DECOMMISSIONING | PU REACTORS
Right: ADE-2 provided heat and electricity to the town of Zheleznogorsk, its main function after 1993.
military-grade plutonium, I-1 was closed in 1990, EI-2 in 1991 and ADE-3 in 1992. ADE 4 and ADE 5 continued operating until 2008 as they also provided power to the site. SCC in 2010 established UDC UGR, which, in co-operation with leading research centres of the Russian Academy of Sciences, developed a unique decommissioning technology whereby all reactor cavities were filled with a mix of natural clays. The decommissioning of EI-2 was formally accepted
as completed by a government commission in 2015. It was expected that the withdrawal of the remaining four shutdown reactors at SCC would take about five years but this was extended by a year. In 2021, Rosatom signed a state contract with UDC UGR, which was tasked with dismantling and fragmentation of radiation-contaminated equipment and pipelines, as well as concreting of the ADE-5 sub-reactor space. The work was expected to take two years. In the course of the work, some 1,500 tonnes of equipment and pipelines of the first and second circuits of the ADE-4 and ADE-5 reactors were dismantled and fragmented, packaged in containers and placed on a specially prepared temporary storage site. Part of the dismantled pipelines was deactivated and returned to the national economy as scrap metal. A lot of preparatory work was carried out to concrete the sub-reactor space of the ADE-5 reactor mine: access roads for concrete trucks and concrete pump installation sites were organised, walkways and open-air openings were made in the walls and inter-story floors. During preparation of the premises for concreting, 107 tonnes of equipment and metal structures, about eight tonnes of plastic and more than two tonnes of electric cable were dismantled. When concreting the reactor cavity, heavy concrete with a waterproofing additive was used. In total, more than 2,500 cubic metres of concrete was required for the bottom of the reactor. The work was carried using the ‘on-site burial’ option developed by the All-Russia Science
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Research and Design Institute of Power Engineering Technology (VNIPIET). As well as the three uranium graphite reactors built
at SCC, three others were constructed at the Mining and Chemical Combine (MCC) in Zheleznogorsk (Krasnoyarsk). The first AD reactor was launched in 1958 at MCC. The second, ADE-1, launched in 1961, was intended also to produce electricity but never did so as the combined heat and power plant (CHPP) had not been completed. ADE-2 began operation in December 1963 after the CHPP was in place. All three reactors were built underground and used cooling water from the Yenisei River. In 1992, the AD and ADE-1 reactors at MCC were shut
down. MCC has been key to the development of new technologies and equipment for the liquidation of the nuclear legacy. Practical work began there in 2015 with the concreting of AD, and in 2020, concreting work began on ADE-1. Decommissioning includes the construction of the necessary infrastructure facilities, the extraction and processing of radioactive waste (RW), and the establishment of safety barriers around the underground part of the reactor, namely localisation of the graphite stack. The process involves laying a barrier of 8,700 cubic
metres of concrete and 37,430 cubic metres of clay material in each reactor. Additional security barriers are also put in place and there is also natural protection in a reliable rock mass as they were built underground. The volume of waste from dismantling is minimal, which means that there is no need to build new RW storage facilities. This technology was patented by MCC specialists in 2010. By contrast, decommissioning of the reactors at SCC presented more complex waste disposal problems since they were not built underground. ADE-2 was the last of Russia’s dual purpose plutonium
production reactors to be closed in 2010. It also provided heat and electricity to Zheleznogorsk and nearby areas, which was its main function after 1993. in 2021 ADE-2 sealed its legacy, becoming a nuclear industry museum. ■
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