Karachay Lake and the Mayak Production Association
For a long time, in the nuclear projects of both the USSR and the USA, the practice of radioactive waste management was to create temporary storage facilities for radioactive waste in the place of their formation - near defense enterprises and at nuclear fuel cycle facilities. Over 70 years, more than 500 million m 3 of radioactive waste has been accumulated in Russia over the territory of Russia (the regions of their location can be viewed on the website of the National Operator for RW Management ).
Most of them are liquid wastes concentrated in open reservoirs near the plants involved in the production and separation of weapons-grade plutonium. There are three such plants in Russia - Production Association Mayak (Ozersk, Chelyabinsk Region), SCC (Seversk, Tomsk Region) and the State Chemical Plant (Zheleznogorsk, Krasnoyarsk Territory). In the process of ensuring the country's nuclear shield, the issue of the final isolation of the generated RW was not a high priority. But by the 1990s, many facilities were in extremely dangerous condition and further postponement of the problems threatened with serious consequences and even disasters.
Distribution of volumes of accumulated LRW in storage reservoirs at PA Mayak, SCK and MCC. ( Source )
Almost 99% of LRW volumes are concentrated in Mayak PA in the Chelyabinsk Region. The main one is the Techen cascade of water bodies. The description of it and the problems associated with it is worthy of a separate article, and now I will focus on other, smaller, but much more dangerous objects leading in terms of accumulated activity - first of all, this is Karachay Lake and the Old Swamp at Mayak Production Center and B reservoirs -1, B-2 and B-25 at the Siberian Chemical Plant in Seversk.
PA "Mayak"
The largest industrial site of the USSR nuclear complex is the Mayak Production Association (Mayak Production Association, formerly Plant No. 817, “Forty”), in the city of Ozersk (formerly Chelyabinsk-40) in the Chelyabinsk Region. The first-born of the nuclear industry (operating since 1949), the Mayak Production Association simultaneously became the most complex fragment of the nuclear legacy associated with the initial stage of creating nuclear weapons full of haste, lack of knowledge and lack of resources.
The chemical plant included several reactors for producing weapons-grade plutonium from natural uranium, a radiochemical production for the separation of plutonium-239 from irradiated fuel, and a chemical and metallurgical department for the production of metallic plutonium.
Since the USSR was catching up with the USA in the atomic race, many decisions were copied. By analogy with the American plutonium production plant, initially in the Mayak project it was assumed that liquid radioactive waste (LRW) of medium and low specific activity would simply merge into the Techa River. True, the river in the Urals was not as full-flowing as the Columbia River at the Hanford plant in the United States, and from 1948 to 1951 the Techa was so polluted that it was decided to stop the discharges into it. After that, natural and artificial reservoirs - Lake. Kyzyltash (V-2), lake Tatysh (V-6), reservoirs V-9 (Karachay), V-17 (Old Swamp).
The layout of the reservoirs around the industrial site of PA Mayak. B-9 - Lake Karachay. ( Source )
A similar, but much less large-scale picture took shape at other plants for producing weapons-grade plutonium. Thus, it is open water bodies that have become the main stores of radioactive waste - both in activity and volume. However, they carried a huge threat, because they are in the open air, they are at risk of flooding, drying out, leakage, and the removal of activity from the water and coasts during hurricanes or tornadoes (something similar happened on Karachay in 1967, about which a little lower). It was precisely the bringing of such reservoirs into a safe or at least stable position, primarily when it was decided to comprehensively eliminate the USSR’s nuclear legacy.
Karachay (accumulated activity - 120 million Ci, volume 0.3 million m 3 )
The V-9 pond, created in 1951 on the site of the former drainless Karachay swamp at the Mayaka industrial site, is a surface liquid storage facility that is unique in terms of accumulated activity. In total, more than 500 million Ki of activity was discharged into it during operation, which is several times greater than emissions from the Chernobyl accident. By 1985, taking into account the decay, about 120 million Ci of activity were accumulated in Lake Karachay. With the start of operation as a result of discharges, the water level of the V-9 reservoir and the surface area of the water constantly increased. So, in May 1962, the water area was 51 ha. The dose rate on the shoreline of the reservoir was 50 mR / h.
Comparison of waste volumes and accumulated activity in reservoirs of Mayak Production Association. Karachay (B-9) with a minimum volume concentrated the main activity of the waste. ( Source )
In the arid spring of 1967, the shores of the reservoir were exposed, and the wind carried radioactive dust from them outside the industrial site. The pollution area was about two thousand square kilometers. This pollution (Karachaevsky trace) was added to the East-Ural trace of pollution formed from the accident almost 10 years earlier - as a result of the 1957 accident (I studied both its effects on the population and worked on my diploma and worked at the Ural Branch of the Russian Academy of Sciences) . The natural-technological accident of 1967 did not lead to serious radiation consequences for the population and the environment, but showed the potential danger of the recurrence of such situations under abnormal meteorological conditions.
An indicative pattern of the spread of radioactive contamination of the soil as a result of the activity of Mayak. A source
Liquidation of Karachay Lake
After the 1967 incident, the Government of the USSR decided to liquidate the Karachay reservoir, as well as on the conduct of measures to prevent the recurrence of such cases. During 1967-1971, work was carried out to backfill bare previously flooded areas, backfill shallow water, and to reclaim the areas around the reservoir. Until the mid-70s, work continued on liquidation of the consequences of the emergency of 1967, arrangement of the coast and experimental work on filling the water area.
Gradual liquidation of the open water area of Lake Karachay.
By the mid-1980s, the technology of filling the reservoir with rocky soil was finally worked out using special constructions - hollow concrete blocks, allowing localization of bottom sediments and the most active silts without their bulging to the surface.
The backfill technology of the lake included developed operations for installing hollow concrete blocks and backfilling with rocky soil.
“Puff pie”, which covered Karachay.
More than 200 thousand m 3 of highly active technogenic sludge and loam are localized and isolated in the Karachay reservoir, the total accumulated activity of which in the mid-1980s reached 120 million Ci, which is at least two times more than the emission from the Chernobyl accident.
View of the Mayak Production Center, tentatively 1990. Lower left - Lake Karachay with partially covered water area. Above left - Lake Kyzyltash.
In the period 1988-1990, the first stage of the Karachai closure took place - the northwestern part of the lake was filled and dividing dams were constructed, which reduce the likelihood of wave formation and wind spray of aerosols. In 1990-2000, 80% of the water backfill was carried out, which significantly reduced the dose loads near the lake. Within the framework of the federal target program “Ensuring Nuclear and Radiation Safety for 2008-2010 and for the Period Until 2015” (FTP YaRB-1) in 2008-2015, the final stage of the liquidation of the lake’s mirror was carried out. And on November 26, 2015 , the Karachay reservoir was finally bombarded.
In addition to closing the water area and waterproofing the lake to drain surface water, drainage channels were dug around it to prevent flooding. In the future, in the next 10-20 years, the reservoir will be transferred to the special radioactive waste storage facility, and then to the special radioactive waste disposal facility. The next step is the creation of a groundwater monitoring system using about 450 observation wells around the former lake. Simulation of the movement of the most mobile radionuclide - Sr-90, shows that during the complete decay of activity (the next 200-300 years) it should not lead to pollution of groundwater.
Thus, the risk of the main threats associated with the most dangerous object of the nuclear heritage of the USSR is now significantly reduced.
Old swamp (accumulated activity - 1.2 million Ci, volume - 0.4 million m 3 )
The second most accumulated activity after Karachai in the open storage of liquid medium-level waste at the Mayak industrial site is B-17 pond called the Old Swamp. The reservoir is an artificial reservoir formed by blocking the natural log with earth dams in 1952 and 1954. Its shores are reinforced with crushed stone and loam, the height of the embankment is 1.5–2 m. The reservoir is used to receive and store liquid waste from radiochemical production. Over the entire period of operation of the B-17, about 10 million m 3 of liquid radioactive waste with a total activity of about 15 million Ci were dumped into it. Since the early 1970s discharge activity was reduced by several orders of magnitude. For the past 30 years, the reservoir has been operated primarily in self-cleaning mode. The total activity of the radionuclides stored in it is about 1.2 million Ci. Most of the activity is concentrated in bottom sediments and bottom soils and is mainly due to Sr-90.
The scheme of the reservoir Old swamp
To date, preparatory work is being carried out on it for the same backfill as carried out on Lake Karachay. It is planned to complete the work by 2025 as part of the federal target program YaRB-2 .
Reservoirs of the Siberian Chemical Plant
After the launch of the Mayak software, it was decided to build additional plants for the production of nuclear weapons materials in Siberia. Now they bear the names of SCHK JSC in Seversk and GKHK in Zheleznogorsk. They have their own characteristics, but like Mayak, they included industrial reactors and radiochemical plants for producing plutonium. Therefore, their activities were also accompanied by the formation of large volumes of waste. But the experience of the Mayak was taken into account and the use of open storage reservoirs was not so large-scale. Both plants later used the practice of underground disposal of liquid radioactive waste (this is a separate story, controversial in my opinion).
In total, about 46.8 million m3 (150 Karachaev) were pumped into the underground liquid waste storage at SCC, and their total activity was 1515 million Ci (more than 10 Karachaev). Due to the collapse to the current moment, this activity fell 3-4 times. ( source )
The open storage pools of the MCC included volumes of hundreds of thousands of m 3 , however, the total activity in them did not exceed several thousand Ci, which is thousands of times lower than the activity in the open pools of Mayak and SCK. At the same time, as of 2007, more than 6.4 million m 3 of LRW with a total activity of 982 million Ci were pumped into the underground storage facilities of the Mining and Chemical Combine (“Severny Polygon”), which to date has decreased by 3-4 times.
In the initial period of work, the SCC adopted a scheme for the management of LRW using open waste storage facilities as well as at Mayak. These are the B-1, B-2 basins and the B-25 basin, which functioned until the end of the 1980s, and were second only to Karachai in terms of accumulated activity. The total activity in them (according to 1997 data) was approximately 54 million Ci (half the activity of Karachai).
Siberian Chemical Plant
The volume of the B-1 basin is 65,000 m 3 , the accumulated activity is about 30 million Ci (1/4 of Karachai), the volume of the B-2 basin is 135,000 m 3 , the activity is about 20 million Ci. The design of the pools fully took into account the hard experience of the Mayak Production Association: the necessary survey work was carried out and insulating layers were provided, which made it possible to operate them normally, without incidents and accidents. Nevertheless, in 1982, a decision was made to conserve open radwaste storage facilities in order to eliminate the potential risk of radionuclide removal from open storage facilities into the environment. In the same year, the acceptance of LRW into the pools was discontinued.
View of the currently bombarded B-2 Pool ( source )
In 2012, the conservation of the B-2 basin was completely completed at SCC. At present, the B-2 basin is a green field with an average radiation background for Tomsk.
Work on the conservation of the B-1 basin is still ongoing, their completion is expected in 2020. At the same time, experience and technologies are used, tested on the conservation of Karachai, for example, a reservoir was cut by dividing dams, but new solutions are being worked out. For example, during the conservation of water bodies an additional protective barrier is created. Special wells are drilled around 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" it from the environment. In addition, a special technology was used to fix the pulp to prevent it from reaching the surface of the poured soil.
For the conservation of LRW storage pools at the SCC, equipment was used that was protected taking into account the experience gained on Lake Karachay. ( source )
Next in line for conservation is the most dangerous pool in the SCC - B-25. LRW was supplied to it until 2015. In 2016, preparatory work for his burial began, in the fall of 2018, the decantation was pumped out. Work on the complete isolation of the B-25 from the environment will be completed in 2020. At the same time, monitoring of the condition of the facilities will be conducted for at least another 100 years.
Instead of conclusions
Open reservoirs of radioactive waste are the most capacious objects of nuclear heritage. Their appearance is caused by the importance of the main task - the creation of nuclear weapons in the USSR and the lack of liquid radioactive waste management technologies in the early 1950s. The once deferred decision on the conservation of such reservoirs led to a lot of environmental problems in the regions of their location. However, at the moment, the situation with water bodies has practically stabilized, and the most dangerous of them no longer exist in open form, which excludes possible disasters such as the one that was in 1967 or more dangerous. It is hoped that the decisions made will justify themselves and not become a problem for future generations.
Sources:
1. Decommissioning and environmental restoration in the Russian Federation: main results and plans for the future. Abramov. November 2016
2. The concept of decommissioning of surface storage reservoirs LRW FSUE "PA" MAYAK ". 2013.
3. Problems of nuclear legacy and ways to solve them. Volume 1
4. The basis of future development. The country of Rosatom.
5. Conservation of the Karachay reservoir, Mokrov, 2015.
6. How to bury radionuclides: radioactive waste disposal technologies have been revealed at SCC
7. Conservation of pools B-1 and B-25 of JSC "SKhK"
8. Atlas of pollution of the territory from the activities of PA Mayak