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DECOMMISSIONING TECHNOLOGIES

DECOMMISSIONING TECHNOLOGIES. MODULE “ CHARACTERIZATION OF NUCLEAR FACILITY FOR DECOMMISSIONING PURPOSES”. “ SAFE DECOMMISSIONING OF NUCLEAR POWER PLANTS ” Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”. Contents. 1.1 Physical characterization 1.2 Radiological characterization

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DECOMMISSIONING TECHNOLOGIES

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  1. DECOMMISSIONING TECHNOLOGIES MODULE“CHARACTERIZATION OF NUCLEAR FACILITY FOR DECOMMISSIONING PURPOSES” “SAFE DECOMMISSIONING OF NUCLEAR POWER PLANTS” ProjectBG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  2. Contents 1.1 Physical characterization 1.2 Radiological characterization 1.3 Mass flow Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  3. Nuclear Facilities Definition A Nuclear Facility (NF) is a civil facility and its adjoining territories, buildings and equipment in which radioactive materials are generated, treated, used, manipulated, stored or disposed at such a scale that requires reporting on safety. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  4. Nuclear Facility Decommissioning Definition Nuclear facility decommissioning is a set of administrative and technical measures undertook upon its operation is finally terminated to remove the ionizing radiation sources subject of regulatory control from the nuclear facility site. Purpose The final goal of nuclear facility decommissioning is the entire and final release of site from regulatory control with possibility of its subsequent utilization for economic and/or other purposes. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  5. Nuclear Facility Decommissioning A view of Maine Yankee site, USA, 900 MW PWR reactor prior and after its final decommissioning in 2005. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  6. Characterization of Nuclear Facilities for the Purposes of Decommissioning Definition Characterization is identification of physical, chemical and radiological characteristics of a nuclear facility and materials at their treating, processing, conditioning, storage, disposal or release from control. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  7. Characterization of Nuclear Facilities for the Purposes of Decommissioning Characterization of materials and nuclear facilities is carried out: • At commencement of decommissioning activity; • periodically during the implementation of different stages and operations related to processing, conditioning, storage, release or disposal of waste; • at final decommissioning of nuclear facilities. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  8. 1.1 Physical characterization Training objectives Trainees should be able to: • Define the parts of the nuclear fuel cycle, which generate the main RAW during decommissioning. • List the parameters, which determine the type and the quantity of the RAW. • Describe the main types of materials, defined by physical characterization of RAW. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  9. 1.1.1 Reactor construction and operation features relevant to decommissioning Activities associated with decommissioning will depend substantially on: • Fuel composition • Type of moderator • Type of cooling agent Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  10. THERMAL REACTORS Light water moderator LWR Graphite moderator Heavy water moderator HWR Heat-transfer medium -water PWR Heat-transfer medium -water CANDU-BLW Heat-transfer medium – CO2 AGR Heat-transfer medium -water PWR Heat-transfer medium -water CANDU-PHW Heat-transfer medium - helium HTGR Types and designs of nuclear reactors Basic types of reactors according to type of moderator and type of heat-transfer medium Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  11. 1.1.2 Material inventory Main construction materials subject of treatment in the course of decommissioning: • Concrete • Low-alloyed types of steel • Building ceramics • Heat-isolating and electricity-isolating materials Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  12. Material inventory Main construction materials subject of treatment in the course of decommissioning: • Alloyed types of steel • Graphite • Water • Carbon dioxide Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  13. 1.2Radiological characterization Training objectives Trainees should be able to: • Define the purposes of radiological characterization during decommissioning of nuclear facilities. • Specify materials contamination mechanism. • Describe the methods for determination the total quality of radionuclides. • Describe the radioactive investigation groups, in dependence of RAW management method during nuclear facility. • Define the purposes of radiological characterization, coming to a completion stage. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  14. 1.2.1 Purposes of radiological characterization The main objectives of a radiation outline of a nuclear facility consist in receiving reliable information on both amount and composition of the radionuclides and the distribution thereof within a nuclear facility. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  15. 1.2.2 Total available quantity and composition of the radionuclides in decommissioned NF In the course of a nuclear reactor’s operation, three categories of radionuclides are generated: • products of fission • products of activation • trans-uranium elements Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  16. Total available quantity and composition of the radionuclides in decommissioned NF After the operation of a nuclear reactor has terminated, two categories of radionuclides dominate: • products of activation • radionuclides resulting from contamination of materials Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  17. 1.2.3 Activation of the reactor materials Definition This is the process of generation of artificial radioactivity of nuclides, contained within the composition of materials of a reactor, being subject neutron radiation in the course of operation of a reactor. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  18. Activation of the reactor materials In the process activation of materials, the following products may be obtained: • steel: Fe-55, Ni-59, Co-60, Ni-63, Mo-93, Nb-94, Ag-108m; • concrete: CI-36, Ca-41, Fe-55, Ni-59, Co-60, Ni-63, Eu-152, Eu-154, Eu-155; • graphite: Ca-41, Fe-55, Ni-59, Co-60, Ni-63, Eu-152, Eu-154, Eu-155. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  19. 1.2.4 Contamination of the materials Definition This is the accumulation of products of activation resulting from physical deposition, absorption and adsorption processes onto the surface and penetration into the surface layer thereof. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  20. Contamination of the materials Internal and external surfaces of facilities within a nuclear power plant get contaminated as a result of: • Migration (advance) of activated corrosion and erosion products • Migration of fission products • Trans-uranium elements Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  21. 1.2.5. Parameters, with impact on the total available quantity and composition of radionuclides in nuclear facility under decommissioning Overall existing amount and composition of radionuclides are affected by: • Constructive characteristics and parameters of the reactor • Operational parameters and events Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  22. Parameters, with impact on the total available quantity and composition of radionuclides in nuclear facility under decommissioning Constructive parameters affecting the amount and composition of radionuclides • type of reactor, its design and rated output • chemical composition of constructive materials, impurities inclusive Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  23. Parameters, with impact on the total available quantity and composition of radionuclides in nuclear facility under decommissioning Operational parameters and events affecting the amount and composition of radionuclides • Chemical regime of reactor’s heat-transfer medium and technical servicing • Unscheduled events in the course of operation • Length of operation and period of safe storage Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  24. Methods for identifying the overall amount of radionuclides Quantitative data needed for outline of materials are produced by means of: • Methods for identifying induced activity • Methods for identifying the contamination level Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  25. Methods identifying the amount and composition of radionuclides in a nuclear facility in a process of decommissioning Identification of induced activity is performed by means of: • Accounting methods for identifying the radionuclide composition • Measuring of the nuclear facility (in-situ) • Analysis of samples of constructive materials from a nuclear facility Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  26. Methods identifying the amount and composition of radionuclides in a nuclear facility in a process of decommissioning Identification of the contamination level is performed by means of: • measuring the power of the dose taken in • measuring the contamination level • spectrometric measuring of values of relative activities of each existing radionuclide Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  27. 1.2.6 Radioactive characterizing during the process of decommissioning of NF The radiation outline in the process of decommissioning is performed: • when materials are being sorted out • prior to processing thereof • at acceptability inspection thereof • when released Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  28. Radioactive characterizing during the process of decommissioning of NF Dose meter - radiometer МКС-АТ1125 Radiometer-spectrometergamma-, beta- and neutron radiation МКС-15ЕЦ (СРП-98) Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  29. 1.2.7 Final radioactive characterizing of buildings and territories Objective A final radiation outline of both buildings and grounds aims at proving that all normative requirements have been met associated with release of a site for either limited or unlimited use in accordance with the approved plan for decommissioning. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  30. 1.3. Mass flow Training objectives Trainees should be able to: • Categorize RAW, generated during decommissioning of a nuclear facility. • Characterize non-contaminated materials and waste. • Define the factors and methods for waste minimization. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  31. 1.3.1 Waste categorization Wastes produced in the process of decommissioning of nuclear facilities are classified as: • Wastes released for disposing into the environment • Radioactive wastes By definition, radioactive wastes are considered to be the following: Radioactive materials in gas, liquid or solid form any further use of which is not planned and which are controlled by the regulating authority as radioactive wastes pursuant to the adopted national legislation. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  32. Waste Release from Control Definition Materials, received in result of activities associated with nuclear facility decommissioning, can be used and recycled without restrictions with respect of their origin, type or application sphere on the condition the specific radionuclides that are they contain are less or equal to the limits for release from control as given in the Radiation Protection REGULATION for work with radioactive sources. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  33. Waste categorization Solid radioactive wastes are classified into three categories: • category 1- transitional radioactive wastes • category 2- low and medium active radioactive wastes • category 3- high activity radioactive wastes Gas and liquid radioactive wastes are rated according to the features of eventually produced solid radioactive wastes, which are expected to be obtained after having been conditioned. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  34. 1.3.2 Waste minimization Objective Minimising wastes in the process of decommissioning pursues the following: • Reduction of burden the environment suffers • Reduction of the risk of any radiation impacts over personnel, people and environment both at present and in the future • Reducing resources needed for decommissioning • Reduction of the burden transferred to generations to come within sensible limits. Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  35. Waste minimization Minimising wastesis achievable by means of: • Classifying materials • Separation of materials • Processing of wastes Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  36. Building and structure materials and facilities Waste Freely removable for other usage Removable for industrial usage Freely removable in environment Removable for nuclear purposes usage Radioactive waste Removable as scrap Waste minimization Material Characterization Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  37. Waste minimization After separated and reprocessed, the mass of radioactive waste from the protected area of PWR reactors usually remains within 4-8% of the total mass of waste in result of decommissioning. Released after treatment Radioactive waste Full mass of protected area waste Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  38. Waste minimization Physical separation - building waste - contaminated soils Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

  39. Characterization of waste at release Installation for automatic characterization at waste release Maximum weight of one portion – up to 1000 кg Efficiency – up to 10 t/h Project BG/04/B/F/PP-166005, Program “Leonardo da Vinci”

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