Currently, pursuant to the National Programme of Chornobyl NPP Decommissioning and Shelter Transformation into an Environmentally Safe System the activities in terms of ChNPP Cooling Pond decommissioning are under way.
Chornobyl NPP Cooling Pond is an artificially created process basin of intended use.
The Cooling Pond is located on the right bank of the Prypiat River 1.5 km downstream of Chernihiv-Ovruch railway bridge (click here to view the map). It was commissioned in 1976 together with the ChNPP Unit 1. By the commissioning date this water body had been constructed as a bowl filled with water only up to half of the level. Following Units 3 and 4 commissioning in 1983, the Cooling Pond bowl was extended from 12.7 km2 to 22,9 km2 (the area is equal to the area of about 3,000 football pitches).
When the ChNPP worked in a power-generating mode the Cooling Pond was removing heat from the plant’s systems and equipment. Following the shutdown of the last ChNPP power-generating unit this water body stopped to ensure its functional purpose and its existing area multiply exceeds the required area.
Commencing in 1986, the scientific organizations conducted study of Cooling Pond's condition. In 2006, their study results were summarized in “Ecological Feasibility Report on the Cooling Pond Decommissioning and Determination of Initial Data for Feasibility Study”.
Based on this report data the Chornobyl NPP management with involvement of the government regulatory authorities and research institutions of Ukraine made a decision about development of Cooling Pond decommissioning feasibility study.
In February 2007, the ChNPP Scientific and Technical Council determined the following areas:
1. Providing the systems remaining in operation with service water (civil works project). Activities to implement the working design “SSE ChNPP. Service water supply system. Service water source (service water pond) with make-up pumping station” were completed within 2012-2014.
2. Development of Feasibility Study, Environmental Impact Assessment, Radiation and Environment Monitoring Programme (non-construction project).
Crucial factors that determined the necessity to decommission the ChNPP Cooling Pond are the following:
1. Significant operational costs.
2. Risks and expenses associated with high groundwater level at the site.
In 2009, the following document was elaborated: “Requirements for contents and structure of the ChNPP the Cooling Pond decommissioning FS (Feasibility Study) and EIA (Environmental Impact Assessment) data”. In 2013, these documents were completed and in 2014 the positive conclusions of state expert review conducted by the State Nuclear Regulatory Authority of Ukraine, the Ministry of Health of Ukraine, the Ministry of Ecology of Ukraine was obtained.
The Feasibility Study contains the assessment of Cooling Pond as-is condition and review of potentially possible decommissioning scenarios, analysis of the potentially possible consequences of water body transformation after the water drawdown, forecasts, potentially possible remediation strategies, assessment of the Cooling Pond decommissioning environmental impact and the established criteria for completion of the Cooling Pond decommissioning.
Based on the review of the scenario implementation advantages and disadvantages it was decided that the most reasonable one is a scenario of step-by-step drawdown with a feasibility to carry out remediation actions within the dried areas.
For a period of the Cooling Pond drawdown a Radiation and Environment Monitoring Programme (PREM) was developed.
In the second half-year of 2014 within the Cooling Pond pre-decommissioning activities the water level in the Prypiat River lowered significantly. That’s why it was impossible to take water for the Cooling Pond make-up. In October 2014, water drawdown started in the Cooling Pond.
Within a period from the drawdown start till the Cooling Pond decommissioning activities start, additional radiation situation monitoring was arranged to ensure radiation protection of the personnel.
Following the completion of activities in terms of preparation for the Radiation and Environment Monitoring Programme in August 2016, the SNRIU issued a permit for start of the ChNPP Cooling Pond decommissioning activities and the entire set of the envisaged within this Programme actions started.
In 2016 in the course of the drawdown, the Cooling Pond started to split into separate so-called “lakes” within its former area. In summer 2017, the dried area of the Cooling Pond made 42% of its entire previous area.
Project status:
Project was completed in August 2019. The criteria of work completion in terms of Cooling Pond decommissioning were achieved; these criteria had been established by Feasibility Study.
Water level of the wetland ecosystem is determined by the precipitation level, groundwater level and natural hydrological regime of the Prypiat River.
Equivalent dose rate around the drained areas is within the range of values specified in the design documentation. Due to the wind transport of the radioactive aerosols from the drained territory the changes in the radiation situation within the areas adjacent to Cooling Pond are within the range of the aerosol activity level of the Exclusion Zone surface layer of the atmosphere and dependant on natural and man-induced factors.
Vegetation cover is formed depending on physical and chemical properties of the soils within the drained area. Here, negative erosion processes that cause deterioration of the ecological and radiation conditions of the adjacent territories are not observed. ChNPP Cooling Pond area is transformed into the wetland ecosystem without degradation of the sanitary-and-epidemiological situation and there are no prerequisites for its deterioration.
Read more here: The IAEA Report based on project results
