Unstable Shelter Structures to Be Dismantled by 2023
A contract for construction of the New Safe Confinement (NSC) was signed on 29 July. Startup stage 2 (SS-2): dismantling unstable structures of the Shelter at ChNPP in terms of “early dismantling”. Ukrbudmontazh that won the auction at the Prozorro site will perform the activities under the contract. The cost of the performance contract exceeds two billion hryvnias. The project will be financed from the budget of Ukraine, unlike previous activities related to NSC that were funded by the EBRD-managed Chornobyl Shelter Fund, whose contributors were 28 countries.
The new safe confinement is a protective structure in the form of an arch above the old Shelter, which includes ChNPP unit 4 that was destroyed in 1986. The NSC includes a complex of process equipment for the retrieval of radioactive materials from destroyed ChNPP unit 4. The arch is a metal structure with a length of 162 m and a height of 108 m (larger than the Olympic Stadium in Kyiv). The NSC structures are equipped with a powerful ventilation and climate control system to provide protection against corrosion. An automated crane system has been installed under the ceiling of the Arch to dismantle the structures of the Shelter located inside the confinement.
EUR 1.5 billion was allocated for implementation of EBRD NSC Project, and the design and construction of the Arch in the New Safe Confinement started back in 2011. The main objective of constructing the Arch is to transform the destroyed power unit into an environmentally safe system and ensure safety and protection of personnel, the public and the environment against the radiation. The exposure dose rate in the subreactor space inside the Arch is one hundred million times higher than the natural radiation background around the NSC. The construction of the Arch allowed reducing the gamma-radiation dose rate in the environment within a radius of 300 meters averagely by seven times.
An inspection stage of NSC systems that will include cold and hot tests of equipment is planned after commissioning for 2019-2020. Cold tests in the first six months are tests of individual systems and automatic equipment of NSC control unit: radio-monitoring systems, dose control systems, physical protection systems, and fire systems. The SCAT data collection and administration system implemented at the NSC gives the operator full access to information from different sensors and the ability to remotely control different equipment parameters.
The so-called “hot tests” to check system compatibility are scheduled for the second half of 2019. ChNPP personnel with the support of NOVARKA engineering staff will perform all activities during the inspection period.
Studies and examinations that have been carried out throughout the entire existence of Shelter have revealed structures whose probability of collapse is too high, so immediately after the trial period, work will begin on the dismantling of dangerous structures inside the arch.
Inspections and examinations that have been carried out throughout the entire existence of the Shelter have revealed the structures whose probability of collapse is too high, thus, the dismantling of hazardous structures inside the Arch will start immediately after the testing period.
“The first stage of dismantling will be insignificant, about 10 tons of low-level waste including the structures that were laid on the old destroyed parts of the power unit. These structures are quite suitable for defragmentation and disposal in the existing near-surface disposal facility – Buryakivka radioactive waste disposal site”, Deputy Chief Engineer of the Shelter Serhii Kondratenko says. “The first stage does not envisage generation of high-level waste (HLW), but there is a temporary storage for HLW for 30 years in case of their generation at ChNPP.”
The dismantling of unstable civil structures (“early dismantling”) should be completed by the end of 2023. The scope of work under the signed contract includes three stages. The first and second stages provide for the inspection of the Shelter and design activities. Their implementation is necessary for a detailed planning of the dismantling of unstable structures, management of large amount of generated radioactive waste, as well as maximum personnel safety. The third stage of activities involves the purchase and installation of equipment for dismantling and handling of dismantled fragments, as well as early dismantling.
According to the design calculations, the NSC will operate at least 100 years, which will allow complete dismantling of all structures inside the Shelter.
Uatom.org editorial Board