A program of decommissioning of MR research reactor in the Kurchatov institute started in 2008. The decommissioning work presumed a preliminary stage, which included: removal of spent fuel from near reactor storage; removal of spent fuel assemble of metal liquid loop channel from a core; identification, sorting and disposal of radioactive objects from gateway of the reactor; identification, sorting and disposal of radioactive objects from cells of HLRW storage of the Kurchatov institute for radwaste creating form the decommissioning of MR. All these works were performed by a remote controlled means with use of a remote identification methods of high radioactive objects. A distribution of activity along high radiated objects was measured by a collimated radiometer installed on the robot Brokk-90, a gamma image of the object was registered by gammavisor. Spectrum of gamma radiation was measured by a gamma locator and semiconductor detector system. For identification of a presence of uranium isotopes in the HLRW a technique, based on the registration of characteristic radiation of U, was developed. For fragmentation of high radiated objects was used a cold cutting technique and dust suppression system was applied for reduction of volume activity of aerosols in air. The management of HLRW was performed by remote controlled robots Brokk-180 and Brokk-330. They executed sorting, cutting and parking of high radiated part of contaminated equipment. The use of these techniques allowed to reduce individual and collective doses of personal performed the decommissioning. The average individual dose of the personnel was 1,9 mSv/year in 2011, and the collective dose is estimated by 0,0605 man×Sv/year. Use of the remote control machines enables reducing the number of working personal (20 men) and doses. X-ray spectrometric methods enable determination of a presence of the U in high radiated objects and special cans and separation of them for further spent fuel inspection. The sorting of radwaste enabled shipping of the LLRW and ILRW to special repositories and keeping of the HLRW for decay in the Kurchatov institute repository.
The salient features of the organization and execution of the work performed to remove radioactive wastes from and rehabilitate ten old repositories located on a special site of the Institute, which were distinguished by their design and the form and composition of the wastes contained in them, are described. The old repositories were located close to a housing development, so that special attention was devoted to the choice of technologies and technical means used for the rehabilitation. The technical approach and the sequence of operations are presented, and the technology and technical means are described. The problems of providing the proper technological equipment for this work are analyzed.The present paper describes the approach which was implemented for removing wastes and for liquidating old repositories located on a special site of the Institute, describes the technology and technical solutions deployed, and discusses the problems of providing the proper technological equipment for this work [1,2].Technological Sequence of the Operations. Waste extraction and liquidation of old repositories were performed in the following sequence:• development and coordination of the project; • opening and removing the top cover; • removing wastes from the repository, sorting the wastes, including according to the γ-ray dose rate, and loading into certified containers; • examining and liquidating the structures; • performing a final radiation survey of the foundation; • sorting and removing contaminated soil from the pit; • documenting the work performed and processing the paperwork showing that the rehabilitation work has been completed; • backfilling the pit with clean soil. All work was performed with continual dosimetric monitoring of the work zones, monitoring of the activity of the air, and monitoring the radiation conditions on the storage sites as a whole. Dust suppression was used to keep the radionuclides in air at a minimum.
as part of the unified project Reabilitatsiya, during liquidation of old storage sites for radioactive wastes at a special site of the Russian Science Center Kurchatov Institute. Methods for dust suppression of radionuclides, means for monitoring the volume activity of aerosols, and methods for organizing such monitoring are described. The concentrations of individual radionuclides in air and the wind-erosion coefficients are presented, and the monitoring results obtained are discussed.Radioactively contaminated objects and sections on the territory of the Russian Science Center Kurchatov Institute were rehabilitated in 2003-2006 [1, 2]. The main work was performed on the site of storage areas for radioactive wastes, which is located in the northwest part of the Institute's territory and adjoins a densely populated area. This made it necessary to use tested technical solutions and technologies for handling the extracted wastes, ensuring radiation safety and preventing radioactive aerosols from spreading.Since 2003, wastes have been extracted on this site and 10 old storage sites with different construction were liquidated systematically. The wastes contained in them consisted of various components of disassembled equipment of research reactors and hot chambers, laboratory equipment, construction refuse, and soil. The radioactive contamination of the wastes was mainly due to 137 Cs and 90 Sr; α emitting nuclides were present mainly in the No. 4 storage facility for high-level wastes.To prevent radioactive substances spreading beyond the boundaries of the territory, the rehabilitation work was performed using dust suppression and constantly monitoring the volume activity of aerosols in the work zones at the site of old storage areas and outside its outer perimeter.Binding and Removal of Radioactive Aerosols. When wastes are extracted and old storage facilities were liquidated, dust suppressing localizing and isolating protective coatings and decontaminating solutions were used to protect workers and the population in nearby regions from exposure to radioactive aerosols [3]. The same means but with grass seeds added were used to secure the surface soil when the pits in the storage facilities being liquidated were backfilled.
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