Radioactive Hotspot at Lake Karachay, Russia
Lake Karachay, in the Chelyabinsk region, is a prime example of the consequences of human carelessness. This seemingly harmless, undrained body of water is several times more deadly than the hazards of Chornobyl. To date, 12 to 15 million curies of long-lived radionuclides such as cesium-137 and strontium-90 have accumulated in the waters of Karachay. The fog that rises over the lake contains such a dose of radiation that a huge area would be exposed to contamination in the event of a tornado or hurricane. In 2015, the lake was covered with concrete and rock slabs. However, environmentalists are sure that Karachay is a potential radioactive threat even today.
How do radionuclides affect the environment and human health?
Waste discharged into the lake is still detrimental to the environment. Once in the water, first of all, radionuclides are diluted and absorbed by the bottom and microflora. Radioactive substances are actively sorbed by the bottom and bottom sediments. Bottom sediments are the secondary sources of water contamination due to the desorption of radionuclides. Radioactive waste dumping is the main cause of radioactive contamination in Chelyabinsk Oblast. Between 1947-1996 an increase in the malignant tumor mortality rate was detected among the population affected by atmospheric emissions and liquid radioactive waste discharges, the cancer mortality rate increased by 2.0 times or more. It is known that such substances as radionuclides have the good penetrating ability. And have the property to accumulate in the tissues, internal organs, and bones. The impact of these substances on the body contributes to the destruction of the DNA structure, which becomes the cause of severe genetic diseases. Strontium-90 and cesium-137 pose the greatest danger to the human body. These radionuclides may not degrade in the human body for up to 30 years. The danger of strontium is that it accumulates mainly in the skeleton and hematopoietic organs. Cesium, in its turn, is localized in muscle tissue up to a certain value, after which radiation sickness may occur.
Contaminated water from Lake Karachay may get into other water bodies
Despite the measures taken to conserve the lake, the danger posed by it is still topical. At the moment, there is a serious threat of possible radionuclide migration, which may lead to contamination of ground and groundwater. The lens of contaminated groundwater formed under the lake is 100 meters thick and 10 square kilometers in area. And it keeps increasing at a rate of 100 meters per year, which means it could lead to a new source of radioactive substances. The nearest source for which there is a threat of contamination is the Misheliak River. Further, hazardous waste can get into the Techa River, which, in turn, flows into the Arctic Ocean. Thus, if radioactive substances sealed in the lake reach other bodies of water, the consequences will be catastrophic - from complete soil contamination to poisoning of drinking sources with cesium - 137 and strontium - 90.
Oleg Tarasov, an employee of the Mayak PA central plant laboratory, says, "It is not dangerous to be near Lake Karachay today, but economic activities on this land are still forbidden, and entry is formally prohibited: Rosatom guards are monitoring this". The level of gamma radiation near the lake is normal, but when the radioactivity indicator switches to beta mode, there is a characteristic confused crackle and the number appears on the screen - 15 decays per square centimeter per second. In one hour on 16 thousand hectares of the reserve 25 trillion particles will decay, and this only in the surface layer. Strontium-90 has been "smoldering" here for over half a century and will continue to do so for another 100 years, slowly losing activity.
Rosatom will spend 130.5 million rubles to maintain the safe condition of the filled-in lake Karachay in Ozersk. The relevant documentation was published on the government procurement website.
The B-1 pool conservation work is still ongoing and is expected to be completed in 2020. At the same time, experience and technologies tested on the conservation of Karachay are used, for example, a reservoir was cut through by dividing dams, but new solutions are also being developed. For example, an additional protective barrier is created during the conservation of water bodies. Special wells are drilled along the perimeter and under the bottom of the pools, into which gel based on liquid glass is injected under pressure. After it hardens, an impermeable layer is created under the entire storage, which "cuts off" it from the environment. In addition, a special pulp fixation technology was used to prevent its exit to the surface of the poured soil.
Scientists have said that Lake Karachay will exist as a repository for the lake's nuclear waste for hundreds or even thousands of years. Researchers say it is safer to leave Karachi's radioactive waste where it is instead of trying to move it elsewhere. New complex layers of debris and soil will be added to the lake as safety measures. In the future, the area will be covered with grass and shrubs.
Between 1978 and 1986, the lake was covered with nearly 10,000 hollow concrete blocks to prevent radioactive deposits from shifting and spreading.
Lake Karachay began to dry up. Its area shrank from 0.5 km2 in 1951 to 0.15 km2 by 1993. In 1968, after a drought in the region, winds carried 185 PBq (5 million Ci) of radioactive dust from a dried-up section of the lake, irradiating half a million people.
On August 7, 1951, it was decided to use Lake Karachay for the disposal of nuclear waste. At that time it was called "Spetsvodoy-9". Six years later, due to a failure of the cooling system, a stainless steel tank exploded at the chemical plant. The radioactive cloud, containing about 80 tons of waste, rose over the lake to a height of about 2 kilometers and covered the territory of the Chelyabinsk, Sverdlovsk, and Tyumen regions. 217 settlements were contaminated. And during the drying up of the lake, there was a threat of penetration of dangerous radioactive substances into the air.