Half-life. Will We Cope With Radioactive Legacy?
The Prydniprovsky Chemical Plant is our Soviet legacy. When Ukraine became independent, the plant was closed and abandoned due to the termination of raw material supplies and the territory already significantly contaminated at that time was transferred to the use of dozens of state and private companies.
What plans does the state have for this territory and is there a hope for land decontamination and return to the use for the good of society?
Prydniprovsky Chemical Plant
In 1945, when American atomic bombs were dropped on Hiroshima and then on Nagasaki, Japan, a special committee for the development of nuclear weapons was established by the decision of the USSR State Defense Committee. Two years later, in 1947, an order was issued on the construction of a plant for processing uranium ores and uranium-containing blast furnace slag in Dniprodzerzhynsk (now Kamyanske), Ukraine: Prydniprovsky Chemical Plant. The plant was secret, and neither the director nor employees knew what was nuclear material and how to get it.
The international situation did not allow any delay in implementing the atomic project, therefore the construction was carried out by force: deported Germans and prisoners of three forced labor camps worked at the facility. In total, 16,000 civilian workers and prisoners were involved in the construction. They constructed the plant very quickly and qualitatively. After all, to meet the schedule of putting structures into operation, each day of work was counted for three days of the imprisonment term. Thus, the pace of construction was simply enchanting. The first facilities were put into operation in two years.
“The workers, engineering and technical employees of the lower and middle level did not know and did not have the right to know what kind of raw materials and final product they were working with. In the workshops there were constant spills and overflows of radioactive slurry, which entered the storm sewer, the level in apparatus was maintained “manually”, one of plant former workers recalls.
Former enterprise “Prydniprovsky Chemical Plant” (PChP) was one of the most powerful enterprises for processing uranium raw materials in the former USSR. From 1949 to 1991, the PChP processed uranium ores to produce yellow cake, usually in the form of triuranium octoxide (U3O8). The enterprise practiced, in particular, acid and sodium leaching technologies. Various production rooms or buildings were prepared for each stage of uranium production. They were integrated into a single complex production system.
In addition to the production of yellow cake, former PChP facilities also processed zirconium ores, produced hafnium, ion-exchange resins, mineral fertilizers and many other related components. During the production process, tailings from uranium ore processing and production waste were accumulated at the enterprise industrial site and adjacent territories in special tailing pits and storage facilities. Now there are 5 tailing pits for uranium ore processing waste, as well as several storage facilities for production waste of the former PChP. They have accumulated about 42 million tons of waste contaminated with natural radionuclides.
In 1992, the production of yellow cake at the PChP was terminated. This led to the shutdown of the enterprise uranium system, which was not decommissioned in accordance with the regulatory documents in force at that time. The consequence of this was the destruction of protective barriers and spread of materials and dust contaminated with natural radionuclides into the environment. This caused formation of zones with increased and high levels of external gamma radiation at the site.
Current radiation situation at the former PChP site allows its division into the northern and southern sectors according to radioactive contamination signs. In the northern sector, contamination levels of the territory are insignificant and allow production activities of enterprises almost with no restrictions. On a third part of the southern sector, the levels of gamma radiation equivalent dose rate (EDR) are increased from 0.4 to 30 μSv/h. In Kamyanske, background gamma radiation levels are 0.1-0.2 μSv/h (when natural background is 0,12-0,13 μSv/h).
The areas with increased gamma radiation EDR are characterized with an increased content of uranium and its derivatives in soil. In some areas, the accumulation of production residues with a high content of thorium-230 and radium-226 was revealed.
The main process waste of uranium production at the site is concentrated in tailing pits and some buildings of the former uranium production. Three tailing pits located in the site southern sector (Zakhidne, Tsentralnyi Yar and Pivdenno-Skhidne) contain several hundred thousand m3 of waste. The Pivdenno-Skhidne and Zakhidne tailing pits have a biocover system made in accordance with up-to-date requirements. The Tsentralnyi Yar tailing pit has a soil cover made more than thirty years ago, which is partially destroyed and does not meet environmental protection standards.
The Dniprovske tailing pit is covered with a phosphogypsum layer, which now prevent the entry of natural radionuclides into the environment. However, such protection cannot be used as an effective protective barrier in the future.
The Sukhachevske tailing pit (section-1) does not have an effective protective cover and is the largest potential source of environmental contamination both due to the spread of radioactive dust and due to groundwater contamination. Calculations performed using mathematical modeling showed that the spread of radioactively contaminated groundwater from all tailing pits is a slow process that does not require immediate intervention. The most urgent is the need for maintenance activities at tailing pits, whose dams are in critical condition in some places.
The territory of the Base C storage facility is also a radiation hazardous facility. It includes 5 open reinforced concrete bunkers with a total area of 8.4 ha in the south-eastern part of the storage facility, which were used to store uranium ore; open site with an area of 6 ha in the south-western part of the storage facility, which was used to store uranium ore; DP-6 disposal facility in the northern part of the Base C storage facility.
The main structures of Base C are bunkers and open areas for ore storage and railway access routes to them. The bunkers are concrete tanks shielded with soil dams with a height of 2.5-4.5 m. The north-western part of Base C includes a closed storage facility for residues of the DP-6 blast furnace located in a 2-2.5 m deep trench, size of 215×28 m.
The analysis of radioactive contamination of the main former uranium production workshops showed that a number of rooms have accumulated significant amounts of radioactive materials: in devices, containers and fragments of equipment of the former production. The equivalent dose rate of gamma radiation in the immediate vicinity of the devices and “dirty” places can be from 10 μSv/h to 100 μSv/h and more.
Indoors, high volume content of radon-222 and hazardous long-lived natural radionuclides can also be observed, which leads to high risks of internal exposure through inhalation. In addition, the site contains a significant amount of toxic substances and chemical waste of former production, which also requires safe disposal.
After the termination of PChP activities, it was restructured. This resulted in several dozens of enterprises located on plant territory, whose functioning mostly had nothing to do with any activities in nuclear energy use.
To perform remediation measures at PChP uranium facilities carried out within the State Target Environmental Programs, in 2000, the Ministry of Fuel and Energy of Ukraine established State Enterprise “Barrier”, which owned all tailing pits and storage facilities of uranium production waste, as well as some industrial buildings and other structures with radioactively contaminated equipment and piping of the former PChP.
The story with the newly established enterprise is rather sad, because for a long time its work, mildly speaking, was not effective, and the obligations were not fulfilled.
In 2003, the Barrier received the currently valid license of the State Nuclear Regulatory Inspectorate of Ukraine for processing uranium ores in terms of the termination of the operation of former PChP uranium facilities by decommissioning, closure or conversion, as well as for reconstruction, conversion and further operation of Sukhachivske tailing pit section 2. in Ukraine.
Currently, the Barrier is implementing international technical assistance project “Priority measures to mitigate the critical condition of the Prydniprovskyi chemical plant (PChP) in Kamyanske (former Dniprodzerzhynsk) in Ukraine” and is also the executor of the State Target Environmental Program for the priority measures to bring the former uranium production facilities and site of the Prydniprovskyi Chemical Plant to a safe condition for 2019-2023 that was approved by Cabinet Resolution No. 756 of 21 August 2019.
Bringing the PChP site to a safe condition
The first target State Program of Measures was developed in 2003. Its task was to reduce radiation impact on personnel of the enterprises located on the PChP territory. However, regular observations of the radiation situation and environmental contamination started only after 2005. At the same time, contaminated slurry piping was dismantled and stored at the temporary storage site; dams were repaired and protective covers of some tailing pits were restored. Several projects were developed for dismantling and decontamination of former uranium production workshops, but no practical measures were taken.
From 2009 to 2011, within the second stage of the state support program for activities at the former PChP industrial site, an inventory of civil structures condition of the most contaminated buildings was performed for the first time, drilling and assessment of tailing material condition in tailing pits was performed, characteristics of the contaminated territory, surface and ground water were preliminarily assessed. The inspection of the most contaminated industrial rooms and equipment of the former uranium workshops has started. However, the work was not completed, since after 2011, the financing situation was very difficult and in 2013, the state support was almost completely stopped.
Today, according to experts, the reason for the failures and non-fulfillment of the planned activities at the site is not only underfunding, but also the lack of a clear state policy to solve the issues of uranium production legacy in Ukraine as a whole.
Great support in solving a difficult issue of bringing the territory of the former Ukrainian industrial giant to a safe condition is provided by the European Commission and other international donors, which help to form a long-term strategy and carry out a set of preparatory activities for PChP remediation facilities.
The cooperation of Ukrainian and European experts allowed determining the priority measures to ensure site safety and to carry out further remediation activities: construct fences for all the main most contaminated areas and structures on the industrial site; implement a reliable radiation monitoring system; form effective coordination of all PChP enterprises for the period of remediation activities. Moreover, the priorities include stabilization measures to preserve integrity of the most hazardous site buildings (No. 103 and No. 104) before their dismantling starts. In addition, it is important to reconstruct the existing temporary storage site for contaminated scrap metal and equipment and to collect all small-sized residues of uranium production and radioactive waste scattered on the site.
It is also planned to establish an infrastructure to manage uranium ore processing waste, dismantle the most contaminated structures and equipment, decontaminate individual rooms, areas around structures, remove the top soil layer and replace it by clean one is probable where EDR gamma radiation levels exceed 0.5 μSv/h, collect radioactively contaminated scrap metal, pipes, residues of overpasses and equipment outside the main radioactively contaminated buildings and transfer them to temporary storage sites, etc.
Such activities can be performed within the next 10 years, subject to financial and technical assistance from the EU, as well as legislative, regulatory and organizational support by the state.
The main goal of the Program approved in 2019 by the Cabinet of Ministers is to prevent an emergency in Ukraine due to deterioration of the ecological situation in the territory of the former Prydniprovskyi Chemical Plant, conduct continuous monitoring of the radiation state of uranium ore processing facilities owned by the Barrier now, implement technical supervision and priority measures to bring them to a safe condition, as well as form safe conditions for the public in the Dnipropetrovsk region.
In the 2020 budget, 44,500,000 hryvnias were allocated for this program implementation. However, due to the COVID-19 pandemic, in April 2020, the state budget was redistributed and the Program was left without funding.
Currently, project “Risk Reduction, Control of Radioactive Contamination and Improvement of the Environmental Monitoring System on the PChP Territory” is being implemented in Kamyanske at the expense of the European Union. It provides construction of controlled zones (fencing); arrangement of a waste storage site, collection and placement of radioactively contaminated scrap metal on it, as well as pipes, residues of overpasses and equipment outside the main radioactively contaminated buildings.
The official information of the Ministry of Environmental Protection and Natural Resources of Ukraine, State Nuclear Regulatory Inspectorate of Ukraine, Kamyanske Town Council, Dnipro State Technical University and information from our own sources were used in preparing this material.
Uatom.org. Editorial Board.