set of such and other measures has led us today to the fact that radioactive particles are located under a thick layer of river sediments and are isolated from the working water flow systems. In the exclusion zone, the level of radionuclides is constantly monitored. And one could even say that today the Pripyat River is clean in terms of radiation. Compared to other water sources.